THE INTERNATIONAL ACADEMY FOR PRODUCTION ENGINEERING

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CIRP ANNALS 2000

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 STC A 

Agile Assembly System by "Plug & Produce"
T. Arai (1), Y. Aiyama, Y. Maeda, J. Ota  
STC A,  49/1/2000,  P.1
Keywords: Assembly, Holonic system, Agile system
Abstract : Next generation assembly system is required to have high flexibility and agility for changes in quantity of production. For this purpose, supplement and reduction of manufacturing devices at low setup cost should be required. In this paper, we propose "plug & produce" concept. It is methodology to introduce/install a new manufacturing device quickly and easily into a manufacturing (sub-)system, and to remove it easily from the system. It is made by analogy of "plug & play" concept in computer world. Since our "plug & produce" works in real world, calibration among devices is of importance. We discuss procedures from the viewpoint of agility; set up interface between devices and control system, calibration among devices and timing coordination.
Non-contact handling using high-intensity ultrasonics
G. Reinhart (2), J. Hoeppner  
STC A,  49/1/2000,  P.5
Keywords: Non-Contact Handling, Acoustic Positioning, Ultrasonic Gripper
Abstract : Increasing requirements placed on the handling of parts in microsystem technology and semiconductor fabrication necessitate the development of new innovative approaches for handling and transporting miniaturised, fragile and surface-sensitive components. This is where the technology of high-intensity ultrasonics offers itself as a suitable approach for non-contact handling of parts and substrates. While microparts can be positioned and manipulated within a standing wave pattern, the application of the principle of near field levitation makes it possible to design non-tactile grippers and transfer systems as methods particularly suitable to ensure the material flow in microsystem and semiconductor manufacturing and wafer processing. The piezo-electric sound transducers used in this process, apart from the non-contact application of forces, are designed to monitor these forces by measuring the power input of the vibrators.
New Feeding System for High Speed Assembly of Small Parts
P.B. Petrovic (2), V.R. Milacic (1), G.M. Dzelatovic  
STC A,  49/1/2000,  P.9
Keywords: Automatic assembly, Part handling system, Axiomatic design
Abstract : This paper presents the new general purpose automatic feeding system, developed for high speed assembly of small parts. The new design is a result of the consequently applied Axiomatic Design Theory. The feeding system is functionally uncoupled, leading to minimisation of problems in system tuning, parts damage and noise emission. Moreover, the new design gives the possibility for simple introduction of additional functional modules such as: sensorized modules for non-geometrical orientation of parts, or active orientation modules for improving efficiency of the system. The proposed system is verified by the prototype developed for feeding screws on pneumatic screwdriving station.
A method for sequencing the disassembly of products
H. Kaebernick (2), B. O'Shea, S. Grewal (2)  
STC A,  49/1/2000,  P.13
Keywords: Disassembly, Sequencing, Task Allocation
Abstract : In this paper a method for the creation of optimum disassembly sequences is described. The method takes a graphical representation of the product's structure and maps component disassembly cost and recovery value, along with disassembly equipment requirements to the components within the product. From this data the product is broken down into sub-units of sequentially disassemblable component cells. All possible parallel disassembly options are then displayed and the disassembly sequence is optimised against the equipment available for the disassembly process.

 STC C 

Ultra-precision cutting for ZKN7 glass
F.Z. Fang, L.J. Chen (2)  
STC C,  49/1/2000,  P.17
Keywords: Cutting, Brittle material, Surface finishing
Abstract : ZKN7 is a silicate glass with a high softening point of 721 degrees Celsius and a Knoop Hardness of 530 kg/mm2. With this material, there is an immense need to obtain nanometric surface finish owing to the advantage of improved performance of the components. However, the mere use of ultra-precision machining for this brittle material would not yield mirror surface finish. Therefore, experiments were conducted for the first time using diamond cutting for machining ZKN7 glass. Based on the experimental work, a new strategy was proposed for obtaining nanometric surface finish and the cutting mechanism was studied in detail, where the surface roughness of Ra = 14.5 nm was achieved. The sharpness of the cutting tools is a major factor to influence the surface finish of workpieces. Thus, a new method for checking the sharpness, namely tool edge radius was introduced in this study, which is called Confocal Laser Scanning Microscopy (CLSM). Also, in this paper an alternative approach was recommended for the fracture toughness measurement of brittle materials.
Suppression of tool wear in diamond turning of copper under reduced oxygen atmosphere
S. Shimada (2), T. Inamura, M. Higuchi, H. Tanaka, N. Ikawa (1)  
STC C,  49/1/2000,  P.21
Keywords: Cutting, Diamond turning, Tool wear suppression
Abstract : Tool wear mechanism in diamond turning of copper is investigated by thermodynamics analysis and an erosion test which simulates the wear process. The mechanism involves the removal of carbon atoms on tool face due to oxidization accompanied with deoxidization of copper oxide, which is formed with the atmospheric oxygen, by diamond. Based on the results of the analysis and test, diamond turning of copper under a reduced oxygen atmosphere is proposed. The cutting test results in the decrease of tool wear to less than a few percent of that measured under the normal one. These results suggest that the use of the reduced oxygen atmosphere will be an effective way to supress excessive tool wear in diamond turning of copper when large quantity production is essential requirement.
Predictive models for machining with multi-edge form tools based on a generalised cutting approach
E.J.Armarego (1), A.B. Herath  
STC C,  49/1/2000,  P.25
Keywords: Cutting, Form Tool Operations, Predictive Force Modelling
Abstract : In this paper predictive models for the force components, chip flow and power in single and multi pass turning of helical vee grooves as well as single pass turning at high and low feed to depth of cut ratios with triangular profiled form tools have been developed. The predictive models are based on generalised mechanics of cutting analyses for machining with single and multi-edge form tools together with a ?generic? database of basic cutting quantities and edge force coefficients found from ?classical? orthogonal cutting tests. The mathematical models allow for all the tool and cut geometrical variables as well as the cutting speed while the database allows for the tool-workpiece material effects and tool coatings. The models have been experimentally verified over a wide range of operation variables and their predictive capabilities estimated in terms of the percentage deviations between the measured and predicted forces. The developed models are capable of predicting the tangential, feed and radial forces within a deviation of 10 %37; ?on average?. This investigation has enabled the ?Unified Mechanics of Cutting Approach? to performance prediction to be extended to include machining with form tools.
Improving productivity and part quality in milling of titanium based impellers by chatter suppresion and force control
E. Budak   / L. Kops (1)
STC C,  49/1/2000,  P.31
Keywords: Milling, Chatter, Adaptive Force Control
Abstract : Large axial depth of cuts used in the flank milling of gas turbine impellers result in severe chatter vibrations and high cutting forces. Variable pitch cutters can be used to suppress chatter in milling of these extremely flexible components. A novel design method for variable pitch cutters is presented. Cutting forces in 5-axis milling cycles continuously vary due to changes in tool orientation and depth of cut. Adaptive force control or milling force models can be used to keep the forces at a constant level which reduces cycle times significantly. Benefits of both approaches are demonstrated through examples.
The stability of low radial immersion
M.A. Davies (2), J.R. Pratt, B.S. Dutterer, T.J. Burns  
STC C,  49/1/2000,  P.37
Keywords: High Speed Milling, Stability, Radial Depth
Abstract : Traditional regenerative stability theory predicts a set of spindle speeds with locally optimum stability at integer fractions of the natural frequency of the most flexible mode of the system. The assumptions of this theory become invalid for highly interrupted machining, where the ratio of time spent cutting to not cutting (denoted rho) is small. This paper proposes a new stability theory for interrupted machining that predicts a doubling in the number of optimally stable speeds as the value of rho becomes small. The predictions are verified against experiment and numerical simulation.
High speed ball nose end milling of Inconel 718
E.G. Ng, D.W. Lee, A.R.C. Sharman, R.C. Dewes, D.K. Aspinwall   / J. Vigneau (1)
STC C,  49/1/2000,  P.41
Keywords: High speed machining, Inconel 718, cutting environment, tool coating
Abstract : High speed machining (HSM) using ball nose end mills, is attracting interest in the aerospace industry for the machining of complex 3D aerofoil surfaces in nickel based superalloys and titanium alloys. The paper initially reviews published data detailing the effect of cutter/workpiece orientation (¡?BfN and ¡?Bf), tool coatings/materials and cutting environments (spray mist, high pressure flood, etc.) on tool performance. Experimental work is subsequently detailed aimed at determining the effect of cutter orientation, tool coating and cutting environment on tool life, tool wear mechanisms, cutting forces, chip formation, cutting temperature and workpiece surface roughness, when high speed ball nose end milling Inconel 718¢â. A horizontal downwards cutter orientation with high pressure cutting fluid (70 bar, 26 l/min) provided the best tool life with cut lengths of ~15 m which were twice as long as when employing a dry cutting environment. Temperature measurements from the implanted thermocouple technique, indicated that high pressure cutting fluid application substantially reduced workpiece temperature from 320¢ªC when cutting dry, to 175¢ªC.
Identification of effective zones for high pressure coolant in milling
M. Rahman (2), A.S. Kumar, M.R. Choudhury  
STC C,  49/1/2000,  P.47
Keywords: High pressure coolant, Tool wear, Cutting force
Abstract : Effective zones of high pressure coolant have been identified in milling performing a wide range of machining operations on ASSAB 718 mould steel using un-coated tungsten carbide inserts. The effects of high pressure coolant are evaluated in terms of machining parameters by comparing with those of conventional coolant and dry cut. Chipping and catastrophic failure are the dominant factors of insert rejection for dry cut and conventional coolant, whereas progressive flank wear is observed for high pressure coolant within its effective zones at lower depth of cut, lower feed rate and higher cutting speed. It is found that the cutting force is reduced, surface finish is improved, chip width is narrowed and cooling effect is better with the use of high pressure coolant.
Analysis of cutting fluid aerosol generation for environmentally responsible machining
Z. Chen, A. Atmadi, D.A. Stephenson, S.Y. Liang   / P.K. Venuvinod (1)
STC C,  49/1/2000,  P.53
Keywords: Cutting Fluid, Environmental, Predictive Modeling
Abstract : An analytical model is presented for the prediction of aerosol generation from the use of metal cutting fluids. The model examines the primary mechanisms of spin-off, splash, and diffusion to formulate the airborne particulate concentration and size distribution in quantitative terms of fluid properties, fluid application conditions, cutting process parameters, as well as machining time. Experiments were performed with the use of light scattering particle measurement to calibrate and verify the analytical models. The predictive models developed herein can serve as a basis for the control and minimization of the use of cutting fluids in the interest of environmental consciousness.
Comparison of methods for cutting fluid performance testing
L. De Chiffre (1), W. Belluco  
STC C,  49/1/2000,  P.57
Keywords: Machining, Cutting fluid, Performance testing
Abstract : A comparison is made of those methods for cutting fluid performance evaluation that involve metal cutting operations under controlled laboratory conditions. An analysis in terms of repeatability, resolution and cost is carried out, based on results from comprehensive experimental investigations in turning, drilling, milling, reaming, and tapping. Different workpiece materials, such as carbon steels, stainless steels, and aluminium alloys, as well as different kinds of cutting fluids, including water based products, straight mineral oils, and vegetable oil based formulations, are considered. The analysis is carried out grouping the tests according to the main measurand: tool life, cutting forces, and workpiece surface finish. The ratio /, where  is the standard deviation of measurements and  the range of variability of test results, was introduced to express the relative resolution of a test, and a cost model was developed. It was concluded from the analysis that tool life tests are connected with limited repeatibility (=10-50%37;) and resolution (/ ranging from 0.25-0.75), with costs ranging from 1000? to 2000?. Tests based on cutting forces are connected with a much better repeatibility and resolution, featuring values for  in the range 0.5-6%37; and a / ratio of approximately 0.2, with test costs of about 500. Surface finish tests feature repeatabilities of approximately 50%37; and resolutions of 0.3-0.4, with costs of approximately 1000?.
An experimental investigation of air quality in wet and dry turning
J.W. Sutherland, V.N. Kulur, N.C. King   / B.F. Von Turkovich (1)
STC C,  49/1/2000,  P.61
Keywords: Air Quality, Machining, Cutting Fluid
Abstract : Environmental and industrial hygiene issues are receiving increased attention by manufacturers. As a result a number of important issues have arisen, one of which is air quality and its effect on worker health. This paper presents the results of experiments focused on characterizing the aerosol emissions associated with wet and dry turning. Air quality is characterized by measuring the mass concentration and particle size distribution of the dust and mist created during a set of machining experiments. The relative importance of vaporization/condensation and atomization as mist generating mechanisms is also explored.
Interpretation of PVD coated inserts wear phenomena in turning
K.-D. Bouzakis (1), N. Michailidis, N. Vidakis, G. Erkens  
STC C,  49/1/2000,  P.65
Keywords: PVD coatings, HM inserts, Turning
Abstract : PVD coatings attribute excellent cutting performance to cemented carbide inserts. Based on the continuous chip formation, coatings experience distinct failure mechanisms in turning. To clarify the influencing parameters on coating wear resistance release, turning experiments with a TiAlN derived coating, deposited on cemented carbide inserts, have been carried out. The experimental results are explained through analytical ones obtained by means of FEM calculations, indicating a coating static decohesion at low cutting speeds, owing to its overstressing. At higher cutting speeds, a coating adhesion improvement was found out, whereas a further cutting speed increasing reveals the dominant influence of tribomechanical abrasive phenomena and adhesion release on the coating behavior. As the overall cutting length increases, a progressive local coating decomposition occurs. Herewith chip formation alterations are induced, such as a gradual increase of the chip compression ratio and a consequent reduction of the tool contact stresses.

 STC Dn 

A methodology for collaborative design process and conflict analysis
S.C.Y. Lu (2), J. Cai, W. Burkett, F. Udwadia  
STC Dn,  49/1/2000,  P.69
Keywords: Process, Engineering System, Co-operative Design
Abstract : The process of collaborative engineering design is relatively complex, and often results in various conflicts due to technical and social factors. Therefore, to understand the relationships between design process and design conflict is critical to improve the collaborative design productivity. This paper provides a methodology for analyzing collaborative design process and conflict based on a new Socio-Technical design framework. The methodology can identify the interdependencies among design tasks, and manipulate the evolution of various design perspectives to facilitate the management of design conflicts. An initial computer implementation of this methodology is presented and its features are discussed.
Coordination between product and process deifinitions in a concurrent engineering environment
S. Tichkiewitch (2), D. Brissaud  
STC Dn,  49/1/2000,  P.75
Keywords: Design, Product model, Process model
Abstract : This paper deals with the necessary co-ordination among the designing team members in a concurrent engineering environment. It focuses on models and methods for co-ordination based on a co-operative work. The classical activity-based approach must be coupled with a professional-based approach to have a co-ordination system close to industrial practices. Then a first attempt to cluster the co-ordination methods of the literature in a specific typology is discussed.
Optimal combined usage of formulas, fuzzy-logic and neural networks for calculation in product development
F.-L. Krause (1), A. Carl  
STC Dn,  49/1/2000,  P.79
Keywords: knowledge modeling; product development; neural network
Abstract : This paper describes the optimal representation and application of calculation-related knowledge in product development. Classification into verified, uncertain and empirical knowledge supports the choice of suitable representation methods: formulas, fuzzy logic and neural networks. Potential use of neural networks will also be described in further detail. Joint application of different knowledge types is achieved by means of a hybrid simulation model combining the advantages of different representation methods to provide the best possible supply of knowledge. The modularization of knowledge components, which significantly facilitates further use, and their representation according to the quality of information are significant potential applications of the hybrid simulation model.
Design for bulk recycling: analysis of materials separation
W.A. Knight (2), M. Sodhi  
STC Dn,  49/1/2000,  P.83
Keywords: Life Cycle Design, Product Analysis, Material Selection.
Abstract : Increased interest in the life cycle design of products has resulted in emphasis on the disassembly and recovery of materials at product end-of-life. For many products the cost of disassembly will outweigh the value of any materials recovered and such products will be processed by bulk recycling involving shredding and mechanical material separation. The efficiency of bulk recycling is influenced by a number of factors including the selection of materials during product design. This paper deals with the analysis of materials separation, which determines the least cost or maximum profit level of materials separation. This can be used for the evaluation of product designs for efficient bulk recycling and the combination of disassembly and bulk recycling.
Waste-stream analysis of independent and original equipment automotive remanufacturers to support design for remanufacture
M. Sherwood, L.H. Shu   / R.G. Fenton (1)
STC Dn,  49/1/2000,  P.87
Keywords: Design, Remanufacture, Waste stream
Abstract : Waste streams of three automotive remanufacturers were analyzed to determine factors that impede the reuse of parts. The eventual goal of this work is to enable the design of products that facilitate reuse. Remanufacturers disassemble and clean used products, replace or repair failed parts, and reassemble products in a production-batch process. Although design that facilitates any of these steps benefits remanufacture, the essential goal of remanufacture is to reuse parts. Parts not reused enter the waste stream. Worn parts that could not be further refurbished were found to constitute the highest contribution to the waste streams of the remanufacturers studied.
The virtual maintenance system: a computer-based support tool for robust design, product monitoring, fault diagnosis and maintenance planning
F.J.A.M. Van Houten (1), F. Kimura (1)  
STC Dn,  49/1/2000,  P.91
Keywords: Computer Aided Design, Maintenance, Simulation
Abstract : Digital (geometric) product models can be used for maintainability analysis and maintenance planning. It is not feasible to build digital product models for maintenance purposes only, but if a digital product model is available, it may be used to support many maintenance-related engineering tasks. Examples are: Product life cycle simulation (the influence of product use on product performance), deterioration analysis (the influence of wear on product function), Failure Mode Effect Analysis (FMEA), product model-based monitoring (to relate sensor signals to failure modes), failure diagnosis, disassemblability analysis (for repair and replacement), maintenance ergonomic analysis (to ease the work of maintenance personnel), etc. At the University of Tokyo, a Virtual Maintenance System has been developed to support the activities mentioned above. The system makes it possible to relate predicted product behaviour and specific signals, which can be detected by sensors and can be used to avoid catastrophic failure. This creates better possibilities for condition-based maintenance and Design for Maintainability. Future CAD systems should support product life cycle issues right from the start of the design process.
Axiomatic design of software systems
N.P. Suh (1), S.H. Do  
STC Dn,  49/1/2000,  P.95
Keywords: software, axiomatic, design
Abstract : Software is playing an increasingly important role in manufacturing. Many manufacturing firms have problems with software development. Software engineering is still labor- intensive and prone to errors. Industrial firms are under pressure to shorten the lead-time required in introducing new software, increase the reliability of their software, and increase their market share. Software must be designed correctly from the beginning to end. With this end in mind, axiomatic design theory has been applied to software design. This paper presents how the combination of axiomatic design has been combined with the object-oriented programming method to create a large software system.
Design of a microactuator array against the coupled nature of micro-electromechanical systems (MEMS) processes
S.G. Kim (2), M.K.Koo  
STC Dn,  49/1/2000,  P.101
Keywords: micro-actuator, micro-machining, axiomatic design
Abstract : Piezoelectric micromirror array is developed based on microelectromechanical systems (MEMS) technology. The inherent coupled nature of the thin-film processes generates many problems unless the design of the microactuator is properly uncoupled or decoupled among the functional domain, the physical domain and the process domain. The design of the first generation microactuator array was highly coupled between the functional domain and the physical domain, and could not be implemented successfully over 24 months of fabrication effort. Once the design has been uncoupled, successful arrays could be fabricated within 6 months and could be upgraded easily. The brightest projection display system has been developed with the microactuator arrays.
Product and assembly design for a fibre reinforced plastic track wheel
S. Lange, H. Schmidt, G. Seliger (2)  
STC Dn,  49/1/2000,  P.105
Keywords: FRP wheel, product design, assembly process
Abstract : The design of silent and lightweight components with minimised life cycle costs are the main requirements for modern railroad systems. The track wheel as the interface between railroad and vehicle offers a high potential for optimisation. The application of fibre reinforced plastic (frp) in the wheel body simultaneously minimises sound emissions and reduces wear effects by lowering unsprung wheel masses. This paper presents a new modular track wheel design with frp discs in combination with steel flanges. Several design and assembly alternatives have been analysed and an optimised solution based on numerical simulation and new fibre preform technologies has been selected. With regard to the high security requirements on track wheels, design specific quality assurance test methods and maintenance plans and operations have been developed.
Heterogeneous solid modeling for layered manufacturing
D. Dutta, M. Shpitalni (1)  
STC Dn,  49/1/2000,  P.109
Keywords: images/cirpfichiers/annals/ CAD/CAM, Geometric Modeling, Rapid Prototyping
Abstract : We consider layered manufacturing as a fabrication technique for metallic, functional parts. While commercial machines still do not support metals, several research systems are already in existence in universities and research laboratories. Such systems can create multi-material parts and can vary material composition within the layer. A key enabling technology for the automation of such layered manufacturing systems is heterogeneous solid modeling. Current CAD systems do not provide the capability to deal explicitly with material heterogeneity. We provide an overview of this new field, propose a method for modeling and representing material in addition to geometry and topology, and discuss some related research.
Visibility theory applied to automatic control of 3D complex parts using plane laser sensors
A. Bernard (2), M. Veron (1)  
STC Dn,  49/1/2000,  P.113
Keywords: Reverse engineering, Scanning, Inspection, Optimisation
Abstract : Rapid product development is today widely developped in design and industrialisation stages of the development of a new product. Rapid tooling and manufacturing technologies allow to produce rapidly very complicated parts, from a numerical model. The model is to be able to obtain a rapid validation of the technological processes in order to verify the conformity of the part compared to the numerical reference model. So, the goal is to control efficiently parts that have most often a very complex geometry. Based on our experience on laser [Veron, 99], our paper proposes a solution in order to improve the efficiency of the geometric and dimensionnal control process [Sidot, 99]. The proposed solution is an application and adaptation of the visibility theory to the automatic determination of the scanning strategies for the digitization of 3D complex parts, using a plane laser sensor. This has been applied in different industrial fields lidke foundry, plastic injection, etc...

 STC E 

Development of multi-spark EDM
M. Kunieda (2), H. Mutoh  
STC E,  49/1/2000,  P.119
Keywords: Die-sinking EDM, Multi-spark, Discharge point
Abstract : This paper describes the Multi-spark EDM method which was newly developed to obtain higher removal rates and lower energy consumption compared with conventional EDM. The basic circuit of Multi-spark EDM comprises a pulse generator, a first tool electrode, the workpiece, and a second tool electrode that are connected serially in the order as listed here. Accordingly, for each generator pulse, one discharge occurs in the gap between the first tool electrode and the workpiece, and another discharge occurs at the same time in the gap between the other tool electrode and the workpiece. To balance the removal rates in both gaps, the polarity of the pulse generator is changed adaptively to equalize the gap voltages measured at both gaps.
A new process of additive and removal machining by EDM with a thin electrocode
N. Mohri (2), H. Takezawa, K. Furutani, Y. Ito, T. Sata (1)  
STC E,  49/1/2000,  P.123
Keywords: Electrical discharge machining, Electrode, Surface
Abstract : Removal machining or additive machining can be performed in electrical discharge machining (EDM), under proper machining conditions. In this paper, rapid accretion of a thin electrode material and rapid manufacturing of a thin electrode are proposed. The material of a thin electrode can be accreted onto a work piece in an instant through an explosion process. A needle of 35mm in diameter and 300mm length can be made under a single discharge pulse instantaneously from a tungsten wire of 125mm in diameter. Micro drilling and rapid implantation of electrode material onto a work piece can be performed. The machining mechanisms are discussed taking into consideration the thermal properties of the thin electrode and the machining conditions.
3D Micro-EDM using CAD/CAM
K.P. Rajurkar (2), Z.Y. Yu  
STC E,  49/1/2000,  P.127
Keywords: EDM, Micro-machining, Wear
Abstract : It is necessary to integrate CAD/CAM systems with micro-EDM to generate tool paths when simple shaped tools are used to machine three-dimensional (3D) micro parts. Currently available CAD/CAM systems cannot be directly used because of the continuous tool electrode wear during machining. This paper proposes an approach to integrate CAD/CAM systems with micro-EDM while accounting for tool wear using a recently developed uniform wear method. This approach is verified by successfully generating very complex 3D micro cavities. Additionally, the feasibility of the approach is illustrated by generating complex macro cavities using conventional EDM with single simple shaped electrodes.
A quality evaluation method for laser welding of Al alloys through neural networks
L.M. Galantucci (2), L. Tricarico, R. Spina  
STC E,  49/1/2000,  P.131
Keywords: Welding, Laser, Quality
Abstract : The authors propose an integrated methodology to evaluate the quality of Aluminium alloy butt joints welded by laser. The method, starting from the observation of the results of an experimental investigation, focuses on the definition of a omni-comprehensive quality index for welded joints. This index is obtained using the limits of imperfections for the quality level defined by the ISO 13919 standard. A neural network system has been developed to classify and evaluate the different welds. The experiments were performed on Al 6110 T61 alloy, welded using a 6 kW CO2 laser beam on plane sheets with a continuous butt joint. Computerised image processing has been used to recognise and to quantify the imperfections in the weld cross section. The defects have been divided into groups, as required by the EN 26520 standard. Due to the huge number of measurements required to imperfections, the artificial neural network very greatly simplifies the relationship between the quality index and the main process parameters. The neural network was trained with a set of data containing very different welding parameter choices. Application of the system aids process parameter selection that has proved to be in good agreement with quality levels measured on experimental welds made under the same conditions. Inverse calculation of power density for laser surface treatment /G.R.B.E. Römer, J. Meijer (2)/ STC E, 49/1/2000, p. 135 Key words: Laser, Surface treatment, Heat transfer Laser beam surface treatment requires a well defined temperature profile. In this paper an analytic method is presented to solve the inverse problem of heat conduction in solids, based on the 2-dimensional Fourier transform. As a result, the required power density profile of the laser beam can be calculated for any desired temperature field. Methods to reduce the effects of errors introduced by calculations on a finite grid and physically impossible temperature gradients are addressed. A software utility, which interactively calculates the power density distribution for a user defined temperature field, will be presented. Results are given for the laser beam hardening process.
A new method for three dimensional excimer laser micromachining, Hole Area Modulation (HAM)
T. Masuzawa (1), J. Olde-Benneker, J.J.C. Eindhoven  
STC E,  49/1/2000,  P.139
Keywords: LBM, excimer laser, micromachining
Abstract : A new excimer laser system configuration for three dimensional (3D) micromachining, called Hole Area Modulation (HAM) method, is proposed and the feasibility of the system is experimentally confirmed. In this method, information on the depth of machining is converted to the sizes of small holes in the mask. The machining is carried out with a simple 2D movement of the workpiece. Since the total area of the targeted cavity is machined simultaneously, a 2.5-µm-deep, 800µm x 1600µm 3D cavity was machined in about 5s. This method can be applied for machining various kinds of microcavities in various materials. Owing to the short machining time, the fabrication of a mold with repeated shapes, for example a mold for a microlens array, will be a good application in the future.
Synthesis and analysis of a digital droplet-size control system
J.H. Chun (2), J.C. Rocha, J.H. Oh  
STC E,  49/1/2000,  P.143
Keywords: Metal Powder, Digital Feedback Control System, On-line Monitoring
Abstract : This paper presents a digital control system for the production of uniformly sized molten metal droplets using laminar jet break-up caused by Rayleigh¡¯s instability. First, the control plant is represented as an algebraic affine nonlinear system with disturbances. To obtain an on-line droplet diameter measurement, an imaging system was employed and an image processing algorithm was developed. Then, a digital integral controller was synthesized, and explicit stability conditions were derived and incorporated in the design of the controller. The proposed control system is shown to provide uniformly sized droplets of molten metals with the melting temperatures of up to 1200 degrees C., with less than 3%37; variation over the diameter range of 100-800 microns, despite the existence of disturbances.
An experimental and analytical study of ice part fabrication with rapid freeze prototyping
M.C. Leu (2), W. Zhang, G. Sui  
STC E,  49/1/2000,  P.147
Keywords: Rapid Prototyping, Freezing, Ice Part
Abstract : This paper will present the results of study on a novel, environmentally conscious solid freeform fabrication process called Rapid Freeze Prototyping. This process builds a three-dimensional ice part by depositing and rapidly freezing water according to its CAD model in a layer-by-layer manner. It provides a means to build a solid part with the potential of better performance than other rapid prototyping processes, including use of cheap and clean material, potential to build accurate ice parts with excellent surface finish, and ease of building color and transparent parts. An experimental system with a low-temperature building environment, a three-axis positioning mechanism, a water feeding and extruding subsystem, and control hardware and software has been built. Experiments conducted on this system demonstrate the feasibility of making three-dimensional ice parts. A heat transfer analysis helps understand the freezing process and provides useful information to the selection of building parameters.
Precision ECM by process characteristic modelling
A.K.M. De Silva, H.S.J. Altena, J.A. McGeough (1)  
STC E,  49/1/2000,  P.151
Keywords: ECM, precision, modelling
Abstract : Electrochemical machining (ECM), which is not normally considered as a precision process, is used to achieve accuracy better than 5 m and surface finish 0.03 m Ra by using pulsed power of relatively short durations (1 - 10 ms) and narrow inter-electrode gaps (10 - 50 m). The narrow gaps, however, make the control and prediction of the process much more complex than normal ECM. An empirical model is developed based on the characteristic relationships of ECM to predict and optimise the process parameters such as dissolution efficiency, current density, electrolyte concentration and pulse duration, in narrow gaps. This model is then used to facilitate new applications of high precision ECM without recourse to the lengthy trial-and-error approach, by predicting selective dissolution of the workpiece and tool design.
Development of electroformed diamond tool with fine grains coated by metal oxide film
T. Semba, H. Sato (1)  
STC E,  49/1/2000,  P.157
Keywords: High speed electroforming, Fine grains, Modified grain surface
Abstract : A high-speed electroforming technique that can produce an electroformed tool efficiently is developed to overcome a disadvantage of the conventional sediment codeposition technique that an extremely long time is required for the production of thick composite coatings. Aggregated diamond grain particles sedimented on a tool surface are agitated at a low speed with a rubber blade to increase the electric conductivity and to disperse the grain particles uniformly on the tool body. The time required to produce a thick nickel-diamond coating of 1 mm thickness is successfully reduced to 2.5 hours from the minimum of 81 hours required by the conventional sediment codeposition technique.

 STC F 

Fundamental study of dry metal forming with coated tools
K. Osakada (1), R. Matsumoto  
STC F,  49/1/2000,  P.161
Keywords: Forming, Friction, Tool
Abstract : To realize dry metal forming processes without lubrication, the frictional behavior of some working metals sliding over tool surfaces without lubricant is studied. To measure the coefficient of friction in the high friction range by the ring compression test, an optimum shape of ring specimen is proposed. The work-metals are Al, Cu and carbon steel, and the cemented carbide tools are coated with TiC, TiN, TiCN, TiAlN and DLC (diamond like carbon). It is found that DLC is effective to reduce the friction with aluminum under dry condition. The oxide layer formed on the steel surface raises the friction to a great extent. The coefficient of friction is sensitively affected by the roughness of the tool surface irrespective of the coated material.
Lubricant behavior trapped within pockets on workpiece surface in lubricated upsetting by means of direct fluorescence observation technique
A. Azushima (2), T. Tanaka  
STC F,  49/1/2000,  P.165
Keywords: Upsetting, Tribology, Direct measurement
Abstract : It is important to understand the trapping behavior of liquid lubricant within pockets on the workpiece surface at the tool-workpiece interface during metal forming in order to characterize and qualify the surface structure of workpiece. Therefore, it is tried to measure the lubricant behavior trapped within pockets in lubricated upsetting. In order to measure the lubricant behavior, a direct fluorescence observation technique which consists of a direct observation method and a conventional fluorescence method. The lubricant behavior and the pocket geometry are measured by means of the technique. The volume of the oil pocket decreases with increasing reduction in height. From these results, it is confirmed that the lubricant trapped within the pockets is permeated into the real contact area. The volume change of the oil pocket depends on the position on the end surface of workpiece and the geometry of cylindrical specimen.
Prediction of dimensional difference of product from tool in cold backward extrusion
T. Ishikawa, N. Yukawa, Y. Yoshida, H. Kim, Y. Tozawa (1)  
STC F,  49/1/2000,  P.169
Keywords: Cold forging, Dimensional accuracy, FEM
Abstract : The effects of forming stresses and generated heat on the dimensional change of punch, die and work piece during forging are discussed analytically. The change in outer and inner diameter of backward extruded cup is investigated numerically using thermo-elastic-plastic FEM code according to the actual forging sequence, namely extruding, unloading of punch force, and ejection and air cooling of extruded cup. The calculated results of outer and inner diameters of product are in good agreement with the experimental results. The simulation can be used to determine the initial tool dimensions for precision parts in the tool design process of cold forging.
A development of ceramic inserts for forging tools
H.H. Kwon, A.N. Bramley (1)  
STC F,  49/1/2000,  P.173
Keywords: Forging, Die, Ceramic
Abstract : The use of ceramic inserts in steel forging tools offers significant technical and economic advantages over other materials of manufacture. These potential benefits can however only be realised by optimal design of the tools so that the ceramic inserts are not subjected to stresses that lead to their premature failure. In this paper the data on the loading of the tools is determined from a commercial forging simulation package as the contact stress distribution on the die-workpiece interface and as temperature distributions in the die. This data can be processed as load input data for a finite-element die-stress analysis. Process simulation and stress analysis are thus combined during the design, and a data exchange program has been developed that enables optimal design of the dies taking into account the elastic deflections generated in shrink fitting the die inserts and that caused by the stresses generated in the forging process. The stress analysis of the dies is used to determine the stress conditions on the ceramic insert by considering contact and interference effects under both mechanical and thermal loads. Simulation results have been validated as a result of experimental investigations. Laboratory tests on ceramic insert dies have verified the superior performance of the Zirconia and Silicon Nitride ceramic insert in order to prolong maintenance life.
Development of integrated and intelligent design and analysis system for forging processes
D.Y. Yang (1), Y.T. Im, Y.C. Yoo, J.J. Park, J.H. Kim, M.S. Chun, C.H. Lee, Y.K. Lee, C.H. Park, J.H  
STC F,  49/1/2000,  P.177
Keywords: metal forming, finite element method, expert system
Abstract : An intelligent system for supporting the whole design procedure of metal forming processes has been developed by integrating the expert systems, the FEA programs and the CAD interface modules. The system is developed to reduce the time, effort and cost in order to establish the successful metal forming processes of planned products. In order to promote practical applications by engineers in medium-size enterprises who are not theoretically expertized in the FEA and the other related knowledge, various databases and intelligent user interface modules have been developed in PC environment.
An investigation of the pinch and roll process of compressor airfoil manufacture
J.S. Gunasekera (2), R.A. Belinski  
STC F,  49/1/2000,  P.181
Keywords: blade forming, fem, data acquisition
Abstract : This paper is concerned with a scientific study of the pinch and roll process that is currently used to produce compressor blades for jet engines. The investigation jointly uses experimental data and validated 3-dimensional finite element analysis to improve the process. A unique data acquisition system was developed to gather process data as well as to improve the press set up for production runs. The data acquisition system provides process information such as die separation forces and displacements, and rotational die mismatch. Designed experiments were carried out on both the actual process and the simulations. The process experiments identified the intricacies of this complex process. The simulation experiments clarified the significant factors for proper simulations of the process. All of these methods of analysis are combined to improve the competitiveness of the pinch and roll process by improving the quality of the product while reducing the number of roll passes required, thus reducing the overall cost.
Manufacturing of superconducting silver/ceramic composites
B. Seifi, J.I. Bech, M. Eriksen, p. Skov-Hansen, W.G. Wang, N. Bay (1)  
STC F,  49/1/2000,  P.185
Keywords: Manufacturing of superconductors, Drawing and rolling, Metal/ceramic composites
Abstract : Manufacturing of superconducting metal/ceramic composites is a rather new discipline within materials forming processes. High Temperature SuperConductors, HTSC, are manufactured by the Oxid-Powder-In-Tube process, OPIT. A ceramic powder containing lead, calcium, bismuth, strontium, and copper oxides is inserted into a silver tube and reduced by multistep drawing. These singlefilaments are packed in a new silver tube thus forming a multifilament containing e.g. 37 singlefilaments, which is subsequently reduced by drawing and rolling to tapes approximately 0.2 mm thick by 3 mm wide. After the mechanical deformation the tapes are heattreated at approximately 835C whereby the powder-cores by phase diffusion and grain growth are converted into superconducting, ceramic fibres. The geometry, density and texture of the powder cores before heattreatment is essential for the quality and current leading properties of the final superconducting fibres. The present work describes studies on alternative packing geometries and on process parameters in the flat rolling operations in order to obtain homogenous filaments with advantageous geometry and good texture while avoiding potential defects such as cracks, shear band formation and sausaging.
Developments in powder co-injection moulding
D.J. Stephenson   / P.A. Mckeown (1)
STC F,  49/1/2000,  P.191
Keywords: Powder Injection Moulding, Coating, Modelling
Abstract : Powder co-injection moulding (PCIM), is a novel technique for the surface engineering of PIM components. The process uses two moulding feedstocks which are injected into a mould sequentially, so that one feedstock forms the surface layer of the component and the other forms the core. Work to date has shown that the injection moulding time and the viscosity ratio of the two feedstock materials are critical in determining the surface layer profile. This has been confirmed through finite element modelling predictions of the skin layer thickness distribution which correlate well with experimental observations.
A new Constitutive model for hot forging of steels taking into account the thermal and mechanical history
P.F. Bariani (1), S. Bruschi, T. Dal Negro  
STC F,  49/1/2000,  P.195
Keywords: Hot forging, Flow stress, Thermo-mechanical cycle
Abstract : The paper presents a new constitutive model which accurately describes the rheological behaviour of steels in hot bulk metal forming operations both in single- and multi-step deformation conditions. In the proposed formulation the effects on the flow curve of all the significant phenomena accompanying the deformation process are accommodated and the previous thermo-mechanical history is represented through the average austenitic grain size measured immediately before the deformation. The number of coefficients to be evaluated is reasonably restricted and the testing required to this aim not too complex.
Strain history curves and simulative material testing
M.S. Nielsen, T. Wanheim (1), M. Lindegren  
STC F,  49/1/2000,  P.199
Keywords: metal forming, non-linear strain, graphical method
Abstract : A way of describing the deformation in a process where large plastic deformation occurs is presented. For a point in the volume, the total strain tensor history is viewed as a curve in the 6-dimensional shear strain, normal strain space henceforth called a strain history curve (SHC). This paper focuses on the SHC concept and the uniqueness of the SHC representation. The SHC may be used to give a useful representation of the total course of the deformation with respect to directions and magnitudes of the strain, and hence the development of the plastic properties, but may also be used for developing variables describing plasticity. A direct use of the SHC is to measure the yield surface at different points at a SHC, thus establishing data describing the importance of strain rotations or even strain reversals within a process. Two subcases for displaying SHC will be mentioned: The plane strain case and the axisymmetrical case. The origin of the SHC in this paper is to make a method of classifying processes after strain path and hence the need for using advanced plasticity models. Use of the SHC is presented in the following process examples: 1) Extrusion process (numerical) 2) Simple shear followed by upsetting (experimental) 3) Plane strain upsetting with subsequent orthogonal reversals of straining direction (experimental) 4) Upsetting with orthogonal reversals of straining direction (experimental)
An improved relationship between vickers hardness and yield stress for cold formed materials and its experimental verification
E. Tekkaya   / K. Lange (1)
STC F,  49/1/2000,  P.205
Keywords: Cold forming, Vickers Hardness, Yield stress
Abstract : Cold formed products are increasingly serving as high duty machine parts. Designers and users need to know their properties as accurate as possible. One such product property is the new yield stress, which can be approximated by the final flow stress of workpiece material during forming. Vickers hardness measurements provide an easy and inexpensive method for evaluating the new local yield stress in cold formed workpieces. In this study, an improved relationship for the conversion of Vickers hardness values to yield stress is proposed. The agreement between theoretical and experimental results is better than 4%37; error.
Overall thermal analysis of hot plate / sheet rolling
M. Kiuchi (1), J. Yanagimoto, E. Wakamatsu  
STC F,  49/1/2000,  P.209
Keywords: Sheet, Hot Rolling, Numerical, Thermal, FEM
Abstract : A new scheme of three-dimensional thermal analysis of workpiece temperature and roll temperature in hot plate/sheet rolling is proposed. Mathematical models and numerical analysis are based on a modified finite element method. The results are as follows. (1) The temperature change at each portion of workpiece during hot rolling was calculated in detail. (2) The effects of rolling parameters on the workpiece temperature and roll temperature were consistently clarified. (3) The calculated results were used for process design and process control. (4)They are essential for innovation of hot plate/sheet rolling processes as well as quality control of rolled products.
Processing effects in plasma forming of sheet metal
T. Male, C. Pan, Y. W. Chen, p. J. Li, Y. M. Zhang   / T. Altan (1)
STC F,  49/1/2000,  P.213
Keywords: Hot forming, Sheet metal, Plasma
Abstract : A non-transferred arc plasma torch has been used as a controllable heat source to produce internal stress in sheet metals, causing plastic deformation without the necessity of hard tooling. This method has the potential to reduce development cost and lead time for forming sheet metal prototype parts. Experimental work using a robotic system has been performed on 0.8mm thick sheets of Type 304 stainless steel and of low carbon (mild) steel. The effects of various process parameters on the obtained shape changes and on the resulting material microstructures has been studied. Data is presented for the development of simple linear bends in the two materials as a function of the process parameters which directly affect the rate of heat input.
Hydromechanical deep drawing with uniform pressure on the flange
J. Danckert (1), K.B. Nielsen  
STC F,  49/1/2000,  P.217
Keywords: Sheet metal, Deep drawing, FEM
Abstract : Conventional hydromechanical deep drawing is difficult to simulate due to difficulties regarding the determination of the pressure distribution on the flange when leak flow occurs between the draw die and the flange. To avoid this problem the hydromechanical deep drawing process has been modified in such a way that the pressure on the flange is uniform throughout the deep drawing. The uniform pressure on the flange makes it easy to simulate the modified hydromechanical deep drawing process. The modified hydromechanical deep drawing process has been investigated experimentally and the experiments show that the new concept works in practice; cylindrical cups made from aluminium have been drawn succesfully with a drawing ratio as high as 2.75. The paper presents the modified hydromechanical deep drawing process and experimental results are compared to results obtained using FEM.
An intelligent controller for improving the quality of deep drawn components
S. Hinduja (2), J. Atkinson, D.K.Y. Lau, A.W. Labib, p. Agirrezabal  
STC F,  49/1/2000,  P.221
Keywords: Deep Drawing, Control, Quality
Abstract : A prototype system, which detects wrinkling and tearing in sheet metal parts, has been developed. A spatial variation of the blankholding force (BHF) is achieved by hydraulic adjustment of the force in the BHF pins which are subdivided into groups. Neural networks predict the presence of wrinkles. Tears are predicted from the punch force signals using feature extraction techniques. A fuzzy logic controller (FLC) recommends changes to the BHF and lubrication to improve the quality of the next part. The results obtained when drawing the back panel of a washing machine are discussed.

 STC G 

Stability diagram for chatter free centerless grinding and its application in machine development
F. Hashimoto (2), S.S. Zhou, G.D. Lahoti (1), M. Miyashita  
STC G,  49/1/2000,  P.225
Keywords: Centerless Grinding, Chatter Vibration, Stability Diagram
Abstract : Suppression of work regenerative chatter vibration is one of the most important issues for improving centerless grinding performance. Current practice to avoid such chatter vibration largely relies on a trial-and-error method. Based on the stability diagram, this paper introduces a systematic approach to achieving chatter free centerless grinding. In the paper, the significance of the ratio of work rotational speed to center-height angle is first discussed, the chatter free zones are then identified from the diagram. The conditions for chatter free centerless grinding are further determined by considering the effect of lobing stability and contact filtering. Practical significance of the approach is demonstrated with grinding test results. Further, the performance of a high precision centerless grinding machine developed with enhanced dynamic stability is presented.
Development of a sensor-integrated "intelligent" grinding wheel for in-process monitoring
B. Varghese, S. Pathare, R. Gao, C. Guo, S. Malkin (1)  
STC G,  49/1/2000,  P.231
Keywords: Grinding, Wheel, Sensor
Abstract : A sensor integrated "intelligent" diamond grinding wheel was developed for in-process monitoring of the wheel preparation and grinding processes for machining of ceramics without the need for any instrumentation of the machine tool. The "intelligent" grinding wheel consists of an aluminum core integrated with piezo-ceramic sensors and having diamond abrasive segments bonded on to the periphery. Multiple sensors embedded near the wheel periphery are used to measure the instantaneous normal force and its variation during each wheel revolution, and additional sensors on the wheel face monitor the acoustic emission. A DSP-based telemetric data acquisition system module attached to the wheel face is used to acquire, process, and transmit data from the rotating wheel to a remote receiver. Experimental results are presented which demonstrate the performance of the intelligent wheel.
Grinding monitoring system based on power and acoustic emission sensors
B. Karpuschewski, M. Wehmeier, I. Inasaki (1)  
STC G,  49/1/2000,  P.235
Keywords: Grinding, Dressing, Acoustic Emission
Abstract : Improvement of monitoring techniques is essential to make the complex grinding and dressing process more reliable, economical and user friendly. A system utilizing data fusion from different sensor sources and AI methods combined with a graphical user interface has been applied for this purpose. The main task of the grinding monitoring system is the detection of disturbances and the grinding cycle optimization based on the AE and power signal. The influence of different dressing parameters on the AE-signal has been investigated and a dressing monitoring system is proposed. Reliable data acquisition techniques, which make a continuous scanning of such wide bandwidth signals possible, have been applied.
Coolant induced forces in CBN high speed grinding with shoe nozzles
F. Klocke (1), A. Baus, T. Beck  
STC G,  49/1/2000,  P.241
Keywords: Grinding, Lubrication, Force
Abstract : Constantly increasing cost pressures in production as well as questions of environmental compatibility and the disposal of wastes have motivated many producers to re-evaluate the application of cooling lubricants over the past few years. Seen against this background, it is understandable that industry and research should be concerned with longer service lives and lower quantities of cooling lubricants. The use of shoe nozzles in CBN High Speed Grinding is one possible step on the way to coolant flow reduction in grinding. These nozzles ensure that most of the lubricant (especially in the case of oil) reaches the grinding gap, which is the only point where it can help to reduce friction. Besides reducing the friction, the oil in the grinding gap leads to coolant induced forces such as those known from hydrodynamic bearings. These forces can lead to geometrical errors especially when grinding small workpiece diameter. Therefore this paper starts with a calculation of the coolant flow which can be fed to the grinding gap without producing coolant induced forces. Following this, a model for the coolant induced forces is presented, taking the cutting speed, the coolant viscosity and the coolant flow into consideration. The paper ends with results of grinding tests with different coolant flow nozzles and coolant flow rates.
An investigation of high speed grinding with electroplated diamond wheels
T.W. Hwang, C.J. Evans (2), S. Malkin (1)  
STC G,  49/1/2000,  P.245
Keywords: high speed grinding, plated diamond wheel, silicon nitride
Abstract : The more widespread utilization of ceramics materials for mechanical components has been inhibited by the high machining cost and the need to maintain required surface integrity. Single layer electroplated diamond wheels offer the potential for efficient machining of ceramics due to their good grit protrusion, safety at high wheel speeds, and relatively low cost. An investigation was conducted of the grinding mechanisms, wheel wear, wheel life, and surface integrity for high speed grinding of silicon nitride using electroplated diamond wheels at speeds of 85 m/s and 149 m/s. Experimental results are presented for the grinding forces, radial wheel wear, and surface roughness, together with microscopic observations of both the ground surfaces and wheel surfaces. A statistical model is developed to characterize the wheel topography and its effect on the grinding process in terms of active cutting grains and wear flat area. Some preliminary results of acoustic emission monitoring and modulus of rupture (MOR) strength tests are presented.
Torsional vibration effects in grinding?
M.A. Mannan (2), S.J. Drew, B.J. Stone   / J.G. Wager (1)
STC G,  49/1/2000,  P.249
Keywords: Grinding, vibration, chatter
Abstract : The vast majority of models of vibration in grinding assume that there are no torsional vibration effects. In a recent doctoral study, it was found possible to eliminate grinding chatter by changing the torsional stiffness of the workpiece drive. In that study, a frequency domain model for the grinding process was developed that included torsional effects. It was concluded that for the assumed grinding force model, chatter could be influenced by the torsional characteristics of both the workpiece and wheel systems. This paper describes experiments conducted to determine how the grinding force varies with oscillating workpiece speed and oscillating chip thickness. It concludes with the description of a time domain model of the grinding process that includes a force model consistent with the experimental force measurements.
Simulation of tool-gringind with finite element method
K. Weinert (1), M. Schneider  
STC G,  49/1/2000,  P.253
Keywords: Grinding, Tool, Finite element method (FEM)
Abstract : Thermal stress, in particular, is one of the main problems when grinding cutting tools. If the process temperatures are too high, lasting damage to the cutting tool can result. The thermal and thermo-mechanical stress on tools is of major relevance when describing the influences on the surface near-zone. In this regard the grinding of cutting tools was modelled with the help of the finite element method (FEM). The FEM clearly demonstrates some fundamental relationships between the simulated thermo-mechanical stress and the wear behaviour of the tools when being used. Furthermore, temperature measurements have shown that the FEM represents an appropriate means for describing what is actually going on in the tool during the grinding operation.
Fabrication of micro carbide tools by ultrasonic vibration grinding
H. Onikura, O. Ohnishi, Y. Take   / A. Kobayashi (1)
STC G,  49/1/2000,  P.257
Keywords: Ultrasonic vibration grinding, Micro tool, Carbide
Abstract : This paper deals with the fabrication of micro cylindrical tools and micro flat drills of ultra-fine grain cemented carbides by grinding with ultrasonic vibration. The concept of this grinding is to reduce the grinding forces such that they will not cause any breakage to the micro tools. The grinding operations are performed using the end face of an offset grinding wheel. In grinding with ultrasonic vibration, better results in aspect ratio and tools of smaller diameter than conventional grinding are obtained. Due to the lower tensile strength of carbides, grinding under compressive force has made it possible to grind to a diameter of 11 um with a length of 160 um.
Grinding ratio and cost issues in magnetic and non-magnetic fluid grinding
T.H.C. Childs (1), D.J. Moss  
STC G,  49/1/2000,  P.261
Keywords: Ceramic ball grinding, Wear, Process cost
Abstract : Grinding rates, diamond consumption and grinding ratios are reported for the magnetic and non-magnetic fluid grinding of silicon nitride balls with loose grit, and resin-bonded and electro-plated diamond drive shafts. Diamond consumables costs are assessed and the grinding ratios are compared with those measured in surface grinding with the same material combinations, at similar grit loadings. Resin-bonded diamond drive shafts give the lowest diamond consumables costs, estimated to become less than £0.05 ($0.08) per ball on process scale-up, for 10 mm diameter balls reduced to 9.8 mm. Grinding ratios less than 10, compared to values in surface grinding of more than 100, are the process's weakness.

 STC M 

Sliding mode controller design for high speed feed drives
Y. Altintas (1), K. Erkorkmaz, W.-H. Zhu  
STC M,  49/1/2000,  P.265
Keywords: Feed, Drive, Control
Abstract : An adaptive sliding mode control technique is presented for the control of high speed feed drives. The proposed control system is robust against uncertainties in the drive?s parameters, maximizes the bandwidth within physical limitations, and compensates for external disturbances such as friction and cutting force. The algorithm is briefly presented, followed by machining tests conducted with contour milling of circles and diamond trajectories. The contour errors are compared against those of a pole placement controller with feedforward friction and servo dynamics compensation. It is shown that the sliding mode controller has practical advantages in rapid tuning and implementation, but requires smooth reference trajectory generation.
Direct adaptive generalized predictive control. Application to motor drives with flexible modes
D. Dumur (1), P. Boucher (2), G. Ramond  
STC M,  49/1/2000,  P.271
Keywords: Control, Machine tool, Drives
Abstract : Predictive control has proved to be an efficient control strategy, and its application in the motor drives field has provided good results, even with small sampling rates. However, in case of important parameters variations, a high level of performance may be impossible to maintain with a fixed controller, so that an adaptive version becomes necessary. This paper presents a direct adaptive generalized predictive control structure, including a least squares-type strategy for the controller parameters on-line identification, and a conditional updating test. An application to motor drives with flexible transmissions is finally developed, taking into account some variations of inertia.
Parallel kinematic machines (PKM) ? limitations and new solutions
G. Pritschow (1)  
STC M,  49/1/2000,  P.275
Keywords: Parallel kinematic machines, Limitations, Improvement
Abstract : The main advantages of parallel kinematic machines are their simple designs and common parts. However they also possess some inherent disadvantages which include limited orientation angles, non-linear force transmission and stiffness characteristics, a poor ratio of working envelope to machine size as well as mediocre accuracy. This paper discusses the factors which contribute to these negative characteristics and offers new ways to overcome these disadvantages.
Deterministic metrology of parallel kinematic machines
V.T. Portman (2)  
STC M,  49/1/2000,  P.281
Keywords: Accuracy, Parallel kinematic machine, Modelling
Abstract : The deterministic metrology (DM) establishes links between accuracy parameters of the machine units and a functional accuracy of the machine itself. An interrelationship between the quasi-static errors of the PKM and deviations of the points of the nominal surface from the actual machined surface is considered. PKM-related mathematical models of the DM (the matrix of the Euler angles, the inverse kinematics, the Jacobian for a current platform position, etc.) are formulated. The Gaussian coordinates of a current point of the machined surface are used to set up the correspondence between the models and to map the error distribution over the PKM working space. The DM approach for the PKM is modeled for milling operations and ball-bar test.
A simple yet effective approach for error compensation of a tripod-based parallel kinematic machine
T. Huang, D.J. Whitehouse (1)  
STC M,  49/1/2000,  P.285
Keywords: Parallel kinematic machine, Forward kinematics, Error compensation
Abstract : This paper presents a simple yet effective approach for the error compensation of a tripod-based parallel kinematic machine. In this approach, the forward kinematics is formulated in such a way that the coordinate of the tool tip in z direction can be explicitly represented by the dimensional parameters and actuated variables. This enables one to implement the linear least square method to estimate the kinematic parameter errors. This approach has been successfully used for the error compensation of a prototype. The measurements of a test workpiece show that once the error in the z direction is properly compensated, the errors in x and y directions can be automatically compensated.
Design of a spherical motor with three degrees of freedom
M. Weck (1), T. Reinartz, G. Henneberger, R.W. De Doncker  
STC M,  49/1/2000,  P.289
Keywords: Machine Tool, Drive Technology, Control Technique
Abstract : In this paper the development of a new spherical motor which provides multi-coordinate movements in one drive module is presented. Due to the ever increasing demands on product quality and the need to machine free form surfaces modern machine tools and robotic devices require five degrees of freedom. Thus there is the need for new machine tool concepts and drive technologies. The spherical motor is able to eliminate most disadvantages of conventional open kinematics consisting of sequential axes. It is based on a spherical rotor, which is - like a ball joint - guided in a sphere. Thus three-dimensional movements can be performed. A high torque in all positions is achieved by permanent magnets on the rotor and electromagnetic coils in the stator which are separately controlled by single power converters. Possible applications are the replacement of a robot hand axis unit or the inte-gration in a machine tool to perform five axis milling operations. This paper reports on the development of the mechanical components, the power converter and control hardware as well as the magnetic design.
Development of 5-axis control ultraprecision milling machine for micromachining based on non-friction servomechanism
Y. Takeuchi (1), Y. Sakaida, K. Sawada, T. Sata  
STC M,  49/1/2000,  P.295
Keywords: Ultraprecision milling, 3-dimensional micromachining, Non-friction servomechanisms
Abstract : The study addresses the development of a 5-axis ultraprecision milling machine to create tiny 3-dimensional workpieces as well as microstructures. 3-axis control ultraprecision milling machines allow microstructures on tiny workpiece surfaces to be manufactured; however it is difficult to create 3-dimensional workpieces such as very small heads, statues etc., which will be important in micromanufacturing in the future. Thus, a 5-axis milling machine consisting of three translational and two rotational axes has been developed benefitting from the use of non-friction servomechanisms. 5-axis micromachining was conducted to create a half cylindrical workpiece. It was found that the ultraprecision milling machine is accurate enough to machine tiny 3-dimensional workpieces.
Ultraprecision 6-axis table driven by means of walking drive
E. Shamoto, H. Murase, T. Moriwaki (1)  
STC M,  49/1/2000,  P.299
Keywords: Feed table, Piezoelectric actuator, Positioning
Abstract : A new ultraprecision 6-axis table is developed by employing the principle of "walking drive". The table is driven by nine pairs of supporting and feeding piezoelectric actuators. It can travel smoothly over a long stroke of 60 mm in X and Y directions and can also rotate around C axis, although the stroke of each actuator is extremely small. Furthermore, the attitude of the table can be controlled by applying additional commands to the supporting actuators, i.e. the table can be moved in Z direction and also around A and B axes within short strokes. The walking table developed in the present research has 6 degrees of freedom of motion driven simultaneously. It has unique advantages compared to conventional tables, such as extremely high positioning resolution, smooth motion, multi-axis motion, direct drive without conventional guides, no use of lubricant, etc.
Predicting high-speed machining dynamics by substructure analysis
T.L. Schmitz   / R.R. Donaldson (1)
STC M,  49/1/2000,  P.303
Keywords: High speed machining, Sub-structure analysis
Abstract : The practical implementation of high-speed machining (HSM) requires accurate knowledge of the machine dynamics. We apply receptance coupling substructure analysis to the prediction of the tool point dynamic response, combining frequency response measurements of individual components through appropriate connections to determine assembly dynamics using simple vector manipulations. This paper shows that the dynamic response before and after system changes may be predicted, thus dramatically reducing the number of required experimental measurements. The application of this technique to the tuning of tool dynamics for improved stability by overhung length variation is demonstrated.
Power and stability limits in milling
S. Smith (2), W.R. Winfough, H.J. Borchers  
STC M,  49/1/2000,  P.309
Keywords: Milling, Spindle Power Limit, Stability Limit
Abstract : The metal removal rate (MRR) in milling is typically limited by the dynamics of the tool-spindle combination or by the power. If the tool is stiff, the power is limiting, and the spindle stalls before chattering. If the tool is flexible, there is a spindle speed range where chatter is limiting. Many tools have some spindle speeds where chatter is limiting and others where power is limiting. This paper presents a new "power lobe" diagram which is independent of the workpiece material. Combined with the power curve for the spindle, this "stable power" diagram defines the achievable MRR for the entire machine dynamics.
Actively controlled compliance device for machining error reduction
K. Matsumoto, Y. Hatamura (1), M. Nakao  
STC M,  49/1/2000,  P.313
Keywords: Machining error reduction, Compliance control, Grinding
Abstract : Deformation of the tool itself, due to cutting forces, is one of the major causes of machining error in precision machining. The authors propose a new solution to the problem that employs an actively controlled compliance device. By applying 'negative' compliance of the device, deformation of the machining tool can be compensated, and the machining error can be reduced to zero. This paper reports our analysis of the machining process to compensate machining error using negative compliance. It also evaluates our method through experiments of grinding silicon wafers and turbine blades.
A fast analytical method to compute optimum stiffness of fixturing locators
S. Jayaram, B.S. El-Khasawneh, D.E. Beutel   / M.E. Merchant (1)
STC M,  49/1/2000,  P.317
Keywords: Fixture, Design, Optimization
Abstract : Machining fixtures are used to rigidly hold and support workpieces during machining. The quality of the machined part directly depends on the combined stiffness of the workpiece and the fixture. Low fixture stiffness causes poor quality parts, while large fixture stiffness causes the fixtures to be expensive and cumbersome. Finite element models can be used to optimize the fixture stiffness; however these techniques are computationally expensive for complex workpiece geometries. This paper develops a fast analytical method for optimizing fixture locator stiffnesses for workpieces that are more rigid than the fixture elements. The developed methodology is validated through finite element simulations and experiments.
Fuzzy modeling of inverse dynamics for robotic manipulators base on genetic algorithm
B. Qiao, J.Y. Zhu (1)  
STC M,  49/1/2000,  P.321
Keywords: Genetic algorithm, Fuzzy control, Robotic manipulator
Abstract : Genetic Algorithm (GA) can be applied to a wide range of unstructured and nonlinear optimization problems. In this paper a Progressive Genetic Learning Algorithm (PGLA) is proposed. The main idea of PGLA is to progressively change the survival environment of gene according to the converging process of GA. In each operation the excellent gene schemas are selected and maintained through their fitness, while the lower fitness schemas are not discarded completely but put into a pool where mutation is taken place with a high probability. The proposed PGLA is used to optimize the parameter and structure of a fuzzy control system. Simulation on a three linked robotic manipulator. is conducted and its results are worked out.

 STC O 

From a business opportunity identification up to its manufacturing in virtuel enterprises: a reference model and case study
C.F. Bremer   / W. Eversheim (1)
STC O,  49/1/2000,  P.325
Keywords: Virtual Manufacturing, Life Cycle, Technology Integration
Abstract : In the recent years the model of Virtual Enterprises has been described as a new or innovative organisation form for manufacturing enterprises. Nevertheless there is a lack of a complete reference model of virtual enterprises that could be largely used and applied. The present paper describes such a reference model and its application in a project carried out in Brazil since July 1998, with a group of nine manufacturing and technology based Small and Medium Enterprises (SME's) which forms a Virtual Organisation. A Framework has been developed at the beginning of the project as a structure and guideline for its creation. In this Framework the Virtual Organisation is considered as a stable network of enterprises that aim to co-operate among them and target to create several different Virtual Enterprises. Therefore a Virtual Enterprise is defined as a Business Opportunity driven co-operation between existing and independent enterprises. A proposed reference model (function and information) is then described as well as its methods, tools and infrastructures. Examples of the methods adapted or developed are Benchmarking, Business Plan, Competence Matching and others. In terms of tools an Internet based Competence search has been developed. Regarding the infrastructures three of them are detailed: legal, information and cultural.
Throughput time control in production systems supported by neural networks
B. Scholz-Reiter, St. Müller   / H.P. Wiendhal (1)
STC O,  49/1/2000,  P.331
Keywords: Production, Control, Neural Network
Abstract : In addition to the developed buffer inventory control with neural networks, the suitability of neural networks for control of throughput time in production systems is examined. A hybrid self controlling system was developed from this examination, which can be used in metal-working companies, functioning according to the workshop principle. A cascade closed loop control structure is introduced for the control of the throughput time which is supported by the neural networks. The neural networks influence the release time of orders and the level of buffer inventory at the work systems, due to the difference of set-value of throughput time.
Finite schedule monitoring and filtering in a computer integrated manufacturing environment
R.G. Wilhelm (2), R. Chandrashekar, R. Sun, M. Hegedus, B. Chu, W.J. Tolone, J. Long  
STC O,  49/1/2000,  P.335
Keywords: Integrated, Scheduling, Monitoring
Abstract : An efficient and effective method of filtering is described for reactive scheduling in an integrated manufacturing environment. The filter evaluates the significance of schedule deviations in near-real-time and gives a statistical estimate of the importance of each schedule deviation; Highly important deviations being those that prevent schedule objectives from being achieved. A typical result from STC filtering would be an indication that there is a 95%37; probability of failing to meet the schedule if the resource were to continue working at the same rate. The technique is well suited for bottle-neck resources but may be applied to all resources in an enterprise. The filter, based on statistical throughput control (STC) is compared to past work in DEDS and reactive scheduling. Model formulation is presented to show extensions from previous applications of STC for short-term production control in a CONWIP (Constant WIP) production system. Data requirements are detailed with reference to Business Object Documents (BODs) defined by the Open Applications Group (OAG). A summary of the CIIMPLEX framework is presented to show how the filter is applied.
New strategies and tools for increasing simulation efficiency
H. Bley (2), C. Franke, C.C. Wuttke  
STC O,  49/1/2000,  P. 339
Keywords: Simulation, Multifunctional Models, Planning Tools
Abstract : In recent years, the progress of simulation technology led to modeling software showing a very high level of perfection and functionality. However the expense of modeling has held the number of users lower than original expectations. The central idea to increase acceptance is the multiple use of simulation models. Based on this perception, comprehensive strategies have been developed for three different kinds of simulation projects: small/standardized, spontaneous and large/long-running projects. These strategies are supported by tools for planning and implementation of efficient simulation projects. The methods and tools have been implemented to prove their feasibility in event-driven material flow simulation.
Reinforcement learning approaches to biological manufacturing systems
K. Ueda (1), I. Hatono, N. Fujii, J. Vaario  
STC O,  49/1/2000,  P.343
Keywords: Manufacturing Systems, Machine Learning, Uncertain Environment
Abstract : The concept of Biological Manufacturing System (BMS) aims at dealing with unpredictable changes in the external and internal environments during whole product life cycle, based on biologically-inspired ideas such as self-organization, learning and evolution. We previously developed evolution-based and self-organization models of the floor level that are able to cope with environmental changes such as system reconfiguration, machine breakdown and unforeseen production requests. This paper describes reinforcement learning approaches to the modeling of BMS, in order to deal with the various kinds of complex global objectives. The effectiveness of the proposed model is also discussed by simulation with global objectives.
Self organization of the cellular manufacturing system
S. Kondoh, Y. Umeda, T. Tomiyama, H. Yoshikawa (1)  
STC O,  49/1/2000,  P.347
Keywords: Cellular manufacturing system, Conceptual layout design, Reinforcement learning
Abstract : Determining configuration of production facilities is difficult problem. To solve this problem, the authors introduce the Cellular Manufacturing System as a rapid prototyping and strategic decision-making tool for configuring facilities and product task assignment. At the conceptual design stage of the cellular manufacturing system, there is no decision about facility configuration and product or machining task assignment. The configuration and assignment are determined by self-organization at the operation stage. This makes it possible for the cellular manufacturing system to decide strategic facilities configuration adapting to changing manufacturing requirements. This paper describes a model of the cellular manufacturing system and its self-organization algorithm through software simulations.
Prediction, optimization and functional requirements of knowledge based systems
B.N. Colding (1)  
STC O,  49/1/2000,  P.351
Keywords: Prediction, Requirement, Knowledge based system
Abstract : The ability to accurately predict the performance of physical systems across a large range, using functions of 3 variables z = f(x,y), depends on the type of mathematical model used. Linear or nonlinear programming, and statistical models are often inaccurate in describing the physical problems, and require a large number of data. Forecasting methods should be based primarily on experimental evidence, coupled with preferably fundamental laws of nature, using proper functions with minima and maxima, often contained in physical systems. The paper describes a function of 3 variables with five constants, which satisfies the minimum energy principle. It requires 5 accurate experimental or calculated values achieving reasonable accuracy over a large range of thefunctional variables. Starting with a brief review of past research described in this Author's CIRP papers for temperature, tool-life and cutting force functions, recent developments including system optimization are reported in the paper. The accuracy of the ascribed method is compared with the results using other mathematical and statistical methods. Its use is demonstrated for surface finish predictions and its relationship to tool-life, applications to manufacturing cost relationships, to forecasting enterprise sales and profit with intellectual capital as parameter, ending with a comparison with a global warming forecasting model.
Business innovation - innovative teams, competence brokers and beehive structures - in a sustainable work organization
A. Kjellberg (2), A. Werneman   
STC O,  49/1/2000,  P.355
Keywords: Knowledge Development, Sustainable Organization, Human Factor
Abstract : New demands on wide and deep knowledge and competence, stress the need for teams, for 'complete' teams. Innovative teams, working in a dynamic and temporary structure, will support one of three demands. This demand is to quickly grasp the 'invisible' market indicators and to chase information for the purpose of inventiveness. Technological progress toward a communications and knowledge society is creating new business opportunities and a future that is difficult to predict. Increasingly open data systems allowing individuals to trace and use information at all levels in the company, requires open and flexible fellow-workers - and Transparency. To handle variances in demands, products and processes we will, however, also have to rely on a Sustainable Work Organization. The company core excellence values and attitudes as well as the vision and the learning of the organization are like a platform. Platforms are Sustainable Work Elements. This paper will also highlight the need for individual, spontaneous and temporary acting based on Transparency.
Tolerance analysis and synthesis using Jacobian transforms
L. Laperriere, H. ElMaraghy (1)  
STC O,  49/1/2000,  P.359
Keywords: tolerances, synthesis, functional requirement
Abstract : This paper presents a mathematical tool to help the designer in the difficult task of tolerancing mechanical assemblies. It starts with the identification of a critical tolerance chain around some functional requirement of the assembly. A mathematical relationship which quantifies the effects that possible small displacements of functional elements in the chain have on the functional requirement is obtained. This corresponds to the solution of the tolerance analysis problem. This is expressed as a set of equations in matrix form with a Jacobian matrix which provides the desired analysis relationship. The solution to the tolerance synthesis problem is obtained by simply pseudo-inverting the Jacobian matrix, where small displacements of the functional element pairs in the chain are expressed as a function of the desired small displacements of the functional requirement. The paper presents the procedure for obtaining both the analysis and synthesis equations. An example is used to illustrate the generation of tolerance equations. The paper is concluded with a discussion of how the equations could be used in a statistical tolerancing context using Monte Carlo simulations.
Environmental versus conventional planning for machined components
P.S. Sheng (2) N. Krishnan  
STC O,  49/1/2000,  P.363
Keywords: Environment, planning, machining
Abstract : A process planning agent is presented, that enables automatic planning for 3 Axis CNC Machining for minimal environmental impact along major hazard categories. Utilizing an Internet-based CAD interface, the planner enables feature (micro) and part (macro) level planning through the ACIS format, resident machining process models and a multi-criteria hazard (MCH) assessment tool. The process planner is also designed to interact with conventional generative planner (optimizing machining time and quality factors) as an advisory environmental "agent". Remote feedback to the designer is provided through visual coding via the CAD interface. Application of the agent to a complex machined component is presented.
Efficient NC-programming of multiaxes milling machines through the integration of tool path generation and NC-simulation
B. Lauwers, J.-P. Kruth (1), P. Dejonghe, R. Vreys  
STC O,  49/1/2000,  P.367
Keywords: Computer Aided Manufacturing (CAM), Simulation, Milling
Abstract : This paper describes the development of an "extended CAM system" for multi-axes milling, integrating tool path generation, axes transformation (postprocessing) and NC-simulation. The system performs an immediate verification of each generated cutter location and in case a collision occurs (e.g. between machine and part), it takes the appropriate action by applying a collision avoidance algorithm. Different collision avoidance algorithms have been implemented: change of tool orientation, selection of other machine axes configurations and simple tool retract. The effect of a tool orientation change on the quality of the machined surface has been studied in order to define the range of tool orientations that may be used for collision avoidance.
Improving high speed flank milling operations in multi-axis machines
K. Sorby, K. Tonnessen, J.E. Torjusen   / F.O. Rasch (1)
STC O,  49/1/2000,  P.371
Keywords: Flank milling, High speed milling, Optimization
Abstract : Flank milling is an efficient method for machining of ruled surfaces generated by straight ruling lines. The method is also interesting with respect to general free form surfaces. The geometric cutting conditions in flank milling, characterized by a small radial depth-of-cut to diameter ratio, leads to the possibility for use of high speed technology. High speed machining will give a high material removal rate and relatively low cutting forces, which is important in order to reduce the deflections of the cutting tool in flank milling. Typical applications for high speed flank milling can be found in the aerospace industry where a large amount of the components are thin-walled and complex shaped, and have to be manufactured within narrow tolerances. Besides, the materials are generally difficult to machine. Introductorily, the paper presents the technological aspects of flank milling, with focus on selection of cutting tool, cooling/lubrication, and machining data. The approximation of general free form surfaces by ruled surfaces is also discussed. A new method for optimization of the economy in flank milling is presented. The method is based on a tool life model, a cutting force model, cost data, and machine tool limitations related to spindle speed and feed rate. Such limitations are especially relevant for large machine tools with rotating axes. The parameters of the models for tool life and cutting force are experimentally determined for machining Greek Ascoloy by use of coated carbide tools. The optimization model is demonstrated by examples from the aerospace industry.
Incremental supervised learning of cutting conditions using the fuzzy ARTMAP neural network
M.W. Park, B.T. Park, H.M. Rho (2), S.K. Kim  
STC O,  49/1/2000,  P.375
Keywords: CAPP, Cutting Conditions, Neural Network
Abstract : As a part of an effort to systematize operation planning for cutting processes, the fuzzy ARTMAP neural network has been applied to model the process of selecting cutting conditions and subsequently to learn cutting conditions for training the model. The fuzzy ARTMAP neural network is capable of incremental supervised learning, which enables the model to be reinforced continually and efficiently. In addition, a new algorithm called the replacement algorithm is proposed. When new cutting conditions that are more effective for a certain circumstance are obtained, the proposed algorithm deletes the old information learned, and then makes the network learn the better ones. Examples of decisions of cutting conditions using the fuzzy ARTMAP neural network and the replacement algorithm are provided and discussed.
A concurrent-engineering approach toward the online adaptive control of injection moulding process
K.K. Wang (1), J. Zhou  
STC O,  49/1/2000,  P.379
Keywords: Computer Adaptive Control, Concurrent, Molding
Abstract : Injection molding is the most effective process to produce plastic parts of complex shape to the highest precision at the lowest cost. Considerable progress has been made over the last two decades in modeling and simulation of the molding dynamics. However, due to complex material properties and other uncontrollable disturbances, consistency of part quality cannot be assured in production. As a result, an off-line Statistical Process Control (SPC) scheme has to be established which can be costly. This paper presents a new approach to the problem. Based on the concept of Concurrent Engineering, we make full use of the power of simulation for the design of the part, the mold, and setting up process control parameters automatically. The control system consists of a feed-forward loop and three feedback loops with numerous associated sensors in each loop. With an online PC and a smart part-quality sensor, the system can control the variation of part weight (one measure of quality) ten times better than existing methods.
Predictive monitoring and control of the cold extrusion process
S. Spiewak (2), R. Duggirala, K. Barnett  
STC O,  49/1/2000,  P.383
Keywords: Extrusion, Predictive Control, Press
Abstract : Cold extrusion and forging processes require significant improvements in productivity to ensure the continued competitiveness of press manufacturers and users. Current average productivity rates are less than 60 percent, while the lost production capacity is mainly due to equipment failures and unreliable processes control. A group of companies representing press manufacturers and users collaborated within National Center of Manufacturing Sciences to diagnose the common problems and recommend solutions. Major findings presented in this paper pertain to identifying and eliminating root causes of lost production in an automated facility running multiple high tonnage mechanical presses. Example results that indicate the feasibility of predictive process control are included.
Integrated condition monitoring and fault diagnosis for modern manufacturing systems
Z.D. Zhou, Y.P. Chen, J.Y.H. Fuh, A.Y.C. Nee (1)  
STC O,  49/1/2000,  P.387
Keywords: Condition monitoring, Failure diagnostics, Intelligent manufacturing system
Abstract : A multi-sensor and multi-parameter condition monitoring and fault diagnosis system is designed and implemented for modern manufacturing systems, such as flexible manufacturing cells and systems. The overall hardware and software designs of this system, together with the functional sub-systems, are presented. This implemented system monitors power, vibration, temperature and pressure of the drives and spindles with a total of 72 diagnostic features and uses a cost-weighted function to identify diagnostic solutions with the lowest cost. Condition monitoring, data acquisition, knowledge acquisition and representation, as well as the diagnostic reasoning strategy of the knowledge-base system are presented in detail. The system was implemented and tested in a textile plant with satisfactory results.

 STC P 

Design of a high-accuracy CMM based on multi-lateration techniques
E.B. Hughes, A. Wilson, G.N. Peggs (1)  
STC P,  49/1/2000,  P.391
Keywords: Coordinate Measuring Machine, Laser Interferometry, Accuracy
Abstract : To address the industrial requirement for the calibration of two-dimensional and three-dimensional artefacts, NPL is developing a new primary CMM with a target uncertainty of 300 nm (k = 1.96) within a cubic working volume of side 600 mm. This CMM is based on the principle of multi-lateration whereby spatial coordinates are determined solely from measurements of displacement of a moving probe relative to a number, probably as many as eight, of fixed measuring stations. A prototype measuring station has been designed, built and tested. The design of the measuring station has been optimised to minimise uncertainties due to beam steering. This paper describes the design of the measuring station, presents an evaluated uncertainty and outlines test results obtained from the prototype system.
Assesment of uncertainties in dimensional metrology by Monte Carlo simulation: proposal of a modular and visual software
H. Schwenke, B.R.L. Siebert, F. Wäldele, H. Kunzmann (1)  
STC P,  49/1/2000,  P.395
Keywords: Uncertainty, Simulation, Software
Abstract : An accurate assessment of the uncertainty associated with measured dimensions is increasingly important in industrial routine. The GUM [1] provides definitions and suggests a standard procedure for the assessment of uncertainties. However, this procedure is tedious or even impossible in the case of complex dimensional meas-urements. This paper demonstrates, that the Monte Carlo simulation allows a straightfor-ward and accurate as-sessment of uncertainties in complex dimensional measurements. A modular software concept is proposed which allows the set up of the model function for such complex measurement processes by concatenation of modules from a library. A validation of the method is provided by comparison measurements.
A method for optical CMM calibration using a grid plate
G.X. Zhang (1), J.Y. Fu  
STC P,  49/1/2000,  P.399
Keywords: Error Calibration, Optical CMM, Algorithm
Abstract : The reduction in feature size on microchips has generated an urgent need to improve the accuracy of lithography machines and optical CMMs. Error calibration and compensation of these machines can meet this need. The geometry of an optical CMM or a lithography machine can be calibrated in two dimensions by measuring an uncalibrated reversible grid plate in three different positions. In the initial position the plate is aligned with the machine coordinate system. Next it is reversed about the Y axis of the machine. In the third position the grid plate is rotated 90 degrees about the Z axis of the machine. In order to determine the scale error (establish the metric) one of the machine axes should be calibrated using a stabilized laser interferometer. This paper presents a new and simple algorithm for obtaining the compensation data from grid plate measurements assuming that one axis has been calibrated with a laser. Both computer simulation and experiments have been performed to access the effectiveness of the proposed method.
A study on the development of a three dimensional linear encoder system for in-process motion error calibration and compensation of a machine tool axes
K. Yamazaki (2), U. Mueller, J. Liu, J. Braasch  
STC P,  49/1/2000,  P.403
Keywords: Measuring instrument, Optoelectronic sensor, Motion calibration,
Abstract : Precision machine tools require in-process measurement of volumetric accuracy for machining and calibration. This paper describes the development and evaluation of a volumetric linear encoder for measuring the on-axis volumetric motion accuracy. The encoder is based on three cross-grid gratings as measurement bodies and a sensor-head consisting of six optical sensing elements. The encoder uses a non-touching interferential scanning principle that allows the measurement of six axial displacements. The displacement information is interpolated by an application specific integrated circuit (ASIC) and transformed in three volumetric linear and angular displacement. The prototype encoder was evaluated to verify its effectiveness under laboratory conditions and in the factory.
An advanced ceramic optical diamond turning machine ? design and prototype development
J.P.M.B. Vermuelen, P.C.J.N. Rosielle, P.H.J. Schellekens (1)  
STC P,  49/1/2000,  P.407
Keywords: High-precision design, Ceramic laminate material, Diamond turning
Abstract : A new high precision optical diamond turning machine was designed and developed, having a vertical axis and all ceramic slides, performing submicrometer accuracy (0.3 micrometer without software error compensation) and mirror surface quality (6 nm Ra). In view of improving repeatability, basic fundamentals like kinematic design, the Rule of Abbe, high stiffness structural loop design, hardware compensation of thermal expansion, force compensation and (thermal) symmetry were built in throughout the machine. The vertical axis machine with all aerostatic slides and linear direct drives differs significantly from conventional lathes in both design at the component level and in material utilisation. By the development and application of ceramic laminate composite materials, the specific stiffness of functional moving parts was increased by a factor of three compared to steel, aluminium and granite, and furthermore, viscoelastic material damping was incorporated within the structural material itself. Consequently, the dynamic behaviour of the machine was considerably improved having the first natural frequency at 200 Hz. The work in this paper that was carried out in a Ph.D. project, focuses on machine design aspects showing analytical and experimental results and design synthesis.
Novel multi degree of freedom piezoelectric actuators
J.A.G. Knight   / J.R. Crookall (1)
STC P,  49/1/2000,  P.411
Keywords: Actuator, Piezoelectric, Bearing
Abstract : This paper considers the design of a piezoelectric multi-degree-of-freedom actuator/sensor by introducing the concept of an active kinematic pair in which one or both links are made from piezoactive material which through the application of suitable excitation enable the generation of static displacements, quasi-static or resonant oscillations resulting in the generation of forces or torque in the contact zone between links. These forces or torques lead to the generation of motion of one link relative to the other. Several novel actuators have been designed, developed and realised based on an active kinematic pair. Different configurations are considered in the paper including three arrangements for two degree of freedom active bearings and a three degree of freedom robot eye. The performance of these actuators has been established by testing and evaluation and the paper presents these results in terms of number of sectioned electrodes, voltage-angular velocity and frequency-angular velocity, response time and accuracy, and resolution of movement. Based on the extensive experimentation a design methodology for actuators configured from active kinematic pairs is presented.
Angle metrology of dispersion prisms
W.T. Estler (2), Y.H. Queen  
STC P,  49/1/2000,  P.415
Keywords: angular measurement, index of refraction, calibration
Abstract : We present a new technique for calibrating the apex angles of dispersion prisms, which are used in the measurement of the index of refraction of optical glasses. The new method requires only a phase measuring interferometer, together with an electronic autocollimator, and eliminates the need for a rotary or indexing ta-ble. The apex angles of a nominally equilateral prism of fused silica were measured and the results compare favorably with a traditional calibration using an indexing table comparator.

 STC S 

Comparison of conventional light scattering and speckle techniques concerning an in-process characterisation of engineered surfaces
P. Lehmann, G. Goch (2)  
STC S,  49/1/2000,  P.419
Keywords: Scatter, Roughness, In-process
Abstract : It is well known that several features of engineered surfaces can be determined by light scattering techniques. However, the characterisation of surface icrotopography by scattered light sometimes only yields a qualitative ssessment or does not directly correspond to common roughness parameters. The latter shortcoming may even lead to ambiguity, so that these techniques are hardly accepted for industrial quality inspection. Nevertheless, the technological progress in the field of optoelectronics (laser diodes, CCD- and CMOS-cameras, digital image processing) allows a compact realisation of novel arrangements. In this contribution, light scattering and speckle techniques for a measuring range from 1 nm to about 10 µm (rms-roughness) will be introduced. Conventional light scattering methods relevant to industrial applications are known as "angle resolved scattering" (ARS) and diffuseness measurement. The speckle techniques include the method of polychromatic speckle autocorrelation and the doubly scattered light approach, which have been recently developed by the authors. The different parametric methods will be compared with respect to their in-process capabilities and the correlation between optical output parameters and statistical parameters of the surface profile under investigation. Furthermore, it will be shown that 3D-quantities of engineered surfaces can be obtained from the measuring data.
3D micro-profile measurement using optical inverse scattering phase method
A. Taguchi, T. Miyochi, Y. Takaya, S. Takahashi, K. Saito (2)  
STC S,  49/1/2000,  P.423
Keywords: Micro-profile, Optical measurement, Nano-technology
Abstract : With the advance of the nano-technology, especially micromachining, in-process measurement techniques for micro-machined profiles in the submicron order are increasingly required. However, conventional Scanning Probe Microscopes (SPM) come with numerous problems in applications to in-process measurement. In this paper, we propose a new optical measuring method which can be applied to the in-process measurement of three-dimensional micro-profiles with accuracy in the nanometer order. The optical inverse scattering phase method offers the advantage of measuring a three-dimensional profile within the whole area illuminated by the laser beam simultaneously. No scanning process is required. Employing Fourier phase retrieval algorithm, three-dimensional micro-profiles are reconstructed from only the measured Fraunhofer diffraction intensity. Computer simulations and actual measurements were performed for the verification of the proposed method. The result obtained in the measurement for an ultra precision grid plate, which has rectangular pockets 44nm deep at intervals of 10mm, shows the validity of this method.
Measurement and topography characterisation of surfaces produced by selective laser sintering
P.M. Lonardo (1), A.A. Bruzzone  
STC S,  49/1/2000,  P.427
Keywords: Laser sintering, Optical measurement, Surface topography
Abstract : Selective Laser Sintering (SLS) permits to manufacture physical models, suitable to be used as sand moulds in the casting processes. SLS presents some technological limits as regards the dimensional precision and surface roughness, which require an accurate assessment. Unfortunately contact methods are not able to carry out these measurements. This paper investigates the possibility of using a new non-contact instrument based on conoscopic holography to measure both microgeometry and macrogeometry of SLS samples. The reliability of measures and its influence on roughness parameters is discussed. A procedure for characterising and identifying the sample edges is introduced.
Properties of honed gears during lifetime
H.K. Tönshoff (1), T. Friemuth, C. Marzenell  
STC S,  49/1/2000,  P.431
Keywords: Gear honing, Workpiece property, Fatigue life
Abstract : Properties of tooth flanks such as roughness, surface topography, residual stresses, material structure and hardness influence the lifetime of a gear running under load. These properties have been generated by the gear's finishing process, but they do not remain constant when the gear comes into mesh. This paper describes the alterations of the tooth flanks' properties with the example of hardened gears that were finished by gear honing with electroplated tools. The results enlarge the knowledge of fatigue mechanisms that lead to failures of gears when high loads persist over a long running time.
Generation of reaction layers on machined surfaces
E. Brinksmeier (1), A. Walter  
STC S,  49/1/2000,  P.435
Keywords: chemical surface integrity, cooling lubrication, machining
Abstract : Machined surfaces are influenced by the generation of reaction layers resulting from the formulation of the metalworking fluid. Coolants reduce friction at the tool/surface interface and significantly influence the heat dissipation in machining operations and the generation of the surface layer. Nowadays, machining processes are evaluated with respect to the forces, grinding wheel wear, surface roughness, surface integrity, residual stresses, process stability, and reproducibility of the work result. Considering the chemical performance of the used coolants, it is necessary to gain additional information about the chemical mechanisms in the contact zone in order to evaluate the surface quality. This paper deals with investigations of the influence of machining processes on the generation of reaction layers. These layers were generated by using certain coolant additives in machining. For industrial applications it is very interesting to know which effects different coolant additives have on the workpiece surface, because it is well known that adsorption and reaction layers of machining processes hinder thermochemical heat treatment.
Nano-machining instrument for nano-cutting of brittle materials
W. Gao, R.J. Hocken (1), J.A. Patten, J. Lovingood  
STC S,  49/1/2000,  P.439
Keywords: Nano-cutting, instrument, brittle material
Abstract : This paper presents a nano-machining instrument, which was developed for conducting nano-cutting experiments especially on brittle materials. A PZT tube scanner is employed to accomplish a maximum depth of cut of 4 micrometers with 0.1 nm resolution, and a length of cut of more than 20 micrometers. The depth of cut is feedback controlled by using the output of a capacitance probe. The flexural stiffness and the axial stiffness of the instrument were designed to be 6 x 106 N/m and 7 x 107 N/m, respectively. There are two force sensors to measure thrust and cutting forces with a resolution of sub-milliNewtons. The sample is kinematically mounted on the PZT scanner, and the tilt of the sample can be adjusted precisely. Experimental results of nano-scratching and Nano-cutting on single crystal silicon will be presented.
Planar ion channeling study of subsurface damage in polished CdS
D.A. Lucca (1), C.J. Maggiore, M.J. Klopfstein  
STC S,  49/1/2000,  P.443
Keywords: Surface, Polishing, Sub-surface damage
Abstract : Planar ion channeling has been used to investigate the near surface lattice disorder of minimally damaged surfaces of CdS produced by polishing. Surfaces produced by mechanical and chemomechanical polishing were examined along the { } and { } planes of (0001) oriented crystals using incident beam energies of 1 and 2 MeV. Results were compared to those previously obtained under axial channeling conditions. Planar channeling was seen to exhibit increased sensitivity to near surface damage and enabled the identification of damage beyond that detectable with axial channeling for a 1/4 µm diamond abrasive mechanically polished surface.
An analysis of surface properties of hetero-epitaxially grown SiC surface on Si substrate elements
N. Moronuki, Y. Furukawa (1)  
STC S,  49/1/2000,  P.447
Keywords: Silicon carbide, Mirror surface, Deposition process
Abstract : The molecular beam epitaxy process can produce single crystal and smooth surface at atomic level as well as synthesizing the desired material by supplying the multiple materials on substrates. This paper deals with an application of the hetero-epitaxial process of silicon carbide (SiC) on silicon (Si) substrate, and aims to make clear the attainable surface roughness and its properties. It was found that the steep pits were formed during the carbonization process before the epitaxy and that they strongly affected the final roughness. The attainable roughness was 0.4nm rms. Finally, the applicability to toroidal mirror optics was discussed.