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Qualification of standard industrial robots to cope with sophisticated assembly tasks
G. Reinhart (2), R.-G. Gräser, R. Klingel  
STC A,  47/1/1998,  P.1
Keywords: assembling, on-line compensation, robot accuracy
Abstract : New fields of application such as low-tolerance laser welding, micro and precision assembly or measurement technology are to be achieved by standard industrial robots for higher economic efficiency. However actual implementation fails due to the temperature drift caused by time variable internal and external sources of heat. A compensation method for fast online-correction of the time variable, thermal robot behaviour is introduced. This method is based on measuring the temperature-caused deviations and subsequent compensation by software during operation. The presented results show that the temperature caused deviations are minimized to the level of the system inherent repeatability. Hence constant position accuracy of robots can be achieved.
Collision free control of a multi-arm testing robot
H. Terada, H. Makino (1)  
STC A,  47/1/1998,  P.5
Keywords: robot, circuit test, multi-arm
Abstract : A multi-arm testing robot system has been developed in which quadruple SCARA arms move simultaneously in a single working area. To avoid collision, the "occupied quadrant" algorithm is developed. Every quadrant is assigned for each arm and the testing points are selected as there are positive margins between the quadrants. Together with the linear continuous path control in the Cartesian space, with overlapped horizontal and vertical motion, and with simultaneous motion control for all arms, high speed collision-free movement was obtained. The minimum tact time was proved to be less than 0.1 second per moving distance of 8mm.
A concept of an intelligence fuzzy control for assembly robot
P.B. Petrovic, V.R. Milacic (1)  
STC A,  47/1/1998,  P.9
Keywords: robotic assembly, compliance, fuzzy control
Abstract : Active accommodation of robotic manipulator in assembly applications is considered. Mechanical impedance control concept has been chosen for development an intelligent controller for assembly robots, where target impedance appears as a control variable. Basic assumption for successful part mating process according to part mating theory is mechanical isotropy of support system. Consequently, target impedance should be adopted as isotropic. The main problem appearing here is complex analytical formulation of isotropic target impedance and uncertainty of parameters related to the robot and environment model. To overcome this problem an adaptive fuzzy model of isotropic target impedance is proposed. The fuzzy model is incorporated into general impedance control law form, to obtain new fuzzy-impedance control law. Proposed control law has been verified by computer simulation.
Dexterous assembly - manipulation of a compact array of objects
Y. Aiyama, T. Arai (1), J. Ota  
STC A,  47/1/1998,  P.13
Keywords: assembly machine, compliance, manipulator
Abstract : It is often said that a product has few advantages in market if an assembly line of the product can be easily mechanized. Operations turn more dexterous in advanced manufacturing systems. In this paper, a manipulator with three fingers handles a box in a compact array of six boxes. First one of the fingers tumbles one box to make two side faces free from the obstacles. Then the other two grasp both the sides and pick it up. To fulfill such a sequence of dexterous manipulations onto various objects, the design of compliance of the fingers is essential. The paper deals with design of compliance of each finger and with planning of its motion. The proposed methodology is experimented by the robot with three fingers, each of which has three direct drive joints.
Multivariate analysis and evaluation of adaptive sheet metal assembly systems
D. Ceglarek   / M. Szafarczyk (1)
STC A,  47/1/1998,  P.17
Keywords: flexible assembly, error compensation, dimensional error
Abstract : The flexibility of sheet metal assembly processes is one of the most critical issues in the design stage of assembly systems. Currently in the automotive industry, flexibility and adaptability of assembly systems are mainly considered as the capability to assemble a family of products. The notion of assembly system flexibility, as understood from the point of view of error compensation by upstream processes, has not been widely researched. This paper presents a systematic method of flexible/adaptive assembly system evaluation, based on its ability to compensate for part dimensional variability caused by upstream processes. This allows for the expansion of the present design for manufacturability approaches by applying multivariate analysis and fixture diagnostic techniques. The proposed method was applied to evaluate a flexible assembly system at a US manufacturing plant.
Alternative placement systems for three dimensional circuit boards
K. Feldmann (1), S. Krimi  
STC A,  47/1/1998,  P.23
Keywords: assembly, robotic, flexible manufacturing
Abstract : The three dimensional circuit board technology leads to advantages and new special challenges concerning electronics assembly. Two different placement systems were realized at the FAPS institute. The first concept was developed to extend the limits of a Cartesian Placement System. An advanced module for handling the Molded-Interconnect-Device-Technology (MID) in the working space of a SMD assembling system, as well as the use of a pipette with an additional axis, make the 3-dimensional assembly of components into MID possible. The second concept is a Robot Placement System, which consists of hardware components like a six axis robot, a tool changing system, a transport system, moving feeders and a vision system. A critical point in surface mounted technology is the necessary accuracy in cantering the SMD to the pipette and the accurate placement of components. This is realized with the use of vision systems. Thereby, a new strategy for failure compensation was developed. A way to optimise the control structures and kinematic of MID placement systems is the use of modern simulation based development and test systems, which provide facilities to perform structural analysis, collision detection, cycle time calculation as well as off-line programming capabilities.
Simulation of the soldering process
J. Niemeier, G. Seliger (2)  
STC A,  47/1/1998,  P.27
Keywords: soldering, computerized simulation, thermal analysis
Abstract : The expenditure for planning and setting-up of automated facilities for single point soldering is currently very high, since adjusting of process parameters is based on the operator's experience. A process model has been developed which describes the process of single point soldering and allows predictions of its behaviour. The model lakes into account the heat flow into the joint and inside the joint. The model was implemented as a software-tool for computing the temperature profiles in different sectors of the solder joint. With this model the planning and setup time of single point soldering facilities is significantly reduced and control software can be developed.


Catastrophic tool failure detection based on acoustic emission signal analysis
K. Jemielniak (2), O. Otman  
STC C,  47/1/1998,  P.31
Keywords: cutting, tool condition monitoring, acoustic emission
Abstract : Acoustic emission (AE) signal analysis is considered to be a very useful mean of on-line tool breakage detection. Many publications have proclaimed that catastrophic tool failure (CTF) causes an eminent peak in the AE signal. Therefore the magnitude of the AE_RMS signal has been considered as a measure of the CTF. While strong bursts of AE signals similar to those arising from the CTF can be generated by tool engagement and disengagement in interrupted turning, this measure was found to be not always sensitive to the CTF. The aim of this paper is to present a method of the CTF detection in turning which uses symptoms other than the direct AE_RN ,_S signal value taking into considerations the likely bursts that can be generated due to interruption. The method is based on the statistical analysis of the distributions of the AER_MS signal. The kurtosis and the sum of the (3 distribution parameters r and s were the main measures employed. They were found to be highly sensitive to tool chipping and breakage and have given promising results with regard to CTF detection.
An automatic system for elaboration of chip breaking diagrams
J.L. Andreasen, L. De Chiffre (2)  
STC C,  47/1/1998,  P.35
Keywords: turning, chip breaking, automatic recognition
Abstract : A laboratory system for fully automatic elaboration of chip breaking diagrams has been developed and tested. The system is based on automatic chip breaking detection by frequency analysis of cutting forces in connection with programming of a CNC-lathe to scan different feeds, speeds and cutting depths. An evaluation of the system based on a total of 1671 experiments has shown that unfavourable snarled chips can be detected with 98%37; certainty which indeed makes the system a valuable tool in chip breakability tests. Using the system, chip breaking diagrams can be elaborated with a previously unattainable productivity and objectivity.
The temperature of a single crystal diamond tool in turning
T. Ueda, M. Sato, K. Nakayama (1)  
STC C,  47/1/1998,  P.41
Keywords: ultra-precision turning, temperatures, single crystal diamond
Abstract : The temperature on the rake face of a single crystal diamond tool in precision turning is investigated experimentally and theoretically. The infrared rays radiated from the contact area between the chip and rake face, and transmitted through the diamond tool, are accepted by a chalcogenide fiber and led to a two-color detector which consists of InSb and HgCdTe detectors. The temperature distribution in the tool and in the workpiece is calculated numerically using FEM. From these results, the maximum temperature on the rake face is found to be approximately 190°C for aluminum and 220°C for copper at a cutting speed of 620 m/min. The temperature increases with the increase of cutting speed for the range of cutting speeds investigated.
Diamond cutting of silicon with nanometric finish
F.Z. Fang, V.C. Venkatesh (1)  
STC C,  47/1/1998,  P.45
Keywords: mirror surface, diamond cutting, brittle material
Abstract : Micro-cutting is a viable alternative to grinding and polishing techniques in the fabrication of high quality brittle materials. Using different diamond tools with rake angles of 0 degree and -25 degree at different cutting speeds, taper cutting experiments were carried out with increasing depth of cut on silicon. The grooves formed were analysed by Scanning Electron Microscopy and Optical Measurement Inspection System. Topographic details were studied using Atomic Force Microscope. For turned silicon surfaces with roughness value of Ra=23.8 nm and Rmax=140 nm, mirror surfaces of 1 nm roughness were achieved repeatedly by micro-cutting. The integrity of the resulting surfaces were then studied in detail by using Atomic Force Microscopy and Scanning Electron Microscopy. The results prove that the micro-cutting mechanism, proposed in theory, is justified in actual material removal in the range of nanometers.
A model for simulation of vibrations during boring operations of complex surfaces
J.F. Rigal, C. Pupaza, C. Bedrin (2)  
STC C,  47/1/1998,  P.51
Keywords: boring, simulation, stability
Abstract : The dynamics of the cutting process, as well as the behaviour of the piece and the tool, have a strong influence on the quality of the machined surface, particularly in the boring operations of complex surfaces with thin walls. On the basis of a parameterised model of the tool-material interaction, a linear FEM model describing the behaviour of the workpiece, tool and their contact is presented. The frequency responses are processed and the simulation extends with a mixed procedure (FEM analysis and simulation using Matlab). The purpose is to characterize the stability conditions of the cutting process.
On the dynamics of high-speed milling with long, slender endmills
M.A. Davies, B. Dutterer, J.R. Pratt, A.J. Schaut   / J.B. Bryan (1)
STC C,  47/1/1998,  P.55
Keywords: milling, vibration, modelling
Abstract : Tool deflections of high length-to-diameter ratio endmills are measured with capacitance probes during high-speed milling and compared with the predictions of regenerative chatter theory. Poincaré sectioning (once per revolution sampling) techniques are introduced as a new means of characterizing and identifying chatter. The regenerative chatter theory seems to accurately predict the stability of high-immersion slotting cuts: however, undesirable vibrations observed in partial immersion cuts seem inconsistent with existing theory. The practical utility of in-depth knowledge of the stability behaviour of long endmills is demonstrated by the high-speed machining of an example component using a dynamically tuned tool.
Milling titanium compressor blades with PCD cutter
E. Kuljanic (1), M. Fioretti, L. Beltrame, F. Miani  
STC C,  47/1/1998,  P.61
Keywords: milling, titanium, diamond
Abstract : This paper investigates the possibility of finishing milling of titanium alloy TiAI6V4 compressor gas turbine blades with polycrystalline cubic diamond POD cutter that can be used successfully for milling "slim" - low stiffness - blades. The tool life of POD cutter was very long T=381 minutes while surface roughness of the machined surface was low and the geometrical accuracy was satisfactory. A suitable inclination of the cutter axis to the surface has been determined. A basic consideration of milling titanium based alloy with PCD cutter and an analysis and discussion of the chip formation are presented. Better results are obtained when cooling refrigerant was applied. Finishing milling of titanium alloy TiAI6V4 "slim" blades with PCD cutter is promising.
Improved cutting processes with adapted coating systems
F. Klocke (2), T. Krieg, K. Gerschwiler, R. Fritsch, V. Zinkann, M. Pöhls, G. Eisenblätter  
STC C,  47/1/1998,  P.65
Keywords: cutting, coating, process improvement
Abstract : Since the introduction of coated metal cutting tools, there has been continuous development and improvement of substrates and coatings. These improvements are invariably aimed at better resistance to the stresses involved in specific cutting tasks like interrupted cutting, machining of adhesive materials or hard and dry machining. Examples of improved performance coatings include multilayer hard thin films or composite hard/soft coatings. The paper documents fundamental research work indicating how various advanced coatings affect contact conditions and wear mechanisms during the machining of different ferrous and non-ferrous metals. Layers formed during the cutting process are also considered. Results are supplemented by application-oriented experiments during a number of cutting processes.
Experimental and FEM analysis of the fatigue behaviour of PVD coatings on HSS substrate in milling
K.-D. Bouzakis (1), K. Efstathiou, N. Vidakis, D. Kallinikidis, S. Angos, T. Leyenderker, G. Erkens,  
STC C,  47/1/1998,  P.69
Keywords: PVD coatings, fatigue, HSS
Abstract : The new generation of single and multilayer thin hard coatings ensures the improved tool life and the enhanced superficial quality of the workpiece material. However, in interrupted cutting processes such as in milling, the tool coating life time may be limited by fatigue phenomena. Nowadays, the fatigue performance of coatings is quantitatively predictable. In the present paper, the fatigue prospects of PVD coatings on High Speed Steel (HSS) inserts are examined experimentally and analytically in milling. The coating failure is depicted by means of Scan Electron Microscopy (SEM) investigations and Energy Dispersive X-ray (EDX) microspectral analyses. The cutting process is simulated by means of a Finite Elements Method (FEM) parametric model and the stress results illustrate a fatigue prediction that fits to the experimental ones. Data required for the FEM simulation, such as material properties, cutting forces, chip compression ratio etc. are determined experimentally.
A contribution to the study of the cutting mechanisms during high speed machining of hardened steel
G. Poulachon, A. Moisan (1)  
STC C,  47/1/1998,  P.73
Keywords: chip formation, hard turning, modelling
Abstract : A 1000r6 steel with a hardness HRC62 was machined. Quick stop tests were carried out to observe the different chip formation mechanisms. A limit was found between the shearing or cracking chip formation. Experimentations for the selected steel at HRC62 were led at various cutting speeds and feed rates. The "saw tooth chips" obtained were examined geometrically and metallurgically on longitudinal midsections. Relations have been established between the chip geometry and the cutting conditions. A theoretical study on the chip shape was made, in particular about its thickness. The friction stick slip velocities, as the segment apparition frequency were calculated. Each stage of the chip formation could be observed on each micrography of Q.S.T, especially the crack initiation.
The mechanism of chip formation when hard turning steel
M.C. Shaw (1), A. Vyas  
STC C,  47/1/1998,  P.77
Keywords: cutting, chip formation, hard turning
Abstract : Steels having a hardness of H_RC 60 or greater are presently being finished by turning instead of grinding. This is usually done using a polycrystalline cubic boron nitride insert having a rather large nose radius on a very rigid machine at a relatively high cutting speed. In order to understand this process it is important that the sequence of events occurring in the formation of the unique type of chip involved be correctly identified. Experimental evidence to this end is presented and discussed in fundamental terms.
An investigation of material structure transformation in the cutting process
J. Peklenik (1), M. Kisin  
STC C,  47/1/1998,  P.83
Keywords: plastic deformation temperature, energy quanta, transformation of microstructures
Abstract : An understanding of the cutting process and its mathematical modelling requires knowledge about the material structures and their behaviours under the mechanical and thermal loads in the transformation zone. The tests with single and double phase microstructures - copper and carbon steels, with preliminary deformed and undeformed structures have been executed. The influence of various microstructures and process conditions on the energy quanta and the plastic deformation temperature in the transformation zone and the dislocation mechanism are better understood. Preliminary accumulated energy in the material structure contributed to the transformation energy and to a decrease of the temperature. Based of these results some elements of the transfer function of the process may contribute to a generic expression for an on line cutting process identification.

 STC Dn 

Engineering environments in the information age : research challenges and opportunities
F. Kimura (1), H. Lipson, M. Shpitalni (1)  
STC Dn,  47/1/1998,  P.87
Keywords: engineering environments, information technology, life cycle engineering
Abstract : This paper examines changes to the contemporary product engineering cycle resulting from the Information Age and identifies information-related obstacles that correspond to the human dimension of information overload in engineering. These obstacles may explain why increases in productivity have been disappointing and why information technology has not been able to satisfy the increasing demands placed on contemporary engineers. Three productivity impeding categories are discussed: (a) detail overload, (b) constraint overload, and (c) versatility overload. The authors suggest how new emerging paradigms and technologies can be harnessed to alleviate the identified difficulties. Three directions for improvement are discussed: (a) bringing computer tools into the engineering process earlier, permitting more extensive exploration and informed selection of alternatives, (b) improving human-computer interfaces towards in-context natural interaction, making information exchange more fluent and fast, and (c) transforming computers from passive to active self-initiated engineering aids that can suggest alternatives and convey relevant information. The paper discusses applications to areas such as design, manufacturing, simulation, quality assurance, and maintenance.
3D scanning and level of detail modelling for design and manufacturing
A. Fischer (2), S. Park  
STC Dn,  47/1/1998,  P.91
Keywords: reverse engineering, scanning, progressive models
Abstract : 3D scanning and modelling of manufacturing products play an important role in the rapid prototyping cycle. In order to achieve accurate reconstructed products, points are sampled at high density. However, for reconstruction, conventional methods usually reduce the data homogeneously without taking shape behavior, such as curvature and topology, into consideration. As a result, essential characteristic details may be lost. In this paper, an advanced method for reconstructing progressive models is proposed. Through this method, the reconstructed geometric model is represented by hierarchical levels of detail. The option to explicitly control the levels of detail is essential for design, modelling and analysis. The main advantage of the approach is that the sampled points are significantly reduced to several levels of abstraction, while at each level the geometric behaviour is preserved. That is, even at lower resolution levels, critical details are preserved. Moreover, the method has been extended to progressive time and geometric models for simulation and is demonstrated by several examples.
Automatic determination of 3-D parting lines and surfaces in plastic injection mould design
A.Y.C. Nee (1), M.W. Fu, J.Y.H. Fuh, K.S. Lee, Y.F. Zhang  
STC Dn,  47/1/1998,  P.95
Keywords: injection moulding, automated design, CAD
Abstract : In this paper, a methodology to generate the 3-D parting lines and parting surfaces is presented based on the optimal parting direction, the geometrical characteristics and topological relationships of injection moulded parts. The moulding surfaces are first classified into three main groups according to their orientation to the parting direction and their topological relationships. The largest edge-loop of the surface group is then defined and the algorithm to generate the edge-loop in different surface groups is proposed. The method to calculate the projected area of an edge-loop on the plane perpendicular to the optimal parting direction is also introduced. The 3-D parting lines are generated based on the proposed criterion of considering the above projected areas of edge-loops. After the parting lines are determined, the parting surfaces are generated by extruding the parting lines perpendicularly outwards to the parting direction. The case studies show that the methodology is efficient in determining the parting lines and the parting surfaces automatically in an intelligent mould design system.
Integration of manufacturing processes in design
S. Tichkiewitch, M. Véron (1)  
STC Dn,  47/1/1998,  P.99
Keywords: design, integration, manufacturing
Abstract : Constraints concerning the manufacturing of product parts must be integrated as early as possible in the product design process, in order to reduce costs and time to market. For this, a part of manufacturing knowledge must be at the design team's disposal all through the design process. In order to facilitate the consideration of machining and forging capabilities by a group of designers, we have developed computer tools. This paper describes the linkage of these tools with our CAD system and the benefits of such integration in the form of shape and cost evaluation.
Design by customers for mass customization products
M.M. Tseng (2), X. Du  
STC Dn,  47/1/1998,  P.103
Keywords: product design, requirement analysis, computer aided design
Abstract : Producing what customers need with near mass production efficiency, or Mass Customisation, has become a major trend in industry. Effective definition of customer requirements is a pre-requisite for realizing mass customisation. We propose "Design by Customers" as an approach for companies to communicate to customers about what the company can offer, to find out customer needs, to assist customers in making choices and to negotiate for agreements. In this paper, the design and manufacturing capabilities of a company are represented in a Product Family Architecture. Adaptive Conjoint Analysis is then applied to help customers assert their needs, define variations from base products, visualize their options and assess alternatives.
An agent supported approach to collaborative design
Y. Jin, S.C.Y. Lu (2)  
STC Dn,  47/1/1998,  P.107
Keywords: design, coordination, system
Abstract : Contemporary design problems are inherently complex and involve many highly coupled sub-tasks that require multiple designers to work together collaboratively. The designers' objectives are often in conflict and activities inconsistent. How to provide effective technology to support collaborative design has been a challenge for the research community. This paper presents an agent-supported framework, called ASCAD, for collaborative design. In ASCAD, a collaborative design team is viewed as a collection of /design cells /and each design cell is composed of a designer, a software agent, and a number of computer tools. By monitoring designer's design activities, the agent in ASCAD can help its designer coordinate with other designers through identifying needs for coordination, establishing links between designers, and providing suggestions for coordination decision-making. A brief description and discussion of an initial demo application of ASCAD is included to demonstrate the effectiveness of the ASCAD framework and to illustrate future research directions.
Scheduling and coordination of distributed design projects
F. Liu, P.B. Luh, B. Moser   / R.L. Kegg (1)
STC Dn,  47/1/1998,  P.111
Keywords: scheduling optimization, distributed design project, coordination
Abstract : In the era of time-based competition, companies are tending to distribute product design across regions to cut short design cycles and better penetrate local markets. This distributed design involves many uncertainties and risks, and generating good decentralized schedules and effectively coordinating distributed activities without intruding organizations' propriety information and decision-making authorities are important and challenging. This paper studies the scheduling and coordination of distributed design projects with uncertainties while managing design risks. A novel mathematical optimisation model that balances modelling accuracy and computation complexity is presented, and a solution methodology that combines Lagrangian relaxation and stochastic dynamic programming is developed. Numerical results demonstrate that near optimal solutions are obtained, and uncertainties are effectively managed for problems of practical sizes.
Product design for disassembly and bulk recycling
M. Sodhi, W.A. Knight (2)  
STC Dn,  47/1/1998,  P.115
Keywords: design, disassembly, environmental
Abstract : The recycling of manufactured products depends greatly on the efficiency with which material can be separated from each other. For the long term, recycling can be made more effective by the design of products for greater use of disassembly and recycling. This requires the development of suitable product analysis tools to enable design teams to evaluate the ease of disassembly and recycling of alternative product concepts during the early stages of design. This paper describes the development of product analysis procedures for combined disassembly and bulk recycling such that consequences of material selection upon the end-of-life recovery of materials can be investigated.
Product quality evaluation based on behaviour simulation of used products
F. Kimura (1), T. Hata, H. Suzuki  
STC Dn,  47/1/1998,  P.119
Keywords: life cycle design, product quality evaluation, deterioration
Abstract : For aiming at maintaining proper product functionality with reduced disposal, a rapid product life cycle is proposed, which accelerates product flow in product life cycle, and realizes early take-back of obsolete products for reuse and upgrade. Commodity products, such as household appliances and computer peripherals, are considered as target products. As a basis for such life cycle design, a computer simulation method is investigated for product quality evaluation under deteriorated conditions. The proposed method has been tested for a functional mechanism of a copying machine.
Product modelling for model-based maintenance
F.J.A.M. van Houten (1), T. Tomiyama, O.W. Salomons  
STC Dn,  47/1/1998,  P.123
Keywords: product, modelling, maintenance
Abstract : The paper describes the fundamental concepts of maintenance and the role that information technology can play in the support of maintenance activities. Function-Behaviour-State modelling is used to describe faults and deterioration of mechanisms in terms of user perception and measurable quantities. Fault diagnosis, repair and maintenance strategies are explained briefly. Model-based Maintenance is discussed in terms of inspection, monitoring, diagnosis and planning, based on functional, behavioural and state models. Some examples of mechanisms illustrate the advantage of using computer-based models as a reference for fault diagnosis. Underlying techniques like qualitative physics, tolerance analysis, and dynamic simulation are discussed. The proposed method is aiming at functionally robust designs, reduction of preventive maintenance cost and more effective fault diagnosis.
Strategic planning of information technological infrastructures for life cycle management
F.-L. Krause (1), C. Kind  
STC Dn,  47/1/1998,  P.129
Keywords: information technology, life cycle, management
Abstract : In parallel with the increase of the importance of life cycle management aspects the appropriate supply of information according to specific requirements within all life cycle phases becomes more important. By this, an information management system is needed which has to be based on an appropriate information technological infrastructure to secure the information flows between life cycle phases distributed in place and time. Within this contribution a reference model of such information technological infrastructures will be presented, which contains the most important elements to fulfil the complex tasks and can be used to derive specific infrastructures. Based on this reference model a simulation system is described which has the task to model and optimise information technological infrastructures.


Ways to intensify laser hardening technology
V.S. Kovalenko   / D.F. Dauw (1)
STC E,  47/1/1998,  P.133
Keywords: hardening laser, quality, improvement
Abstract : At this stage of the laser material hardening development, few techniques to intensify the process and to improve the quality of the hardened surfaces may be proposed: 1) the development of new absorption coatings to increase laser radiation absorption efficiency of the surface to be hardened; 2) the development of devices to measure material absorptivity and instant temperature in working zone at laser irradiation to control treatment conditions; 3) the new compositions development for alloying arid cladding; 4) the development of combined techniques. The study results of these and other techniques are presented and discussed.
Adaptive control for laser cutting using striation frequency analysis
H. Kaebernick (2), A. Jeromin, p. Mathew  
STC E,  47/1/1998,  P.137
Keywords: cutting, laser, adaptive control
Abstract : An adaptive control system for laser cutting has been developed with the aim to improve the productivity and the cut quality. The control strategy is based on a set of parameters, which have an effect on the quality of the cut, This paper focuses on one of these parameters, namely the striations on the cut surface. A spectrum analysis technique has been developed which allows striation frequency analysis to be used on-line. It utilises a process monitoring system which detects light emissions directly at the cut front. Cutting experiments with a 1.5kW CO_2 laser using this technique have shown that it is possible to improve the cut quality.
Excimer laser cutting : experimental characterisation and 3D numerical modelling for polyester resins
L.M. Galantucci   / F. Giusti (1)
STC E,  47/1/1998,  P.141
Keywords: excimer laser, cutting, modelling
Abstract : Excimer laser has been proposed in these years as a new technology for precision cutting of plastic materials, due to the photo ablative mechanism and to the low thermal damage. Previous experiments, done by the authors, on the cutting of kevlar reinforced composites with epoxy matrix, using excimer laser, highlighted very high qualities not attainable with other technologies. In the present work the attention was focused on thermoset polyester resin, because of the extensive use of this material as matrix for plastic composites. The methodology proposed in this work allows to simulate in three dimensions the laser cutting shape and size by means of a photo-ablation approach, that takes also into account the thermal effects. An experimental characterisation of the resin was performed to determine the threshold fluence (energy surface density) and the other material parameters needed to apply a photo-ablation model. The numerical simulations, compared with the experimental cuts, gave results in good accordance in terms of shape and depth of cut.
Micromachining with excimer laser
G. Ricciardi (2), M. Cantello (2), F. Mariotti, p. Castelli, p. Giacosa  
STC E,  47/1/1998,  P.145
Keywords: excimer laser, micro-machining, polymer
Abstract : This paper deals with micromachining of different materials using a 100 W excimer laser at RTM laboratories. The first part of the works reports the results of optical simulations carried out on several layouts calculated using a sequential ray tracer in order to evaluate the aberrations and improve the performance of the optics and masks. Resolutions in the range of few micrometers have been achieved. The second part of this paper deals with process testing on different base materials such as metals, ceramics, polymers. The best results have been achieved on polymers while metals show undesired effects of growth of materials at the border of the processed area due to typically intense shock waves. The reliability of polymer micromachining opens several industrial fields of applications to the excimer laser technology. As an example a drilling system for ink jet printer heads is briefly described.
An analysis of physico-chemical process of reactive ion etching (RIE) to adapt for three dimensional micro-machining
Y. Furukawa (1), A. Kakuta  
STC E,  47/1/1998,  P.149
Keywords: etching, micro-machining, single crystal silicon
Abstract : Reactive Ion Etching (RIE) is more widely used in LSI production than Plasma and Sputter etching for its inherent property as to act both physically and chemically. The ratio of physical and chemical removing reaction is not a concern so much in LSI production because of its role to generate only surface features. However, some three dimensional micro shapes could be generated by RIE if that ratio would be clarified. The present study identified the RIE removing process model through a variety of experiments by taking accounts both of physical reaction of ions and chemical reaction of radicals to silicon, It became possible to control an aspect ratio of micro-machined profiles by properly selecting a condition of a Radio Frequency power and a reactor's pressure.
Removal characteristics of processing with SPM
T. Miyazaki, S. Yoshioka, Y. Shirai, T. Misu, N. Taniguchi (1)  
STC E,  47/1/1998,  P.153
Keywords: removal, processing, SPM
Abstract : SPM (Scanning Probe Microscope) can be used as a processing tool. In the present paper, process ings are carried out with AFM and STM in air at room temperature. In case of AFM processing with silicon tips, no depression is formed in gold workpiece; however, it is formed in silicon workpiece, which seems to be caused by strong adhesion between the same materials. In case of STM processing with tungsten tips, although depressions are formed in the gold workpiece, the reproducibility is low with hand-made tips; however, field evaporation processing is carried out with high reproducibility.
An experimental investigation into the effect of hatch pattern in stereolithography
S.O. Onuh, K.K.B. Hon (2)  
STC E,  47/1/1998,  P.157
Keywords: stereolithography, rapid prototyping
Abstract : The implementation of rapid prototyping technology in industrial and domestic manufacturing processes has revolutionised new product development process. The aim of this investigation is to study the effects of layer thickness, hatch styles, hatch spacing, hatch overture and hatch fill cure depth on specimens produced by stereolithography. Previous investigations have shown that when layers are scanned in only one direction, shrinkage forces occur mainly in the scanning direction. Hence alternating the exposure of the layers will results in a more homogeneous structure of residual stress in the part. A unique experimental investigation has been carried out with a new hatch pattern that has significantly improved the stereolithography product quality adding a novel dimension to the technology.
Rapid prototyping by selective electrodeposition using electrolyte jet
M. Kunieda (2), R. Katoh, Y. Mori  
STC E,  47/1/1998,  P.161
Keywords: rapid prototyping, electro-deposition, micro-machining
Abstract : This paper describes the development of a rapid prototyping technique which can produce metal parts by electrodeposition using an electrolyte jet. The calculated results verify that electrodeposition occurs selectively at the spot where an electrolyte jet is impinged. To prevent instability in electrodeposition, lapping was inserted regularly between each deposition cycles, enabling walls to be formed without limiting the height. Using copper nitrate aqueous solution as the electrolyte and a round nozzle with a diameter of 0.53 mm, a copper micro-part was fabricated successfully.
Minimization of machining allowance in electrochemical machining
K.P. Rajurkar (2), D. Zhu, B. Wei  
STC E,  47/1/1998,  P.165
Keywords: electro-chemical machining, environment, allowance
Abstract : Electrochemical machining (ECM) provides one of the best alternatives for producing complex shapes in advanced materials used in aircraft and aerospace industries. However, the reduction of sludge and memory errors continue to be major challenges for industries in addressing waste generation and accuracy improvement. This study focuses on minimizing the material to be removed by predicting minimum machining allowance and improving the degree of localized dissolution. Experiments have been conducted to verify the prediction results on an industrial ECM system. The use of pulse current with passivating electrolyte has been found to mitigate the sludge generation and improve accuracy.
Micro-EDM for three dimensional cavities - development of uniform wear method -
Z.Y. Yu, T. Masuzawa (1), M. Fujino  
STC E,  47/1/1998,  P.169
Keywords: EDM, Micromachining, microcavity
Abstract : In this paper, we present a new method, called uniform wear method, for 3D micro-EDM. Simple electrodes such as with round or rectangular section are used. Uniform wear at the end of the electrode was realized by layer-by-layer machining. This maintains the original electrode shape and converts the three dimensional electrode wear to a linear one. By compensating the linear electrode wear, complicated three dimensional cavities were successfully machined. This technique was developed for micromolds, but the applicability for normal size molds was also confirmed.
System identification of wire electrical discharge machining
N. Mohri (2), H. Yamada, K. Furutani, T. Narikiyo, T. Magara  
STC E,  47/1/1998,  P.173
Keywords: wire EDM, vibration, identification
Abstract : In wire electrical discharge machining (wire-EDM). it is very important to restrain the vibration of the tool wire electrode for the improvement of machining accuracy. In this paper, investigation is carried out toward the dynamic wire vibration mechanism and a mathematical model is derived. This model is compared with experimental results. The measured displacement of a wire electrode in machining a thin plate is analysed with impulsive force measured through impulse response by a single discharge. The force acting on the wire depends on the direction of the wire movement in vibration. A 3rd order system equation for the wire EDM system is derived considering machining removal and vibrational features of the system are discussed with the equation. As the discharge circuit suddenly changes according to gap condition, this vibration system is essentially nonlinear. Simulation of wire-EDM is performed with the modelled system.


On predicting the forming limit diagram for automotive aluminium sheet
S.G. Xu, K.J. Weinmann (1)  
STC F,  47/1/1998,  P.177
Keywords: forming limits, aluminium sheet, analysis
Abstract : Aluminum has considerable potential as a material for automotive panels. The ability to predict forming limit diagrams accurately for aluminum is important for preventing failure in the forming process. A method is proposed to develop forming limits using Hill's1993 yield criterion. Predicted limit strains based on both Hill's 1948 and 1993 yield criterion are compared with experimental data for Aluminum 6111-T4. It is found that Hill's 1993 yield criterion can characterize localized necking in aluminum sheets well, while Hill's 1948 criterion cannot. The critical thickness rule is found useful in predicting the left hand side of FLDs.
Enhancement of drawability by local heat treatment
F. Vollertsen, K. Lange (1)  
STC F,  47/1/1998,  P.181
Keywords: aluminium alloy, laser heat treatment, deep drawing
Abstract : A method is described which can be used to increase the drawability of aluminium alloys significantly. It is based on a local heat treatment of the blanks, reducing the local flow stress by a restitution of the precipitation particles. The term of homologous heat is introduced to characterize the heat treatment parameters. Laser heat treated blanks were deep drawn. The failure modes are discussed using an analytical model for the drawing force of such blanks. It is shown that an increase of the limiting drawing ratio from 2.1 for homogeneous blanks up to more than 2.4 for inhomogeneous blanks can be reached.
Calculation of isothermal flow stress by combination of FEM and simple compression test
O. Kada, T. Miki, M. Toda, K. Osakada (1)  
STC F,  47/1/1998,  P.185
Keywords: forging, flow stress, finite element method
Abstract : In forging processes, simulation by the FEM with temperature calculation is frequently carried out to predict the forging load and others. For the simulation, exact flow stress of the materials is essential but almost no complete data of flow stress for temperature calculation are available. This is because isothermal flow curve cannot be obtained directly by simple compression test as the temperature in the specimen is changed during deformation. The calculation method of isothermal flow stress for the FEM with temperature calculation is proposed by removing the effects of friction, heat generation, and heat transfer from the results of simple compression tests.
An inverse approach for the design of the optimal preform shape in cold forging
R. Di Lorenzo, F. Micari (2)  
STC F,  47/1/1998,  P.189
Keywords: closed die forging, process design, statistical analysis
Abstract : In closed die forging the preform design plays a critical role for the success of the process: in fact it must ensure that in the finishing step the desired product is obtained without shape defects such as underfilling or folding and with a minimum material loss into the flash. In the paper an inverse approach is applied to the preform shape optimisation problem: the method permits to evaluate a response function which links the set of parameters defining the preform shape with the fulfilment of the product design specifications. The proposed approach has been applied to a closed die forging process aimed to the production of a C-shape component, and has allowed to determine the optimal preform geometry which ensures the complete filling of the die cavity.
A new forging preform design approach using reverse simulation
C.C. Chang, A.N. Bramley (1)  
STC F,  47/1/1998,  P.193
Keywords: forging, upper bound, die design
Abstract : A new reverse simulation approach for the optimal design of forging preforms using the Tetrahedral Element Upper Bound Analysis (TEUBA) is presented. The approach employs a criterion based on the concept of the material distribution to determine the boundary condition and to evaluate the complexity of the deformed shapes resulting from reverse simulations. The approach aims to predict an initial billet section which is close to a rectangle as ideal, or a preform shape where preform stages are required. The produced preforms are assessed by performing forward simulations with a commercial modelling package. The approach is shown to have a considerable potential in preform design.
Controlled bending of aluminium extrusions
M. Geiger (1), A. Sprenger  
STC F,  47/1/1998,  P.197
Keywords: bending, aluminium extrusion, neural network control
Abstract : This paper presents a control circuit for a stretch bending process of aluminium extrusions. The control strategy is derived from an analytical model which accounts for the process parameters allows the calculation of springback. The first component of the control circuit is the definition of suitable target and control values, for the later of which tensile stresses have been qualified. Furthermore different sources of information as for the characterisation of the workpiece are discussed. The calculation of a new reference input variable is executed by a neural network. Results as to the controlled bending process will be given.
An integrated approach in design tooling, setting-up and timing of forging transfer-machines
P.F. Bariani (1), G. Berti, L. D'Angelo, J.J. Yang  
STC F,  47/1/1998,  P.203
Keywords: forging, tooling, press
Abstract : Multi-station forging machines with automatic work transfer between stations permit very high production rates to be reached, but considerable time and effort by skilled personnel must be spent in workplanning and their setting up and timing. The paper presents an integrated approach to the computer-assisted design of the tooling systems and identification of appropriate setting conditions and timing for multi-station presses to be used in cold, warm and hot forging. The approach is based on (i) the classification of possible configurations of punch- and die-side tool subassemblies, (ii) the automatic retrieval of the tool-holder assembly configuration for the specific station of the press, (iii) the assembly rules and automatic scaling and fitting of individual tool components and (iv) the animation -with check for interference- of die, punches, slugs, grippers and ejectors according to the kinematic model of the press.
In-process punching with pressure fluids in sheet metal forming
E. Von Finckenstein (1), M. Kleiner, W. Homberg, E. Szücs  
STC F,  47/1/1998,  P.207
Keywords: punching with pressure fluids, process analysis
Abstract : The economical efficiency of metal forming procedures based on pressure fluids can be increased e. g. by integrating the additional (auxiliary) operation of punching into the metal forming process. The potentialities resulting from this proceeding are discussed exemplarily for a high pressure sheet metal hydroforming process. The present investigation is using the FE method for analysing and optimising various approaches to in-process punching on high pressure sheet metal hydroforming. Experimental tests are carried out in order to verify the different approaches.
Modelling and control of hydroforming processes for flanges
J.C. Gelin (1), O. Ghouati, p. Paquier  
STC F,  47/1/1998,  P.213
Keywords: deep drawing, aquadraw, sensitivity
Abstract : The modelling of hydroforming processes is studied from experiments and numerical modelling using advanced finite element methods. The paper demonstrates that simulation results fit well experiments. It also demonstrates that is possible to access control of process driving parameters, i.e. pressure in the die cavity or blank holder load in order to achieve a specified result in term of shape or thickness variation. The reliability and the accuracy of the proposed procedures are illustrated in the case of flange forming for different geometries and materials. It is demonstrated that the proposed method provides an accurate tool to help the process designer to assess the effect of process parameter on the final resulting sheet metal part.
Sheet metal forming of Titanium blanks using flexible media
N. Alberti (1), A. Forcellese, L. Fratini, F. Gabrielli  
STC F,  47/1/1998,  P.217
Keywords: sheet metal, titanium, FEM
Abstract : Sheet metal forming processes using flexible media are increasingly utilized in the industrial practice due to the relatively low tooling cost. In the present investigation, a rubber forming process is applied to the manufacturing cycle of a titanium alloy component for acoustic tweeters. The proposed process allows a reduction in manufacturing costs and production time since it permits the elimination of some joining operations. The FEM analysis has permitted the definition of the optimal process parameters and tooling geometry. Accordingly, several components have been produced, the achieved quality level is comparable with the one obtained utilizing the conventional technology and consistent with the FEM predictions.
A study of mechanisms of liquid lubrication in metal forming
J. Bech, N. Bay (1), M. Eriksen  
STC F,  47/1/1998,  P.221
Keywords: liquid lubrication mechanisms, metal forming
Abstract : Applying a transparent tool technique the lubrication in plane strip drawing of aluminium sheet is studied providing the strip with surface pockets for entrapment of lubricant. The compression and eventual escape of trapped lubricant by Micro Plasto HydroDynamic Lubrication (MPHDL) as well as Micro Plasto HydroStatic Lubrication (MPHSL) is observed and quantified experimentally with varying lubricant viscosity, drawing speed, reduction, die angle, back tension, workpiece material and friction conditions. All these parameters are shown to influence the mechanisms of lubricant escape in an explicable way. Theoretical models for the two observed mechanisms of lubricant escape, i.e. backward escape by MPHDL and forward escape by MPHSL are established combining a continuum mechanic analysis of the pressure distribution in the tool/workpiece interface with fluid mechanic analyses of the lubricant escape. Experimental observations of oscillations in the drawing force are quantitatively shown to be caused by the two mechanisms of lubricant escape.
Mashy metal/alloy joining a new process for manufacturing new products
M. Kiuchi (1), J. Yanagimoto, S. Sugiyama  
STC F,  47/1/1998,  P.227
Keywords: forming, semi-solid, bonding
Abstract : A new process to join metal and ceramics components on to aluminum, copper and magnesium alloys was proposed. The process is based on joinability of mashy (mushy/semi-solid) alloys. This paper shows the obtained results regarding two types of joinings as follows. (1) Multi wire fins (pins) were joined on to base blanks of an aluminum alloy. (ex. Wire fin type heat- sinks were made.) (2) Multi sheet fins were joined on to base blanks of an aluminum alloy (ex. Sheet fin type heat- sinks were made.). The effects of process parameters on the shear strength of interfaces between joined fins and base blanks and their internal structures were investigated. Through the study, it is found that the mashy- state joining makes it possible to join various materials together which can not be joined by other processes such as welding and soldering.


Experimental investigation of methods to enhance stock removal for superfinishing
B. Varghese, S. Malkin (1)  
STC G,  47/1/1998,  P.231
Keywords: superfinishing, abrasion, loading
Abstract : Superfinishing is widely used as a subsequent operation after grinding to reduce surface roughness and increase bearing load capacity The present investigation was undertaken to explore methods for enhancing superfinishing performance. Experiments conducted on hardened bearing steel indicate the existence of an optimal applied contact pressure where both the stock removal and the finishing ratio are maximum and the specific energy is minimum. Above the critical pressure, the stock removal is adversely affected by loading of debris on the stone surface. Applying ultrasonic vibrations normal to the surface was found to reduce loading by promoting stone wear. Further enhancement in superfinishing performance was achieved by providing axial grooves on the stone surface. The use of ultrasonic vibrations together with axially grooved stones increased the stock removal by as much as 65%37; while providing comparable surface roughness.
Analysis on lapping and polishing pressure distribution
G.Q. Cai, Y.S. Lu, R. Cai, H.W. Zheng (1)  
STC G,  47/1/1998,  P.235
Keywords: lapping, polishing, pressure
Abstract : In the processes of plane lapping and polishing, the pressure distribution between the workpiece and the lapping plate or the polishing pad is very important to flatness generation. This paper presents elastic contact models for plane lapping and polishing with or without guard ring. Based on these models. the pressure distribution has been obtained. Furthermore, the effects of various parameters on the pressure distribution, such as the material properties of the workpiece, the plate and the pad, the ratio of load bearing on the guard ring to the total load, the width of the guard ring, the gap between the workpiece and the guard ring, and the thickness of the polishing pad, have been discussed.
Rapidly renewable lap : theory and practice
C.J. Evans (2), R.E. Parks, D.J. Roderick, M.L. Mc Glauflin  
STC G,  47/1/1998,  P.239
Keywords: lapping, polishing, abrasion
Abstract : The Rapidly Renewable Lap (RRL) uses a textured substrate over which thin films are slumped. The substrate provides the geometry of the lap and a localized texture, depending on the film thickness, properties, and means by which it is deformed over and adhered to the substrate. Abrasives, added to the film, lap or polish without touching or changing the substrate geometry. Depending on process parameters, the RRL gives brittle or ductile (two-body) lapping. This paper has two major themes: it describes the RRL and some applications: and it shows that some relatively simple lapping models predict of process characteristics.
Infeed grinding of silicon wafers applying electrophoretic deposition of ultrafine abrasives
Y. Tani (2), T. Saeki, Y. Samitsu, K. Kobayashi, Y. Sato  
STC G,  47/1/1998,  P.245
Keywords: surface grinding, mirror finish, silicon wafer
Abstract : The application of electrophoretic deposition of ultrafine abrasives to grinding cut-off of brittle materials has enabled both no chipping and a mirror surface finish to be achieved using the developed aluminum-bonded diamond cutoff wheels. Then we examined its application to infeed grinding of silicon wafers to replace the lapping process. A series of experiments clarified that desiccation due to electroosmosis caused agglomeration of adhered abrasives onto the grinding wheel; and that easy dropping-off of the agglomerates caused numerous scratches. Both the increase of viscosity of grinding fluid by the addition of a thickener and the decrease of applied voltage were performed to restrain electroosmosis, which enabled a mirror surface finish of 23nmRt with no scratches to be achieved.
Surface formation in creep feed grinding of advanced ceramics with and without ultrasonic assistance
E. Uhlmann   / G. Spur (1)
STC G,  47/1/1998,  P.249
Keywords: grinding, ceramics, surface formation
Abstract : The process performance in grinding of advanced ceramics can be enhanced by various kinematics of tool engagement. Based on the process principles of creep feed grinding with and without ultrasonic assistance, the surface formation of both methods is analysed using analogy tests which simulate the engagement of single grains into the surface. The ultrasonic superposition leads to altered mechanisms of surface formation as well as wear behaviour of grains. SEM-pictures, residual stress analyses and bending strength tests serve to evaluate surfaces ground both with and without ultrasonic assistance. This furnishes proof that ultrasonic assistance results in significantly higher removal rates, but not in an additional damage of the sub-surface.
Generative precision grinding of optical glass
V. Sinhoff   / W. König (1)
STC G,  47/1/1998,  P.253
Keywords: grinding, glass, model
Abstract : The deployment of cup wheels to precision-grind optical glass, offers both considerable economic advantages and significant increases in flexibility. In this contribution, the material removal mechanisms of the grinding process will be analysed on the basis of material-specific characteristics. Attention will focus on the transition phase from brittle to ductile chip formation. The first step in which the process model engages, is the identification of process-determining model components. The material-specific machining characteristics are added to the equation, permitting subsequent modelling of the interrelationships which influence the process. By comparing the theoretical result with the practical outcome, it is possible both to evaluate the model and to determine which machining strategy is most suitable for the glass type in question.
Computer-aided modelling of the fluting process for twist drill design and manufacture
E.J.A. Armarego (1), D. Kang  
STC G,  47/1/1998,  P.259
Keywords: twist drills, geometric modelling, CAD/CAM modules
Abstract : Computer-aided models of a typical flute grinder, incorporating both 'forward' and 'backward' analyses, are outlined and used to simulate the flute grinding process and study the intended or design flute profile of twist drills. Based on recommended wheel profile and flute grinder settings, the 'forward' analysis has shown that the generated lip flute profile closely approximated the ideal profile for straight lip production while the heel flute profile approximated a parabolic curve. Furthermore the flute profile was partly generated by the 'envelope' of the wheel profiles and partly by the locus of the point of discontinuity on the wheel profile. The effects of the wheel profile and machine settings on the generated flute profile have been studied. The 'backward' analysis, based on the 'contact curve' method, has shown that only portions of the required wheel profiles to generate the given 'design' drill flute profiles were physically feasible so that the generated flute profiles are only good approximations of the design flute profiles. The use of these computer models in drill design and manufacture are also discussed.
Kinematic simulation for analyzing and predicting high-performance grinding processes
G. Warnecke (2), U. Zitt  
STC G,  47/1/1998,  P.265
Keywords: grinding, modelling, simulation
Abstract : In grinding technology, the application of superabrasives and increasing demands for higher productivity and higher quality require an appropriate selection of optimum set-up parameters. Therefore, the development of analytical or empirical models for reliable prediction of machining performance and work results is a key issue. This paper presents a comprehensive concept for process modelling which provides a software tool for analysing and designing high performance grinding processes, using the method of kinematic simulation. On the basis of synthetic 3D-models describing the macro- and micro-geometry of the grinding wheel and the workpiece, together with mathematical models describing the relative motions and kinematic engagement conditions, grinding processes can be reproduced as the cumulation of multiple grit engagements. The proposed simulation tool allows the generation of optional grinding wheel topographies and the analysis and prediction of the machining performance and work result for different grinding techniques, taking into account thermo-mechanical and dynamic effects in the contact area.
Development of resin -bonded diamond wheels with improved wear resistance using surface modified fine grains treated by radio-frequency magnetron sputtering
T. Semba, H. Fujiyama, H. Sato (1)  
STC G,  47/1/1998,  P.271
Keywords: diamond wheel, fine grain, surface modification
Abstract : Experimental research for decreasing the wear of a resin-bonded diamond wheel was conducted for the mirror grinding of dies and molds. The gripping strength of diamond grains to the bond material was increased by modifying grain surfaces with an SP_2 film using radio-frequency sputtering. In addition, the adhesion strength in both the surfaces between grain/S;02 film and S;02 film/bond material was increased using the plasma activation technique and a silane coupling agent. The grinding test revealed that the superficial area of diamond grains increased conspicuously and chemical binding between grain surfaces and bond material was generated, so that wear resistance superior to that obtained using conventional nickel plated grains can be derived.
Validation of thermal properties in grinding
W.B. Rowe (1), M.N. Morgan, S.C.E. Black  
STC G,  47/1/1998,  P.275
Keywords: grinding, temperature, cbn
Abstract : Thermal properties of the abrasive material are required for energy partitioning and prediction of temperatures in grinding. Alumina and cubic boron nitride wheels are investigated by several methods. A novel sensor was designed to measure bulk thermal property. It is shown that the effective thermal properties exhibited in the grinding process are lower than the values measured directly. It is therefore concluded that a grain model is more appropriate than a bulk property model. A case study based on grinding AISI 52100 with cbn and alumina is used to illustrate the sensitivity of the most significant parameters for fine grinding.
Safe operations and friction characteristics of regulating wheel in centerless grinding
F. Hashimoto (2), G.D. Lahoti (2), M. Miyashita  
STC G,  47/1/1998,  P.281
Keywords: centerless, friction, safety
Abstract : In the centerless grinding process, it happens on rare occasions that the workpiece rotation suddenly speeds up toward the peripheral velocity of the grinding wheel and, in the worst case, the workpiece jumps from the grinding area. This phenomenon called "spinners" sometimes causes the grinding wheel to burst. In this paper, the mechanism of spinner occurrence is discussed. The existence of safeoperation zone, where there is no risk of spinners, is presented with primary set-up conditions. This paper also describes friction characteristics of the regulating wheel that are the dominant factor in determining the safe-operation zone. The test results of friction coefficients of various regulating wheels are discussed, and the set-up guidelines to avoid the spinner problem are proposed.
Forces in generating gear grinding-theoretical and experimental approach
B. Kruszynski, S. Midera   / J. Kaczmarek (1)
STC G,  47/1/1998,  P.287
Keywords: gear grinding, forces, model
Abstract : Results of investigations carried out on the generating gear grinding process, the so-called Niles method, are presented in the paper. A detailed analysis of tooth profile generation shows that, due to the complex kinematics, grinding conditions vary substantially during the cycle of gear tooth creation which may, in turn, influence the grinding forces. It was found that workspeed and dimensions of the layer being removed in a particular generating stroke are the factors having the greatest influence on the grinding forces. On the basis of extensive analytical and experimental work the equations were proposed which allow the calculation of the normal and tangential grinding forces in each particular generating stroke of grinding wheel during tooth profile generation. The analysis of maximum grinding forces in the tooth profile grinding cycle as a function of process parameters is also presented in the paper.


Advantages of an open architecture structure for the design of predictive controllers for motor drives
D. Dumur (2), P. Boucher (2), J. Röder  
STC M,  47/1/1998,  P.291
Keywords: machine tool, CNC design, control
Abstract : Due to the rapid innovation speed in the development of microprocessors and communication technology, it becomes more and more necessary to generate software in a hardware-independent /way. /The consequence of this requirement is the introduction of a link between application software and hardware, in an open architecture oriented structure. This paper presents an open architecture structure of motor drives control with a particular application to an induction machine axis control, showing the connection between the motor (including load, PWM inverter, current sensors, incremental encoders) and the software developments for the end users (automatic design of the tuning parameters, design of the controller) through a DSP based implementation of the real time part.
Open architecture modular tool kit for motion and machining process control
Y. Altintas (1), N.A. Erol  
STC M,  47/1/1998,  P.295
Keywords: CNC, machine tool, robot
Abstract : An open and reconfigurable modular tool kit is presented for the design of CNC systems for machine tools and machining process monitoring. By selecting standard commands from the software tool kit library, the user is able to design a new CNC system automatically. The developed system allows integration of user developed program modules to the tool kit library. The developed CNC is based on a fully integrated, open, real-time, preemptive DSP operating system and a Windows NT application. It has hardware independent architecture, and supports multiple DSP boards and multiple host computers for machine tool and robot drive motion control, trajectory generation and sensor based machining process control and monitoring applications. The system can be quickly configured to control different machine tools, robots and sensor based processes by selecting standard script commands from the design library. The paper contains sample applications for machine tool control and sensor assisted machining applications.
Supervisory machining control : design approach and experiments
R.G. Landers, A. Galip Ulsoy (2)  
STC M,  47/1/1998,  P.301
Keywords: computer numerical control, machining module coordination, face milling
Abstract : Monitoring and control of machining systems has been shown to dramatically improve operation productivity and part quality; however, very little attention has been given to the coordination of multiple complex machining modules. The current practice is to design the module coordination and to debug the resulting computer code in an /ad hoc /manner. In this paper, the concept of supervisory machining control, in the context of machining module regulation, is presented. The structure of, and elements contained in, a supervisory controller are detailed, and a systematic design procedure for constructing these controllers is presented. The design procedure is utilized to construct a supervisory machining controller which is experimentally implemented in a face milling operation.
The effect of tool length on stable metal removal rate in high speed milling
S. Smith (2), W.R. Winfough, J. Halley  
STC M,  47/1/1998,  P.307
Keywords: metal removal rate, end milling, high speed machining
Abstract : This paper describes the effect of the tool length on achievable stable metal removal rate in high speed milling. Through finite element computation and experiment, it is shown that the tool length most strongly affects the natural frequency of the most flexible mode. The change in frequency changes the most stable speed in the stability lobe diagram. The highest metal removal rates occur when the tool length is selected to match the stable zone to the highest spindle speed. Sometimes longer tools can provide higher metal removal rates than shorter tools because they utilize the stability lobe phenomenon more effectively.
Linear magnetic bearing and levitation system for machine tools
M. Weck (1), U. Wahner  
STC M,  47/1/1998,  P.311
Keywords: linear magnetic bearing, linear direct drive, high-speed machining tool
Abstract : Magnetic bearings work without abrasion, (static) friction and attrition while providing the highest possible travel velocity and acceleration. Consequently magnetic bearings could be ideal guideways for high-speed machine tools. This paper describes a new linear magnetic bearing system suitable for machine tools. Within this contribution the development of a test bench with a linear synchronous direct drive and a magnetic bearing and levitation system is presented. The conjunction of electrical, electronic and mechanical components as parts of a mechatronical system is shown. In addition, measurements of the stiffness are presented to demonstrate the feasibility of the approach.
Analysis of thermal deformation of an ultraprecision air spindle system
T. Moriwaki (1), E. Shamoto  
STC M,  47/1/1998,  P.315
Keywords: thermal deformation, ultraprecision air spindle, transfer function
Abstract : Thermal behavior of the main air spindle system of an ultraprecision machine tool is analyzed experimentally. Influences of the heat generated due to the spindle rotation and the temperature variation of the ambient air are considered. It is found that the thermal deformation due to the ambient temperature change increases with an increase in the rotational speed, which is considered to be caused by an increase in the heat transfer. The transfer functions between the rotational speed of spindle and the thermal deformation and between the ambient temperature and the thermal deformation are obtained separately. A simple method to estimate and compensate the thermal deformation is proposed by utilizing the measured transfer functions and the convolution integral, and machining errors due to the above two heat sources are successfully reduced to less than 15%37;.
Balancing requirements for fast rotating tools and spindle systems
H. Schulz (1), T. Würz  
STC M,  47/1/1998,  P.321
Keywords: balancing, high-speed machining, vibration
Abstract : Technical standards as they are defined in ISO 1940 are more and more insufficient for high-speed tools and spindle systems in order to guarantee a stable machining process. This paper shows the system-specific limitations of the component focused balancing. The effects of the unbalanced tool onto the machining process as well as the machine's behaviour can be used as system focused criteria in order to evaluate the required balancing status. These will be discussed by means of analytical and numerical approaches and are verified by experimental results. The new aspect to set the balancing requirements by vibrational loads of the spindle bearings is confirmed by simulation models.
Robust control of feed drives with linear motors
H. Van Brussel (1), P. Van Den Braembussche  
STC M,  47/1/1998,  P.325
Keywords: machine tool, control
Abstract : Linear motors experience a real breakthrough for machine tool applications. Besides their outspoken advantages, they have the important drawback that load variations are directly felt by the motor. Robust controllers are needed to cope with these problems. This paper presents results obtained with two robust control schemes, one based on H synthesis and the other on sliding mode control. Excellent robust performance has been obtained, like e.g. load changes up to 300^0 1/. can be dealt with and have only a negligible influence on the tracking error.
Form-shaping system of machine tools : theory and applications
V. Portman, I. Inasaki (1), M. Sakakura, M. Iwatate  
STC M,  47/1/1998,  P.329
Keywords: machine tool, form generation, accuracy
Abstract : The form-shaping process is the main functional process performed by a machine tool. A theory of the form-shaping system (FSS) investigates interrelationships between, on the one hand, geometry and kinematics of the machine tool and, on the other, geometry and accuracy of the machined part. In this paper, the FSS theory is developed in the following ways: (1) the general approach spreads also to the FSS with parallel-type links (previously, only chaintype systems were discussed); (2) direct and inverse form-shaping problems are formulated.
Modular synthesis of machine tools
M. Zatarain, E. Lejardi, F. Egana   / R. Bueno (1)
STC M,  47/1/1998,  P.333
Keywords: machine, module, dynamics
Abstract : In the current state of the art, calculation of static and dynamic behaviour of machine tools requires the modelling of the complete structure and components by the Finite Element Method. If calculation at several machine positions is required, major adaptations of the FEM model are needed. The article shows a method by means of which "precalculated structures" can be used to obtain the complete model of the machine at any position of its axis in a very straightforward way. Besides being a helpful tool for the analysis of a particular machine, the method permits the organisation of a database in which general-purpose modules can be introduced for the calculation of the complete machine in a very short time. The whole method and database have been programmed, and results obtained correlate very closely with the ones obtained by the classical FEM.
Development of hexapod based machine tool
H.J. Warnecke (1), R. Neugebauer, F. Wieland  
STC M,  47/1/1998,  P.337
Keywords: machine, hexapod, milling
Abstract : Machine tools with parallel structures have been the subject of discussion for a while now. Users are still largely unaware of the advantages offered by these new machine structures. This paper describes the design and variants of parallel-structured machine tools. Different design variants are compared with regard to the load of the structures and the singularity. Starting out from the requirements of die and mold making, this paper presents the development of an hexapod machine tool prototype. The paper is finishing with a processing simulation and a outlook for further investigations.
An integrated methodology for the design of parallel kinematics machines (PKMs)
L. Molinari-Tosatti, G. Bianchi, I. Fassi, C.R. Boer (2), F. Jovane (1)  
STC M,  47/1/1998,  P.341
Keywords: parallel kinematics machine, hexapod, virtual design
Abstract : The paper describes an approach to Parallel Kinematics Machines design integrating tools for machine configuration, synthesis and analysis. An example is shown for a 6 d.o.f. hexapod prototype developed at ITIA-CNR.
The local dexterity, optimal architecture and design criteria of parallel machine tools
T. Huang, D.J. Whitehouse (1), J. Wang  
STC M,  47/1/1998,  P.347
Keywords: parallel machine tools, dexterity, optimum design
Abstract : In this paper, the analytical expressions of the local dexterity loci of parallel machine tools described by the singular values of the Jacobian matrix are formulated. It has been proved that the different kinematic performance indexes to evaluate the dexterity of the machine tools are inherently identical. The parametric relationship to obtain isotropy configurations is derived. By introducing the concept of relative dexterity, the design criteria in conjunction with the detailed procedure are proposed according to the specific requirements. It has been concluded via examples that if the dimensional parameters are designed in such a way that the local kinematic performance is satisfactory, so is the global performance provided that the reachable orientation of the mobile platform is limited due to the constraints of the passive joints and actuated variables.


Product life cycle costing applied to manufacturing systems
E. Westkämper (1), D.v.d. Osten-Sacken  
STC O,  47/1/1998,  P.353
Keywords: decision making, product, cost
Abstract : Life Cycle Costing (LCC) supports the adaptation of product features, both consumer and capital goods; to their life cycle. The costs of production, installation. usage and disposal are analysed and allocated, aiming at the minimum of the total cost. A new method to calculate the life cycle costs of capital goods, such as machines and manufacturing systems, is presented to anticipate the life cycle costs. Single processes connected to the product's life cycle are represented and described in a potential-, program- and process- related way by the above mentioned life cycle costing method. Aiming on a redesign of current product structures, it is possible to derive approaches from the cost structures of the life cycle and also to create possibly new operational and maintenance concepts, as well as new financing models and cooperation forms.
Design-to-cost for production systems
W. Eversheim (1), J. Neuhausen, M. Sesterhenn  
STC O,  47/1/1998,  P.357
Keywords: cost modelling, system design, production system
Abstract : The objective of cost modelling is to evaluate the costs of a product and how these costs are likely to alter with changes to the system design, product components and processes. Specifically, this includes the breaking down and ranking of cost into its core elements. While manufacturing costs are essential to product system evaluation, performance subsequent to customer requirements needs also to be considered. Design-to-Cost for Production Systems presents a generic methodology to combine cost modelling and Quality Function Deployment in order to assess the potential trade-off between cost and performance for competing product alternatives at the early stage of the production system design process.
Product line development with customer interaction
A. Markus (2), J. Vancza  
STC O,  47/1/1998,  P.361
Keywords: optimization, product development, production management
Abstract : While customizing their products, manufacturers attempt to fulfill specific requirements of the customers within the constraints dictated by the manufacturing (design, planning and production) environment, and by the economical necessity of earning profit. This paper offers a generic framework that captures more technical features of this problem than the marketing models: in addition to customer welfare and profit maximization considerations, engineering aspects are made operational, too. Driven by the interaction between customer preferences and the reallocation of manufacturing resources, viable product families emerge from a variety of technically feasible product alternatives.
Approaches to managing changes and uncertainties in manufacturing
L. Monostori (2), J. Hornyak, B. Kadar  
STC O,  47/1/1998,  P.365
Keywords: holonic manufacturing systems, dynamic scheduling, artificial intelligence
Abstract : Today's complex manufacturing systems operate in a changing environment rife with uncertainty. The performance of manufacturing companies ultimately hinges on their ability to rapidly adapt their production to current internal and external circumstances. Two main kinds of approaches to dealing with the enumerated problems are: to enhance the reactivity of traditionally structured (mostly hierarchical) systems by sophisticated new control techniques, and to construct decentralised, distributed systems. Along both of these - overlapping - lines, the authors developed a genetic algorithm (GA) based dynamic scheduler [4] and a distributed, agent-based shop floor control system to be introduced here which relies on the holonic concept. The approaches are realised by using an object-oriented framework for developing and testing new control architectures and algorithms in the manufacturing domain. Finally, the co-operative use of agentbased distributed control structures and the more centralised (GA-based) scheduler is proposed aiming at systems which can handle critical complexity, reactivity, disturbance and optimality issues at the same time.
Impact of manufacturing system configuration on performance
Y. Koren (1), S.J. Hu, T.W. Weber  
STC O,  47/1/1998,  P.369
Keywords: system, quality, productivity
Abstract : Manufacturing systems can be designed in many configurations. Different configurations have profound impact on the performance of the system in terms of reliability and productivity, product quality, capacity scalability, and cost. This paper analyses these performance measures for different system configurations assuming known machine level reliability and process capability.
A method for performance evaluation of automated flow lines
T. Tolio, A. Matta   / F. Jovane (1)
STC O,  47/1/1998,  P.373
Keywords: automated assembling, system modelling, performance evaluation
Abstract : In order to find the optimal configuration of an automated flow line it is necessary to compare the performance of several alternative configurations. In this situation the use of simulation is normally not viable given the high modelling and computational effort it would require; on the other hand, the application of classical analytical tools would often entail the adoption of unrealistic assumptions. To solve this problem, the paper presents an approximate analytical method that overcomes many of the limitations of analytical tools while preserving good accuracy and low computational effort. In particular the method can deal with deterministic processing times, finite buffer capacity and multiple failure modes of the machines. This last feature represents an important improvement over existing techniques and is very useful when dealing with automated assembly lines where each station is composed by different devices that have different reliability and different ways to get repaired. The validation of the method has been carried out by means of extensive testing and comparison with simulation. An application to a real case is also reported.
New concepts and methods for developing shop floor control systems
H.J. Lynggaard, A. Bilberg, L. Alting (1)  
STC O,  47/1/1998,  P.377
Keywords: shop floor, control systems, cell control
Abstract : An industrial research project defines models and methods for design and implementation of computer based control and monitoring systems for production cells. This is primarily documented within automated robot welding cells in the shipbuilding industry. In order to support engineering of cell control systems by the use of enablers, a generic cell control data model and an architecture has been defined. Further an engineering methodology is defined. It is concluded that cell control technology provides for increased performance in production systems, and that the cell control engineering concept reduces the effort for providing and operating high quality and high functionality cell control solutions for the industry. The plans for the next generation industrial shop floor and cell controllers are to develop new concepts based on more distributed systems, which are more robust and agile with respect to changing demands, technological advances and daily operations. The scope of these systems are a network of co-operating cells as opposed to individually operated cells which are co-ordinated in a traditionally (hierarchical planning) manner. This new approach raises new demands for the individual cell as well as its ability to cooperate.
Development of upgradable cellular machines for environmentally conscious products
S. Kondoh, Y. Umeda, H. Yoshikawa (1)  
STC O,  47/1/1998,  P.381
Keywords: cellular, manufacturing, environment
Abstract : To reduce material and energy consumption and amount of disposal, prolongment of product's lifetime is quite promising. Such longer-life products should have functional upgradability besides reliability and fault-tolerance, because most customers buy a new product when the old one is functionally out-of-date. For this purpose, this paper proposes the upgradable cellular machine. A cellular machine is a flexible modular machine that consists of autonomous and intelligent units (called "cells"). This paper demonstrates the upgradability of the cellular machine by illustrating the development of an experimental cellular assembly system based on the cellular automatic warehouse which the authors' group has already developed.
Competence requirements and their impact on manufacturing system performance
A. Kinnander, T. Ilar, U. Eriksson   / G. Sohlenius (1)
STC O,  47/1/1998,  P.385
Keywords: manufacturing, simulation, performance, evaluation
Abstract : Research into "Next generation manufacturing systems" stresses the use of semi-automated systems to handle short product life cycles and customer oriented production. Despite increasing dependency on technology, the importance of humans is expected to increase and to provide a realistic basis for decision support, both technical and organisational processes must be included in simulation models. In a rapidly changing environment, skill development is also important and should be considered when developing simulation models. This paper describes two case studies where competence and skill development were modelled using learning curves to obtain a more representative simulation of system performance.
Interactive manufacturing : human aspects for biological manufacturing systems
K. Ueda (2), J. Vaario, N. Fujii  
STC O,  47/1/1998,  P.389
Keywords: manufacturing systems, interactive system, human
Abstract : Interactive manufacturing is a new idea to cope with the difficulties caused by growing complexity of manufacturing activities. By interaction among humans such as designers, manufactures and consumers, and artifacts throughout artifact life-cycle each participant would iteratively improve. After classifying the problem difficulties in terms of incompleteness of the environment description and system specification, this study focuses on human interaction in production domain based on Biological Manufacturing Systems. This paper shows how the virtual space combined with self-organization enables the human participation, and discusses the effectiveness of interactive manufacturing to solve the difficulties, by demonstrating an example using industry data.
Practical aspects of CALS in design and manufacturing of sheet metal products
M. Shpitalni (1), L. Alting (1), A. Bilberg  
STC O,  47/1/1998,  P.393
Keywords: optimization, sheet metal manufacturing, information technology
Abstract : The transition from design to process planning and to the various stages of manufacturing is traditionally sequential. In many cases, practical problems associated with manufacturing cannot be resolved if only individual processes are examined. These problems can be overcome, however, by adopting the CALS approach. This approach requires global observation and allows actual and current information to flow both forward and backward. This information, regardless of the specific process in which it has been generated, is used to improve the entire global process. This paper is concerned with the design and manufacture of sheet metal parts. It is demonstrated that through implementation of the CALS approach, the overall process can be optimised and products can be manufactured significantly more accurately, faster and less expensively.
Life cycle simulation applied to a robot manipulator - an example of aging simulation of manufacturing facilities -
S. Takata (2), A. Yamada, T. Kohda, H. Asama  
STC O,  47/1/1998,  P.397
Keywords: life cycle management, deterioration evaluation, robot manipulator
Abstract : Evaluation of the aging process of manufacturing facilities is essential for life cycle facility management, which includes such activities as design for reliability and maintainability and maintenance planning. For this purpose, we have developed a life cycle simulation system for robot manipulators. The developed system car simulate the wear of gears and bearings of joints as component deterioration and evaluate the resultant positioning error of an end-effector as functional degradation. The system is applied to assembly robots of a car parts manufacturing plant. The simulation results correspond to the failure history of the robots fairly well.
On-line simulation and control in manufacturing systems
H.A. ElMaraghy (1), I.B. Abdallah, W.H. ElMaraghy  
STC O,  47/1/1998,  P.401
Keywords: simulation, scheduling, flexible manufacturing system (FMS)
Abstract : In this paper a novel on-line simulation framework for multi-resource (i.e., machines-workers-auxiliary resources) constrained Flexible Manufacturing Systems (FMSs) is presented. This framework is based on combined optimisation and simulation techniques. Optimisation procedures are used for initial off-line scheduling and on-line rescheduling (in case of disturbance), using Petri nets, genetic algorithms and dispatching rules. Various performance measures such as minimizing the makespan and the mean flow time were considered. This framework is implemented using Arena, Microsoft Access, and Microsoft Visual C/C++. Random events are introduced on-line using a user interface provided by Arena Real-time template. The proposed framework will be implemented for the control of an industrial flexible printed circuit board assembly system.
A fuzzy discrete event simulator for fuzzy production environment analysis
G. Perrone, S. Noto La Diega (1), A. Zinno  
STC O,  47/1/1998,  P.405
Keywords: fuzzy, production systems, simulation
Abstract : Discrete Event Simulation is a powerful tool to help production managers in planning manufacturing systems. The necessity to rapid react to market conditions is pushing production planners to process requirements and information affected by vagueness. Vagueness is related with event definition, therefore it is not manageable through statistical tools, but more properly by using fuzzy mathematics. Production situations where uncertainty takes body in term of vagueness are referred as /Fuzzy //Production //Environments /Classical Discrete Event simulators are not suitable to deal with fuzzy variables, therefore they cannot be used to model Fuzzy Production Environments. This paper aims to fill this gap in the production research exploring a very untouched area within this framework, that is the development of a proper tool for Fuzzy Discrete Event Simulation.
Environmental-based systems planning for machining
P. Sheng, D. Bennett, S. Thurwachter   / B.F. von Turkovich (1)
STC O,  47/1/1998,  P.409
Keywords: machining, environment, planning
Abstract : An approach for incorporating multi-endpoint environmental effects in manufacturing systems planning is presented. This approach combines unit process models, hazard evaluation and systems simulation to develop a predictive capability for energy consumption, waste flows and exposure risks over a planning horizon. Case studies for a machining transfer line are presented to show a hierarchy of decisions supported using this method, including effects of production rate constraints, catalyst selection and resource allocation.
Dynamics of real-time distributed scheduling in multiple- machine heterarchical manufacturing systems
N.A. Duffie (2), P.O. Kaltjob  
STC O,  47/1/1998,  P.415
Keywords: manufacturing, system, control
Abstract : Heterarchical manufacturing systems with highly-distributed, real-time control of arrival times of parts exhibit high levels of robustness and adaptability to changes in machine availability, part mix, processing times, and due dates. However, distribution of control and queuing in these systems makes analysis and modelling difficult, particularly when parts proceed through multiple processing steps and these processing steps can be performed by more than one machine. In this paper, a general approach is presented for modelling these systems. Examples of multiple-machine and multiple-processing-step systems are presented, illustrating their behaviour and closed-form solutions obtained of discontinuous differential equations that represent their dynamics.
An integrated process planning and scheduling system for block assembly in shipbuilding
K.K. Cho (1), J.S. Oh, K.R. Ryu, H.R. Choi  
STC O,  47/1/1998,  P.419
Keywords: assembling, process planning, scheduling
Abstract : This paper describes an integrated process planning and scheduling system for block assembly in shipbuilding. The system consists of process planning module, scheduling module, bottleneck block selection module, and process re-planning module. A rule-based reasoning technology is applied to determine optimal assembly units and assembly sequences in generating initial process plans. For scheduling module, a schedule revision heuristic is developed for efficient reallocation of blocks to alternative assembly shops. For bottleneck block selection which plays a central role in bridging process planning and scheduling, a powerful heuristic is developed by employing an entropy-based partitioning method for identifying bottleneck periods. The experimental results with data from a real shipyard show that our search heuristics are very effective and efficient.
LP-based heuristics for the capacitated lot sizing problem
P. Brandimarte, A. Alfieri   / R. Levi (1)
STC O,  47/1/1998,  P.423
Keywords: production planning, optimization, material requirements planning (MRP)
Abstract : Master Production Scheduling is a cornerstone of MRP II systems, since it represents the link between marketing and production. To overcome the limitations of MRP II systems, we aim at finding a good and realistic MPS by optimisation techniques, rather than by a trial-and-error manual procedure. Due to the complexity of the resulting mathematical model, heuristic solution strategies must be devised. In this paper we report computational experiments on the application of approximate solution methods, based on Linear Programming, to a simplified version of the problem, namely the Capacitated Lot-Sizing Problem (CLSP). We show the usefulness of suitable model reformulations and of interior point solution methods.
A petri net technique for process planning cost estimation
P. Xirouchakis, D. Kiritsis, J.-G. Persson (2)  
STC O,  47/1/1998,  P.427
Keywords: CAPP, cost, petrinet
Abstract : The problem under consideration is the cost estimation of operation sequencing for non-linear process planning, i.e. taking into account processing alternatives in order to determine overall costs for feasible process plans we take into account in our Petri net model costs caused by machine, setup and tool changing in addition to the single operation cost. We introduce a new Petri net model that allows the application of cost analysis algorithms. This is a PP-net (Process Planning net) which represents manufacturing knowledge in the form of precedence constraints and incorporates machining cost, machine, setup and tool information in each transition. We show that the PP-net allows the calculation of the optimum process plan without the need to first develop all possible solutions. We apply the developed methods and calculate the optimum process plan to an industrial case study of a mechanical workpiece of moderate complexity.
A systems approach for modelling mechatronics systems
B.A. Hussein   / O. Bjoerke (1)
STC O,  47/1/1998,  P.431
Keywords: mechatronics, system, modelling
Abstract : This paper presents a unified approach based on utilizing multidimensional arrays in order to model the physical and logical properties of mechatronics systems. A mechatronics system model consists of two interacting submodels. A submodel that describes aspects related to energy flow in the physical system, and another submodel that describes aspects related to information flow in the control system. The multidimensional array based approach of modelling provides us with the possibility to use one terminology and the same formalism for modelling both subsystems. The consequence of using the same formalism is that simulation of the mechatronics system can be performed using only /one /simulation environment.
Coordinative generation of machining and fixturing plans by a modularized problem solver
K. Teramoto, M. Onosato, K. Iwata (1)  
STC O,  47/1/1998,  P.437
Keywords: end milling, fixture, planning
Abstract : In the conventional end-milling research, fixturing and machining plans in operation planning are generated separately, although those generations are mutually dependent. Advanced machining operations are directed to complicated and/or thin shape workpiece precision machining. This trend requires to consider the interdependency between machining and fixturing. This interdependency is dealt with in the newly developed coordination cycle where physical consistency and evaluation coherence are managed. This research paper presents a basic framework and procedure of the problem solving for coordinative generation of machining and fixturing plans. This paper also describes an example to demonstrate the effectiveness of the method.
Simulation of NC machining with cutter deflection by modelling deformed swept volumes
M.C. Leu (2), F. Lu, D. Blackmore  
STC O,  47/1/1998,  P.441
Keywords: numerical control (NC), machining, simulation
Abstract : Most research on the representation of swept volumes has been limited to motion of rigid objects. In this study, a Sweep Differential Equation (SDE) approach is presented for the representation of deformed swept volumes associated with flexible objects. The deformed swept volume analysis is integrated with machining mechanics to account for cutter deflection in NC simulation. End milling is modelled and analysed and the cutter deflections are computed and integrated with an SDE based software program which is developed in C++ for the generation of deformed swept volumes. It is shown that this approach constitutes an effective NC simulation technique with capabilities for geometric verification and machining tolerance checking.


Design of a high-precision 3D-Coordinate Measuring Machine
M.M.P.A. Vermeulen, P.C.J.N. Rosielle, P.H.J. Schellekens (2)  
STC P,  47/1/1998,  P.447
Keywords: coordinate measuring machine, high-precision design
Abstract : In Precision Engineering components are getting smaller and tolerances become tighter, so demands for accuracy are increasing. To improve the precision of Coordinate Measuring Machines (CMMs) we designed an alternative high precision 3D-CMM with measuring uncertainty beneath 0.1 µm in a measuring volume of 1 dm'. The machine design is based on the Abbe and Bryan principle, thus smaller measuring errors are feasible with less effort on software compensation. Application of a light and stiff construction, compensated air bearings and well-positioned linear motors result in high stiffness and favourable dynamic behaviour. A statically determined design, extensive use of aluminium and mechanical thermal length compensation make the machine less sensitive to temperature changes. To prevent mechanical disturbances an active vibration isolation system was designed. This paper focuses on machine design aspects showing analytical- and experimental results and design synthesis.
The influence of measurement strategy on the uncertainty of CMM- measurements
A. Weckenmann, M. Knauer   / H. Kunzmann (1)
STC P,  47/1/1998,  P.451
Keywords: coordinate measuring machine (CMM), uncertainty
Abstract : The accuracy of the results from coordinate measurements depends on the accuracy of the measuring device, workpiece properties, environmental conditions, and especially operator procedures. For the last, and usually most important factor, neither are proven facts known about the combined effects of the various influences nor do any general quantitative statements exist. A proposal is made for structuring the area "operator influence" with special focus on measuring strategy with the components sampling strategy (number and distribution of sampled points), evaluation criteria, and filters, Design and function of a software system to simulate measurements of workpieces with typical deviations are described.
Autonomous coordinate measurement planning with work-in-progress measurement for TRUE-CNC
H. Ng, J. Liu, K. Yamazaki (2), K. Nakanishi, K. Tezuka, S.K. Lee  
STC P,  47/1/1998,  P.455
Keywords: CMM part programming, dimensional inspection, in-process measurement
Abstract : The paper deals with the autonomous programming technology for the high speed coordinate measuring machine (CMM). In order to provide the breakthrough technology to enhance the operability of CMMs to be used for in-line measurement of mechanical parts, a new autonomous programming method which automatically generates a CMM program from the CNC program used for machining of the part is proposed. The developed technology can provide new functionality such as efficient work-in-progress measurement capability without using the CAD product model based approach.
In-process measurement method for detection and discrimination of silicon wafer surface defects by laser scattered defect pattern
S. Takahashi, T. Miyoshi, Y. Takaya, K. Saito (2)  
STC P,  47/1/1998,  P.459
Keywords: optical measurement, surface defect, ultra-precision
Abstract : A new optical measurement method for evaluating the defects on a silicon wafer surface quantitatively, which will be able to be applied to in-process measurement, is presented. The experimental system for measuring the defects consists of the Fourier transform optical system using of a high-power objective. In order to verify the feasibility of application of this method to in-process measurement, scanning experiments for small particles, which are typical defects on the silicon wafer surface, are carried out. It is shown that the proposed method is effective for detecting and discriminating the small defects with the size of sub micrometer order.
On the gap between design and implementation of MEMS
D. Seter, M. Hershkovitz, S. Kaldor (1)  
STC P,  47/1/1998,  P.463
Keywords: precision, micro-machining, silicon
Abstract : The paper discusses implementation problems, adopted during development and fabrication, of Silicon micro-sensors. For example, the paper refers to a micro rate sensor (Micro Gyroscope) under development. Two types of problems are highlighted, in view of their critical effect on sensor performance: fabrication sizes control, and the selection considerations, for the sensor displacement detection mechanism. The influence of foreseen deviations and errors, on sensor performance is shown and compared with relevant data, published during the last years on micro sensors. Some problematic points are discussed, concerning micromachining, in future manufacturing environments, of Micro Electro Mechanical and Optical Systems.
Porous ceramic water hydrostatic bearings for improved accuracy and performance
J. Corbett (2), R.J. Almond, D.J. Stephenson, Y.B.B. Kwan  
STC P,  47/1/1998,  P.467
Keywords: water hydrostatic, bearing, ceramic, precision
Abstract : Demand continues for the supply of machine tools with improved accuracy and productivity. This necessitates machine structures and spindle assemblies with much higher static and dynamic stiffness than are currently available, together with very low levels of thermal drift. The medium term accuracy of oil hydrostatic bearings has traditionally been limited by the thermal effects and although aerostatic bearings have relatively good thermal characteristics they suffer from a low relative stiffness and load capacity. New concepts are therefore required, and the authors describe a programme which is using fundamental principles to develop a new improved generation of porous bearings.


Surface modification of ceramics by laser machining
H.K. Tönshoff (1), H. Kappel  
STC S,  47/1/1998,  P.471
Keywords: surface treatment, laser, ceramic
Abstract : To complement diamond based machining processes, laser beam machining offers new ways in surface modification of ceramics. An excimer laser has been used to study the basic mechanism roughening the surface of silicon carbide. Investigations on different surfaces (lapped, polished) show a minor influence of the initial topography on the development of a characteristic cone structure. Microscopic studies identify the crystal structure and the melting phase as the main influence. The combination of these effects is responsible for the formation of a regular cone like structure ('microspherical caps'). A promising application of this roughening-phenomena is the improvement of adhesive bonding.
Effect of tool edge geometry on the nanometric cutting of Ge
D.A. Lucca (2), P. Chou, R.J. Hocken (1)  
STC S,  47/1/1998,  P.475
Keywords: cutting, surface, force
Abstract : A specially designed ultraprecision instrument for nanometric cutting was used to investigate the cutting and thrust forces and the surfaces generated in the orthogonal cutting of Ge. Single crystal diamond tools with rake angles of 0°, -15°, -30°, and -45° were used over a range of depths of cut below 500 nanometers. Tool edge geometry and the resulting workpiece surfaces were characterized with the use of atomic force microscopy. A significant increase in thrust to cutting force ratio was observed for decreasing depth of cut and for increasing negative rake angle. The depth of cut for onset of significant surface fracture also increased with increasing negative rake angle.
Effect of surface topography of workpiece on pressure dependence of coefficient of friction in sheet metal forming
A. Azushima, J. Miyamoto, H. Kudo (1)  
STC S,  47/1/1998,  P.479
Keywords: tribology, sheet metal, topography
Abstract : In the previous sheet draw tests of AI-Si alloy and aluminum having a dull surface, the authors found that the coefficient of friction was constant in the lower pressure range, whilst in the higher pressure range, it decreased with increasing pressure and the relationship was qualitatively interpreted from results of the direct observation of contact behaviour. In the present work, the pressure dependence is examined, changing the surface topography of workpiece by pre-rolling to different flattening degrees of surface asperities. From the results of direct observation of contact behaviour obtained by making use of a newly developed fluorescence measurement method, the contact model can be interpreted 3-dimensionally for better surface control.
Reconstruction of depth-dependent parameter profiles based on photothermal measurements
G. Goch, H.G. Walther   / E.G. Thwaite (1)
STC S,  47/1/1998,  P.483
Keywords: hardness, non-destructive, sub-surface
Abstract : Microstructural changes in a near-surface zone, as they appear at the hardening of steel, machining of ceramics, laser treatments or wear, occur together with modifications of their thermal properties. Therefore, the influences of such processes on the surface layer become detectable non-destructively by photo-thermal means. Today, the thickness determination of the affected zone via calibration curves is regarded as state of the art, whereas an increasing attention is focused on the numerical evaluation of the depth-dependent parameter profile, i.e. the material changes as a function of depth, mostly obtained by destructive tests, as yet. This paper presents the theoretical basics of a parameter profile reconstruction, based on photo-thermally measured data. It compares analytical solutions, derived directly from the thermal diffusion equation (TDE), with numerical approaches using the Finite Difference Method (FDM), both aiming at a quick and non-destructive control of near-edge affecting processes. Both models are applied to photo-thermal measurements, leading to calculated depth profiles of hardness in steel. which are compared with data, destructively obtained from the same samples using Vickers indentation techniques.
Adaptive control for the optimized adjustment of imaging parameters for surface inspection using machine vision
T. Pfeifer (2), L. Wiegers  
STC S,  47/1/1998,  P.487
Keywords: adaptive control, surface inspection, machine vision
Abstract : This paper describes a new method for the adaptive control of imaging parameters in automized machine vision systems. By these new methods even in case of critical objects, which show metal and specular reflections or having polished surfaces, the imaging parameters like illumination are adjusted optimally without any prior knowledge about the surface characteristics. As a result, an image is generated, which is almost free of irrelevant information in the image. This optimised image only contains the ?real" edges actually found on the object's surface and is free of effects resulting from specular reflections or shadows. Surface inspection for scratches, texture analysis or for dimensional measurements becomes much more reliable now.