THE INTERNATIONAL ACADEMY FOR PRODUCTION ENGINEERING

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CIRP ANNALS 1999

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 STC A 

Learning force control for position controlled robotic manipulator
B. Qiao, J.Y. Zhu (1), Z.X. Wei   
STC A,  48/1/1999,  P.1
Keywords: Robotic manipulator, Force control, Learning
Abstract : This paper presents a learning force control framework for position controlled robotic manipulators. A learning mechanism is established to compensate the uncertainties regarding stiffness of constraint environment in an iterative manner. A target impedance model is specified and its reference trajectory is generated according to on-line data of force feedback and position. The target impedance model is driven by force error to produce a command position, by tracking the commanded position the end-effector of manipulator will follow the unknown constraint surface while tracking a desired interaction force. Computer simulations based on a three linked planar robotic manipulator show that contact force can be effectively controlled as the operations are repeated.
Development of a closed-loop controlled reflow soldering process
P.P. Conway, S.M. Hyslop, D.J. Williams (2)  
STC A,  48/1/1999,  P.5
Keywords: Soldering, Control, Joining
Abstract : The assembly of electronics using surface mount technology is in constant change because of the reduction of the feature size of components that must be assembled. Ideally design for manufacture and process optimisation would be applied to bring processes under control. Unfortunately this approach is not possible because of the wide variation of physical and material properties critical to manufacturing encountered in practice. Consequently we have created the Adaptive Intelligent Bellow (A.I.R.) process using feedback from a line scanning infra red sensor. This paper presents the key features of this novel closed loop processing machine and the challenges addressed in its creation.
Automated assembly of lightweight automotive components
K. Feldmann (1), B. Müller, T. Haselmann  
STC A,  48/1/1999,  P.9
Keywords: Assembly, Control, Handling
Abstract : The assembly of large lightweight components indicates a high rate of manual assembly operations. For a higher degree of automation the Institute of Manufacturing Automation and Production Systems develops systems for complete-assembly. The aim of complete-assembly of large components is to reduce the number of process steps. Failure-tolerant assembly systems are used to detect deviations of process influencing parameters and react independently to them. Both concepts are designed to create robust, shortened process sequences to reduce the costs of production and to improve quality.
Computer-aided visual inspection in assembly
M. Lanzetta, M. Santochi (1), G. Tantussi  
STC A,  48/1/1999,  P.13
Keywords: Assembly, Visual inspection, Image analysis algorithm
Abstract : Some of the more critical aspects for the diffusion of vision systems in assembly plants are the skill required for the system set-up, the definition of algorithms and the programming phase. In this paper a new methodology is proposed to reduce the implementation time and cost by means of a computer-aided system working off-line. The designed system named CAVIS (Computer Aided Visual Inspection System) integrates several modules as product and algorithm databases, expert system for decision support, CAD modeller to generate synthetic images and software design. Some of the modules are still at a development stage. The output are the vision devices configuration and the inspection software. CAVIS has been tested on an industrial application for error detection in assembly: a new general-purpose algorithm for visual inspection is presented and results are discussed. The main features of the algorithm are suitable with the described approach: easy programming, unnecessary vision operator's experience, and off-line preliminary estimation of parameters.
Generation of optimized assembly sequences using genetic algorithms
G. Dini (2), F. Failli, B. Lazzerini, F. Marcelloni  
STC A,  48/1/1999,  P.17
Keywords: Assembly planning, Sequencing, Genetic algorithm
Abstract : This paper describes a method based on genetic algorithms for the generation and the evaluation of assembly sequences. Genetic algorithms are here used to drastically reduce the high computational time, usually necessary to evaluate the best assembly sequences, owing to 'combinatorial explosion' phenomena. The generation of optimized sequences is performed using an appropriate fitness function which takes into account simultaneously the geometrical constraints, the minimization of gripper changes and object orientations, and the possibility of grouping similar assembly operations (screwing, pressing, etc.). The paper also presents the chromosome structure used in the system, the genetic operators and, finally, a meaningful example of application.
Agent-based approach for assembly control
G. Seliger (2), D. Krützfeldt  
STC A,  48/1/1999,  P.21
Keywords: Assembly, Co-operative manufacturing, Agent theory
Abstract : In manufacturing, fluctuations in production occur along the value-adding chain due to changes in customer orders or process failures. In the heterogeneous environment of supplier and customer relations assembly integrates material flows. Assembly is therefore highly susceptible to fluctuations in supply. In order to avoid delays due to parts in short supply, or long queues, the supplier and transportation agency must be an integral part of assembly control. In this paper, an agent-based approach is introduced to achieve a smooth balance between supply, transport and assembly. Agents act according to a predetermined set of rules and know which other agents to turn to when fluctuations in production occur. The assembly of motor-cars is taken as an example to illustrate this approach.
Assembly process and assembly control development - a holistic and consistent approach
G. Reinhart (2), R. Cuiper  
STC A,  48/1/1999,  P.25
Keywords: Assembly, Computer Aided Planning (CAP), Controlling
Abstract : Simultaneous engineering usually covers the integration of design and planning during product development. Yet there is still a gap between the planning and the subsequent implementation of assembly systems. This article describes an approach to the consistent integration of assembly systems planning into the control system of a real assembly facility within the same environment. The control mechanism developed can be used to simulate manufacturing cells for validation purposes as well as to communicate with real assembly fixtures and equipment.

 STC C 

A new method for chatter detection in turning
I. Grabec (2), J. Gradisek, E. Govekar  
STC C,  48/1/1999,  P.29
Keywords: Turning, Chatter
Abstract : A new method for detection of chatter onset is developed based on characterization of changes in process dynamics. Its performance is demonstrated by the experiments with turning in which the transition to chatter is caused by variation of cutting depth. The signal of cutting force is characterized by the normalized coarsegrained entropy rate whose value exhibits a drastic drop at the onset of chatter. For the purpose of automatic on-line chatter detection a characteristic value of coarse-grained entropy rate is determined which is rather insensitive to variation of cutting conditions.
The effects of cutting tool thermal conductivity on tool-chip contact length and cyclic chip formation in machining with grooved tools
A.K. Balaji, G. Sreeram, I.S. Jawahir (2), E. Lenz (1)  
STC C,  48/1/1999,  P.33
Keywords: Machining, Tool thermal conductivity, Chip formation
Abstract : This paper presents an experimental analysis of the effects of cutting tool thermal conductivity on machining performance of grooved tools. A new methodology for defining the tool-chip contact length in grooved tools is proposed. Performance of uncoated carbide grooved tools tested under a range of thermal conductivities (3292 W/m deg.K) are correlated with the variations of cyclic cutting forces, developed chip length, chip thickness and chip breaking patterns. The thickness of the retarded zone and the grain elongation orientation in the chip are measured along the curled chip and their strong influence on the chip formation process is shown.
Dynamic interrogation of a basic cutting process
J.R. Pratt, M.A. Davies (2), C.J. Evans (2), M.D. Kennedy  
STC C,  48/1/1999,  P.39
Keywords: Vibration, Modeling, Turning
Abstract : A dynamic cutting fixture based on the test rig pioneered by Peters et al. has been developed to aid investigations of cutting process dynamics. This active fixture consists of a flexure-based tool holder with a single dominant modal direction, two voice-coil type actuators for excitation and control, sensors for measuring tool displacement and acceleration, and analog electronics for feedback control of the structural dynamics. The sensing and actuation features of this fixture are exploited to identify model parameters and to examine the transition from stable cutting to chatter by comparing experiment to theory and simulation.
A fluid dynamic analysis model of the ultra-precision cutting mechanism
K.B. Kwon, D.W. Cho, S.J. Lee, C.N. Chu (2)  
STC C,  48/1/1999,  P.43
Keywords: Ultra-precision machining, Cutting force, Specific energy
Abstract : The technology required for ultra-precision machining of non-ferrous metals is relatively well established, owing to significant improvements in the performance of the hardware used. However, no satisfactory analytical model has been developed for very small cutting depths of this process, demonstrating that the physics of the ultra-precision machining process are not well understood. This paper presents the development of an ultra-precision cutting model based on fluid mechanics that considers not only cutting tool geometry, including the cutting edge radius, but also the effect of elastic rebound at the flank face. This is the first time that a fluid dynamic model has been used to predict the effect of a cutting edge, its size effect, and the cutting forces during ultra-precision cutting. This model can also be used to provide estimates of the chip curling radius and tool-chip contact length.
Determination of convective cooling conditions in turning
L. Kops (1), M. Arenson  
STC C,  48/1/1999,  P.47
Keywords: Turning, Workpiece, Cooling
Abstract : The convective heat transfer coefficients, necessary for modelling of the thermoelastic behaviour of a workpiece, were determined directly for turning conditions on a lathe, in air and in coolant. A model of a cylindrical workpiece with convective boundaries was solved for temperature distribution using a Control Volume Finite Difference code. An iterative optimization procedure matched the computer prediction with the experimental temperature measurements to within less than 1 oC average difference,. The values of heat transfer coefficient determined for various cooling zones on the workpiece, including the chuck zone and the heat transfer coefficient distribution in the impinging coolant zone, were validated through the cutting experiments. The results are illustrated through the comparison of computed and experimental cooling curves. Presented methodology can be applied to obtain the heat transfer coefficient values for cooling in other conditions, and to establish a convection data bank needed to predict the effect of thermal expansion of a workpiece on resulting accuracy in turning.
The effect of tool flank wear on the heat transfer, thermal damage and cutting mechanics in finish hard turning
J.Y. Wang, C.R. Liu   / K.K. Wang (1)
STC C,  48/1/1999,  P.53
Keywords: Hard turning, Flank wear, Heat transfer
Abstract : Tool flank wear is a major cause of thermal damage in the machined surface layer in finish hard machining. A new methodology is developed to provide the knowledge needed for understanding the heat transfer regarding the formation of the thermal damage and the cutting mechanics. The methodology consists of a thermal model based on Green's function and a microstructure-based method using orthogonal hard turning. The coupling of the interface boundary conditions due to chip formation and flank wear is resolved using the proposed microstructure-based method, which is a departure from the conventionally incorrect approaches based on the assumption of constant chip formation. By incorporating the microstructure-based method with the thermal model, heat generated, heat partition, and the shear forces at the tool-chip and tool-work interfaces can be determined. Interface temperatures that are extremely difficult to be measured are obtained. The results quantitatively explain how the heat transfer and chip formation are altered as the tool flank is progressively worn.
Surface integrity generated by precision hard turning
Y. Matsumoto, F. Hashimoto (2), G. Lahoti (1)  
STC C,  48/1/1999,  P.59
Keywords: Cutting, Residual stress, Hard turning
Abstract : Rolling contact fatigue tests were conducted to find the effect of precision hard turning. The tests showed that hard turning provides as good a fatigue performance as grinding. Hard turning produces compressive residual stresses in a deep subsurface, which contribute to a long fatigue life. The effect of cutting parameters on residual stress was investigated in order to find why deep residual stresses are created. It was determined that the tool edge geometry is the dominant factor deciding the residual stress profile.
Temperature measurement of CBN tool in turning of high hardness steel
T. Ueda, M. Al Huda, K. Yamada, K. Nakayama   / H. Kudo (1)
STC C,  48/1/1999,  P.63
Keywords: Turning, Temperature, Cubic boron nitride (CBN)
Abstract : The temperature at the tool flank, which has an effect on the tool life and on the machined surface integrity, is measured using a two-color pyrometer with a fused fiber coupler. This pyrometer makes it possible to measure the temperature of a very small object without emissivity affecting the results. A CBN tool is used as the cutting tool. A high carbon chromium bearing steel, a chromium molybdenum steel and a quenched carbon steel are used as work materials. The temperature of the tool is highly affected by the cutting speed, but the influence of the depth of cut and the feed rate is not so great. In the cutting of the high carbon chromium bearing steel, the temperature is 800 °C at a cutting speed of 100 m/min and increases with the increase of cutting speed, reaching 950 °C at 300 m/min. There is a close relation between the tool temperature and the hardness of the work material. The influence of cutting speed on tool wear is considerable.
Orientation effects in nanometric cutting of single crystal materials: an MD simulation approach
R. Komanduri (1), N. Chandrasekaran, L.M. Raff  
STC C,  48/1/1999,  P.67
Keywords: Simulation, Single crystal, Cutting
Abstract : Molecular Dynamics (MD) simulations of nanometric cutting on single crystal aluminum were conducted to investigate the nature of the chip formation process with crystal orientation. Extensive dislocation generation ahead of the tool in the workmaterial was found principally along, normal to, along and normal to, or at -- 45 deg. or -- 60 deg. to the cutting direction depending on the specific orientation and direction of cutting. These differences in the dislocation motion observed here for the first time lead to significant variations in the nature of plastic deformation ahead of the tool and consequent variation in the magnitude of the forces, force ratio, specific energy, and subsurface deformation.
Drilling burr formation in Titanium alloy, Ti-6AI-4V
D.A. Dornfeld (1), J.S. Kim, L.J. Chen, J. Hewson, H. Dechaw  
STC C,  48/1/1999,  P.73
Keywords: Titanium, Drilling, Burr
Abstract : Titanium alloy (Ti-6AI-4V) plates were drilled to investigate the effects of tool geometry as well as process conditions on the drilling burr formation. Drilling was done with solid carbide tools with and without coolant and high speed cobalt drills without coolant. Four distinct burr types were observed. During dry cutting, a "rolled back" type burr was observed at high feed rates and cutting speeds and is believed to be due to thermal effects. A "ring" type burr was observed when drilling with coolant. While cutting conditions had little effect on the burr sizes formed, drill geometry (helix angle, split point vs. helical point, lip relief angle and point angle) affected burr thickness and height.
Machinability of graphitic Metal Matrix Composites as a function of reinforcing particles
V. Songmene, M. Balazinski (2)  
STC C,  48/1/1999,  P.77
Keywords: Composite, Machining, Wear
Abstract : Aluminum Metal Matrix Composites (MMCs) reinforced with ceramic particles have been developed for high wear resistance applications such as cylinder liners and brakes as a replacement for gray cast iron. Ceramic particles in an aluminum matrix improve its wear resistance property, but also cause high abrasive wear on cutting tools, which results in poor tool life and inconsistent part quality. A new family of MMCs (GrA-Ni(D) consisting of an aluminum matrix reinforced with nickel-coated graphite particles and SiC or AI203 particles was recently developed. This paper presents the results of machining tests conducted to assess the machinability of the new graphitic ceramic reinforced MMCs. It was found that graphitic aluminum MMC reinforced with alumina is easier to machine than those reinforced with both SiC and graphite or SiC particles only. The incorporation of graphite into these composites and the variation of hard particle content improve their machinability.
Crack initiation in machining monocrystalline silicon
T. Inamura, S. Shimada (2), N. Takezawa, N. Ikawa (1)  
STC C,  48/1/1999,  P.81
Keywords: Machining, Brittle material, Computer simulation
Abstract : Based on the discussion in which the defect as a source of cracks must be created during cutting a silicon monocrystal, the renormalization group molecular dynamics has been proposed to simulate the defect initiation process. The method can be applied to a model of micrometer size, which is necessary to bring about brittle mode cutting, and yet permit the observations of the defect initiation process of an atomic size. The result of the simulation shows that a microcrack-like defect can be initiated during cutting through the interaction between a local static stress distribution and global dynamic stress associated with acoustic waves.

 STC Dn 

Development of DVD for the next generation by axiomatic approach
S.W. Cha, K.K. Cho (1)  
STC Dn,  48/1/1999,  P.85
Keywords: Axiom, Performance, Digital-Versatile-Disk
Abstract : DVD(Digital Versatile Disk) is a media for data storage device for high density and high speed information processing. Therefore higher rotational speed and better accuracy in optical pick-up are required compared with the existing devices. These functional requirements must be satisfied in order for DVD to keep its status as the high capacity data storage device. This paper first evaluates the currently developed DVD, and also provides methods to improve the current design using an Axiomatic Approach which is an excellent tool in deriving a new design as well as evaluating an existing one.
Managing design knowledge : active document system
S. Ha, G. Pahng, M. Chang, S. Park, H.M. Rho (2)  
STC Dn,  48/1/1999,  P.89
Keywords: Design information, Knowledge management, Product function deployment
Abstract : Sharing design knowledge within a company is critical to retain market competitiveness, especially when the company develops a family of products. The goal of this study is to develop a Web-based design knowledge management system, named Active Document System, that helps designers retrieve critical design information promptly. In order to manage unstructured knowledge such as design know-how systematically, Active Document System classifies design knowledge in accordance with product functions as well as product structures. This paper explains Active Document System and a method to deploy the product function. The concept is implemented and applied to the management of design knowledge for the refrigerator design process.
An information modelling framework for product families to support mass customization manufacturing
J. Jiao, M.M. Tseng (2)  
STC Dn,  48/1/1999,  P.93
Keywords: Engineering Design, Product Family, Modeling
Abstract : Developing product families has been recognized as an effective means to support Mass Customization Manufacturing (MCM). A Product Family Architecture (PFA) resembles the underpinning logic of assisting customers to converge to what a firm can deliver in terms of its capabilities and capacities. The representation of a PFA is essential for managing variety effectively across the entire product realization process encompassing sales, marketing, design, and manufacturing. This paper proposes a generic PFA representation in terms of representing multiple views of product families in a single context, using one generic variety representation structure for different views to minimize data redundancy, and generating specifications of individual product variants for different business functions coherently. Accordingly, an information modeling framework for product families is developed based on a combination of elements of semantic relationships with the object-oriented data model. An application of the proposed framework is demonstrated for power supply products. Also reported is a prototypical implementation using KAPPA-PC`'.
Utilizing image processing techniques for 3D reconstruction of laser-scanned data
A. Fischer (2), A. Manor  
STC Dn,  48/1/1999,  P.99
Keywords: Reverse Engineering, Image Processing, Surface Reconstruction
Abstract : In Reverse Engineering, laser scanners are commonly used since they can sample 3D data fast and very accurately relative to other systems. Laser scanner systems, however, yield an enormous amount of irregular and scattered digitized point data that requires intensive processing in order to reconstruct the surface of the object. It appears that combining 3D scanned data with 2D intensity images can significantly improve the reconstruction process. This paper proposes a new adaptive reconstruction method that integrates information from a CCD camera with scanned laser data. The method is based on: (a) Detecting a 3D boundary of the parametric base surface. (b) Adaptively reconstructing a parametric base surface with a non-self-intersecting grid. (c) Calculating the parameterization of the 3D sampled points. (d) Fitting the surface by applying a least square (LSQ) approximation method with boundary constraints. The feasibility of the parameterization algorithm is demonstrated on sculptured free objects.
A new concept for the design and the manufacturing of free-form surfaces: the Machining Surface
E. Duc, C. Lartigue, C. Tournier, p. Bourdet (1)  
STC Dn,  48/1/1999,  P.103
Keywords: Design Intents, Geometric Modeling, Free-Form Machining
Abstract : This paper deals with a modeling method of free-form surfaces based on the new concept of the machining surface. The machining surface is built so that design intents and manufacturing requirements are ensured and so that it completely defines the tool movement necessary to produce a part. Therefore, approximations appearing during the elaboration process (CAD modeling, tool path calculation and free-form machining) are minimized. The concept of the machining surface described here relies on an analysis of the process quality.
Diverse aspects of tolerancing on an integrated design context
S. Tichkiewitch (2), D. Brissaud  
STC Dn,  48/1/1999,  P.107
Keywords: Integrated Design, Product model,Tolerancing
Abstract : During design, tolerancing is typically a distributed activity in order to respect the clearances of the functional specifications, the capabilities of the manufacturing processes, the possibilities of the assembly process and to increase the time to failure in service. We show how a product model used in an integrated design system is able to take into account the specificities of the tolerancing. This model permits to specify the relations between the different views.
Analysis and validation of 3D laser sensor scanning process
A. Bernard, M. Véron (1)  
STC Dn,  48/1/1999,  P.111
Keywords: Scanning process simulation, Inspection, Optimization
Abstract : This paper presents research results [1] performed on automating the digitizing process of a complex part using a precision 3D laser sensor. Operations that perform digitizing are largely manual leading to data redundancies or missing points. In addition, the time taken for part digitizing immobilizes the machine reducing its overall optimization. A new method to automatically scan a well-known part is presented. After introducing the digitizing environment, an analysis of the critical steps in the procedure is described. The acquisition procedure is introduced and adapted by CAD software to simulate and validate 3D laser-scanning paths. Additional procedures, still under study, are described for the automation of data generation of the laser scanning process.

 STC E 

Reverse simulation of die-sinking EDM
M. Kunieda (2), W. Kowaguchi, T. Takita  
STC E,  48/1/1999,  P.115
Keywords: Die-sinking EDM, Reverse simulation, Tool electrode wear
Abstract : This research aims to develop a simulation method for die-sinking EDM to solve the inverse problem of obtaining the appropriate tool electrode shape for achieving the desired final workpiece shape. In the reverse simulation method developed, the same algorithm as that used in forward simulation is adopted. The workpiece is however fed towards the tool electrode in the direction opposite to forward simulation, and the values for the depth of the layers removed from the tool electrode and workpiece surface per pulse discharge are the reverse of forward simulation. The algorithm is a simple repetition of the procedure comprised of: 1) determining the next discharge location, 2) removing the tool and workpiece electrodes, 3) distributing the debris particles, and 4) feeding the tool electrode.
Integration of rapid prototyping and electroforming for tooling application
B. Yang, M.C. Leu (2)  
STC E,  48/1/1999,  P.119
Keywords: Rapid prototyping, Tooling, Mold
Abstract : Solid freeform fabrication integrated with electroforming as a novel process for the generation of metal molds and EDM electrodes is presented in this paper. A part built by stereolithography is metalized by electroless plating and then placed in an electroplating solution where metal is deposited upon the part by electrolysis. After the desired thickness of metal has been reached, the part is removed from the metal shell by heating. The shell is then backed with other materials to form a mold cavity or an EDM electrode. The accuracy of the formed mold cavity or EDM electrode influenced by materials and process parameters is discussed.
Effect of flushing and electrode material on die sinking EDM
P.M. Lonardo (1), A.A. Bruzzone  
STC E,  48/1/1999,  P.123
Keywords: Die-sinking EDM, Surface quality, Productivity
Abstract : The most important parameters of EDM are the removal rate, the electrode wear, accuracy and surface texture. In this paper the influence of electrode material, flushing, electrode dimension, depth of cut and planetary motion on EDM performance is discussed. An experimental analysis was carried out on a Cr, Mo, V steel for die casting by using both copper and graphite electrodes. Roughing and finishing operations were considered, by adopting for each condition the parameters commonly recommended in industrial production. The observed results show the importance of electrode material, injection flushing and geometry of cutting on removal rate, electrode wear and surface quality.
Typical metrology of micro-hole arrays made in stainless steel foils by two-stage micro-EDM
D.M. Allen (2), H.J.A. Almond, J.S. Bhogal, A.E. Green, P.M. Logan, X.X. Huang  
STC E,  48/1/1999,  P.127
Keywords: Micro-EDM, Metrology, Bore Surface Quality
Abstract : Two-stage micro-EDM utilises one machine to fabricate electrodes and a second machine to manufacture holes. The diameter and taper of a hole are dependent on the accuracy of the electrode fabrication which has now been quantified. The accuracy of hole positioning has also been measured using commercial equipment in a novel application. The surface roughness and uniformity of the internal surfaces of the holes (typically 50 ~im in diameter) have been examined using a novel method not involving cross-sectioning. Random surface microcracks appear to be metallurgy-dependent, not process related.
Micro-ultrasonic machining by the application of workpiece vibration
K. Egashira, T. Masuzawa (1)  
STC E,  48/1/1999,  P.131
Keywords: Ultrasonic machining, Micromachining, Workpiece vibration
Abstract : A new method for microultrasonic machining (MUSM) has been developed. In order to obtain high-precision tool rotation, the spindle mechanism employed in micro-EDM machines was introduced. Since the mechanism does not allow the vibration of tools, the workpiece was vibrated during machining. Using this setup, we have succeeded in machining microholes as small as 5Nm in diameter in quartz glass and silicon. In this machining range, high tool wear posed a problem. To solve this problem, a sintered diamond (SD) tool was tested and was proven to be effective.
Ultrasonic machining : an analytical and experimental study on contour machining based on neural network
Y. Benkirane, D. Kremer, A. Moisan (1)  
STC E,  48/1/1999,  P.135
Keywords: Ultrasonic Machining, Neural Network, Performance
Abstract : Ultrasonic machining is a process used to machine brittle and hard materials (glass, quartz, ceramic). The material is removed by the abrasion and erosion caused by particle agitation and pressure variation within the abrasive fluid. Much work has already been done on the process: the effects of parameters on performance have been described, but restricted to sinking or drilling. This paper concerns the study of contour machining using a 3 axis numerical control machine. In order to understand its principles and to be able to predict the material removal rate for modelling and simulation of the process, an experimental and analytical work is being carried out. Plans of experiments have made it possible to get the performance of the process, characterized by the removal rate and surface quality. The effects of the main parameters have been studied using two statistical methods. They show an advantage for the neural network one, which gives a more precise prediction of the removal rate compared with the Taguchi method. Moreover the proposed approach seems to be well adapted to the modelling of multi parameters processes.
Improvement of electrochemical machining accuracy by using orbital electrode movement
K.P. Rajurkar (2), D. Zhu  
STC E,  48/1/1999,  P.139
Keywords: Electro-chemical machining, Accuracy, Improvement
Abstract : The improvement of machining accuracy of electrochemical machining (ECM) continues to be a major challenge for user industries. This study focuses on the development of a precision ECM process by using an eccentric orbital anode movement with traditional ECM. The feasibility of the proposed process has been experimentally verified. Theoretical and experimental analyses indicate that orbital ECM distributes the electrolyte flow more uniformly and hence leads to a significant reduction in the flow field disrupting phenomena that adversely affect machining accuracy. The proposed method has been found to offer substantial gains in the accuracy and the uniformity of machined components.
The effect of pad wear on the chemical mechanical polishing of silicon wafers
G. Byrne (1), B. Mullany, p. Young  
STC E,  48/1/1999,  P.143
Keywords: Chemical Mechanical Polishing, FEM, Wear
Abstract : The Chemical Mechanical Polishing process planarises wafers with a high degree of success, however wear on the polishing pad causes the planarisation rate and the post-process planarity to deteriorate. To date, there has been no method of predicting the effect of this wear on the wafer planarity. Using finite element models of the process for new and worn pads the wafer stress distribution on the wafer surface can be predicted. Equating high stresses to high material removal rates these models predict that the process should become `centre slow' as the pad wears. This correlates well with experimental data.
A non-invasive solidification sensor for metal casting
J.H. Chun (2), M.M. Hytros, I.M. Jureidini, N. Saka, R.C. Lanza   / N.P. Suh (1)
STC E,  48/1/1999,  P.147
Keywords: On-line Sensor, Casting, Real Time
Abstract : A non-invasive sensor based on high-energy x-ray computed tomography has been developed for monitoring the progression of solidification in metal casting. The sensor comprised a 6 MeV linear accelerator and a 128-channel CdW04 detector array. Laboratory experiments were performed on cylindrical castings of pure aluminum and its alloys. The sensor produced a series of time-lapse images showing the movement of the liquid/solid interface during solidification. The solidification front was imaged every two minutes with a planar spatial resolution of 1.6 mm and a contrast sensitivity of 1.5%37;. The tomography results agreed well with those obtained by thermocouple measurements.
Investigation on multi-layer direct metal laser sintering of 316 L stainless steel powder beds
W. O'Neill, C.J. Sutcliffe, R. Morgan, A. Landsborough, K.K.B. Hon (2)  
STC E,  48/1/1999,  P.151
Keywords: Laser Sintering, Metal, Powder
Abstract : Research and development of laser based sintering technology has occurred at a rapid pace since its invention in the 1980s'. A wide range of materials have been developed including polymers, metals and ceramics. The ultimate goal for this technology is to provide manufacturing industries with fast and flexible means of producing parts that are truly functional. Step by step this active research area is leading towards rapid manufacturing solutions which will be significantly different from the rather limited rapid prototyping solutions of today. In processing metallic materials, porosity is still a major problem although a number of notable solutions such as infiltration with low melting point alloys or direct fusing with binary powder mixtures have been proposed. Neither of these solutions allows one to build components without compromising part strength and functionality. A process route is required that will allow solid parts to be built from a single powder component without requiring time consuming downstream processes. The surface quality must be consistent with those attainable by modern machining techniques. To this end, the present work examines the feasibility of using low energy high peak power laser pulses from a Q-switched Nd:YAG laser to melt stainless steel powder fractions whilst examining the melt displacement and the effects of rapid vaporisation of the powder layer.
An experimental and numerical study on the influence of not uniform beam energy distribution in laser steel hardening
L.M. Galantucci, L. Tricarico   / G. Perotti (1)
STC E,  48/1/1999,  P.155
Keywords: Laser, Hardening, Modelling
Abstract : In this work the influence of the beam not-uniform energy distribution, typical of new sources such as diode lasers, was investigated in the laser hardening of carbon steels. A transient numerical model, based on the Finite Element Method, was implemented in order to analyse the process in these particular conditions, and to provide a tool for the off line design and simulation of the treatment. An experimental set up was prepared to have beam characteristics similar to those that will be offered when high power diode lasers will be available for industrial applications: an elliptical beam with a not uniform energy distribution was obtained operating with an integrator mirror on a CO2 CW laser. The heat treatment was performed with various parallel beam tracks, also by experimenting different degrees of overlapping; the numerical results were compared with the microstructures and the measured micro-hardness obtained on the specimens. The study shows that the FEM simulation can give prediction in good agreement with the experimental observation, considering how the microstructures and the obtainable hardness are influenced by the beam.
On-line process control used in the laser welding of metal sheet lightweigth structural panels
G. Ricciardi (2), M. Cantello (2), F. Mariotti, p. Castelli, M. Penasa  
STC E,  48/1/1999,  P.159
Keywords: Laser, Welding, Quality assurance
Abstract : Lightweight Structural Panels (LPS) made out of multilayer thin metal sheets are innovative materials which allow high structural performances combined with low weight and low material cost. Among the possible configurations a new option defined Cellular and Stratified lamination (C&S) makes use of a double corrugated core joined to external skins which leads to isotropic performance. Double corrugation creates a grid of bumps which have to be welded to the external flat skins. Nd:YAG laser spot welding was selected to reduce distortion. Since C&S structural performance is affected by spot weld strength, a process control based on plasma emission during laser processing was developed. The system described in the paper allows continuous monitoring of the weld quality, highlights the unrecoverable defecs, and modulates laser parameters in order to compensate efficiency decay and assure product quality.
Theoretical and experimental investigation of pulsed laser cutting
H. Kaebernick (2), D. Bicleanu, M. Brandt  
STC E,  48/1/1999,  P.163
Keywords: Cutting, Laser, Modelling
Abstract : A three-dimensional analytical model of pulsed laser cutting has been developed, particularly aimed at predicting the quality of cut under various cutting conditions. The model is based on infinitesimal point heat sources, representing the effect of the laser beam on the surfaces inside the cutting zone, and it includes the contribution of the oxygen reaction to the heating of the metal. Experiments with an NdYAG-Laser, cutting mild and stainless steel, were carried out to verify the predicted cutting results for various speeds, powers and pulse characteristics.

 STC F 

CAOT - A computer aided optimization tool applied on metal forming processes
R. Kopp (2), S. Posielek  
STC F,  48/1/1999,  P.167
Keywords: Optimization, FEM, Computer aided planning
Abstract : The high demand of simulations for process optimization and the large computational effort for practice relevant examples require a new basic approach for optimization concept. This led to the development of the parallel organized optimization model CAOT. The new system reduces, as a result of the parallel organization, the high simulation times and accelerates therewith the complete optimization process. The open architecture allows the application of diverse optimization algorithms, as well as a direct coupling to any simulation program. Miscellaneous metal forming processes can be handled and optimized under consideration of component properties and die loading.
Product development support for suppliers of forgings
E. Doege (1), M. Muckelbauer, M. Michael  
STC F,  48/1/1999,  P.171
Keywords: Hot forming, Product development, CAD
Abstract : This paper describes software tools which were developed at the Institute for Metal Forming and Metal Forming Machine Tools at the University of Hanover, Germany (IFUM) as add-ons for the CAD system Pro/ENGINEER. The software tools support the entire forging design process from the rough design to the finished part. It is now possible to use information on the functionality of the product for forging design instead of technical drawings or conventional CAD models. The described approach supports the migration of the product development from the customer to the supplier. The use of FEM for the load simulation and the PRINZ simulation tool (also developed by IFUM), which calculates and visualizes the material flow during the forming process, are also described.
An intelligent computation approach to process planning in multiple-step cold forging
R. Teti (2), A. Langella, D. D'Addona  
STC F,  48/1/1999,  P.175
Keywords: Cold Forging, Process Planning, Neural Networks
Abstract : An intelligent computation approach to time and cost reduction in process planning of cold forging operations is illustrated. The problem taken into consideration is the generation of optimized working sequences in the fabrication of multi-diameter shafts through multiple-step cold forging. A supervised learning neural network paradigm was employed in order to identify the technologically feasible working sequences to be considered for process planning decision making. The process planner can then select the appropriate solution according to his experience or resort to further methods of detailed analysis (e.g. FEM analysis), with the advantage of applying time consuming numerical investigations only to a small number of cases suggested by the intelligent computing system. Neural network training and testing allowed to verify the system performance in classifying working sequence feasibility and its computational speed in providing technologically acceptable working sequences for process planner consideration.
Experiments and computational modelling of metal injection molding for forming small parts
J.-C. Gelin (1), T. Barriere, M. Dutilly  
STC F,  48/1/1999,  P.179
Keywords: Powder injection molding, Finite element method, Simulation
Abstract : The metal injection molding process is mainly used for manufacturing small metallic components with complex shapes. The process includes four stages and the present study is concentrated on the injection and the densification ones. A multiple cavities mold has been designed and realized that permits to characterize the effects of injection parameters on the final results in terms of shape and integrity. A mechanical model and a set of numerical simulations have been carried out that enhance the experimental results and that allow to access to the influence of the main process parameters. Finally it is shown that computational modeling could be used to help the process designer to produce accurate parts.
Material response to continuously varying rate of straining during hot forging operations
P.F. Bariani (1), T. Dal Negro  
STC F,  48/1/1999,  P.183
Keywords: Hot forging, Strain rate, Flow stress
Abstract : The analysis of hot bulk forming operations reveals that strain rate and temperature at the different material points often vary in a wide range during deformation. The effects on material rheology of continuous variations of process parameters are investigated through physical simulation experiments. They accurately reproduce on steel samples the mechanical and thermal events occurring during representative forging operations. The material response exhibited by the material under varying process conditions is compared with that derived from conventional constant-strain-rate and iso-thermal tests as well as with the flow stress calculated by FEM. The discrepancies demonstrate the inadequacy of conventional flowstress equations.
Computer simulation and control of microstructure and mechanical properties in hot forging
Z. Wang, T. Ishikawa, N. Yukawa, A. Kono, Y. Tozawa (1)  
STC F,  48/1/1999,  P.187
Keywords: Hot forging, Property prediction, FEM
Abstract : An analytical procedure for predicting the microstructure and mechanical properties of forged microalloyed steels is presented. Empirical relationships between recrystallized grain size, temperature and strain as well as the relationship between austenite grain size and ferrite grain size are obtained. These relations are expressed as an incremental formula and incorporated into thermo-coupled FEM code. By applying this analysis to practical multiple stage hot forging of range companions or automotive parts made of microalloyed steel, the microstructure and hardness of forged parts can be predicted. The results of these predictions are in good agreement with the experimental results. The simulation is used to investigate the thermo-mechanical processes for forging functional parts with partially fine grain and high hardness.
Microstructure and mechanics interaction in the modelling of hot rolling of rods
P. Pauskar, R. Shivpuri (2)  
STC F,  48/1/1999,  P.191
Keywords: Hot rolling, Flow stress, Microstructure
Abstract : During hot metal working, strain, strain rate, temperature, microstructure and chemistry along with associated metallurgical phenomena such as strain hardening, dynamic recovery and recrystallization are known to have a significant effect on the flow stress of the metal. Simple flow stress models such as the power law were found to be inadequate for the accurate prediction of !cads and metal flow using numerical simulation. In this study, a microstructure dependent flow stress model was developed by performing uniaxial compression tests on the Gleeble test machine. This model was implemented, using a computationally efficient procedure, into the finite element method based metal flow simulation model for hot rolling. Reasonably good agreements were obtained in comparing predicted roiling loads and rod geometry with those measured on a multi-pass production mill.
Application of a decision making method to improve an industrial hot extrusion forging process
A. Barcellona, L. Cannizzaro (2), D. Antonelli  
STC F,  48/1/1999,  P.195
Keywords: Hot forging, FEM, Sensitivity analysis
Abstract : Success of a bulk forming process is significantly affected by several operative parameters, such as dies and workpiece temperature, friction factor, preformed dimensions and its initial positioning. In the paper the hot extrusion forging of an half shaft of a two stroke motorcycle engine has been investigated. The combined effect of the most influent operative parameters has been determined by means of a consistent factorial plan. A sensitivity analysis was performed using an advanced numerical finite element code as a powerful CAE tool able to assist the analyst in the design of the process. The geometry of the part has allowed a combined 2D-3D numerical analysis; in fact, the influence of some parameters has required a full 3D analysis very expensive in terms of numerical computations.
Linear motor drive CNC press using learning control
T. Nakagawa (1), T. Higuchi, R. Sato, M. Sogabe  
STC F,  48/1/1999,  P.199
Keywords: Metal stamping, CNC, Noise reduction
Abstract : A mechanical press drivers directly by a linear motor, which is mainly used for feeding machine tool tables, has been developed for the first time and its performance in blanking and sheet metal forming confirmed. By incorporating a learning control system, a very high accuracy level (±54m) of the bottom dead point can be achieved in blanking operations. Other advantages such as CNC ram stroke motion control and very low noise level in blanking were also confirmed. Interesting applications of the linear motor can also be looked forward in pressuring devices.
A basic study of the influence of surface topography on mechanisms of liquid lubrication in metal forming
C.G. Sorensen, J.I. Bech, J.L. Andreasen, N. Bay (1), U. Engel, T. Neudecker  
STC F,  48/1/1999,  P.203
Keywords: Lubrication mechanisms, Metal forming, Surface topography
Abstract : Applying a transparent tool technique the tool/workpiece interface in plane strip drawing of aluminium is studied. The strips are provided with macroscopic lubricant pockets, and the compression and eventual escape of trapped lubricant by the mechanisms Micro Plasto HydroDynamic Lubrication (MPHDL) and Micro Plasto HydroStatic Lubrication (MPHSL) is observed and quantified experimentally with respect to the lubricant pocket parameters, shape, volume, and angle to the edge. The two mechanisms have proved to depend very differently upon these parameters. The level at which the hydrostatic pressure is stabilised is shown to be independent of the volume of a pocket and the MPHDL mechanism is therefore solely dependent on the angle to the edge, which is shown both experimentally and theoretically by a fluid mechanic analysis. For the MPHSL mechanism a dependency of the volume is observed.
Formability of non-symmetric aluminum panel drawing using active drawbeads
R. Li, K.J. Weinmann (1)  
STC F,  48/1/1999,  P.209
Keywords: Aluminum Sheet, Drawbeads, Formability
Abstract : Aluminum is expected to gain popularity as material for the bodies of the next generation of lighter and more fuel-efficient vehicles. However, its lower formability compared with that of steel tends to create considerable problems. A controllable restraining force caused by adjusting the penetration of drawbeads can improve the formability of aluminum. The paper describes a spatial and temporal FE model for the analysis of this technique, especially in non-symmetric panel forming. Comparison of the results of numerical simulations with the corresponding experimental results shows that the predictions of strain distribution on the panel are in excellent agreement. Furthermore, FLD analysis indicates that the active drawbead concept is beneficial to the formability of AI 6111-T4.
Rotary blanking
H. Hoffmann, M. Schweitzer   / J. Milberg (1)
STC F,  48/1/1999,  P.213
Keywords: Blanking, Rotary, Kinematic
Abstract : Rotary blanking is a method of blanking and punching with rotating tools whereby the cutting tools are fixed to a pair of rollers performing a continuous blanking operation on a strip of sheet metal. The purpose of this paper is to outline the determining conditions under which the rotary blanking process takes place and to discuss advantages, restrictions, applications and optimization of this technology.
New possibilities for improved bending of vibration damping laminated steel sheets
M. Kleiner (2), V. Hellinger  
STC F,  48/1/1999,  P.217
Keywords: Bending, Vibration damping sheets, Springback
Abstract : Bending of vibration damping laminated sheet metal has been presenting serious difficulties arising from time dependent material springback, undesired deformation of the long bending legs, and separation of the steel sheets. New methods of improving the bending behaviour of steel sheets have been established as a consequence from experiments and investigations on the viscoelastic-plastic core layer of composites. Considerable improvement will be obtained by the selective use of temperature fields in connection with heated bending tools. A following heat treatment will significantly reduce the delayed springback time which has been up to two weeks at room temperature so far.
A method for deep drawing with multiple elastomer membranes
F. Vollertsen, R. Breede, K. Lange (1)  
STC F,  48/1/1999,  P.221
Keywords: Deep drawing, Flexible tooling, Tribology
Abstract : A deep drawing technique is introduced where sheet metal is formed between a rigid punch and a flexible tool component made of multiple elastomer membranes. For this process the punch force is determined, using a fundamental analytical model. During the drawing process a relative movement and therefore friction forces between the membranes and the sheet metal are assumed. These effects were investigated in special strip drawing tests. The results are used in FEM-calculations to determine the membrane deformation caused by friction and to simulate the drawing process of a cylindrical part. Furthermore, a comparison between deep drawing methods with a single membrane and using multiple membranes is described, using a model for the membrane deformation.
Determination of the forming limit diagrams using image analysis by the corelation method
P. Vacher, A. Haddad, R. Arrieux (2)  
STC F,  48/1/1999,  P.227
Keywords: Strain measurement, Image analysis, Forming limit diagrams
Abstract : This paper deals with a new method of strain measurement applied to the experimental determination of the forming limit diagrams of thin steel sheets. This method uses the correlation technique to determine the displacement field between two images taken on the same area of the sample at two different strain levels. The strains are calculated from this field. The range of strains determined between two images may be very wide. This allows to compare the initial image to one before the sample fracture or two successive images during the straining. This method shows that the strain localization may occur early during the forming process and so the onset of localized necking is not a sudden phenomenon. A method is proposed to draw the forming limit diagrams for necking.
Optimal blankholder force path in sheet metal forming processes : an AI based design procedure
R. Di Lorenzo, L. Fratini, F. Micari (2)  
STC F,  48/1/1999,  P.231
Keywords: Deep drawing, Process design, Optimization
Abstract : Blankholder force plays a fundamental role in the deep drawing process mechanics since it controls, by friction, the material flow into the die cavity. The availability of computer controlled hydraulic presses in the industries promoted a new research field focused on the definition of optimal BHF histories, function of the punch displacement; such studies were aimed to the determination of the so called "process window", i.e. the BHF path which permits to obtain the maximum height sound component avoiding both wrinkling and tearing. In the paper a design procedure is proposed in order to determine the optimal BHF path in an axisymmetric deep drawing process: in particular, a closed-loop control system based on the fuzzy reasoning has been set up and interfaced with a FEM code. The determined BHF path has been experimentally verified assessing the effectiveness of the proposed approach.
Analysis tool for roll forming of sheet metal strips by the finite element method
N. Kim, S.I. Oh (1)  
STC F,  48/1/1999,  P.235
Keywords: Roll forming, Computer simulation, Finite element method
Abstract : A computational method based on the three-dimensional finite element method is developed for the deformation analysis of roll forming process. The method approximates the process as a kinematically steady state deformation of strip. For industrial usefulness of the simulation method, several rolls with arbitrary shapes in one stand can be considered. The shapes and the thickness distributions of strip after roll forming were examined by comparing computation results with experiments. It is concluded that the tool is useful enough to predict the process. The overall simulation method was integrated into a software package to help the industrial roll-pass design.
Net shape approach for sintering process of graded laminated powder materials using finite element simulation
K.I. Mori, K. Osakada (1)  
STC F,  48/1/1999,  P.239
Keywords: Sintering, Near net shape, FEM
Abstract : A net shape approach for sintering of graded laminated powder compacts using finite element simulation is proposed. This approach is composed of shape optimisation and fracture prediction in the sintering. In the shape optimisation, the geometry of the compact for producing a flat one of the sintered product is determined using the finite element simulation in order to minimise the difference from the flat shape. On the other hand, the occurrence of sintering fracture is predicted from a difference in volumetric strain between non-uniform and uniform shrinkages calculated by the simulation. The difference in volumetric strain represents average hydrostatic stress during the sintering. For the simulation of the sintering process, a viscoplastic finite element method calculating viscoplastic deformation generated by the difference of shrinkage is employed. The predicted shapes of the compacts are available to actual sintering operations. The effectiveness of the present approach is demonstrated in sintering of circular graded compacts consisting of zirconia and alumina powders.

 STC G 

Surface grinding machine with linear-motor-driven table system : development and performance test
I. Inasaki (1)  
STC G,  48/1/1999,  P.243
Keywords: Grinding, Linear motor, Speed-stroke grinding
Abstract : In order to fully exploit the advantages of speed-stroke surface grinding characterized by high workpiece speed with small depth of cut, a grinding machine with a linear-motor-driven table system was developed. The maximum table speed and acceleration achieved were 60 m/min and 1,0 G, respectively. The paper describes the results of a performance test of the machine during the idling phase and a speed-stroke grinding test. These tests confirmed that the developed surface grinding machine was able to meet the intended design specification in terms of grinding force and ground surface quality.
Temperatures and energy partition for grinding with vitrified CBN wheels
C. Guo, Y. Wu, V. Varghese, S. Malkin (1)  
STC G,  48/1/1999,  P.247
Keywords: Grinding, Cubic boron nitride (CBN), Temperature
Abstract : An investigation is reported of the temperatures and energy partition for grinding with vitrified CBN wheels. Temperature distributions were measured in the subsurface of hardened bearing steel workpieces using an embedded thermocouple during grinding with a water soluble fluid at specific removal rates from 5 to 60 mm 2/s. The energy partition to the workpiece and heat flux distribution within the grinding zone were estimated using temperature matching and inverse heat transfer analyses. In all cases, the maximum grinding zone temperature rise was less than 120°C. The energy partition to the workpiece was found to be only 4.0 to 8.5%37;. Such low energy partitions are consistent with a thermal model which takes into account conduction to the workpiece, conduction to the abrasive grains, and cooling of the workpiece by the fluid at the grinding zone.
Model of grinding thermal damage for precision gear materials
J.E. Mayer, Jr (2), G. Purushothaman, S. Gopalakrishnan  
STC G,  48/1/1999,  P.251
Keywords: Grinding, Thermal damage, Gear steels
Abstract : Thermal damage, specifcally burn, in carburized and hardened precision gear steels caused by grinding was investigated. Excessive grinding temperatures cause grinding burn and result in excessive scrappage. AISI 9310 and X53 gear steels, used in helicopters and tilt-rotor aircraft, respectively, were prepared and heat-treated by a production partner. Grinding tests were conducted on these steels. Nital etching was used to detect grinding burn. Models were established to predict onset of thermal damage for AISI 9310 and X53 steels based on specific grinding energy determined from grinding force measurements. The models were compared to results published for other steels.
Grind-hardening: a comprehensive view
T. Brockhoff   / E. Brinksmeier (1)
STC G,  48/1/1999,  P.255
Keywords: Grinding, Surface hardening, Hardness penetration depth
Abstract : The invention of advanced grinding processes enabling the surface hardening of steel parts was described for the first time in 1994 [1]. In such operations, named grind-hardening the dissipated heat in grinding is utilized to induce martensitic phase transformations in the surface layer of components. A grinding process then becomes a heat treatment operation like induction or flame hardening. The fundamentals of this new process, which had been developed up to first industrial applications, will be illustrated in this paper. Especially the impact of different grinding parameters on the structure and the achievable hardness penetration depth are discussed in detail.
Optimization of the dynamic behavior of grinding wheels for grinding of hard and brittle materials using the finite element method
G. Warnecke (2), C. Barth  
STC G,  48/1/1999,  P.261
Keywords: Grinding wheel, Dynamic property, Finite element method
Abstract : In grinding of hard and brittle materials such as advanced ceramics or hard metal, process behavior and work result are closely connected with material removal mechanisms. Material removal mechanisms are determined by complex interactions between material properties, geometry of the grits, the kinematics of grit engagements and the mechanical and thermal .loads acting on workpiece and tool due to energy transformation in the grinding process. Experimental investigations of surface grinding processes show that material removal mechanisms are also influenced by dynamic conditions in the contact zone. These dynamic conditions, that are not chatter vibrations, can have both a positive and negative influence on surface quality, process forces and wear of the grinding wheel. For a given machine tool and workpiece the dynamic contact zone conditions can be optimized by the dynamic properties of the hub of the grinding wheel. For analyzing the dynamic contact zone conditions based on the behavior of the grinding wheel the finite element method is used. By means of these analyses the dynamic properties of grinding wheels can be adapted to meet the requirements of a determined grinding process with regard to tool wear, surface roughness of the workpiece and process forces.
ECD (Electrochemical in-process Controlled Dressing), a new method for grinding of modern high-performance cutting materials to highest quality
D. Kramer, F. Rehsteiner (1)   / B. Schumacher (1)
STC G,  48/1/1999,  P.265
Keywords: Grinding, In-process dressing, Electrochemical dressing
Abstract : The steadily increasing demand for cutting tools with high wear resistance coupled with an adequate toughness has led to the development of new cutting materials that are extremely difficult to machine by conventional grinding techniques: Cermets, Ceramics, PcBN, PCD. A new method of in-process dressing of metal bonded diamond grinding tools by a controlled electrochemical process, called ECD, opens up completely new ways.of grinding these materials. As a result not only the quality of the ground pieces is strongly improved but also an economical application of multi-layered, metal bonded diamond grinding wheels to the machining of modern cutting materials is achieved, which would be impossible otherwise. This new method has been applied successfully on an actual insert grinding machine.
Vacuum-preloaded hydrostatic shoe for centerless grinding
Y. Yang, B. Zhang (2), J. Wang  
STC G,  48/1/1999,  P.269
Keywords: Centerless grinding, Hydrostatic shoe, Out-of-roundness error
Abstract : An innovative workpiece support, vacuum-preloaded hydrostatic shoe, is developed for lobing and chatter suppression in centerless grinding. The hydrostatic shoe applies vacuum-preloading to a hydrostatic bearing so as to provide a workpiece support of non-contact, good damping and high stiffness. The paper presents stability analysis and simulation results to demonstrate the effectiveness of the hydrostatic shoe in lobing and chatter control. Grinding experiments are conducted on bearing raceways to confirm the simulation results. The hydrostatic shoe is demonstrated to be superior to conventional contact shoes. Under the same grinding conditions, the hydrostatic shoe results in 42%37; less out-of-roundness error over the conventional shoes.
Development of a resinoid diamond wire containing metal powder for slicing a silicon ingot
T. Enomoto, Y. Shimazaki, Y. Tani (2), M. Suzuki, Y. Kanda  
STC G,  48/1/1999,  P.273
Keywords: Wire sawing, Silicon grinding, Metal powder
Abstract : Loose-abrasive wire sawing widely employed for slicing silicon ingots has problems of dirty working environment and inefficiency. Fixed-abrasive wires, namely electroplated diamond wires and resinoid diamond wires, have been developed to overcome these problems. Resinoid diamond wires, which can be produced at a lower cost, can be put to practical use, but they have a low breaking twist strength. In this study, metal powder is added to the resinoid bond to strengthen it. A series of experiments revealed that the breaking twist strength, heat resistance, tool wear resistance, and slicing efficiency of this wire are significantly improved.
Ultraprecision surface grinding of chemical vapor deposited silicon carbide for X-ray mirrors using resinoid-bonded diamond wheels
Y. Namba, H. Kobayashi, H. Suzuki, K. Yamashita   / N. Taniguchi (1)
STC G,  48/1/1999,  P.277
Keywords: Ultra-precision surface grinding, X-ray mirror, Silicon carbide
Abstract : Chemical Vapor Deposited Silicon Carbide (CVD-SiC) on sintered silicon carbide has been ground by the ultraprecision surface grinder having a glass-ceramic spindle of extremely-iew thermal expansion with various cup-type resinoid-bonded diamond wheels for getting high-brightness synchrotron radiation mirrors. The surface roughness depends upon the average grain size of a wheel, feed per wheel revolution and degree of cutting edge wear. A very smooth surface of 0.266nm rms was obtained by ultraprecision grinding without polishing. A high specular reflectivity of 88.7°io at 0.834nm in wavelength was obtained on the ground surface at the grazing incident angle of 0.7-0.95 degree, parallel to the grinding direction.
Influence of kinematics on the face grinding process on lapping machines
E. Uhlmann, T. Ardelt   / G. Spur (1)
STC G,  48/1/1999,  P.281
Keywords: Grinding, Lapping machine, Ceramics
Abstract : The substitution of many lapping processes by face grinding on lapping machines offers a new field of application for the kinematic model of relative motions in lapping. The selection of path types and velocities between parts and grinding wheels does not, as in lapping, primarily serve to avoid the profile wear of the wheels. Rather, the process development and thus, the part quality are directly influenced. Ceramic parts are used as an example to illustrate the improvement in performance made possible by the analysis of machining kinematics.
Warp in high precision cutt-off grinding of Al2O3-TiC ceramic thin plate
Y. Ohbuchi, T. Matsuo (1), N. Ueda  
STC G,  48/1/1999,  P.285
Keywords: Grinding, Abrasive cut-off, Quality assurance
Abstract : High precision cut-off grinding has been carried out on A1_2 0_3 -TiC ceramic thin plates with metal bond thin diamond wheels. The warp of the cut-part as well as the flatness of work surface, i.e, deflection of wheel, was precisely measured and thus, the warp generation mechanism was analyzed and the optimum slicing condition was investigated. Grinding forces were measured for discussing the warp. Also, the effect of V-shaped guide groove for depressing the deflection was studied. It is evident that the warp of workpiece and the wheel deflection largely depend on grinding type and pre-processing conditions. The high feed cut-off grinding is most effective for restraining the deflection, and the use of a V-shaped groove is a useful way to depress the deflection.

 STC M 

Nanometer positioning of a linear motor-driven ultraprecision aerostatic table system with electrorheological fluid dampers
H. Shinno, H. Hashizume   / H. Sato (1)
STC M,  48/1/1999,  P.289
Keywords: Nanotechnology, Ultra-precision machine, Nano-positioning
Abstract : With the ever increasing demand for higher accuracy and higher productivity in the world-wide manufacturing environment, ultraprecision table positioning technology is urgently required. In order to establish an ultraprecision technology of nanometer accuracy capability, it is important to develop ultraprecision table systems based on new design concepts. In this study, therefore, a linear motor-driven ultraprecision aerostatic table system equipped with electrorheological fluid dampers is described, with proven nanometer positioning accuracy.
The effect of drawbar force on metal removal rate in milling
S. Smith (2), T.P. Jacobs, J. Halley  
STC M,  48/1/1999,  P.293
Keywords: Milling, Metal removal rate, Dynamic stiffness
Abstract : The metal removal rate in milling is often limited by the tool-spindle dynamics. Higher stiffness and damping as seen at the tool tip allow higher metal removal rates. While increasing the drawbar force leads to greater static stiffness in the tool-spindle interface, dynamic measurements indicate that higher drawbar forces also diminish the damping. Whether higher drawbar force is beneficial for stable metal removal depends on whether the gain in stiffness is greater than the loss in damping. This paper presents test-stand measurements of stiffness and damping for tool holder - spindle interfaces at various drawbar forces, and similar measurements in spindles.
Spindle and toolsystems with high damping
M. Weck (1), N. Hennes, M. Krell  
STC M,  48/1/1999,  P.297
Keywords: Metal cutting, Chatter vibration, Damping system
Abstract : Today's machine tool spindles are generally designed in rolling bearings to achieve high rotational speeds. However, the damping capacity of these elements is much lower than that of hydrostatic or hydrodynamic bearings. Low system damping quite often causes chatter vibrations during the metal cutting process. The use of tools with a long overhang often leads to dynamic instability. Placing the rolling bearings in a hydrostatic arrangement promises an increase of damping with unchanged capability of high rotational speed. By the use of passive damping elements, integrated in the tool holding fixture, the dynamic behaviour of the spindle / tool system can be optimized. Material substitution as well as geometric shape optimization leads to increased dynamic stability of boring bars.
Advantages and characteristics of a dynamic feed axis with ball screw drive and driven nut
H. Weule (1), T. Frank  
STC M,  48/1/1999,  P.303
Keywords: Feed-drive, Optimization, Machine tools
Abstract : This paper describes the advantages and characteristics of a Dynamic feed axis with bail screw drive and driven nut in comparison with the conventional electromechanical drive. In contrast to the classical drive the ball screw leadscrew is rigidly located at both ends and the nut is driven by a servomotor. The investigation considers two drive variants: the indirect drive with a standard servomotor driving the nut via a toothed belt and the direct drive with a hollow shaft servomotor. The feed system developed at the Institute for Machine Tools and Production Science at the University (TH) of Karlsruhe opens up new prospects for the development of new dynamic machine generations with traverse speed up to 120 m/min and acceleration up to 45 m/s . In addition to the high acceleration and traverse speed, the development program also has the objective of optimised transmission behaviour of the feed kinematic system with positional control. The design features and operating characteristics achieved with the innovative test device are described.
A self-tuning controller for digitally controlled electromechanical servo drives in machine tools
G. Pritschow (1), J. Bretschneider  
STC M,  48/1/1999,  P.307
Keywords: Control design, Drive, Machine Tool
Abstract : The authors present a new paradigm for a self-tuning controller applied to servo-drives in machine tools. To facilitate controller tuning, measured data from the drive instead of a dynamic model are utilised. Using a set of user-defined dynamic performance criteria, a numerical optimisation process tunes the controller parameters. The conventional procedure of successive optimisation of the cascade controller from the inner to the outer loop is deliberately avoided, thus allowing all variable controller parameters to be simultaneously tuned. Thus this self-tuning concept can be applied to a wide variety of servo-control paradigms. This paper presents the results achieved in practice with this self-tuning controller strategy.
Design of a precision, agile line boring station
Y. Koren (1), Z.J. Pasek, p. Szuba  
STC M,  48/1/1999,  P.313
Keywords: Machine Tool, Cutting, Control
Abstract : This paper describes a new agile line boring station for machining of long bores in automotive applications, e.g. crank and camshaft bores in engine blocks. The machine includes a "smart" lire boring tool with an on-line compensation mechanism, relying on sensing and intelligence built into the tool itself, for real-time correction of the boring process. To supplement the advantages provided by the "smart" tool, a prototype agile line boring machine was developed as a joint effort between the University of Michigan and Lamb Technicon, a machine tool builder. The design integrates multiple new concepts of mechanical structure of the machine with an intelligent controller.
Machinery fault diagnosis and prognosis: applications of advanced signal processing techniques
J. Suh, S.R.T. Kumara (1), S.P. Mysore  
STC M,  48/1/1999,  P.317
Keywords: Machine, Monitoring, Intelligent system
Abstract : Machinery health prediction based on process models and/or process parameters is an important function in automated manufacturing set-ups. Sensor data is collected and used to indirectly model the equipment. Due to the short response times required it is important to investigate robust sensor data representation schemes. Traditional Fourier Analysis is not sufficient to preserve the information in both frequency and time domains. In this paper we describe the use of wavelets, both continuous and discrete, for equipment diagnosis and prognosis. We detail wavelet-based techniques for gear fault diagnosis and prognosis.
Dynamic influence on workpiece quality in high speed milling
U. Heisel (2), A. Feinauer  
STC M,  48/1/1999,  P.321
Keywords: High speed machining, Dynamic parameter, Workpiece quality
Abstract : The high speed milling process places completely new demands on the dynamic behaviour of machining centres. This paper describes the causes of vibrations in high speed milling. It includes a quantification of vibrations due to imbalances, accelerations and cutting forces. The effects on the quality of workpieces are simulated by a dynamic model of the machine. Therefore, also the mechanical structure and the axis control system are taken into account. The results of the simulation are verified by some cutting examinations. To improve the quality of workpieces suggestions are made to avoid vibrations or to compensate the effects on vibrations due to imbalance.
Experimental and computer aided analysis of high-speed spindle assembly behaviour
M. Zeljkovic, R. Gatalo   / M. Kalajdzic (1)
STC M,  48/1/1999,  P.325
Keywords: Machine Tool, Spindle, Experimentation
Abstract : A methodology of experimental identification of machine tool spindle assembly behaviour has been developed at the Institute for Production Engineering in Novi Sad. The methodology allows analysis of the spindle assembly in terms of static, dynamic and thermal behaviour. This methodology is applied to high-speed machine tool spindle assembly analysis. To increase reliability of experimental results, the methodology is combined with computer aided modeling of static and dynamic behaviour, using software packages based on the finite elements method (I-DEAS, ALGOR, SAP-90, VRETENO). Special attention has been paid to the influence of the used bearing arrangement on the spindle assembly behaviour.
Development of an intelligent design system for embodiment design of machine tools
M-W. Park, J-H. Cha, J-H. Park, M. Kang (2)  
STC M,  48/1/1999,  P.329
Keywords: Design system, Machine Tool, Knowledge-based system
Abstract : An intelligent software system which can support efficiently and systematically machine tool design by utilizing design knowledge is described in this paper. The process of embodiment design of a machining center was modelled, represented by IDEFO, and embedded in the system. A hybrid type inference engine has been introduced so that the system can effectively deal with knowledge represented in diversified forms. The design system was developed on the basis of object-oriented programming, and has been coded into one software system which can be ported on Windows NT.
Development and study of a new kind of 3-DOF tripod
G.Q. Cai (2), M. Hu, C. Guo, B. Li, Q.M. Wang  
STC M,  48/1/1999,  P.333
Keywords: Parallel machine tool, Kinematics, Dynamics
Abstract : A novel 3-DOF parallel machine tool based on a tripod mechanism has been developed and studied. The main aspects of its structure, kinematics, workspace, parameter design, error analysis and force analysis are introduced. Through theoretical analyses and operation tests, it shows some distinctive advantages, such as high ratio of force-to-weight, simple structure and simple kinematic equations, large workspace with no kinematic coupling and no singularity configuration. The unique performance of the tripod machine tool provides a high potential and a very good prospect for its practical implementation in manufacturing industry.
A new parallel mechanism machine tool capable of five-face machining
J. Kim, F.C. Park, J.M. Lee (1)  
STC M,  48/1/1999,  P.337
Keywords: Machine Tool, Parallel mechanism, Rapid machining
Abstract : This paper introduces a new parallel mechanism machine tool that can machine the top surface and four lateral surfaces of a prismatic workpiece with one setup. No B-axis motion is necessary. Five-axis simultaneous machining can be executed in any workspace. This machine is based on a new parallel mechanism, Eclipse, which was invented by the authors. The Eclipse allows the spindle of the machine tool to tilt to 90 degrees from the vertical posture, and also to sweep the lateral surfaces of the workpiece over 360 degrees. This paper presents the overall structure, the detailed design aspects, and the performance evaluation of the new parallel mechanism machine tool.
Closed-form resolution scheme of the direct kinematics of parallel link systems based on redundant sensory information
P.B. Petrovic, V.R. Milacic (1)  
STC M,  48/1/1999,  P.341
Keywords: Parallel kinematic structure, Kinematic transformation,
Abstract : Non-numerical resolution In this paper, the direct kinematics transformation in parallel link systems, based on redundant sensing approach is addressed. The redundant sensory information is provided by additional position sensors, connected directly to the parallel structure in a parallel manner. Optimization of position and the number of redundant sensors is performed by a proposed Geometrical-Structure-Partitioning Method. The efficiency of the method is verified by two examples - type 3-3 and 6-3 spatial structures, where only one redundant sensor is identified as sufficient for unique closed-form solution of the direct kinematics problem.
Putting parallel kinematics machines (PKM) to productive work
F. Rehsteiner (1), R. Neugebauer, S. Spiewak (2), F. Wieland  
STC M,  48/1/1999,  P.345
Keywords: Parallel machines, Hexapod, Specification
Abstract : It is embarrassing to observe that out of the rapidly growing number of PKMs hardly any are doing productive work in industry while most of them stay in University labs. The paper deals with two aspects of this problem. First, the results of discussions with industrial partners, both users and manufacturers, are presented. The main result is to improve communication between developers and users. In the second part, ways are suggested on how to convert these ideas into successful products. The viability of this approach is demonstrated by the successful cooperation between a PKM manufacturer and a potential user.
Fundamental comparison of the use of serial and parallel kinematics for machine tools
J. Tlusty (1), J. Ziegert, S. Ridgeway  
STC M,  48/1/1999,  P.351
Keywords: Hexapod, Machining, Stiffness
Abstract : Classical cartesian kinematics Machining Center (MC) structures are compared with parallel kinematics hexapods (HX) structures from the point of view of workspace, stiffness, accuracy, acceleration ability, and motion dynamics for use as high speed milling machines. Concrete stiffness values are used as achievable. It is concluded that variable strut length HX are fundamentally inferior to the MC and cannot practically be used as high speed milling machines. The constant strut length HX offer larger workspace and higher strut stiffness and may produce characteristics comparable to MC in particular designs.

 STC O 

Simulation based analysis of complex production systems with methods of nonlinear dynamics
H.P. Wiendahl (1), H. Scheffczyk  
STC O,  48/1/1999,  P.357
Keywords: Production process, Methods, Analysis
Abstract : The most recent, and probably the most discussed approach in connection with systems complexity, has been the attempt to apply the results of chaos research to production systems. But the question concerning the amount and quality of data necessary to analyze manufacturing systems with methods of non-linear dynamics is still to be answered. To get further knowledge in analyzing data from manufacturing systems with methods of nonlinear dynamics, simulation experiments are made. The interaction and evolution of dynamic system parameters are visualized in a phase space. Although human imagination is restricted to three dimensions, it is possible to analyze higher dimensional phase spaces by modern computation. The aim is to discover laws which describe the behavior of the system as a whole.
A petri net technique for batch delivery time estimation
P. Xirouchakis, D. Kiritsis, C. Gunther, J.-G. Persson (2)  
STC O,  48/1/1999,  P.361
Keywords: CAPP, Cost, Petri net
Abstract : The problem under consideration is delivery time and cost estimation in batch manufacturing of mechanical parts. We consider non-linear process planning with explicit resource modeling. We present a two-level Petri net class which are high level nets extended with time that allow the interleaving of transitions. They consist of a system net modeling the job shop layout (including the machines) and token nets modeling the jobs and setups. We calculate the optimum delivery time and associated cost of a batch of one type of mechanical workpiece together with the associated resources.
Object-oriented design of a modular scheduling architecture
P. Brandimarte   / R. Levi (1)
STC O,  48/1/1999,  P.365
Keywords: Production scheduling, Object-oriented programming, Conceptual modelling
Abstract : The importance of finite-capacity schedulers is increasing, with respect to the widespread MRP packages, due to their ability to model the shop floor more accurately. However, this very advantage may turn into a disadvantage, since it is quite difficult to devise a high-quality general purpose scheduler able to cope with the technological peculiarities of different production environments. Furthermore, a detailed schedule is prone to disruptions due to the uncertainty affecting the shop floor. Hence, we need both a modular approach to devise and assemble local schedulers and a way to link predictive and real time scheduling. To cope with both requirements, we propose a scheduling approach based on a generalization of the well-known shifting bottleneck method. The scheme is based on the coordination of local schedulers by a general scheme, such that the knowledge needed to cope with technological peculiarities is locally confined. The aim of the coordination mechanism is to generate a set of local due dates .which can be used as targets to drive real time dispatching.
A genetic algorithm based approach for scheduling of dual-resource constrainded manufacturing systems
H. ElMaraghy (1), V. Patel, I.B. Abdallah  
STC O,  48/1/1999,  P.369
Keywords: Scheduling, Manufacturing systems, Genetic algorithms
Abstract : This paper presents a scheduling approach, based on Genetic Algorithms (GA), developed to address the scheduling problem in manufacturing systems constrained by both machines and workers. The GA algorithm utilizes a new chromosome representation, which takes into account machine and worker assignments to jobs. A study was conducted, using the proposed scheduling method, to compare the performance of six dispatching rules with respect to eight performance measures for two different shop characteristics, i) dual-resources (machines and workers) constrained shop and ii) single-resource constrained shop (machines only). An example is used for illustration. The results indicate that the dispatching rule which works best for a single-resource constrained shop is not necessarily the best rule for a dual-resources constrained system. Furthermore, it is shown that the most suitable dispatching rule depends on the selected performance criteria and the characteristics of the manufacturing system.
Architectural design of neural network hardware for job shop scheduling
P. B. Luh, X. Zhao, L.S. Thakur, K.-H. Chen, T.-D. Chiueh, S.-C. Chang   / J.M. Shyu (1)
STC O,  48/1/1999,  P.373
Keywords: Job shop scheduling, Neural network, Hardware design
Abstract : By combining neural network optimization ideas with "Lagrangian relaxation" for constraint handling, a novel Lagrangian relaxation neural network (LRNN) has recently been developed for job shop scheduling. This paper is to explore architectural design issues for the hardware implementation of such neural networks. A digital circuitry with a micro-controller and an optimization chip is designed, where a parallel architecture and a pipeline architecture are explored for the optimization chip. Simulation results show that the LRNN hardware will provide near-optimal solutions for practical job shop scheduling problems. It is estimated that the parallel architecture will obtain one order of magnitude speed gain, and the pipeline architecture will obtain two orders speed gain as compared with the currently used method.
An emergent synthetic approach to supply networks
K. Ueda (1), J. Vaario, T. Takeshita, I. Hatono  
STC O,  48/1/1999,  P.377
Keywords: Manufacturing, Synthesis, Interactive system simulation
Abstract : To deal with complex supply networks a new approach based on emergent synthesis is proposed. The approach is demonstrated and studied under simulation. The simulation model consists of customer, dealer, producer, supplier, and product elements. The emergence of products and supply networks by the customers' preference can be observed as a global behavior resulting from the local interactions between these elements. The possibility to experiment with various management strategies by interactive functions of the simulator is also discussed. The user can carry out several scenarios and observe whether the product succeeds on the market and how the supply networks change.
A reference scenario for IMS strategic design
G. Perrone, S. Noto La Diega (1)  
STC O,  48/1/1999,  P.381
Keywords: IMS design, Programming models, Genetic algorithms
Abstract : Today is fully acknowledged that manufacturing is a formidable competitive weapon. The strength of such a weapon is essentially defined during the first step of the design phase called strategic design. During this phase, in fact, the principal characteristics of the manufacturing systems are to be defined taking into account the competitive environment and the competition strategy. Classical analytical models for IMS design often neglect this aspect and, perhaps, this is one of the causes of IMS failure. The paper proposes a set of analytical models for strategic IMS design; they have been classified into four classes, each one pursuing a determined set of objectives, providing, in this way, a general reference framework for IMS designers.
Information management in process planning
D. Lutters, T.C. Wijnker, H.J.J. Kals (1)  
STC O,  48/1/1999,  P.385
Keywords: Information management, Integration, Design and process planning
Abstract : A recently proposed reference model indicates the use of structured information as the basis for the control of design and manufacturing processes. The model is used as a basis to describe the integration of design and process planning. A differentiation is made between macro- and micro process planning. Macro process planning employs production method knowledge and context information to evaluate candidate production methods. Decisions in this respect are already relevant in the design stage. In working in the opposite direction, method knowledge can be applied to generate geometry and to supply material information. This enables both the completion of abstract features and the selection of production methods for the less functional, roughly defined parts of a product, ultimately resulting in a fully specified design. This approach is primarily based on Information Management.
Maintenance data management system
S. Takata (2), Y. Inoue, T. Kohda, H. Hiraoka, H. Asama  
STC O,  48/1/1999,  P.389
Keywords: Maintenance data management, Failure analysis, Knowledge based system
Abstract : For the effective management of manufacturing facilities throughout their life cycle, it is important to collect maintenance data and make use of them for operation and maintenance planning or design of new machines. However, it is seldom that the maintenance data are properly recorded and utilized in a systematic way. To solve these problems, we have proposed a maintenance data management system. In this paper, two major modules of the system are discussed. The first one is a malfunction data collection system which can navigate users to input malfunction cases in a proper format. The second one is a feedback data generation system which induces common causes implied in the malfunction cases by means of the attribute-oriented induction algorithm. An experimental system is applied to malfunction cases of machine tools for demonstrating its effectiveness.
Life cycle design - a route to the sustainable industrial culture ?
M. Hauschild, H. Wenzel, L. Alting (1)  
STC O,  48/1/1999,  P.393
Keywords: Life cycle design, Environmental performance, Sustainable industrial culture
Abstract : In the attempt to reorient Society's development in a more sustainable direction attention is focused on the environmental impact of products and systems over their entire life cycle, but how can the environmental life cycle perspective be introduced into the design of new solutions and how much can be obtained through life cycle design? The authors' experience with integration of environmental considerations in product development is presented, ranging from the detailed interactive approach of the EDIP-method through various simplified approaches. The potential for environmental improvements is reviewed and the overall question of to what extent life cycle design is a route to the sustainable industrial culture is discussed.
Variation modelling for a sheet stretch forming manufacturing system
R. Suri, K. Otto   / G. Boothroyd (1)
STC O,  48/1/1999,  P.397
Keywords: Stretch forming, Variation, Modelling
Abstract : A system-level model of variation propagation in a sheet stretch forming manufacturing system is developed and explored. The system model is composed of sub-models of heat treatment. including quenching and natural aging, and stretch forming. Both the nominal and variation predictions of the model are compared to measured production data. Factors in the system which are most sensitive to variation are identified, and a variation reduction strategy is discussed. This strategy lead to a 30°i; reduction in part strain variation on the factory floor.
Aggregate product and process modelling for the welding of complex fabrications
P.G. Maropoulos   / J. Crookall (1)
STC O,  48/1/1999,  P.401
Keywords: Process planning, Design manufacturing integration, Welding
Abstract : The integration of design with manufacturing planning has been the subject of numerous investigations over the past two decades. Whilst a lot has been achieved, most of the research relates to the detailed design stages. Of primary importance are the early design stages when there is a plethora of options available for product configuration and manufacturing process selection. This paper describes the aggregate product and process modelling methods which are developed to facilitate the integration of early design stages with process planning. The application of aggregate methods for complex fabrications is described together with results from testing using industrial data.
Algorithms for the design verification and automatic process planning for bent sheet metal parts
J. Duflou, J.P. Kruth (1), D. Van Oudheusden  
STC O,  48/1/1999,  P.405
Keywords: CAPP, Sheet metal, Bending
Abstract : Sheet metal bending processes require detailed process planning in order to eliminate infeasible set-ups or avoidable ergonomically demanding manipulation requirements. In this paper it is demonstrated how the complexity of a bend sequencing task can be handled by means of an efficient reduction of the search field through well-chosen representation schemes and the identification of geometric constraints. The expertise established by experienced process planners was integrated in search algorithms based on precedence constraint solving and dynamic branch-and-bound techniques. A case study is used to illustrate these procedures. Additionally, the characteristics of a dedicated collision detection algorithm, developed for fast sequence verification during search procedures, are outlined.
Networked manufacturing with reality sensation for technology transfer
M. Mitsuishi, T. Nagao (1)  
STC O,  48/1/1999,  P.409
Keywords: Open-architecture CNC manufacturing system, In-process monitoring, Man-machine system
Abstract : This paper describes a networked remote manufacturing system with reality transmission capability for simultaneous technology transfer. The technologies presented in the paper can be used to establish a remote operation and monitoring function as an advanced user interface. The system consists of an open-architecture CNC controller, sensors to monitor the machining state, mechanical fuses to prevent overloads, apparatuses to present visual, auditory, force and tactile information to the user interface, and an input device to operate a machine tool. In the experiment, visual, force, auditory and tactile information were successfully presented to operate the system remotely using multi-axis force information.

 STC P 

Results of the CIRP-form intercomparison 1996-1998
O. Jusko, J.G. Salsbury, H. Kunzmann (1)  
STC P,  48/1/1999,  P.413
Keywords: Form-measurement, CMM, Cooperative project
Abstract : Between 1996 and 1998, an international form intercomparison was completed. Among the 19 participants, there were 3 from industry, 9 from universities, and 7 from national metrology institutes. The artifacts under test included a ring, a plug, and three spheres of different materials. The measurement tasks included roundness, straightness, and parallelism. The participants were allowed to choose the type of measuring instrument, and therefore the results include measurements from both classical spindlebased form testers and also coordinate measuring machines (CMMs). For all the measurements, the participants were instructed to estimate their measurement uncertainty. The closeness in agreement between the results of the various participants depended on the measurement task, the assessment parameters, and the instrument type used.
Design for a compact high-accuracy CMM
G.N. Peggs (2), A.J. Lewis, S. Oldfield  
STC P,  48/1/1999,  P.417
Keywords: Coordinate measuring machine, Laser interferometry, Miniaturisation
Abstract : The trend towards miniaturisation in manufacturing has led to a requirement for a coordinate measuring machine (CMM) capable of measuring tiny features on small components. A compact CMM has been designed and built which has a working volume of a cube of side 50 mm, and a measurement uncertainty estimated to be 50 nm. The machine utilises a self-calibrated solid cube to provide a geometrical reference that is transferred into the CMM by means of a combination of three, mutually orthogonal, mirrors, six laser interferometers and three dual axis autocollimators. In situ measurement of the mirrors' flatness and orthogonality and redundancy of measurement are used to minimise systematic uncertainties. This paper describes the design of the CMM and an overview of the theoretical uncertainty analysis.
Development of the nano-CMM probe based on laser trapping technology
Y. Takaya, S. Takahashi, T. Miyoshi, K. Saito (2)  
STC P,  48/1/1999,  P.421
Keywords: Optical measurement, Micro-machine, CMM probe
Abstract : The 3D nano-position sensing probe serves as an important technology in the development of the nano-CMM used in microfabrication systems. This paper discusses the laser trapping probe whose principle is based on the dynamic properties of optically trapped particles and the Linnik microscope interferometer. Its potentials as a nano-CMM probe were investigated in fundamental experiments. Single-beam gradient-force optical traps of silica particles in air were successfully demonstrated by using an object lens with N.A. of 0.80. Positional detection accuracy of 30nm was also confirmed through measurements of fringe changes with the shifts of the probe sphere.
Evaluation of CMM uncertainty through Monte Carlo simulations
A. Balsamo (2), M. Di Ciommo, R. Mugno, B.I. Rebaglia, E. Ricci, R. Grella  
STC P,  48/1/1999,  P.425
Keywords: CMM, Measurement uncertainty, Simulation
Abstract : In recent years there has been an increasing interest in suitable techniques for evaluating the uncertainties of measurement values yielded by CMMs. Among others, simulation techniques appear to suit the versatility of CMMs and to keep the CMM user involvement to a minimum. The paper outlines the Monte Carlo-based technique under development at the IMGC and illustrates its modular approach which enables a separate treatment of the various uncertainty sources. The importance of measurement correlation is pointed out and a medium-complexity example is given in the case of geometrical errors.
Error compensation in CNC turning solely from dimensional measurements of previously machined parts
Z.Q. Liu, P.K. Venuvinod (1)  
STC P,  48/1/1999,  P.429
Keywords: Error compensation, Measurement, Computer numerical control (CNC)
Abstract : Inadequate shop floor friendliness is a major reason why traditional software based error compensation approaches have failed to be accepted by industry. This paper develops a compensation approach that relies solely on post-process and on-machine measurements of parts previously machined on the same machine. The approach is based on a new method of error decomposition and a simple model of machine deflections induced by the cutting force. The approach is verified by independent measurements of the various model parameters. It is also shown that the machine tool can be made to act as its own dynamometer.
Testing the contouring performance in 6 degrees of freedom
W. Knapp (2), S. Weikert  
STC P,  48/1/1999,  P.433
Keywords: Machine Tool, Contouring performance, Measuring instrument
Abstract : The performance of linear axes is often tested on the basis of one set-up per one or two directions of deviations from a NC path. With the application of multi-axes machining the contouring performance in more than two degrees of freedom is of interest. The paper describes a measuring instrument to check the contouring performance of a machine tool in the six degrees of freedom. The three translations and the three rotations of the relative movement between tool side and workpiece side are measured simultaneously. Results of first measurements are presented and discussed.
'Ductile mode' machining of commercial PZT ceramics
P.A. Beltrao, A.E. Gee, J. Corbett (2), R.W. Whatmore  
STC P,  48/1/1999,  P.437
Keywords: Ceramic, Ductile transition, Precision machining
Abstract : A wide range of products rely on the high-precision fabrication of piece-parts using PZT ceramics. These include ultrasonic medical imaging transducers, ink jet printing heads, etc. Not only is precision important, but also the degree of sub-surface damage needs to be minimised because this is known to compromise performance by engendering depoling. It also leads to in-service problems due to ageing caused by the movement of damage-induced domain walls and cracks. A fundamental machinability investigation was undertaken, commencing with quasi-static and ruling tests, prior to performing diamond turning and grinding experiments. This research has helped in the understanding of the PZT ceramic mechanical and electrical characteristics when machined and also is being used to build up an optimised machining process model.
Ultraprecision diamond cutting of hardened steel by applying elliptical vibration cutting
E. Shamoto, T. Moriwaki (1)  
STC P,  48/1/1999,  P.441
Keywords: Ultra-precision cutting, Steel, Vibration cutting
Abstract : Elliptical vibration cutting, which has been proposed by the authors, is applied to ultraprecision diamond cutting of hardened steel in the present research. Since steel cannot be cut by the ordinary cutting method with a diamond cutting tool due to excessive tool wear, performance of the elliptical vibration cutting is examined in comparison with the conventional vibration cutting. The experimental results show that the proposed method has superior performance, i.e. low cutting force, high quality surface finish and long tool life. Based on these advantages, the elliptical vibration cutting is successfully applied to ultraprecision cutting of hardened steel, such as ultraprecision turning of a spherical die and a flexible micro structure, and ultraprecision micro grooving.
Sensor systems for industrial applications under water
H.K. Tönshoff (1), U. Kruse, H.-J. Mahner  
STC P,  48/1/1999,  P.445
Keywords: Robotic, Distance measurement, Under water
Abstract : For applications of robots in industrial underwater environments sensor systems are required to identify the observed scene and to determine the position of the tool-center-point (TCP) of robots. A laser radar for guidance of a mobile underwater vehicle is based on a different absorption distance measurement method, which calculates the distance by the different attenuation behaviour of water at two different laserlight wavelengths. Therefore, scattering and attenuation processes in water have to be incorporated. An ultrasonic measurement system is built as a trilateration system. It consists of piezo-actuators and uses a time-of-flight method combined with a phase-shift measurement. Thus it is possible to identify the exact position and orientation of the actuator of an underwater robot with a very high accuracy.

 STC S 

Recent developments in hardness testing and their implications for standardisation
T.J. Bell, E.G. Thwaite (1)  
STC S,  48/1/1999,  P.449
Keywords: Hardness, Testing, Standardisation
Abstract : This paper discusses two current developments in the field of hardness testing. Recent proposals for the Rockwell C scale should make it possible for a `Unified' Rockwell scale with agreement between National Standards Laboratories within 0.1 HRC. The need for better understanding of the Ultra Micro Indentation Test, where force and penetration are recorded simultaneously, will also be discussed. Difficulties in standardisation of this technique are exacerbated by metrological problems, a diversity of terminology and numerous variations to the method.
Investigation of surface formation process of silicon molecular beam epitaxy by atomic force microscopy
Y. Furukawa (1), A. Kaneko  
STC S,  48/1/1999,  P.453
Keywords: Physical vapor deposition, Ultra-precision machining, Atomic force microscopy
Abstract : Evaporated Silicon molecules are epitaxially grown on (100), (111) and (110) oriented single crystalline Si substrates by MBE, and their molecular level surface formation processes are observed by both AFM and RHEED. In the case of growth on (100) and (110) at 800°C, the surface was covered with many nuclei at first, then, they began to combine together. In the case of (111) at 800°C, giant steps were formed at first and subsequent growth changed the length and edge shape of steps; however, the steps themselves could never be eliminated. It is now proposed that the molecular level surface formation model be adapted to take these experimental results into consideration.
An optical surface texture sensor suitable for integration into a coordinate measuring machine
C. Bradley, J. Jeswiet (1)  
STC S,  48/1/1999,  P.459
Keywords: Sensor, Texture, Surface
Abstract : A fiber optic sensor system is described for non-contact measurement of surface texture. The sensor employs a fiber optic guide and lens arrangement that forms an interferometric cavity between the lens front face and the surface. Changes in the surface topography are manifested as phase changes between the light reflected from the surface and the front face of the lens. An electronic control and data acquisition system converts the phase change into a voltage signal proportional to surface topography. The sensor performance is evaluated against stylus profilometer results and comparison of the amplitude parameter, Ra, shows good agreement.
Surface topography characterization using an atomic force microscope mounted on a coordinate measuring machine
L. De Chiffre (2), H.N. Hansen, N. Kofod  
STC S,  48/1/1999,  P.463
Keywords: Surface topography, Atomic force microscopy (AFM), Coordinate measuring machine (CMM)
Abstract : The paper describes the construction, testing and use of an integrated system for topographic characterization of fine surfaces on parts having relatively big dimensions. An atomic force microscope (AFM) was mounted on a manual three-coordinate measuring machine (CMM) achieving free positioning of the AFM probe in space. This means that the limited measuring range of the AFM (40 pm x 40 pm x 2.7 pm) can be extended by positioning the AFM probe using the movements of the CMM axes (400 mm x 100 mm x 75 mm). Evaluation of the background noise by determining the Sa value of an optical flat gave values in the order of 1 nm. The positioning repeatability of the two horizontal axes of the CMM was determined to ±1 pm. Sets of four 20 pm x 20 pm areas were traced on flat objects, combining the data into single 40 pm x 40 pm areas, and comparing the roughness values to those for the same areas traced in single scans of 40 pm x 40 pm. The results show that surface mapping on industrial surfaces is possible using the Least Mean Square alignment provided by the AFM software.
Requirements for the application of speckle correlation techniques to on-line inspection of surface roughness
G. Goch (2), J. Peters, p. Lehmann, H. Liu  
STC S,  48/1/1999,  P.467
Keywords: Roughness, Scatter, Optical Sensor
Abstract : Conventional surface roughness measurements using profilometric instruments (either mechanical or optical) are standardized and extensively applied in industry. However, these techniques are not suitable to an on-line inspection of industrial machining processes. If an optically rough surface leading to a diffuse scattering is illuminated by coherent light, a speckle pattern occurs showing a granular spatial intensity distribution of the scattered light. In general, the averaged intensity distribution depends on the distribution of the local surface slopes. However, if two speckle patterns at different laser wavelengths are compared via correlation techniques, a measure of the root-mean-square (rms) roughness (Rq) can be obtained, based on certain statistical assumptions. This paper contributes to the application of speckle correlation techniques to the inspection of machined surfaces. Surface statistics dependent on the manufacturing processes are checked. Optical arrangements of a measuring device are introduced. Furthermore, results showing the limits of speckle correlation are presented.