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Modularity: the basis for product and factory reengineering
G. Erixon, A. von Yxkull, A. Arnström (2)  
STC A,  45/1/1996,  P.1
Keywords: Assembling, Module, Methodology
Abstract : "Products in the Product" (Modules) and "Factories in the Factory" (Assembly Module Workshops) has proved to be an excellent basis for continuous product renewal and concurrent development of the manufacturing system. Modularity based on the use of "module drivers" enables the set up of independent assembly units for each module that can be precisely adapted to the requirements of the actual module. This paper presents a proven methodology for product and factory reengineering using the concept of "module drivers". The methodology consists of 5 design steps, from the clarification of customer requirements to the design of each module and the concurrent development of the assembly system.
Robust assembly processes as a means of achieving systemability
G. Reinhart, R. Lindermaier, R. Gräser, B. Eich   / J. Milberg (1)
STC A,  45/1/1996,  P.7
Keywords: Assembly Machine, Processability, Optimization
Abstract : The operating economy of automated assembly plants is directly related to their yield of OK parts. A hitherto unutilised opportunity for optimization consists in minimizing the scattering in the performance and fault characteristics of an assembly system. The key to this optimization is robust processes which can be created with the aid of various measures. Such measures include avoiding or compensating for variable parameters. or reducing and restructuring process chains. Reference data such as processability or the new system ability indices serve as a basis for assessing the robustness of assembly processes and in particular the complex interplay between them. It thus becomes possible to analyse factors influencing the boosts the efficiency assembly process and system, and to visualise them. By way of information feed back, control circuits which of existing assembly processes and process chains, and which are of use in the planning of new plants, can be built up.
Solving technical problems in assembly system's design
H. Bley, U. Seel   / K.G. Günther (1)
STC A,  45/1/1996,  P.11
Keywords: Problem Solving, CAP, Feature
Abstract : The design of an assembly system leads to very difficult technical problems in which technological, functional and economical aspects must be considered. The designer's experience represents a crucial portion of the information which has to be made available. Another part of the needed information is contained in the product design, and part of it is provided by suppliers of assembly system components. Problem solving based on information incorporated in assembly features will be demonstrated using problems encountered in an existing assembly system. The characterisation of features related to assembly is a research topic at the Saarland University. Preliminary results of a contribution to feature-based CAD-systems will be presented.
Construction and start-up of complex assembly systems
H.-P. Wiendahl (1), J. M. Thies, K. Zeugträger  
STC A,  45/1/1996,  P.17
Keywords: Plant Construction Management, Information Feedback, Problem Solving
Abstract : The construction of production systems is determined by a high technical and organizational complexity. Methods for Project Management help to handle the organizational tasks. However the site itself is often a more or less isolated place with only relatively little information exchanged with the headquarters. In consequence much valuable experience knowledge, especially technical knowledge of the late project phases - start-up and tuning - is lost. In contrast to this, an ascertainment and documentation of problems could be used for future technical and organizational enhancements of the production system or the company's processes. This knowledge could be supplemented by operating data and in this way also help to improve the production and maintenance management of the following operating phase. The following described methods are designed to close this gap between project management and production management to help both the system manufacturer and the system operator.
Automated sewing of textiles with different contours
T. Gottschalk, G. Seliger (2)  
STC A,  45/1/1996,  P.23
Keywords: Automated Assembling, Kinematic, Process Modelling
Abstract : To achieve a three-dimensional form of clothing a sophisticated joining of pieces of fabrics is required. Different lengths and contours have to be fit. A planning system has been realised to achieve the geometrical adaptation with respect to the different material properties of fabrics. Today, only a highly skilled seamstress can operate sewing machines to fulfil these requirements. This paper presents an approach for flexible automation of sewing processes. The distribution of stitching points for planning the seam paths of the pieces to he sewn are calculated based on experimentally investigated fabric properties. The movement commands for fabric transport are calculated from the task requirements for sewing. Finally, a roller feeding device for sewing gently curved pieces has been realised to demonstrate the effectiveness of this approach.
Development of spherical ultrasonic motor
S. Toyama   / A. Kobayashi (1)
STC A,  45/1/1996,  P.27
Keywords: Actuator, Ultrasonic, Motion Study
Abstract : We have successfully developed a new type of spherical motor with two degree of freedom by ultrasonic vibration; it has Ø 445 mm rotor; the maximum speed is 30 rpm; the maximum output torque reaches 0.7 kgf cm; the maximum positioning error is less than 0.3 mm. It has very small and simple structure and has good controllability. We can expect to apply this motor to robotic manipulator's joints, machine vision systems, assembling machines, laser cutting tools and many fields.
Micro SCARA robot as universal adaptive compliant wrist
D. Milutinovic   / V.R. Milacic (1)
STC A,  45/1/1996,  P.31
Keywords: Robotic Assembling, Robotic Mechanism, Compliance Center
Abstract : The newly developed robotic mechanism based on well-known SCARA concept uses two eccentrically positioned rotating discs instead of two joined links. The paper analyzes the capabilities and advantages of the use of this mechanism in the realization of micro SCARA robot as an additional adaptive compliant wrist to standard robot configurations for assembly tasks. The prototype of a universal passive adaptive compliant wrist was developed at this stage. The performance around its true compliance center obtained under precisely determined conditions proved successful.
ASPEN: Computer-aided assembly sequence planning and evaluation system based on predetermined time standard
S. Kanai, H. Takahashi, H. Makino (1)  
STC A,  45/1/1996,  P.35
Keywords: Assembling, Sequencing, Computer Aided Planning
Abstract : The purpose of this research is to objectively evaluate the differences among the feasible assembly sequences. For this purpose, a computer-aided Assembly Sequence Planning and Evaluation system (ASPEN) was developed. ASPEN automatically searches all geometrically feasible sequences by decomposing solid models of a product. ASPEN also chooses an optimum sequence with the least operating time. MTM (Methods Time Measurement) and DFA (Boothroyd's Design For Assembly) which are kinds of predetermined time standards are used to explicitly evaluate the differences of operating time among feasible sequences. The calculation of the operating time based on the data obtained from the sequence planning is discussed. The proposed evaluation method is verified through an experiment on actual assembling work.
An automatic process planning system for block assembly in shipbuilding
K.K. Cho (1), S.H. Lee, D.S. Chung  
STC A,  45/1/1996,  P.41
Keywords: CAPP, Assembly
Abstract : Block assembly in shipbuilding is mainly concerned with cutting and welding operations to construct a block. A block is composed of several steel plates and sections with various sizes and shapes. Process planning for block assembly is to generate cutting and bending operation plans, assembly processes and sequences, and welding operation plans to construct a block. This paper deals with the development of an automatic process planning system for block assembly in shipbuilding. Part assembly graph that is a semantic network type of representation scheme for block structure is proposed and used to represent block information. The approaches adopted are case-based reasoning for block assembly process planning and rule-based reasoning for process planning of cutting and welding operations. The prototype system has been implemented and verified using real blocks in the block assembly shop.
Managing multiple product variants in assembly control with a fuzzy Petri-Net approach
W. Eversheim (1), T. Hack  
STC A,  45/1/1996,  P.45
Keywords: Schedulling, Fuzzy Constraints, Flexibility
Abstract : Companies with make-to-order businesses are facing increasingly dynamic movements within their sales markets. This leads to a growing variety of products and a demand for higher flexibility in order processing. Different logistical goals, process flexibility and fuzzy-expressed dimensions as well as short-term changes due to rush-orders or disturbances, have to be considered within this multiple product variant environment. This paper describes how these controversial requirements can be appropriately represented within a scheduling model, by applying a fuzzy Petri-net approach. All in all, control personnel can be efficiently supported. The described model and methods are verified within an industrial application.
Probabilistic reactive disassembly planning
D. Geiger, E. Zussman   / E. Lenz (1)
STC A,  45/1/1996,  P.49
Keywords: Disassembly, Planning, Statistical
Abstract : A paradigm for reactive disassembly planning is developed which combines prior information about the disassembly task encoded in a predictive plan as well as measurements collected during the process in order to select the current most promising disassembly operation. Planning relies on a probabilistic inference mechanism which employs a Bayesian Network. It integrates perception and action and uses the dependencies among various parts of a product to propagate uncertainty regarding their condition as sensed during the disassembly process. Our methodology allows a computerized assessment of an End-Of-Life value of a product which will enable manufacturers to combine design principles that take into account environmental considerations at minimum cost during the design cycle. The approach is demonstrated by a case study.


An analytical model for cyclic chip formation in 2-D machining with chip breaking
X.D. Fang, I.S. Jawahir (2)  
STC C,  45/1/1996,  P.53
Keywords: Chip Breaking, Machining, Predicting Model
Abstract : This paper presents a new analytical model /for /2-D machining involving a cyclic chip formation process due to chip breaking. This model includes a chip/work contact force at the free-end of the curled chip which contributes to the development of a bending moment in the chip. Chip breaking occurs when the bending moment and the corresponding chip strain reach maximum. The model provides a predictive capability for forces acting on the chip, bending moment, chip thickness, chip velocity, tool-chip contact length, shear angle, friction angle, etc. for a given set of input conditions such as the work material, cutting conditions. tool rake angle and chip-work friction conditions. Oxley's machining theory was used for predicting the work material shear flow stress at the shear plane. The present work provides a deeper insight into the chip breaking process in machining.
A general mechanics and dynamics model for helical end mills
Y. Altintas (2), P. Lee  
STC C,  45/1/1996,  P.59
Keywords: Milling, Forces, Chatter
Abstract : The mechanics and dynamics of helical end milling processes are integrated to a general model. The chip removal geometry is evaluated by considering the true kinematics of the operation and chatter vibrations. The cutting forces are predicted by transforming shear angle, shear stress and friction angle stored in an orthogonal cutting data base to local oblique edge segments along the helical flutes. The general model allows prediction of cutting forces, vibrations, dimensional surface errors and chatter stability lobes for a class of helical end mills. The model is verified experimentally on cylindrical and ball end mills with complex helix geometry.
Predictive force models for point thinned and circular centre edge twist drill designs
E.J.A. Armarego (1), H. Zhao  
STC C,  45/1/1996,  P.65
Keywords: Force Modelling, Drilling, Cutting
Abstract : The geometry and specification of point thinned general purpose and facet point drills as well as the patented `circular centre edge' twist drill design are studied and used to develop predictive mechanics of cutting models for the thrusts and torques for these drill designs. It is shown that the three designs involve point thinning, to improve the rake angle and cutting action at the chisel edge, with the circular centre edge drill being a variation of the point thinned facet point drill. The predictive models have been numerically and experimentally tested. While these drill designs substantially reduce the thrust force when compared to unthinned drills the difference in the forces for the three designs are minimal when compared on a fair basis. The importance of geometry and force modelling in assessing drill designs is highlighted in this work.
A model for chip formation during machining of hardened steel
M.A. Elbestawi (1), A.K. Srivastava, T.I. El-Wardany  
STC C,  45/1/1996,  P.71
Keywords: Hard Turning, Strain Energy Density, Chip Formation, Crack
Abstract : Saw-toothed chips are formed during machining of hardened steel (H_R ,s60-63). This paper presents a new analytical approach for modelling the chip formation mechanism in hard-turning. It has been observed that the chip formation starts with initiation of a crack at the free surface of the workpiece which further propagates towards the cutting edge of the tool. The crack soon ceases to grow at a point where severe plastic deformation of the material exists under higher level of compressive stresses. The chip segment caught up between the tool rake face and the crack is pushed out while the material in the plastic region just below the base of the crack is displaced along the tool rake face thus forming saw-toothed chips. The direction of crack initiation and propagation are predicted using the surface layer energy/strain energy density criterion. The maximum value of surface layer energy, Y,,,,,,, can be used to evaluate the angle of crack initiation while the strain energy density criterion predicts the corresponding crack propagation angle. Here, the process of chip formation is considered to be a mixed mode crack problem of Mode I and Mode II. The theoretical predictions are verified by the resultant chip contours obtained experimentally. The predictions made are shown to be in good agreement with those measured experimentally.
On chip morphology, tool wear and cutting mechanics in finish hard turning
M.A. Davies, Y.S. Chou, C.J. Evans (2)  
STC C,  45/1/1996,  P.77
Keywords: Cubic Boron Nitride (CBN), Tool Wear, Chip Formation
Abstract : Topography of surfaces produced in finish hard turning using cubic boron nitride (CBN) tools is affected by a large number of factors including tool wear and the mechanics of the chip formation process. This paper shows first that tool wear rates are affected by interactions between the work material and the binder phase of the CBN tool. For finish hard turning, low CBN content, ceramic binder tools give longer lives and better finish than high CBN content metallic binder tools. For low CBN tools, wear rate is directly related to the microstructure of the work material and to the CBN grain size. SEM studies suggest that chip morphology is independent of work material microstructure, but varies with tool wear. Orthogonal cutting tests show that, above a critical speed, segmented chips are formed by catastrophic localized shear and that chip segmentation spacing may be reflected in a modulation of the machined surface. Segment spacing is a function of depth of cut, rake angle, and surface speed, approaching a limiting value with speed. Specific cutting energies decrease with speed, also approaching an asymptote. A simple mechanical model gives reasonable predictions of segment spacing along the original surface, although a full thermo-plastic model will be required to account for other aspects of the chip formation process.
Towards active chip control
P.K. Venuvinod (2), A. Djordjevich  
STC C,  45/1/1996,  P.83
Keywords: Chip, Sensor, Control
Abstract : Current reliance on chip formers with fixed geometries suffers from limitations on the work materials and cutting conditions. This paper examines the feasibility of the hitherto unexplored concept of active chip control. An actuator with two degrees of freedom, utilizing an obstruction type chip former, and based on Nakayama's assertion that the position and orientation of the line of separation of the chip from the tool rake determines the chip form, has yielded encouraging results. Stable clusters of chip forms under varying cutting conditions have been obtained through appropriate geometric transformations of the control variables. Experimental work on a variety of sensors has identified chip form sensing through the use of electrostatic induction, optical fibers, and infra-red cameras to be amongst the most promising.
Machinability improvement of steels at high cutting speeds. Study of tool-work material interaction
J.C. Hamman, V. Grolleau, F. Le Maître (1)  
STC C,  45/1/1996,  P.87
Keywords: Tool Geometry, Simulation, Free Machining Steels
Abstract : Special metallurgical treatments after deoxidation of free machining steels allows further improvement in the machinability of these materials using higher cutting speeds. However, the consequences of these treatments on chip flow and tool-work material interactions are not clear as the influence of tool geometry on such treatments is not known. Despite the above, such information is needed to optimize the tools in the context of high speed machining development.This paper presents a comparison between some conclusions found in literature survey concerning the influence of these treatments and experimental facts observed in low carbon free cutting steels and structural free machining steels. These experimental observations are completed by a numerical simulation of chip formation.
On-line prediction of the tool-life
A. Novak (1), H. Wiklund  
STC C,  45/1/1996,  P.93
Keywords: Tool Life, Machinability, Statistical Analysis
Abstract : The paper presents a new approach improving the reliability of on-line prediction of tool-life without the need of pre-process data. The ambition has been to develop a robust monitoring strategy feasible for practical implementation on a CNC lathe. The tool-life is related to a selected critical point on the tool wear curve. Applied multisensing is based on the cutting force ratio correlated with in-process measurement of the flank wear by a vision system. The acquired process data are evaluated and handled by means of the modified and combined statistical methods. Initial cut is used to monitor the process and to evaluate the model parameters when critical conditions are simultaneously supervised by an additional monitoring method. The process model development, reference value setting and tool-life prediction have been automated as machine tool control features. Traditional tool condition monitoring 'can be improved by the reduced need of pre-process reference or machinability data, no need of calibrating procedures and, by early prediction of the tool-life with uncertainty of about 15%37; after 1.5-2.0 minutes of cutting. The efficiency and flexibility of the developed method has been verified by several machinability tests performed under various machining conditions but for the same work material.
An in-process direct monitoring method for milling tool failures using a laser sensor
O. Ryabov, K. Mori, N. Kasashima   / K. Uehara (1)
STC C,  45/1/1996,  P.97
Keywords: On-line Monitoring, Tool Failure, Laser Sensor
Abstract : An in-process tool geometry measurement system for milling has been developed using a commercially available laser displacement sensor. The system reconstructs and displays the 3-D image of a milling tool and evaluates the tool geometric failures via a hybrid laser sensor measurement method which uses displacement and intensity techniques simultaneously. The system is designed to compensate for interruptions in the laser path brought about by chips and coolant drops present under actual cutting conditions. In experimental tests, the reconstructed 3-D geometrical tool image and the intensity measurements enabled us to detect the size and the location of chipped part and to determine the length of the flank wear to an accuracy of 40 µm.
Energy conversion in cutting and grinding
M.C. Shaw (1)  
STC C,  45/1/1996,  P.101
Keywords: Energy, Cutting, Grinding
Abstract : There are similarities and differences with regard to energy conversion in cutting and grinding. In both cases practically all of the energy ends up as heat. However, there are major differences in the dispersion of the heat in the two cases. There are two regimes of grinding depending on the undeformed chip size involved and each of these is associated with a different mode of chip formation. This paper discusses the conversion and transport of energy in cutting and grinding in fundamental terms.

 STC Dn 

The missing element in design for manufacture
T. Lenau, L. Alting (1)  
STC Dn,  45/1/1996,  P.105
Keywords: Design, Producability, Integrated
Abstract : Most work on design for manufacture (DFM) concentrates on the analysis part of the design work. but support of synthesis activities has much less attention. Particularly the early selection of processes and materials needs further research. The paper will describe a systematic method for selection of manufacturing processes and materials as well as the Designers Manufacturing Inspirator - a computer based tool that inspires the designer to examine materials/processes unknown to him or her. An important research question is here the information modelling based on empirical investigations.
Design for disassembly and the environment
T. Harjula, B. Rapoza, W.A. Knight (2), G. Boothroyd (1)  
STC Dn,  45/1/1996,  P.109
Keywords: Design, Disassembly, Environmental
Abstract : The financial and environmental consequences of disassembly and recycling at the end of a product's life are studied. Analyses of a small coffee maker and some large domestic appliances are presented. It is shown that redesign proposals resulting from Design for Assembly analysis are compatible with Design for Disassembly and that significant improvements are achievable. It is also shown that optimization of the disassembly sequence is important in order to maximize any financial benefits, but that to minimize environmental impact considerations additional to Design for Disassembly should be taken into account. Criteria to determine the point at which disassembly should cease are discussed.
Feedback of manufacturing experience for DFM design rules
R. Barton, Y.S. Joo, I. Ham (1)  
STC Dn,  45/1/1996,  P.115
Keywords: Manufacturing, Feedback, Information, Management, Electronic, Circuit
Abstract : In many manufacturing areas, design rules are used to assist in design for manufacturing. These rules are often specific and formal, yet they are usually developed in an ad-hoc manner by design committees and/or design software vendors. This work describes a database architecture and a statistical modeling methodology that enable the formal capture of manufacturing experience as new or revised design rules. The method uses pass/fail or other quality data from the firm's own manufacturing experience to update design limits or to introduce new design rules.
Intuitive physical-based CAD system for designing of sculptured surfaces
P. Kagan, A. Fischer, M. Shpitalni (1)  
STC Dn,  45/1/1996,  P.121
Keywords: Computer Aided Design, Surface, Force
Abstract : The geometrical model for sculptured and highly curved objects is complex and not trivial. Designing such surfaces is therefore difficult if the pure mathematical approach is taken. More natural and intuitive techniques are sought to facilitate the design process. In this paper, an intuitive CAD system for design of sculptured surfaces is introduced. The/ /method/ /is based upon simulating the behavior of curves and surfaces under applied forces. The use of forces makes the system intuitive because it is based or our everyday experience. The B-sline formulation is used both to actually solve the physical model and to represent the geometric model Thus, conversions are eliminated, calculations are accelerated, and interactive operation is maintained. The system gnaws a family of curves (or surfaces) from which the user can choose. Results and examples are demonstrated.
A unified approach to freeform and regular feature modeling
H.K. Tönshoff (1), J.C. Aurich, M. Ehrmann, N. d'Agostino  
STC Dn,  45/1/1996,  P.125
Keywords: Computer Aided Design (CAD), Free-form Feature, Sculptured
Abstract : Surfaces Feature based design for objects with prismatic or conic geometry - also called regular geometry - has proven to be a valuable tool for the designer. Typical examples for design features are slots, pockets, borings or chamfers. Recent research has addressed the use of freeform features in the design of sculptured surfaces. Here, dedicated surface modeling systems and specialized surface models have been used for geometry representation resulting in a separation from existing feature modelers which typically use a solid modeler as a geometry engine. This paper presents a method for the integration of freeform and regular features within one data structure.
Data fitting using dual kriging and genetic algorithms
A. Limaiem, A. Nassef, H.A. ElMaraghy (1)  
STC Dn,  45/1/1996,  P.129
Keywords: Reverse Engineering, Optimization, Geometric Modelling
Abstract : This paper presents a new method for data fitting based on the use of dual kriging for curve and surface fitting and genetic algorithms for optimizing the the model parameters. Classical dual kriging methodology, has been adapted to data fitting problems. Genetic algorithms have been used to choose the optimum set of model parameters in order to globally minimize the average deviation of the data points from the kriging model. The computation time required for this method is much shorter than those required by other methods. The obtained model is very simple and very small deviation values are observed. It has been tested and validated using actual scanned data.
Decision making and software tools for product development based on axiomatic design theory
V. Harutunian, M. Nordlund, D. Tate, N.P. Suh (1)  
STC Dn,  45/1/1996,  P.135
Keywords: Design, Axioms, Software
Abstract : A software tool based on axiomatic design is being developed. Axiomatic Design (AD) provides a framework to describe design objects and a set of axioms to evaluate relations between intended functions (FR's) and means by which they are achieved (DPs). AD analysis can be performed for engineering change orders (ECO) and field support systems with the capability for organizational learning. The software effort attempts to enhance the engineering CAD environment through the documentation of design rational based on AD and the implementation of AD matrices to evaluate design decisions and provide the proper development sequence.
Modelling information in design background for product development support
H. Suzuki, F. Kimura (1), B. Moser, T. Yamada  
STC Dn,  45/1/1996,  P.141
Keywords: Design, CAD, Product Modelling
Abstract : In design environment various kinds of information are generated and used. However most of the information which is generated during product development process, but is not explicitly used in production, is not represented and stored in a useful manner. An approach is proposed for capturing and representing design background information (DBI) to support product development. Based on the evaluation of the prototype system, two issues are discussed in this paper. One is the importance of inclusion of DBI concept to product data management systems, and the other is how to link DBI with engineering simulations.
Planning and multi-criteria optimization of design processes
F.-L. Krause (2), F. Golm  
STC Dn,  45/1/1996,  P.145
Keywords: Design, Optimization, Resources
Abstract : Proceeding from the assumption that in the future an intensified re-engineering of business processes in the area of product development will be necessary, the deployment of powerful tools in this area appropriate. An approach is presented providing the support for the restructuring and optimization of business processes surpassing the functional scope of commercially available tools. The approach sets the further goal of employing the business models generated to perform a multi-criteria process optimization as well. This optimization is to be performed in an automated fashion under end-user control based on a process-related system of key-figures.
Design of a manufacturing resource info-system
T. Kjellberg (2), M. Bohlin  
STC Dn,  45/1/1996,  P.149
Keywords: Information System, Manufacturing Resource, Design
Abstract : Manufacturing resources will be modelled in computer in the future. Standards as STEP and future enhancements of STEP will play an important role. Documentation of manufacturing resources will be distributed to customers in the form of active models in computer. This will give new possibilities for developing more advanced applications for planning etc. in manufacturing. It will influence the design of manufacturing resource info-systems. The design of manufacturing info-system must fulfil a number of requirements like; it should be easily maintained and updated with new resources, new product generations should be easily and directly introduced, planning applications etc. should be easy to update and exchange.
Design for mass customization
M.M. Tseng, X.J. Jiao   / M.E. Merchant (1)
STC Dn,  45/1/1996,  P.153
Keywords: Design, Product, Repeatability
Abstract : Mass customization has recently received a significant amount of attention by the business community. However, the engineering approach to produce an increasing variety of customers' requirements without a corresponding increase in cost has not been well developed. In this paper, we propose a design approach to mass customization (DFMC) that is based on the belief that mass customization can be effectively achieved through design, in particular during the conceptual design and preliminary development stages. The core of DFMC is to develop a mass customization oriented product family architecture (PFA) with a meta level design process integration as an unified product creation and delivery process model. The formulation of PFA enables the optimization of reusability/commonality in both product design and process selection from the product family perspective. It also provides a basis to facilitate the front end configuration in order to fulfil the individual requirements of customers. This paper reports the proposed approach with an example of mass customization of power supply products.
Integrated simulation of manufacturing processes in CAD systems - Ideas and concepts
B. Scholz-Reiter, M. Kleiner   / G. Spur (1)
STC Dn,  45/1/1996,  P.157
Keywords: CAD, Bending, Extrusion
Abstract : Integration of design and computation in CAD systems is a major effort of research. In this paper we describe an approach which for example beside common calculation of strength allows the designer to take into account influences of the considered manufacturing process e.g. the considerable residual stress of bent extrusions resulting from the bending process. Part properties influenced by the intended manufacturing can be controlled continuously during the design process. The results of simulation influence the modification of the geometric design directly. Vice versa geometric data can be input for calculation without transformation..
A relation based product model suited for integrating design and manufacturing
A.J. Van der Net, W.A.H. de Vries, F.L.M. Delbressine (2), A.C.H. Van der Wolf (1)  
STC Dn,  45/1/1996,  P.161
Keywords: Product Modelling, Tolerancing, Computer Integrated Manufacturing
Abstract : In this paper a model of the design process is proposed, based on manufacturable design transformations. The product model enables manufacturability checking while designing. The model is based on relations between geometrical entities, with a tolerance model as an inseparable part. When performing for instance assembly analysis, creating numerical code for a machining centre, or command code for a Co-ordinate Measuring Machine, the product description is interpreted for implications in those specific applications. The authors demonstrate a method to reason with tolerances in several stages in design and manufacturing. A typical example is used to illustrate the method.
Potentials of structural optimization systems in product development
M. Weck (1), J. Asbeck, A. Büssenschütt  
STC Dn,  45/1/1996,  P.165
Keywords: Computer Aided Design, Finite-Element-Method, Optimisation
Abstract : The quality of structural optimisation in product design depends on the intuitively selected initial geometry and is a result of the designer's experience. The improvement in weight reduction or stiffness gain, which is within reach by current optimisation systems, can only be modest. Topology optimisation, however, needs only few boundary conditions for generating a complete preliminary geometry automatically. This rough design can be used as the basic shape for further optimisation strategies, e.g. shape optimisation. So the target should be the integration of topology and shape optimisation in a CAD-System in order to produce a tool which supports the complete design process. This contribution deals with several applications of an integrated topology and shape optimisation system.


Analysis of ultrasonic-aided laser drilling using finite element method
T.M. Yue, T.W. Chan, H.C. Man, W.S. Lau (1)  
STC E,  45/1/1996,  P.169
Keywords: Finite Element Method (FEM), Laser Beam Machining (LBM), Ultrasonic
Abstract : Previously, a novel Ultrasonic-Aided Laser (UAL) drilling technique has been developed to raise the performance of traditional laser drilling method, as well as to improve the overall quality of the "machined" hole. In this connection, a theoretical model using Finite element method (FEM) has now been developed to determine the shape of UAL drilled holes and the thickness of the re-cast layer. In addition, the temperature profile of the hole during UAL processing can be established and from which the size of the re-cast layer can be determined. Experimental results show good agreement with the theoretical predictions.
Laser welding of superalloys for the manufacturing of aeroengine components
M. Cantello (2), G. Ricciardi (2), S.L. Gobbi  
STC E,  45/1/1996,  P.173
Keywords: Welding, Lasers, Metallurgy
Abstract : The paper describes the welding of inconel Superalloy using high power CO2 and Nd YAG lasers, to be adopted in the manufacturing of aeroengine and power plant components. The metallurgy related to the NbC and the Delta phase at grain boundaries, consequent to the typical 10.000 °KIs rapid cooling of the fusion zone, has been investigated using the scanning and transmission electron microscopes Microfissures free welds were achieved in the annealed state with grain sizes of ASTM 10 or finer. Real scale aeroengine components prototypes have been produced out of 0 3 - 1 - 3 5 and 8 mm metal thickness.
New developments in surface technology: laser alloying using Mo/VC and Mn
F. Klocke (2), L. Rozsnoki, T. Celiker  
STC E,  45/1/1996,  P.179
Keywords: Surface, Wear, Laser-Alloying
Abstract : Laser beam alloying of forging and diecasting tools with additional materials has proved in industry its ability to modify the chemical composition and thereby the properties of the surface layers. This results in a manifold increase in tool life. Relying on this knowledge, new surface layers for tools and components were systematically developed. For example, the additional alloying with molybdenum (Mo) and vanadium carbide (VC) significantly increases the tool hardness retention, high temperature-hardness, and hot wear resistance. By alloying with manganese (Mn), it is possible to improve the wear properties of surface layers for components that undergo heavy impact load. This contribution will contain the scientific and fundamental characteristics of surface layers produced in this manner, as well as their analysis with regards to operational properties.
Basic powder metallurgical aspects in selective metal powder sintering
J.P. Kruth (1), B. Van der Schueren,J.E. Bonse, B. Morren  
STC E,  45/1/1996,  P.183
Keywords: Rapid Prototyping, Sintering, Laser
Abstract : A recent evolution in Rapid Prototyping is the direct production of metal parts. The main bottle necks are part accuracy and appropriate material properties. This paper describes the approach of selective metal powder sintering (SMS) where liquid phase sintering actions as the basic binding mechanism between individual metal particles. The merits and drawbacks of this approach are highlighted from metallographic point of view. Next, a few material combinations, which have been experimentally verified, will be described from point of view of performance in the SMS process. Simultaneously, solutions for problems related to this performance are proposed and discussed.
The selective laser sintering of polycarbonate
M. Berzins, T.H.C. Childs (2), G.R. Ryder  
STC E,  45/1/1996,  P.187
Keywords: Rapid prototyping, Sintering, Thermal Modelling
Abstract : This paper investigates thermal modelling of the selective laser sintering process for amorphous polycarbonate powders. The aim is to develop a simulation for process accuracy and control which are key areas of development for the new layer manufacturing rapid prototyping technologies. A state-of-the-art adaptive mesh 2D finite difference code is used simultaneously to consider heating and sintering and its results compared with a classical moving heat source model and with experiments. The analysis shows that the change of material thermal properties with temperature and particularly with position as densification takes place must be included for accurate prediction of both densification and of the phenomenon known as 'bonus z'. The work forms a basis for moving to a 3D simulation.
Marking of computer keyboards by means of excimer lasers
G. Ricciardi (2), M. Cantello (2),G. Savant Aira  
STC E,  45/1/1996,  P.191
Keywords: Excimer Laser, Processing, Plastic
Abstract : An excimer laser-based technique for marking computer keyboards has been developed with the aim of achieving high speed and flexibility on the production line and of avoiding the use of toxic solutions for printing and varnishing. The marking process was developed by investigating contrast and depth of colour change as a function of laser parameters as well as of polymer composition. The laser-printed symbols on various optimised polymeric materials (polystyrene, PC, ABS), both dark and light grey, passed all computer keyboard standards tests This article also describes the prototype system developed for industrial pilot production.
Molecular beam epitaxy (MBE) as an ultra precision machining process
Y. Furukawa (2), A. Kakuta  
STC E,  45/1/1996,  P.197
Keywords: Ultra-Precision Machining, PVD, Silicon Surface Machining
Abstract : The present paper has clarified a possibility to apply a Molecular Beam Epitaxy (MBE) to generate a geometrically flat and crystallography aligned surface. The method is often used to /prepare /new semi-conductive materials, however, the mechanism how a geometric surface for mechanical use is built up by a deposition of molecules is not known. Taking a homo-epitaxial case as an example, silicon molecular beam was deposited onto a single crystallized silicon substrate, and that process was investigated by the help of RHEED, vacuum gauge, etc. A newly obtained surface had a roughness in the order of 2nm and a better crystalline than that of substrates.
Assisting electrode method for machining insulating ceramics
N. Mohri (2), Y. Fukuzawa, T. Tani, N. Saito, K. Furutani  
STC E,  45/1/1996,  P.201
Keywords: Electrical Discharge Machining, Ceramic, Conductivity
Abstract : This paper deals with a new method of machining insulating ceramics by EDM. In this method, a metal plate or metal mesh is arranged on the surface of ceramic insulator as an assisting electrode. The ceramics can be machined very easily with a copper electrode in sinking EDM or with brass wire electrode in WEDM using kerosene as working fluid. Electrical conductive compounds involving cracked carbon from working oil are generated on the surface of the ceramics. It keeps electrical conductivity on the surface of the work piece during the machining. Some examples of machined products with this method are presented. The mechanism of the machining of insulating ceramics is discussed with the principle in the surface modification technique by EDM which has been developed in recent years.


Direct observation of micro contact behaviour at the interface between tool and workpiece in lubricated upsetting
A. Azushima, S. Yoneyama, T. Yamaguchi, H. Kudo (1)  
STC F,  45/1/1996,  P.205
Keywords: Tribology, Lubricant, Upsetting
Abstract : The trapping behavior of liquid lubricant and contact behavior of asperities during upsetting at the workpiece-tool interface are observed directly by means of a compression subpress which is equipped with a transparent die made of quartz, a microscope with a CCD camera and a video system. The experiments are carried out using cylindrical specimens of commercially pure aluminum and liquid lubricants having several viscosities. It is observed that at the beginning of upsetting, the lubricant is trapped between the tool and the workpiece, and then the asperities generated with surface roughening during plastic bulk deformation are flattened by the flat tool. From this observation, the change in the fraction of real contact area with reduction in height is measured by an image processor.
Validation of frictional studies by double cup extrusion tests in cold-forming
A. Barcellona, L. Cannizzaro (2), A. Forcellese, F. Gabrielli  
STC F,  45/1/1996,  P.211
Keywords: Friction Tests, Forming, Finite Element method
Abstract : Studies on frictional conditions in cold-forming have shown that, for a given lubricant, friction factor values are strongly affected by the test method. In the present paper, different cold-forging processes of an aluminium alloy, are modelled by a FEM numerical code using the m values obtained by both the double cup extrusion and ring compression tests. It appears that the m values given by the ring tests can be effectively used in the simulation of upsetting processes, while the m values derived by the double cup extrusion tests are more appropriate for predictions in extrusion and closed-die forging operations.
A numerical model for cold welding of metals
W. Zhang, N. Bay (1)  
STC F,  45/1/1996,  P.215
Keywords: Cold welding, Numerical Modelling, Bond Strength
Abstract : Based on experimental investigations of cold welding of different metal combinations applying various surface preparation methods,, the understanding of the mechanisms of bond formation !n cold welding has been improved by introducing two parameters representing the properties of surface layers at the weld interface. Accordingly, the general model for bond strength in cold welding earlier developed by Bay has been extended and modified The new model presented in this paper simulates the whole cold welding process including the deformation of base metals and the establishment of welds bonding similar as well as dissimilar metals. The calculated bond strengths are verified by comparing with experimental measurements.
Process time reduction by means of integrated casting and rolling
R. Kopp   / E. Doege (1)
STC F,  45/1/1996,  P.221
Keywords: Process Time Reduction, Casting Rolling, Modelling
Abstract : The paper discusses the pros and cons of a process shortening in terms of effectiveness and flexibility. A combined casting/metal-forming process offers great potential for process shortening. This is documented in detail for the case of the double-roller technique of steel strip manufacture. The interlinking of casting and forming provides an integrated analysis of the liquid phase, the solidification process and the directlylinked forming operation which follows solidification. The paper describes various models and their application for the analysis of the process cycle and the resulting properties of the product. Close attention is also given to determining the high temperature yield stress and the heat transmission coefficient for this ultra-high temperature forming process.
A study of dynamic recrystallization during hot rolling of microalloyed steels
J. Biglou, J.G. Lenard (1)  
STC F,  45/1/1996,  P.227
Keywords: Hot Rolling, Metallurgy
Abstract : One of the objectives of the steel industry is to control the thermal-mechanical treatment to create small ferrite grains, which when nucleating from dynamically recrystallized and conditioned austenite may be as small as 3µm. While several hypotheses have been put forward concerning the occurrence of dynamic recrystallization during the process of hot flat rolling of microalloyed steels, no direct proof has yet been provided. The accumulation of strains during strip rolling is possibly responsible for the recrystallization mechanism. In the present project multi-stage hot torsion and compression tests are attempted to confirm whether the softening, observed after the third stand in a hot strip mill, may be caused by metadynamic recrystallization.
Determination of the material properties of an anisotropic metal wire
B. Carlsson, p. Huml (1)  
STC F,  45/1/1996,  P.231
Keywords: Anisotropy, Wire, Test
Abstract : The material properties of cold- drawn wire are not the same in the drawing direction as in the radial direction, due to texture development. The anisotropy usually remains in the material after annealing and has therefore an effect on subsequent forming operations. This article describes a practical way of determining the parameters in the Hill anisotropic yield criterion for a thin wire by the means of compression tests and inverse simulation.
Characterization of three dimensional metal flow in extrusion process
M. Kiuchi (1), J. Yanagimoto, M. Victor  
STC F,  45/1/1996,  P.235
Keywords: Extrusion, Die Design, FEM
Abstract : This paper presents a rigid- plastic FEM code and describes its application to flow simulation during extrusion with aims to obtain knowledges and information usable for eliminating geometrical defects of products. The effects of some variables like the aspect ratio of product's cross section, the bearing length and the position of die opening on the metal flow are studied. Results on the average extrusion pressure and the metal flow characteristics in terms of the velocity distribution profiles in the bearing section and the streamline patterns are presented. From them it is possible to predict the geometric defects of the product and find out the method to reduce them by modification of the die geometry, e.g., bearing length. The extrusion simulation of rectangular and angle sections is chosen to show the applicability.
Analysis and design of industrial hot extrusion process through square dies for manufacturing complicated Al alloy profiles
D.Y. Yang (2), Y.S. Kang  
STC F,  45/1/1996,  P.239
Keywords: Hot Forming, Extrusion, FEM
Abstract : In the analysis and design of hot square die extrusion processes, non-steady state analysis together with temperature analysis is recommended. In the present work, non-steady state analysis are carried out for hot square die extrusion of some typical industrial profiles by using the rigid-viscoplastic arbitrary Lagrangian-Eulerian (ALE) finite element method. Since flow guide and die lands play important roles in controlling the metal flow in the industrial practice, the related analyses are carried out and the effects of die land and flow guide are discussed. In order to estimate the variation of die land length, a scheme has been developed. The scheme is applied to extrusion of L-section without any axis of symmetry. The calculated configuration of die land is compared with the industrial design. As an effective tool for prediction of die wear, a wear map in introduced and demonstrated through the examples.
TEUBA: A simple 3D formulation for modelling forging using the upper bound method
J.M. Pitt-Francis, A. Bowyer, A. Bramley (1)  
STC F,  45/1/1996,  P.245
Keywords: Forging, Modelling, Upper-Bound
Abstract : A method for modelling perfectly plastic metal flow within the forging process, using the well-known upper-bound energy formulation, is presented. The domain of the metal is described by a tetrahedral mech, in which the velocity field is piecewise linear. It is shown that this formulation is significantly faster than existing finite element models, and hence can be used for early validation. The formulation can be reversed readily and an algorithm is discussed which allows nodes to detach from the die surface in an order which optimizes the similarity of the reverse process to user-specified shapes.
Wear in hot and warm forging: design and validation of a new laboratory test
P. Bariani (2), G.A. Berti, L. d'Angelo, R. Guggia  
STC F,  45/1/1996,  P.249
Keywords: Hot-Forging, Wear, Test
Abstract : A simulative wear test for hot and warm forging tools is presented which has been developed by the Authors with the twofold purpose of (i) verifying the applicability cf wear micro-mechanical models in simulation of hot and warm bulk metal forming operations using FEM codes and (ii) evaluating wear parameters by an inverse numerical technique. In its simple configuration, the test embodies many of the tribosytems encountered in industrial forging operations and relevant tool wear and failure mechanisms, such as abrasion, thermal fatigue as well as permanent deformation of tool surface. The paper focuses on the design of the test configuration and the description of testing and measuring apparatuses, including those for temperatures and heat transfer coefficient determination. Validation of the test through test runs and determination of wear profile on tools end the paper.
A method to predict the on set of necking in numerical simulation of deep drawing operations
R. Arrieux (2), M. Brunet, p. Vacher, T. Nguyen Nhat  
STC F,  45/1/1996,  P.255
Keywords: Deep Drawing, Simulation, Anisotropy
Abstract : For an anisotropic material, the principal strain directions may not coincide with the orthotropic axes during a forming operation. In this paper we describe a numerical method to determine the forming limit stress surface of a sheet metal for off axes solicitations. This method is based on Marciniak's model. Experimental comparisons show the good accuracy of this theoretical model. Then the stress surface so determined is introduced in a finite element calculation software in order to detect numericaly the necking occurence during the simulation of the drawing of a square cup. The results so got are in good agreement with experimental data.
Prediction of ductile fractures occurrence in deep drawing of square boxes
F. Micari (2), L. Fratini, S. Lo Casto, N. Alberti (1)  
STC F,  45/1/1996,  P.259
Keywords: Deep Drawing, Formability, Damage
Abstract : The authors propose a new approach for the prediction of tearing in the deep drawing process of square boxes. Such an approach is based on a damage mechanics formulation and in particular on the yield condition for damaging materials proposed by Tvergaard and Needleman and on a strain controlled nucleation model. The flow rule associated to the yield condition is introduced in a finite element explicit formulation founded on the solution of the dynamic equilibrium equation and on an explicit time integration scheme. By this way the developed model allows to calculate the void volume fraction value during the deep drawing process of square boxes and consequently to predict the insurgence of tearing by comparing the maximum achieved void volume fraction with the value corresponding to the coalescence of microvoids. The obtained results have been used to construct a particular type of a- master curve and their goodness has been confirmed by means of a set of experimental tests.
Polycrystal plasticity: Application to earing in cup drawing
L. Anand (2), S. Balasubramanian  
STC F,  45/1/1996,  P.263
Keywords: Plasticity, Texture, Earing
Abstract : Constitutive equations and computational procedures which are capable of modeling the initial and evolving anisotropy in ductile metallic materials due to the evolution of crystallographic texture are used to simulate the formation of earing defects during cup-drawing of face-centered cubic materials. Comparison of the results of the numerical simulations against existing experimental results on earing in single crystalline sheets and in previously rolled polycrystalline sheets show that the predictions of the number of ears and their positions are in excellent agreement with the experiments.
Friction studies in sheet metal forming based on a unique die shoulder force transducer
K.J. Weinmann (2), S.K. Kernosky  
STC F,  45/1/1996,  P.269
Keywords: Drawing, Sheet Metal, Friction
Abstract : A transducer developed for measuring tension in metal strip as it moves over the die shoulder was used to conduct friction studies. The portion of the transducer simulating the die shoulder is cylindric and mounts in the body on a pair of bearings. Incorporated into the design is a means to selectively lock the die shoulder. Strip tension measurements from tests with the die shoulder locked and unlocked are necessary before friction information is extracted. The transducer is used in a forming die simulator with a controlled drawbead to evaluate how drawbead penetration speed influences die shoulder friction.
CNC - controlled segmented stretch forming process
K. Siegert (2), K.-J. Fann, A. Rennet  
STC F,  45/1/1996,  P.273
Keywords: Flexible Manucturing System, Strecht Forming, Sheet Metal
Abstract : A new developed stretch forming process, with several CNC-controlled two axis grippers positioned around the punch, allows to predict the final strength of a convex shaped sheet metal part. Outgoing from the wanted strength over the part and the flow curve of the sheet metal, the moving paths /of /the different grippers are calculated by a FEM simulation /of /the forming process. These paths are corrected by data describing the elastic behavior of the grippers. Then, the corrected data are through DNC sent to the stretch forming machine. Experimental work shows that this new flexible manufacturing system works well.
Fundamentals on the manufacturing of sheet metal micro parts
M. Geiger (1), F. Vollertsen, R. Kals  
STC F,  45/1/1996,  P.277
Keywords: Sheet Metal Forming, Miniaturization, Process Analysis
Abstract : The miniaturization of components and therefore the downscaling of metal forming processes, as it can be observed today especially in the field of electronics production, is closely connected with changes in the relative contribution of those parameters which determine the forming result, like for example the microstructural features of the workpiece material and the roughness of workpiece and tool. In this paper some basic considerations are pointed out concerning bending - both laser bending and mechanical air bending - and punching. The importance of the geometrical and the material parameters for the micro metal forming process are pointed out using theoretical, both numerical and analytical, as well as experimental results. From these results some preconditions are deduced which are a basis for guidelines for sheet metal forming processes in the field of smallest workpiece dimensions.


Utilization of grinding heat as a new heat treatment process
E. Brinksmeier (2), T. Brockhoff  
STC G,  45/1/1996,  P.283
Keywords: Grinding, Surface Hardening, Heat Treatment Process
Abstract : In the past many scientists investigated the heat dissipation in grinding and the resulting influences on the surface integrity of the workpieces. Under abusive grinding conditions the formation of a heat-affected zone was observed which damaged the ground surface of hardened steels. The aim of this paper is to introduce a new surface heat treatment process, namely by making use of the heat flux generated in grinding. In this case the grinding conditions have to be optimized to induce martensitic phase transformations in the surface layers of annealed or tempered steels, such as it is achieved by other surface strengthening processes. The fundamentals of this new heat treatment method called /grind-hardening /are given in this paper.
On-line optimization for internal plunge grinding
G. Xiao, S. Malkin (1)  
STC G,  45/1/1996,  P.287
Keywords: Grinding, Optimization, Adaptative Control
Abstract : An on-line optimization system was developed for cylindrical plunge grinding to minimize production time while ensuring part quality requirements. The system is capable of optimizing the grinding and dressing parameters in response to in-process and post-process measurements which characterize the process and update the process model. As compared with the previous system, the present one encompasses a more complete set of realistic constraints, considers time dependent behavior, and also optimizes the dressing interval. The system has been implemented on an instrumented internal grinder in the laboratory and in actual production.
Cooling characteristics of cutting grain in grinding
T. Ueda, M. Sato, K. Nakayama (1)  
STC G,  45/1/1996,  P.293
Keywords: Grinding, Temperature, Measurement
Abstract : The temperature of a cutting grain when cutting has been completed is investigated experimentally and theoretically. As the model of the cutting grain, a conical tool of ceramic is used. The temperature of the grain at various times after cutting is measured using an infrared radiation pyrometer with an optical fiber. The cooling process of the cutting grain during air cutting is analyzed by reference to unsteady-state heat transfer theory. The cooling of the grain is extremely rapid, that is, the temperature of the grain decreases to one fourth of the maximum temperature in 1 ms after cutting. The maximum temperature of the cutting grain reached at the end of cutting is estimated to be the melting point of the work material.
A simplified approach to control of thermal damage in grinding
W.B. Rowe (1), M.N. Morgan, S.C.E. Black, B. Mills  
STC G,  45/1/1996,  P.299
Keywords: Grinding, Burn, CBN
Abstract : The critical factors for the control of thermal damage in grinding at conventional workspeeds have been established with reference to experimental and previously published work. For ferrous materials, significant damage occurs above a maximum workpiece background temperature of 475°C. It is also known that the energy entering the workpiece is reduced due to conduction into the grinding wheel. It has been found that the partitioning of energy between the grinding wheel and the workpiece remains approximately constant. However, the overall partition ratio to the workpiece, which takes account of energy transfer to the chips as well as energy transfer to the wheel, is variable. The effective thermal properties of the grinding wheel may be established by correlating theory with grinding experiments. An effective coefficient for the temperature equation can be obtained corresponding to the use of the geometric contact length in the equation. Using these conclusions, a simplified approach has been developed for control of thermal damage.
Modelling and optimization of vibratory finishing process
F. Hashimoto   / D.B. DeBra (1)
STC G,  45/1/1996,  P.303
Keywords: Vibratory Finishing, Barrel, Modelling
Abstract : Vibratory finishing has been employed for final finishing of products, because of the capability of the finishing consistency with lower cost. However, it has taken the trial and error method to find a proper process set-up due to the fact that the fundamentals of vibratory finishing have not been established yet. This paper describes the fundamental principles of vibratory finishing and proposes the mathematical modelling which makes the prediction of surface roughness and stock removal possible. The validity of the modelling is discussed with experimental results, and an algorithm to design an optimum process of vibratory finishing is proposed.
Removal rate and surface roughness in high-precision lapping of Mn-Zn ferrite
M. Touge, T. Matsuo (1)  
STC G,  45/1/1996,  P.307
Keywords: Lapping, Roughness, Atomic Force Microscopy (AFM)
Abstract : This paper describes the effect of the motion of diamond grains on material removal rate as well as surface roughness during lapping of Mn-Zn polycrystalline ferrite using a Sn lapping plate and 0.5 - 2.0 µm diamond abrasives. The diamond grains during lapping can be classified into fixed and loose grains, where `.he grains fixed on the lapping plate (fixed grains) can be observed by SEM. It is evident that among a large number of experimental parameters, the pitch size of the grooves on the lapping plate generated by facing operation has a significant effect on the removal rate. This effect can be accounted for by the number of loose grains calculated under various pitch sizes. The average removal rate with fixed and loose grains is about 2.7 times higher than that with only fixed grains, and from this result it is known that during lapping, the work material can be removed mainly by loose grains. It is also evident from AFM images that the lapped surface characteristic by only fixed grains differs very much from that by fixed and loose grains.
Integrated planarization technique with consistency in abrasive machining for advanced semiconductor chip fabrication
H. Jeong, H. Ohmori, T. Karaki Doy, T. Nakagawa (1)  
STC G,  45/1/1996,  P.311
Keywords: Abrasive Machining, Integrated Planning, Pattern Topography
Abstract : This paper proposes the establishment of a new integrated planarization technique using ultrafine abrasive machining for application to advanced semiconductor chip fabrication. The main features implemented are integrated planarization for the silicon substrate, blanket films of oxide and wafers with pattern topography. Planarization concepts were brought out for these wafers with different shape and material. The authors tried to apply not only loose-abrasive methods such as chemical mechanical polishing (CMP), but also bonded abrasive methods such as ductile mode grinding using ultrafine abrasives. New developments in the proposed ultrafine machining processes were presented. Finally the use of planarization machining techniques appropriate for each kind of wafer produced good planar surface respectively.
Development of melamine-bonded diamond wheels with high porosity for smooth and mirror finishing of die materials
T. Semba, Y. Tani (2), H. Sato (1)  
STC G,  45/1/1996,  P.315
Keywords: Diamond Wheel, Mirror Finishing, Die Material
Abstract : Diamond wheels with fine grains and pore structures were newly developed for smoothing and mirror-polishing of die materials. Diamond grains were bonded firmly by melamine resin to prevent the decrease of machining efficiency due to grain sinking within the bond materials. Also, highly foamed structures were developed to increase the flexibility of the wheel, and to induce active self-dressing by increasing contact pressure between the wheel and work surfaces. It was confirmed that flexibility equal to that of a conventional PVA-bonded wheel could be achieved by increasing the porosity to over 75 %37;. Also, it was confirmed that swarf loading of the wheel could be prevented completely and excellent grinding performance assisted by active self-dressing could be derived by increasing the porosity to over 75 %37;.
A process model for robotic cup grinding
W. Persoons, p. Vanherck (1)  
STC G,  45/1/1996,  P.319
Keywords: Robotic Deburring, Grinding, Process Model
Abstract : Robotic heavy-duty deburring is often performed with special shaped grinding cups which allow for rapid material removal, but with secondary concern on surface quality. The cups are not dressed and wear constantly. Little research data is available on this grinding process. The paper presents the results of an extensive study to model this grinding process and presents a new, simple and fundamental process model relating the material removal rate to such factors as the contact force and the grinding angle. The test set-up, consisting of a hydraulic force controlled robot and the Taguchi method to minimise the number of tests, is described. Additionally, a dynamic model to predict the ground profile in the presence of burrs, is presented. Based on the process model, a strategy is proposed for the robotic deburring of small burrs as well as for large burrs with a force controlled grinding cup.
Enhancing abrasive waterjet cutting of ceramics by head oscillation techniques
E. Siores, W.C.K. Wong, L. Chen, J.G. Wager (1)  
STC G,  45/1/1996,  P.327
Keywords: Abrasive Waterjet, Head Oscillation, Ceramics
Abstract : Abrasive Water Jet (AWJ) cutting technology can provide very effective means for shape cutting of ceramics, but the slow cutting speed needs to be improved without compromising cutting quality. In this paper, experimental techniques based on statistical design principles and theoretical investigations were conducted to optimise and predict the AWJ cutting process applicable to ceramics. The new cutting head oscillation technique applied to the cutting process produced superior results and showed that the smooth zone depth increased by more than 30%37; with oscillation as compared to that without oscillation and both striation drag angle and frequency in the striation zone decreased.
An investigation of the AE signals in the lapping process
Y.P. Chang, M. Hashimura, D.A. Dornfeld (2)  
STC G,  45/1/1996,  P.331
Keywords: Lapping, Material Removal Rate, Acoustic Emission Monitoring
Abstract : The material removal mechanisms in lapping processes were studied. The concepts of brittle vs. ductile machining and two-body vs. three-body abrasion were used to classify the lapping mechanisms. The transition of the lapping states between different mechanisms over time was investigated as well. An acoustic emission (AE) setup was evaluated for in-process material removal rate (MRR) monitoring.
Raw acoustic emission signal analysis of grinding processes
J. Webster, W.P. Dong, R. Lindsay (1)  
STC G,  45/1/1996,  P.335
Keywords: Grinding, Acoustic Emission, Monitoring
Abstract : As a different approach to most acoustic emission (AE) research in grinding, this paper focus on analyzing the raw AE signal instead of root-mean-square signal (RMS). Transitional characteristics of the raw AE signal during wheel/workpiece contact in a variety of grinding processes are discussed. Frequency analysis of the raw AE signal is carried out based on knowing the frequency response of the sensor employed. An assessment of the AE RMS technique with different integration time constants is conducted in order to determine appropriate ones for future production applications.
On the relationship between setup parameters and lobing behaviour in centerless grinding
S.S. Zhou, J.R. Gartner, T.D. Howes (1)  
STC G,  45/1/1996,  P.341
Keywords: Centerless Grinding, Process Stability, Roundness
Abstract : Lobing may cause significant workpiece roundness error in centerless grinding. This paper investigates the relationship between the process setup parameters and lobing behavior, and provides general guidelines for selecting proper setup parameters to minimize the lobing effect. In the paper, lobing behavior is characterized by the wave growth rate boundaries and characteristic root distribution of the lobing loop. For a given process setup (K,a,?), overall lobing stability of the grinding process is evaluated by using the wave growth rate boundaries. It was found that the characteristic root distribution of the lobing loop is periodic, and the periodicity is determined by the peak wave frequencies and crossing wave frequencies. This leads to the development of a nominal stability diagram for workpiece center-height angle selection. Also, general guidelines for minimizing the lobing effect are introduced. The effectiveness of these guidelines is discussed analytically and experimentally verified.
Grinding process simulation based on the wheel topography measurement
I. Inasaki (1)  
STC G,  45/1/1996,  P.347
Keywords: Grinding, Simulation, Topography
Abstract : The establishment of a reliable model for the grinding process is a key issue in predicting process performance. In this study a method, based on the optical profilometry, t o represent grinding wheel surface characteristics i s proposed. Considering the wheel topography information, a computer simulation of the grinding process i s performed t o predict the ground surface roughness and the grinding force. A characteristic feature of the simulation method is that the chip removal process of each individual cutting edge is simulated based on the relative motion between the grinding wheel and the workpiece.
Improvement of form accuracy in axisymmetrical grinding by considering the form generation mechanism
T. Enomoto, Y. Shimazaki, Y. Tani (2), T. Sata (1)  
STC G,  45/1/1996,  P.351
Keywords: Precision Grinding, Form Accuracy, Removal Mechanism
Abstract : Countermeasures are proposed to overcome the problem that, in grinding an axisymmetrical surface, the surface profile concavely deviates from the ideal profile. By experimentally investigating the form generation mechanism, it was found that tine grindability deteriorated on the outward surface owing to direct contact between the wheel bond and the workpiece. Using a hard bonded wheel improved form accuracy, and traversing the wheel outward from the workpiece center achieved both high form accuracy of less than 120 nm p-v and good roughness ranging from 20 to 40 nm Ry.


Constrained predictive control for motor drives
D. Dumur (2), P. Boucher (2), A.U. Ehrlinger  
STC M,  45/1/1996,  P.355
Keywords: Control, Machine Tools, Drives
Abstract : Generalized predictive control (G.P.C.) is an efficient strategy for machine tools applications. However, high performance may require the consideration of constraints on the system. This paper presents a modified version of G.P.C., called C.R.H.P.C. (Constrained Receding Horizon Predictive Control), which imposes constraints on the final output values, so that the output matches the reference over a further constraint range. An important result is that theorems guarantee stable closed loop behaviour for particular sets of tuning parameters. This method applied to the velocity control of a motor drive proves that an effective definition of constraints enables better results for severe conditions of use.
High-response XY stage system driven by in-parallel linear motors
Y. Tomita, K. Makino, M. Sugimine   / N. Taniguchi (1)
STC M,  45/1/1996,  P.359
Keywords: Servomechanism, Electrical Actuator, Position Control
Abstract : We present our newly developed high-response XY stage system driven by in-parallel linear motors. Briefly described are operational principles, associated mechanical and control system design based on analysis of stage dynamics, and typical results of system performance experiments. Stepping motion with high-response and accurate positioning was obtained by incorporating a force disturbance observer and jerk-continuous trajectory generation into a conventional control system operated under PID and acceleration feed-forward compensation. Measurements of stage stepping motion demonstrate a highly suitable design, e.g., in response to 2.54-mm step-motion command, positioning error was reduced to ±10 µm in just 37 ms.
Design and optimization of fast axis feed drives using nonlinear stability analysis
O. Zirn, S. Weikert, F. Rehsteiner (1)  
STC M,  45/1/1996,  P.363
Keywords: Feed Drive, Optimization, High-speed Machining
Abstract : Direct drives and ball screw drives are the most promising feed drive systems for high speed machining. For optimum performance the drives and the feedback control system must be exploited to their physical limits. Thus, input saturation of the feed drives becomes a very important design parameter. A new design method based on a nonlinear stability analysis has been developed to take this into account. The improvements regarding machine tool design and the selection of suitable drive systems made possible by this method are shown and discussed.
On the influence of the velocity gain factor on the path deviation
G. Pritschow (1)  
STC M,  45/1/1996,  P.367
Keywords: Path Deviation, Position Control, Velocity Gain factor
Abstract : The velocity gain factor k_v of a position controller decisively determines the lag as well as the dynamic accuracy of a machine tool. The lag is well defined by the k_v factor. There is however, a lack of literature with a sound interpretation of the relationship between the k_v factor and path deviation. Thus this paper concerns itself with the influence of the k_v factor on the path accuracy, on the disturbance behaviour of position axes and on the behaviour of a cross-coupled controller. For comparison. the effects of prefilter technology are also taken into consideration.
A practical machining condition determination strategy using multi-axis force information
M. Mitsuishi, T. Nagao (2), T. Ohta, H. Okabe  
STC M,  45/1/1996,  P.373
Keywords: Machining, Chatter, Force Information
Abstract : A manufacturing system which integrates a machining center with a multi-axis force sensor and real-time controller, CAD system and data-base was developed to realize high precision and high efficiency autonomously. To realize highly efficient machining while maintaining a stable cutting state, both a real-time adaptive control function and learning capability were implemented. Learning behavior was obtained by storing the actual state of the system in the form of an experimentally-determined stability lobe diagram. Efficient machining conditions, including the detailed tool path, were dynamically realized by regenerating the tool path periodically. Experimental results showed the effectiveness of the system.
Real-time open control architectures and system performance
Y. Koren (1), Z.J. Pasek, A. Galip Ulsoy (2)  
STC M,  45/1/1996,  P.377
Keywords: Control, Machining, Real Time
Abstract : This paper analyzes the effect of control architectures and communication networks on a manufacturing system's performance in terms of part precision and productivity; the network bandwidth requirement for a distributed control system is also included. The objective is to design the system such that the control and communications (both hardware and software) would not be the limiting factors in system performance. For simplicity we analyze the performance of a machining center control system. The base-line for comparison is a conventional computerized numerical controlled (CNC) with discrete event management/adaptive system.
Toward virtual engineering in machine-tool design
G. Bianchi, F. Paolucci, p. Van den Braembussche   / F. Jovane (1)
STC M,  45/1/1996,  P.381
Keywords: Integrated Computer Aided Design, Machine Tool, Simulation
Abstract : An integrated modeling technique for high speed machine tool design is proposed. The model contains a description of the structure, derived from a Finite Element. Model via modal reduction, compliant guideways with static and dynamic friction, and a continuous or discrete time controller. This modeling tool permits designers to evaluate, during the first stages of design, how the mechanical structure and control contribute to the dynamic behavior of the machine, estimating, for example, the dynamic compliance at the tool, the lost motion due to friction and the tracking error during acceleration.
Development of machine components with controllable dynamic behaviour
J. Peklenik (1), J. Jurkovic  
STC M,  45/1/1996,  P.385
Keywords: Composite, Structure, Control
Abstract : The paper reports on the development of composite materials suitable for machine tool modules. Several combinations of materials, geometric forms, dimensions and gluing techniques have been used for producing the basic elements - the composite plate structures (CPS). The investigation is focused into determining the static and dynamic properties of CPS-boxes, in particular, the ratios between the stiffness and weight, the resonance damping, the ratios of the resonance stiffness and mass for the CPS and conventional test boxes.
Machine tool design requirements for high speed machining
U. Heisel (2), M. Gringel  
STC M,  45/1/1996,  P.389
Keywords: High Speed Machining, Machine Tool Design, Kinematic
Abstract : The high speed machining process requests completely new demands for the mechanism of such processing equipment, as due to the process, path speeds exceeding 50 m/min can be achieved. In this field, potential capacities of manufacturing processes require a dynamic behaviour ten times higher than conventional machine tools and increased accuracy. This can be solved by the systematical evaluation of suitable machine kinematics, by the application of linear direct drives with high k,-factors as well as by mass reduction of the axis through light weight components of sheet metal.
Techniques for the use of long slender end mills in high-speed milling
J. Tlusty (1), S. Smith, W.R. Winfough  
STC M,  45/1/1996,  P.393
Keywords: End Milling, High Speed Machining, Technique
Abstract : This paper presents two techniques using end mills in high-speed milling. In the first, the top speed and power of the spindle are accepted as fixed, and the structural dynamics are manipulated by adjusting the tool length so as to take advantage of stability lobe effects. Sometimes, lengthening the tool improves the metal removal rate. The second technique permits the machining of parts with very thin ribs. Tools with relieved shanks are used to avoid increases in axial depth of cut associated with forced vibration of the rib. Photographs of parts made with and without such tooling are shown.
Development of an intelligent face grinding machine to fabricate ultra-flat surfaces on thin, brittle substrates
M. Nakao, Y. Hatamura (2)  
STC M,  45/1/1996,  P.397
Keywords: Intelligent Control, Face Grinding Machine, Conceptual design
Abstract : Information processing devices require thin and brittle substrates with surface flatness in the order of 0.1 ,u m per 200 x 200 mm. To realize such ultra-flatness, we designed, fabricated, and evaluated an "intelligent face grinding machine". The machine is a vertical spindle face grinding machine which we newly constructed to have higher rigidity and thermal insensitiveness for passive reduction in tool positioning error. In addition, an active knowledge-based control system with sensors, computers and actuators further reduces the deviation. We verified that the machine produces flatness of 0.5 _p m per 200 x 200 mm on ceramic, glass and silicon substrates.
Ultraprecision 3-D micromachining of glass
Y. Takeuchi (2), K. Sawada, T. Sata (1)  
STC M,  45/1/1996,  P.401
Keywords: Ultra Precision, Micromachining, Brittle Materials
Abstract : It has been theoretically and experimentally confirmed that brittle materials can be machined in the ductile mode under the certain small depth of cut. However, it is extremely difficult to obtain tiny 3D workpiece shapes of brittle materials with high surface accuracy. The study deals with the ultraprecision 3D micromachining of glass workpiece by means of a lathe-type ultraprecision milling machine and pseudo ball end mills. As a result, it is possible to obtain a glass mask of 1 mm in diameter with the surface roughness of 50 nm.
Robotic deburring of small series of castings
W. Persoons, H. Van Brussel (1)  
STC M,  45/1/1996,  P.405
Keywords: Deburring, Off-line Robot Programming, Force Control
Abstract : Robotic cleaning of castings is currently limited to large series of parts with small burrs. The costs for fixtures and clamping and for online programming of the robot largely exceed the potential savings of using robots for small series. Less expensive fixtures only add to the positioning uncertainties by which the use of online programmed robots becomes prohibitive. The paper presents a robotic deburring system for small series of heavy-duty castings with large burrs and risers. Strategies are presented to cope with large burrs and with the allowed large position uncertainty of the casting. CAD data of the nominal castings is used to program the robot offline, resulting in reduced programming time. Active force control is used for burr detection and for coping with uncertainties in the casting position. The test set-up consists of an offline-programmed, hydraulic, force-controlled robot and an example of the cleaning of a gray iron casting of a heavy-duty crank case for a truck is presented.
Artificial intelligence tools in diagnostics of machine tool drives
J. Jedrzejewski (1), W. Kwasny  
STC M,  45/1/1996,  P.411
Keywords: Artificial Intelligence, Diagnostics, Machine Tool
Abstract : Diagnostics of machine tool drives aided with an expert system and neural network and allowing for a variety of drive conditions and diagnostic signals is discussed. An actual solution is presented of a drive self-diagnosing system consisting in on-line temperature- and power-based monitoring supplemented by detailed off-line diagnostics backed by Al tools and knowledge bases and invoked in need only. The detailed diagnostics is based on power and acoustic noise measurements and involves data base propagation, a customized diagnosing algorithm, a mechanism of automatic inferring using fuzzy logic procedures and simulation of the inferring mechanism by a neural network. The exposition is completed by a working example of drive diagnostics application in a machining centre.


Towards a new model of sustainable production : ManuFuturing
C. Boër (2), F. Jovane (1)  
STC O,  45/1/1996,  P.415
Keywords: Integrated Production Systems, Virtual Factory Network, Sustainable Production
Abstract : Mutations of the context : economy, society, technology ; call for continuous changes of products and related processes. Industry response must range from strategic to tactic horizons. The growing importance of environment and social aspects has lead to the emergence of the life cycle concept and to Sustainable Industrial Production. The Products-Processes life cycle matrix must then change to respond to mutations of the context. It may follow a stepwise path combining innovation (new generations) and evolution (within a generation). An appropriate system is required: the Virtual Factory. It "produces" and "maintains" new generations. The combination of a Virtual Factory and a Physical Factory, is the Self-Innovating Factory (SIF). Because of products-process complexity, networks, made up of "physical factories", are emerging. To respond to context changes, appropriate, Virtual Factories networks should be implemented. The integration of both networks would lead to the Self-Innovating Extended Factory (SEIF), capable of responding to context changes, as required by Sustainable Production Paradigm. The model described has been named MANUFUTURING. The main phases to implement and some of the methods and tools to support it, have been described. The model has been adopted by an industrial group to develop its next generation of manufacturing systems.
An integrated approach to the design of cellular manufacturing
H. Kaebernick, M. Bazargan-Lari   / G. Arndt (1)
STC O,  45/1/1996,  P.421
Keywords: Manufacturing, Cellular, Layout
Abstract : The realisation of benefits expected from Cellular Manufacturing (CM) largely depends on how effective the three phases of the design have been performed, namely parts/machine grouping, the layout of machines within cells, and the layout of cells on the shop floor. These phases have been studied and addressed by both practitioners and researchers separately with little or no feedback from one phase to another. The multi-criteria model presented in this paper attempts to address and evaluate the impact of each phase on the other phases, and in particular on the overall performance of the CM, by generating alternative efficient designs. The performance of the model is demonstrated by applying it to an example and to the implementation of CM in a white-goods manufacturing company.
Reengineering production systems: the Royal Netherlands Naval dockyard
W.H.M. Zijm   / H.J.J. Kals (1)
STC O,  45/1/1996,  P.427
Keywords: Engineering, Production System, Maintenance
Abstract : Reengineering production systems in an attempt to meet tight cost, quality and leadtime standards has received considerable attention in the last decade. In this paper, we discuss the reengineering process at the Royal Netherlands Naval Dockyard. The process starts with a characterisation and a careful analysis of the production system and the set of objectives to be pursued. Next, a new production management structure is defined after which supporting planning and control systems are designed and a number of organisational changes are carried through. In this way, the Dockyard may combine high technological capabilities with an excellent logistic performance.
A market approach to holonic manufacturing
A. Markus, T. Kis, J. Vancza, L. Monostori (2)  
STC O,  45/1/1996,  P.433
Keywords: Holonic Manufacturing, Dynamic Schedulling, Artificial Intelligence
Abstract : The concept of holonic manufacturing is based on the cooperation of autonomous, functionally complete entities with diverse, often conflicting goals. The paper introduces a market mechanism for coordinating the activities of intelligent agents that pursue their own interest by operating under bounded rationality in a changing, hardly predictable environment. The market model is used for solving dynamic order processing and scheduling problems: conflicts between local scheduling agents are resolved by negotiating and bargaining on simple common terms of tasks, due dates and prices.
An approach to holonic components in control of machine tools
A. Bengoa, S. Gluch, H.J. Jacobs   / R. Bueno (1)
STC O,  45/1/1996,  P.437
Keywords: Holonic, Control (CNC), Computer Automated Process Planning (CAPP)
Abstract : This paper describes a first step in transfer of machine tools to HOLONIC MACHINING UNITS (HMU). The solution proposed is based on dynamic, NC-internal self-planning of cutting conditions. Supposing this approach, real time adaption of the required machining time to the available time budget can be carried out. In this way the autonomous HMU is able to survive disturbances without any reaction on job-shop-control. Cooperation of machine tools with the same properties to fulfil an order is possible, too. The first soft- and hardware implementation of holonic behaviour within a machine tool's CNC is represented by the so-called Optimizing Controller.
Continuous flow models of manufacturing systems: a review
P. Brandimarte, A. Sharifnia, B.F. Von Turkovich (1)  
STC O,  45/1/1996,  P.441
Keywords: Optimization, Modelling, Production Control
Abstract : Production scheduling approaches in discrete manufacturing environments must cope with discrete material flows subject to different constraints in order to obtain a good solution. Despite the huge amount of literature on machine scheduling, most commercial schedulers take a myopic approach based on priority rules. Among the reasons behind this gap there are issues related to the complexity of optimized scheduling methods and the vulnerability to schedule disruptions. In the paper we review some approaches aimed at bridging the gap between optimization models and real time control. Such models are based on an approximation of the discrete material flow with a continuous flow. We review stochastic control models for repetitive production and mixed-integer programming models for batch manufacturing.
Modelling and analysis of heterarchical manufacturing systems using discontinuous differential equations
V.V. Prabhu, N.A. Duffie (2)  
STC O,  45/1/1996,  P.445
Keywords: Manufacturing, System, Control
Abstract : Heterarchical manufacturing systems with distributed arrival time control provide robustness by adapting to disturbances in real time without explicit notification and compensation. Part processing discontinuously couples entities in these systems and makes their behavior highly nonlinear. Discontinuous differential equations that model the dynamics of a multitude of highly distributed part arrival time controllers can be solved using a method due to Filippov, resulting in closed-form equations that characterize system dynamics and convergence. The global performance of the distributed arrival time control is found to compare favorably with dispatching rules currently used in industry.
Model driven configuration and information sharing in concurrent engineering
R.H. Weston (2)  
STC O,  45/1/1996,  P.449
Keywords: Modelling, Co-ordination, Integrated Computer Aided Manufacturing
Abstract : Interim research findings are described concerned with: - consolidating and developing modelling methods and tools, which support the design and implementation of integrated systems. - identifying requirements for modelling `resources', to support the engineering of manufacturing enterprises. The research is funded jointly by the CDP committee of EPSRC and UK industry and is being advanced in conjunction with a consortium of manufacturing user organisations and their software and system suppliers.
Hierarchical part planning strategy for environmentally-conscious machining
P. Sheng, M. Srinivasan   / G. Chryssolouris (1)
STC O,  45/1/1996,  P.455
Keywords: Machining, Environmental, Planning
Abstract : Integration of environmental considerations into the part planning process occurs at two levels: microplanning (intra-feature) and macroplanning (feature interaction). Microplanning involves the selection of processes, parameters, tooling and catalysts to generate a single geometric feature. Macroplanning involves feature interactions under resource constraints which may have significant consequences in energy and waste generation, including precedence relationships between features and clustering among common setups, tooling and catalysts. This paper presents an overview of a hierarchical part planning strategy for environmentally conscious machining. A case study of a machined component will be developed to illustrate feature interaction issues. The robustness of process planning under uncertainty in environmental impact evaluation will also be addressed.
A collaborative scheduling system for make-to-order manufacturing
K.I. Lee (2), M. Kang, J.H. Park  
STC O,  45/1/1996,  P.461
Keywords: Production Control, Job Shop, Co-operative Scheduling
Abstract : In the make-to-order manufacturing industry, the details about the product specification become gradually known in phases from development, design, and process planning. This makes the production scheduling less accurate, and causes the operations schedule to be revised frequently during the manufacturing. To reconfigure the existing schedule, the monitoring data collected from the shop floor are essential. A collaborative scheduling system for the job shop has been developed to manage the job processing effectively. The system adopts presumptive, predictive and reactive scheduling methods. Each method is built into a module which performs scheduling based on the different data, and collaborates with other modules. The scheduling system is interfaced to a machine monitoring and data collection system. The experience of the implemented system in a factory is encouraging.
A new hybrid method for part-family development
W. Massberg (1), R. Künzel  
STC O,  45/1/1996,  P.465
Keywords: Group Technology, Part-family Development, Statistical Analysis
Abstract : While rationalization measures used to concentrate on technological improvements.. organizational and structural approaches are becoming more and more important. On the one hand companies can be forced to restructure their production areas into group-technology based manufacturing concepts. On the other hand enterprises can also be obliged to estimate their potential for the outsourcing of manufacturing tasks in order to establish common outside suppliers together with suitable partner companies. For all these tasks the development of suitable part-families can be considered as the essential means to ease the restructuring processes or to support the required decision taking. Accordingly this paper presents a new hybrid method for part-family development. which is based on a combination of a modified COSINE-classifier-network (hierarchical analysis) and the FUZZY-clustering procedures (non-hierarchical analysis). Such an efficient procedure involves obtaining a fast classification result, which contains more transparent planning information dealing with a large amount of workpieces.
Multi objectives approach for process plan selection in IMS environment
S. Noto La Diega (1), G. Perrone, M. Piancentini  
STC O,  45/1/1996,  P.471
Keywords: Process Plan, Integrated Manufacturing System, Fuzzy Programming Model
Abstract : In Integrated Manufacturing Systems (IMS) evaluating the most suitable process plan is a very complex task. Technology, quality, production and market requirements are objectives to be pursued in the selection process, subject to the constraints due to the several part types simultaneously manufactured. The paper proposes a new approach to the process planning selection, based on a possibilistic fuzzy programming model in order to face the vagueness coming from the formalization of the objectives and constraints in the selection problem.
Generation of modified cutting condition using neural network for an operation planning system
M.W. Park, H.M. Rho (2), B.T. Park  
STC O,  45/1/1996,  P.475
Keywords: CAPP, Cutting Condition, Neural Network
Abstract : For the rational scheduling of production in discrete machining shop, standard time needs to be estimated correctly. The estimation depends on the accuracy of cutting condition. Machinists usually make modifications to recommended cutting conditions suggested by process planner in order to satisfy requirements for individual operation. The systematization of/ /the modification procedure by using neural network methodology is proposed in this paper. Also. other key functions of the operation planning system for prismatic components which includes the module for cutting condition are briefly described. The results of operation planning are demonstrated with an example part.


Towards instrument-oriented calibration of CMMs
A. Balsamo (2), M. Di Ciommo, R. Mugno, S. Sartori (1)  
STC P,  45/1/1996,  P.479
Keywords: CMM, Calibration, Uncertainty
Abstract : The calibration of CMMs has become a more and more important matter of investigation and discussion stimulated by the increasing demand of calibration in manufacturing. CMM errors are very complex to describe in simple terms suitable to be stated in a calibration certificate; even more complex is the evaluation of uncertainties of these errors and of their combination. This paper proposes a methodology which enables a simple representation of CMM errors in terms of scale factors, and of their uncertainties in terms of binomials, intended to meet the requirements of brevity and simplicity of a calibration certificate. A numerical example is given of the actual calibration result of a CMM.
Accuracy limitations of fast mechanical probing
W.P. van Vliet, P.H. Schellekens (2)  
STC P,  45/1/1996,  P.483
Keywords: Mechanical Probe System, Impact Damage, Dynamic Error
Abstract : Although dynamic errors of CMMs are getting more attention now, still little is published about the dynamic disturbances acting on mechanical probe systems. The process of mechanical probing is subject to dynamic influences, even at generally accepted low measurement velocities. It will be shown that due to the nature of the mechanical probing principle, impact forces are much higher than measurement forces and can result in considerable damage of workpiece surfaces. Further it is proved that the relation between the position of the probe tip and the workpiece position during impact cannot be determined unambiguously due to bouncing, irrespective of the probe construction. Consequently measurement accuracy can be lost, depending on the principle of probing. Analysis shows that this bouncing effect cannot be avoided during probing and therefore should be taken into account to improve probe performance. Measurement results obtained with two different probe systems will be presented to illustrate those impact phenomena. Based on these results recommendations for probe system design are given in order to speed-up probe operation without degradation of probe performance.
A multi channel diode-laser-interferometer for displacement measurements on a CMM
A. Abou-Zeid, K.-H. Bechstein, C. Enghave   / H. Kunzmann (1)
STC P,  45/1/1996,  P.489
Keywords: Laser, Measurement, Multi-Interferometry
Abstract : The increasing demands in the manufacturing measuring technique concerning the accuracy of the production components and the precision of the manufacturing measuring progress make it necessary to find a precise and rapid measuring method that can be integrated into the production machine. The use of laser diodes in the measuring technique has advantages as well as disadvantages. This paper describes the setup, performance and testing of a Fabry Perot Interferometer-stabilized diode laser (FPI) as a light source in an interferometer as well as a transportable lambdameter, and a weather station for calibration of the laser wavelength in air. For length measurements in two axis on a coordinate measuring machine, a two-axis multi function laser interferometer using the FPI-stabilized diode laser was developed and tested under respectively laboratory and workshop conditions.
Measurement uncertainty limit of a video probe in coordinate metrology
S.W. Kim   / P.A. Mc Keown (1)
STC P,  45/1/1996,  P.493
Keywords: CMM, Inspection, Vision
Abstract : Video probes are increasingly used in recent industrial applications of coordinate measuring machines, since they are found more efficient than conventional bail-tip probes especially in inspecting small-sized features of complex shapes. However, no thorough investigation has yet been accomplished to comprehend the measuring capabilities of video probes. In this paper, analytical and experimental approaches are made to explore how the measuring uncertainty limit of video probes is determined by major design parameters related to imaging optics, coherence of illumination, and edge detection algorithms using a CCD array. Finally an exemplary optimal design is discussed to demonstrate that an ultraprecision measurement of 0.01 µm uncertainty can be practically achieved.
Micro-machined profile measurement by means of optical inverse scattering phase method
T. Miyoshi, Y. Takaya, K. Saito (2)  
STC P,  45/1/1996,  P.497
Keywords: Optical Measurement, Ultra-Precision, Micro-Profile
Abstract : A new optical measuring method based on the inverse scattering phase retrieval is presented in this paper, which will be able to be applied to in-process measurement of micro-machined surface profile with an accuracy of nanometer order. In order to verify the validity of the proposed method, first, computer simulations of reconstruction of the different fine groove models are performed. Second, the inverse scattering phase construction system is developed and the measurements of the symmetric and non-symmetric fine triangular grooves which is micro-machined by ultra precision diamond turning are carried out. Consequently, it is found that the proposed measurement method is effective for reconstructing the profile of a submicrometer size workpiece without scanning a probe or a stylus.
A twist-roller friction drive for nanometer positioning: a simplified design using ball bearings
H. Mizumoto, S. Arii, A. Yoshimoto, T. Shimizu, N. Ikawa (1)  
STC P,  45/1/1996,  P.501
Keywords: Nanotechnology, Precision Machine, Position Accuracy
Abstract : The authors have reported in a previous paper that the twist-roller friction drive can realize subnanometer positioning resolution. However, a structural difficulty of the device is that hydrostatic bearings are used to support the twist-rollers. The present paper describes how the structure of the twist-roller friction drive can be simplified by using ball bearings to support the twist-rollers. Even with this simplification, the experiments showed that the positioning resolution is less than one nanometer. The paper concludes that the twist-roller friction drive /of /ball bearing type facilitates the manufacture /of /a nanometer positioning system which can be used in a clean environment, and can take the place of the ball screw or capstan friction drive.
Ultraprecision feed system based on walking drive
T. Moriwaki (1), E. Shamoto  
STC P,  45/1/1996,  P.505
Keywords: Ultra-Precision Feed, Actuator, Control
Abstract : A new ultraprecision feed drive system has been developed based on a driving mechanism named walking drive. The feed system utilizes sets of clamping and feeding units driven by piezoelectric actuators, which are activated repeatedly with certain phase shifts just like the walking motion of animals, The characteristic features of the system are continuous and smooth motion for the whole stroke of the guide, fine resolution down to nm order and high stiffness in the feed direction. The paper presents the mechanism of the feed system developed, the control method of the system and some experimental results.


On material removal mechanisms in finishing of advanced ceramics and glasses
R. Komanduri (1)  
STC S,  45/1/1996,  P.509
Keywords: Ceramic, Finishing, Mechanism
Abstract : Fundamental considerations on the interactions between the abrasive and the work material as well as the micromechanisms of material removal and surface generation process in finishing of advanced ceramics and glasses are addressed. In developing plausible mechanisms, an attempt is made to delineate the failure mechanisms operable in polycrystalline ceramics and glasses versus metals. This is necessary because of the significant differences in the nature of bonding, restrictions on the extent of plastic deformation (including the number of independent slip systems required), microstructure, tribochemistry, and, flaws generated during processing of these materials and their consequent effect on the failure mechanisms associated.
Scale-sensitive fractal analysis of turned surfaces
C. Brown, W.A. Johnsen, R.M. Butland   / J. Bryan (1)
STC S,  45/1/1996,  P.515
Keywords: Machined Surface Texture, Topographic Analysis, Surface Roughness
Abstract : Scale-sensitive analyses using length-scale relations, which have been developed from fractal geometry (coastline, compass or Richardson methods), are applied to a series of turned surfaces with a range of feeds per revolution. This length-scale analysis method calculates the apparent lengths of profiles as a function of the scales of measurement. The profiles are acquired by conventional, stylus profiling. It is shown that this length-scale method can be used to identify the periodic components of profiles and that it is able to distinguish changes in the character of the surface roughness as a function of scale.
Subsurface damage distribution in ultraprecision machined CdS
D.A. Lucca (2), C.J. Maggiore, R.L. Rhorer  
STC S,  45/1/1996,  P.519
Keywords: Surfaces, Ultra-precision Machining, Subsurface Damage
Abstract : The extent and distribution of the subsurface damage in ultraprecision machined CdS was examined by the use of ion channeling using glancing angle detector positioning to provide enhanced depth resolution. Single crystal (0001) oriented CdS was diamond turned over the range of depths of cut of 0.1 - 10 µm, and subsurface lattice disorder was examined for regions cut parallel to, and 30 degrees off, a preferred cleavage plane. Damage depths for the crystals machined along a preferred cleavage plane were found to be consistently larger than those machined 30 degrees off the plane.
Investigation on the surface topography in polishing using atomic force microscopy
L. De Chiffre (2), H.N. Hansen, A. Bronstein  
STC S,  45/1/1996,  P.523
Keywords: Polishing Process, Surface topography Analysis, Atomic Force Microscopy (AFM)
Abstract : An investigation was carried out on the surface topography generation in polishing. Hardened tool steel specimens were polished using different parameters and the surface topography was examined using an Atomic Force Microscope (AFM). Measurements using AFM were initially compared to measurements obtained with a stylus instrument and with an optical profilometer. Contour plots were produced and a number of three-dimensional roughness parameters calculated for each surface. A statistical analysis of the results pointed out the most critical parameter with respect to all roughness parameters, for the material and hardness considered in this investigation, to be the grain size. The process parameters polishing cloth, lubricant, speed and pressure were found to have varying statistical significance with respect to the different roughness parameters. The roughness parameters Sa and Sk were found to be good indicators of the effect of varying the process parameters. An investigation was subsequently carried out on the surface topography generation as a function of the polishing time, for different grain sizes. Good reproducibility of the roughness parameters was found in two different specimens series. Most of the parameters' decrease takes place during the first 100-200 seconds of polishing.
Function-oriented lapping and polishing of ceramic rolling elements through characterization of the workpiece surface
E. Westkämper (1), H.-W. Hoffmeister  
STC S,  45/1/1996,  P.529
Keywords: Lapping, Ceramic, Roughness Parameter
Abstract : Ceramic materials are exceptionally well suited for highly loaded functional surfaces. Their brittleness, however, requires exact knowledge of those cuttig conditions ensuring compliance with the requested function since the surface topography is of decisive importance for the later functional behaviour. On the example of lapping and polishing of ceramic rolling elements, the relationship between surface topography and rolling wear is demonstrated. A comparison of conventional and newly developed roughness parameters for evaluating the rolling wear shows that descriptive wear models can only be built up with new roughness parameters. First results obtained with a new roughness parameter are presented.