Log in




Internet based Diagnosis of Assembly Systems
K. Feldmann (1), J. Göhringer  
STC A,  50/1/2001,  P.5
Keywords: Diagnostics, Knowledge based system, Assembly
Abstract : A high availability is of particular importance for modern assembly systems to ensure the return of the high investment costs. Due to the complexity of the occurring failures and the world-wide use of the systems the manufacturer must provide a global service. Therefore an internetbased diagnosis system was developed, which can be used both for local and for remote diagnosis. The system provides different programs for visualisation and failure diagnosis. These are based on a central knowledge data base that contains all relevant information.
Micro Handling with Rotational Needle-type Tools under Real Time Observation
M. Nakao, K. Tsuchiya, K. Matsumoto, Y. Hatamura (1)  
STC A,  50/1/2001,  P.9
Keywords: Micro, Assembly, Handling, Tool
Abstract : This paper analyzes human operation of an arbitrary single micro object under 1mm while observing the object and systematically studies the design of a micro handling system to perform such operations. This system features the following mechanical elements; (1) a needle-type tool with a tip as small as the micro object to handle; (2) a palette engraved with micro structures to hold the micro object; (3) a driving mechanism not only to translate the tool but also to rotate it; (4) a microscope to observe the tool operation in real time. As the microscope occupies a large volume, the system sets the mechanism elements in a centralized arrangement so the micro object, tool tip, center of tool rotation, microscope focus intersect at one point and the remaining elements are radially arranged around it. We used this system to conduct several operations including a SEM monitored micro house construction by assembling and bonding walls and roof, an optical microscope monitored microscopic insemination by inserting a sperm into an ovum, and a fluorescent microscope monitored DNA surgery cutting out an arbitrary gene from a chromosome. These operations verified the effect of the above design guideline, that is the group of mechanism elements and their construction.
On-line control of robotized Gas Metal Arc Welding
M. Lanzetta, M. Santochi (1), G. Tantussi  
STC A,  50/1/2001,  P.13
Keywords: Welding, On-line control, Image analysis
Abstract : On-line control of welding and soldering is a strategic issue for the complete automation of robotized plants. The proposed control system aims to detect the most critical defects in industrial applications. It is based on the analysis of images coming from two cameras installed on the welding torch: the arc and the pool observation allow monitoring the welding process; a laser stripe is used for the weld bead inspection. The image analysis algorithms developed are based on the extraction of features, which have been selected after a long series of experiments. In addition to pre-processing, different filters have been implemented to increase the system reliability, for the high noise in images. A basic control system is also addressed. The system has been tested in weld overlay cladding.
Integrated Computer Aided Design for Assembly Systems
C.R. Boër (1), P. Pedrazzoli, M. Sacco, R. Rinaldi, G. De Pascale, A. Avai  
STC A,  50/1/2001,  P.17
Keywords: CAAP, Computer Aided Assembly Planning
Abstract : Assembly being the last step of the production cycle of a product, it is normally submitted to the constraints of the precedent step. Techniques like Design for Assembly have been developed to try to take into consideration the peculiarities of the assembly process and reduce costs. The paper present the research and development of an integrated computer aided design for assembly system. The project main aim is to obtain methodologies and tools to design and manage a complete flexible assembly system but in this paper we will describe a CAAP (Computer Aided Assembly Planning) for the determination of gripping features, gripper and finger configuration, assembly sequence, simulation of the assembly system for the design of management rules, three dimensional simulation of robots (serial and parallel) for the design of each single assembly and control cell. The results of the project is tested in a specifically designed and implemented system for the assembly of electro-mechanical components.
Hybrid Automatic-manual Assembly Systems
T. K. Lien   / F.O. Rasch (1)
STC A,  50/1/2001,  P.21
Keywords: Assembly, Flexibility, Productivity
Abstract : Hybrid assembly systems consist of an automatic assembly section that feeds a manual finishing line. They are competitive for medium volume assembly of products with standard basic structures and many variants that require manual finishing. This paper describes two basic principles for the manual assembly: The parallel arrangement of stations, and the sequential arrangement. A theoretical model for the possible output as function of production volume, number of assembly operations, number of product variants, and station operation time imbalance is presented. This model enables prediction of the performance and selection of the optimal system for a given set of conditions.
Reduction of Systematic Dosing Inaccuracies During the Application of Highly Viscous Substances
G. Reinhart (2), J. Gartner  
STC A,  50/1/2001,  P.1
Keywords: Automated sealing application, Process accuracy, Assembly
Abstract : The automated application of adhesives and sealants on three-dimensional components requires that the application profile produced by constant medium dosing along the processing line has to be as uniform as possible in order to ensure adhesive and sealing functions. Incorrect dosing occurs especially frequently during the dosing of highly viscous substances at application points with a high degree of curvature and these inaccuracies later affect the function of the component. Incorrect dosing occurs partly due to the way in which the speed of the handling system responds. For this reason, we have developed a means of compensating for dosing errors arising from the kinematic response of the handling machine by methods of calculated control predictions for the dosing unit based on internal control information.


Generalized Modeling of Mechanics and Dynamics of Milling Cutters
Y. Altintas (1), S. Engin  
STC C,  50/1/2001,  P.25
Keywords: Milling, force, chatter
Abstract : This paper presents a generalized mathematical model of most helical end mills and inserted cutters used in industry. The end mill geometry is modeled by wrapping the helical flutes around a parametric envelope of a cutter body. The edge geometry for inserted cutter is defined in the local coordinate system of each insert, and placed and oriented on the cutter body using cutter's global coordinate system. The coordinates of a cutting edge are mathematically expressed for both cases. The chip thickness at each cutting point is evaluated by using the true kinematics of milling including the structural vibrations of both cutter and workpiece. By integrating the process along each cutting edge or tooth, which are in contact with the workpiece, the cutting forces, vibrations, dimensional surface finish, and chatter stability lobes for arbitrary end mills and inserted cutters are predicted. The predicted and measured cutting forces, surface roughness and stability lobes for helical tapered ball, bull nosed end mills and inserted cutters are provided to illustrate the viability of the proposed generalized end mill analysis. The algorithms are integrated to an advanced cutting process simulation program which is used for process planning of milling operations to avoid chatter vibrations, torque and power limit constraints, and dimensional form errors.
On modelling the influence of thermo-mechanical behavior in chip formation during hard turning of 100Cr6 bearing steel
G. Poulachon, A. Moisan (1), I.S. Jawahir (1)  
STC C,  50/1/2001,  P.31
Keywords: Hard turning, Work hardening, Thermal softening
Abstract : This paper deals with turning of hardened alloy steels (up to HV800). First, the research focuses on the evaluation of flow stress in machining of 100Cr6 (AISI 52100) bearing steel. A material constitutive law including work hardening, thermal softening, and strain-rate sensitivity has been looked for. The work hardening effect has been determined with the help of quasi-static compression tests performed on standard test specimens. The dynamic compression tests performed at "high strain-rates" using the Hopkinson bars, have shown no tendency to viscosity effects. Hot compression tests show that thermal softening plays a significant role in the the process feasibility. Cutting tests performed under various cutting conditions have highlighted the conflicting work hardening?thermal softening processes. This balance is discussed with a shear instability criterion, presenting the work hardening to thermal softening ratio through a revised material behavior law.
Temperature on Flank Face of Cutting Tool in High Speed Milling
T. Ueda (2), A. Hosokawa , K. Oda, K. Yamada  
STC C,  50/1/2001,  P.37
Keywords: End milling, Temperature, Measurement
Abstract : The temperature on the flank face of a cutting tool in high speed milling is measured using a two-color pyrometer with a chalcogenide optical fiber. This pyrometer has a flat response for a pulse signal of 400 kHz, which is rapid enough to measure the temperature of an end milling cutter rotating at 10000rpm. The influence of cutting speed, feed speed, depth of cut on the cutting temperature at the flank face of a cemented carbide insert is investigated. The temperature of the end milling cutter rises rapidly with increase of cutting speed and it is approximately 770 °C at 628 m/min. The heating and cooling characteristics of the cutting tool are examined and the temperature change during an intermittent cutting operation is approximately 150 °C at cutting speed 471 m/min and feed 0.047mm/tooth.
A model for calculation of the geometrical shape of the cutting tool - work piece interface
T. Carlsson,T. Stjernstoft   / B. Lindström (1)
STC C,  50/1/2001,  P.41
Keywords: Tool - workpiece interface, turning, computerised simulation
Abstract : In order to estimate the tool condition, cutting forces, surface roughness and other variables of interest in turning, it is important to understand the physical conditions at the cutting tool ? workpiece interface. The basic parameters in this context are the parameters which describe the geometrical shape of the tool ? workpiece interface, i.e. the chip area and the length of the active cutting edge. For common tools there exist standard formulas for these parameters. However, when using more exotic cutting angles or non-standard tools such as a rotating tool insert, the standard formulas do not comply. This paper presents a general model based on matrix algebra for calculation of the shape of the chip area and the length of the active cutting edge and how it can be applied for a rotating tool insert. The model input is the shapes of the cutting tool and the workpiece, the cutting data such as feed and depth of cut and the cutting angles (approach angle, minor cutting edge angle, inclination angle, rake angle, wedge angle, etc.). The output is the shape of the chip area and the length of the active cutting edge and their variations with changes in input parameters.
An Investigation of the Thermal Effects in Orthogonal Cutting Associated with Multilayer Coatings
W. Grzesik   / C.A. van Luttervelt (1)
STC C,  50/1/2001,  P.53
Keywords: Cutting, Tool coating, Thermal Analysis
Abstract : This paper deals with an experimental and analytical investigation into the tool-chip interface behaviour, influencing the temperature and heat transfer at the multilayered coated-tool rake face during orthogonal cutting of carbon and stainless steels. New methodology for assessing the amount of thermal energy generated when machining with a coated tool insert with natural and restricted contact coupled with a metallic chip, using thermophysical properties of the sliding materials is developed in this study. It was proven, based on the heat flux analysis, that the use of advanced coatings with an intermediate Al2O3 layer can substantially improve the heat flow into the chip at distinctly lower temperatures than other commercially available coatings. The data obtained can be used for the optimization of tool selection with respect to friction and heat transfer and for maintaining the recommended contact temperature.
Micro-Cutting of Steel to Meet New Requirements in Miniaturization
H. Weule (1), V. Hüntrup, H. Tritschler  
STC C,  50/1/2001,  P.61
Keywords: Micro-Cutting, Steel, Process Optimization
Abstract : Due to its hardness, single crystal diamond is the preferred tool material for micro-cutting. As diamond has a very high affinity to iron, micro-cutting is mostly limited to the machining of non-ferrous materials like brass, aluminum, copper or electroless nickel. The particular material properties of steel make it a very important material for extending the field of micro-technology applications. This paper discusses the prerequisites for the micro-cutting of steel using tungsten carbide tools and the interaction between the properties of the materials and the process parameters on the manufacturing result. Further fields of research are identified. The possibilities of this approach are exemplified on microstructured molds.
Cutting Load Capacity of End Mills with Complex Geometry
J.A. Nemes, S. Asamoah-Attiah, E. Budak   / L. Kops (1)
STC C,  50/1/2001,  P.65
Keywords: Milling, Cutter, Failure
Abstract : Cutting load capacity of cemented carbide end mills with high length-to-diameter ratios is determined from critical geometric and loading parameters, including a stress concentration factor (SCF) to account for serrated edges, which is determined by finite element analysis. Tensile strengths are characterised using a statistical Weibull analysis from 4-point bend tests of cemented carbide blanks of two different diameters. The approach is used to predict probability of survival for cutters under different loading conditions. Results are compared to measured failure cutting loads under service conditions as well as to those measured in static three point bend tests.
Geometric Generating Mechanism of Machined Surface by Ball-nosed End Milling
Y. Mizugaki, M. Hao, K. Kikkawa  
STC C,  50/1/2001,  P.69
Keywords: Ball end milling, Machined surface simulation, Kinematic cutter coordination.
Abstract : This paper presents a new geometric estimation method of machined surface by ball-nosed end milling in sphere contouring. Firstly the geometric relationship between a cutting edge and a normal vector of the sphere has been formulated. Through the equation analysis, multi-crossing of them up to three times and the zigzag movement of the cutting edge have been found newly. Also the interference by a major flank was found too. Secondly a numerical calculation solver was developed by Newton-Raphson method. Thirdly the graphical display was realized by a CAD system. Through the observation of machined surfaces, the interference area was confirmed.
Material Aspects of Chip Formation in HSC Machining
H. Schulz (1), E. Abele, A. Sahm  
STC C,  50/1/2001,  P.45
Keywords: Chip formation, High speed cutting, Cutting forces
Abstract : Investigations in the past have shown that chip formation changes by increasing cutting speed, because most of the experimental work had been carried out in the original material stage. In contrary to this new machining investigations were made on an aluminum alloy at different heat treatment states. These investigations confirm that precipitation hardening is the key in changing from continuous to segmented chip formation and not only the cutting parameters. By applying this new knowledge, the relationship between chip formation and cutting forces was examined.
Testing and Design of Tool Coatings with Properties Adapted to the Use of Biodegradable Cutting Fluids
F. Klocke (1), T. Krieg, E. Lugscheider, K. Bobzin  
STC C,  50/1/2001,  P.57
Keywords: Cutting, Coating, Tribology
Abstract : The paper focuses on defining demands on tool coatings developed for use with biodegradable cutting fluids, presenting new coating systems and research results on necessary coating functionalities which match these technological demands. Coating development and a tribological test scheme for the realisation of high tribooxidation stability is also described. The scope for improving the anti-adhesive properties of coatings for drilling tools are outlined. This covers the physical characterisation of surface polarity and surface energy of PVD hard coatings and the behaviour of nano-layered WC/C-coatings in the drilling of austenitic stainless steel.
Chip Formation in Machining Ti6Al4V at Extremely High Cutting Speeds
A. Gente, H.-W. Hoffmeister   / C.J. Evans (1)
STC C,  50/1/2001,  P.49
Keywords: chip formation, titanium, specific energy
Abstract : The chip formation of Ti6Al4V is described in the cutting speed range between 300 m/min and 6000 m/min. The specific cutting forces are measured. A new quick stop method is introduced which allows rapid decelaration from 2500 m/min in a very short distance, providing new information on the formation of segmented chips. The conditions at the onset of segmentation are described. A change in the structure of segmentation is observed with a cutting speed exceeding 2000 m/min. However, no change in specific cutting energy coincides with this change in structure.

 STC Dn 

Creation of Freeform Solid Models in Virtual Reality
M.C. Leu (2), B.Y. Maiteh, D. Blackmore, L. Fu  
STC Dn,  50/1/2001,  P.73
Keywords: virtual, design, modeling
Abstract : A novel method has been developed using a virtual reality (VR) environment to create solid models with freeform surfaces. The VR environment emulates the physical environment for creating freeform objects, i.e. the freeform model is created in a virtual environment by shaping a virtual workpiece with a variety of virtual tools. The trajectories of the virtual tools are generated by the designer?s hand movements and they are obtained by recording the position and orientation of the motion tracker mounted on a device held by the hand. A haptic device can be worn by the designer to provide a feel of the model creation process. In the mathematical algorithm, the swept volumes of the design tools are computed from the tools? geometric data and trajectories. Boolean operations are then performed on the swept volumes of the virtual tools and the virtual workpiece to create the design model. If the virtual tools used have the same geometry as the real tools used in numerically controlled (NC) machining, their trajectories in the model creation process can be postprocessed and used as feasible trajectories in actual NC machining to fabricate the design model.
Tele-Design for Manufacturing
A. Fischer (2), J. Barhak  
STC Dn,  50/1/2001,  P.77
Keywords: Reverse engineering, Surface reconstruction, Rapid prototyping
Abstract : One of the main challenges in manufacturing today is to reduce the time cycle for designing and prototyping new products. Tele-designing for manufacturing systems will make it possible to integrate distributed processes into one unified continuous manufacturing process. Tele-engineering is based on two merged technologies: Reverse Engineering (RE) and Rapid Prototyping (RP). These technologies together form an interactive and collaborative distributed system that transfers, models and analyzes scaled 3D models in real time. However, the current state of the art in these technologies does not provide a complete telemanufacturing system. This paper surveys these RE and RP technologies and outlines their pros and cons with respect to tele-engineering. Then, it proposes a reconstruction method based on a Neural Network (NN) technique that improves the tele-engineering process. Finally, the paper discusses expected future advancements, including the extension of the proposed Neural Network method and its impact in the near future on tele-engineering.
Haptic Interaction with Non-rigid Materials for Assembly and Dissassembly in Product Development
F.-L. Krause (1), J. Neumann  
STC Dn,  50/1/2001,  P.81
Keywords: virtual, tactile sense, deformation
Abstract : The subject of the present research activities include an innovative system for haptic support of handling simulations of flexible parts. The objective of this project is to develop a virtual environment from dedicated methods of one or two handed touching, pressing, pulling, gripping or handling of virtual tools, workpieces or other components. In the current stage of development, highly qualitative interactions such as gripping and the precise movement of flexible objects are being supported. These tests are carried out in order to achieve statements about the ability to assemble or disassemble a product. A PDM Enabler interface provides the link between the system and a PDM database. Using this coordinated approach, optimal integration of the solution within the process chain of product development is ensured.
Integrated Design Method to Improve Producibility based on Product Key Characteristics and Assembly Sequences
L. Mathieu (2), B. Marguet  
STC Dn,  50/1/2001,  P.85
Keywords: Assembly sequencing, Integrated design, Tolerancing analysis
Abstract : Producibility improvement is a major challenge for design and manufacturing firms. For aircraft or car body, this improvement has to go through a better product assemblability. In order to reach this goal, effects of manufacturing variations have to be managed. Two questions are asked about variation reduction: how to control effect of variations on functional requirements and what product characteristics are most sensitive to variations. No global answers exist to these questions. Therefore, we propose to describe in this paper an industrial method. The main idea of this method is that geometrical variation flows belong to the assembly process. During the preliminary design, the first step of our method is to identify where are the Key Characteristics for the product. The second step of the method performs a qualitative product analysis in order to eliminate the worst assembly sequences. At last a quantitative analysis allows to select the most promising assembly sequences. This integrated method has been applied with success to aircraft assembly.
Product Modularization for Parts Reuse in Inverse Manufacturing
F. Kimura (1), S. Kato, T. Hata, T. Masuda  
STC Dn,  50/1/2001,  P.89
Keywords: Product design, Module structure, Product life cycle
Abstract : For reducing environmental burden of industrial products, it is mandatory to rationalize product design and to achieve a closed loop product life cycle by use of comprehensive parts reuse and recycling. It is difficult to introduce parts reuse based on conventional product structure, and appropriate product modularization is necessary to efficiently manage a closed loop product life cycle. A new product modularization strategy is proposed across a family of products and successive generation of products, based on product functionality, product commonality and life cycle similarity. Car air-conditioners are examined for the validity of the proposed method.
Design by Quality Product Digitization
W. ElMaraghy (2), C. Rolls  
STC Dn,  50/1/2001,  P.93
Keywords: Design, Laser Scanning, Reverse Engineering
Abstract : The use of reverse engineering in product design has markedly increased recently. The ability to accurately combine CMM and laser scanning data, and hence realize the potential benefits of both, is impaired by a number of uncertainties inherent to each digitization process. In order to ensure the quality of the digitized data, and accurate representation of the designer?s intent, it is a pre-requisite to assess the measurements uncertainties and their sources, and to develop compensation methodologies. This paper discusses an approach for evaluating and compensating errors, primarily due to view registration. Hence the measurements are made as accurate as possible by design.
Economic Impacts during Microelectronics Product Design
Z. Wang, W.A. Knight (2)  
STC Dn,  50/1/2001,  P.97
Keywords: Product Design, Integrated Circuit Manufacturing, Cost Estimating
Abstract : An integral part of product design for manufacture is the use of predictive cost models to quantify the effects of early design decisions. An investigation has been performed to develop a set of detailed cost models to estimate the economic impact of microelectronics integrated circuit (IC) design alternatives. Cost-of-Ownership models, developed for IC fabrication equipment, are extended to the various cost domains in the microelectronics development cycle, including optical lithography and design for test solutions. The developed cost models have been implemented in software tools and these utilised to assess the effects of various design and processing options on overall IC manufacturing costs.
Analysis of Remanufacturer Waste Streams Across Product Sectors
J. Williams, L.H. Shu   / R.G. Fenton (1)
STC Dn,  50/1/2001,  P.101
Keywords: Design, Environment, Remanufacturing
Abstract : Remanufacture involves the production-batch disassembly, cleaning, repair or replacement of parts, and reassembly of products for reuse. Parts that cannot be reused by the remanufacturer enter the waste stream, examination of which reveals insights about remanufacture difficulties. Extending beyond our previous study of automotive products, the remanufacturer waste streams of electrical motors, toner cartridges, valves and telephones were analysed to support product design that facilitates remanufacture. The results of this research are presented in a format that allows a designer to determine the relevance of the products studied to products being designed.
Product Models for Life-Cycle
D. Brissaud, S. Tichkiewitch (1)  
STC Dn,  50/1/2001,  P.105
Keywords: Design, Life cycle, Product model
Abstract : The product design, manufacturing, assembly and usage processes have to be globally optimised for the competitiveness of the enterprises. The contribution of the paper deals with the product models able to support the views of life cycle engineers to consider those engineers as design actors in a whole product development cycle. Our approach is based on the capitalisation and analysis of quality discrepancies happening in product life cycle. The models themselves and the necessary information feedback are focused.
Axiomatic Design of Machine Control System
K.D. Lee, N.P. Suh (1), J-H. Oh  
STC Dn,  50/1/2001,  P.109
Keywords: Machine Control System, Axiomatic Design, Chemical-Mechanical Polishing
Abstract : Machine control system development typically relies on the developer?s experience and trial-and-error. This ad hoc approach can undermine the very success of the system development, with a lengthy and costly development period and, possibly, an endless cycle of upgrade and maintenance. The resulting system also lacks the interchangeability and reusability. This paper presents the framework based on Axiomatic Design for the systematic design and implementation of machine control systems. It structures a complex control system and guides the design and development of its subcomponents. Various levels of system design issues are addressed in this structural approach. Based on the methodology presented in this paper, a control system for an industrial scale Chemical-Mechanical Polishing (CMP) machine has been developed.
Integrating Altshuller's development laws for technical systems into the design process
D. Cavallucci   / R.D. Weill (1)
STC Dn,  50/1/2001,  P.115
Keywords: Design process, Artificial Intelligence, TRIZ
Abstract : Over several decades, a considerable number of researchers have performed analyses in order to predict technical systems evolution. These analyses are issued mostly from historic, situational observations and results of their works end up often by the formalization of evolution logic?s based on thorough synthesis. In the framework offered by TRIZ1, an advanced analysis of these laws have been performed and the objective of this article is first to introduce these laws and to propose an operative application framework in order to analyse their impact in the design process.


High Precision Finish Cutting by Dry WEDM
M. Kunieda (2), C. Furudate  
STC E,  50/1/2001,  P.121
Keywords: WEDM, dielectric, Finish cutting, Dry process
Abstract : This paper describes the development of a new dry wire electrical discharge machining (dry-WEDM) method, which is conducted in a gas atmosphere without using dielectric liquid to improve the accuracy of finish cutting. In dry-WEDM, the vibration of the wire electrode is minute due to the negligibly small process reaction force. In addition, as the gap distance is narrower than that in conventional WEDM using dielectric liquid, and there is no corrosion of the workpiece, high accuracy in finish cutting can be realized in dry-WEDM. However, some drawbacks of dry-WEDM include lower material removal rate compared to conventional WEDM and streaks are more likely to be generated over the finished surface. Increasing the wire winding speed and decreasing the actual depth of cut are effective to resolve these drawbacks.
ECDM (Electro Chemical Discharge Machining), a New Method for Trueing and Dressing of Metal Bonded Diamond Grinding Tools
M. Schöpf, I. Beltrami, M. Boccadoro, D. Kramer   / B. Schumacher (1)
STC E,  50/1/2001,  P.125
Keywords: Grinding, Electro-chemical dressing, Electrical discharge machining
Abstract : Metal bonded grinding tools cannot be processed efficiently and economically by means of traditional conditioning technologies and are therefore rarely used. A new hybrid technology that combines EDM and ECM, called ECDM, allows both the trueing and dressing of these grinding tools in just one step. Therefore ECDM is the ideal technology for trueing and dressing of metal bonded diamond tools and hence for the grinding of new cutting materials (Cermets, Ceramics, PCD). This new method has been applied successfully on a centerless grinding machine.
Failure of Rapid Prototype Molds during Injection Molding
J.S. Colton, J. Crawford, G. Pham, V. Rodet   / K.K. Wang (1)
STC E,  50/1/2001,  P.129
Keywords: rapid prototyping, injection mold, failure
Abstract : Stereolithography rapid tooling materials (typically epoxy-based photopolymers) show great promise for injection molding of limited numbers of parts, greatly reducing the time to product. Yet, they present challenges to designers because of their strength, thermal characteristics, and shorter lifetimes as compared to other mold materials. This paper presents models of the forces generated during the injection molding cycle so as to evaluate the suitability of rapid tools. The models comprise thermal and mechanical loading during injection, cooling shrinkage, and ejection. The effects of process conditions on material properties are studied. Experimental results are presented.
Influence of Nd:YAG Parameters on the Selective Laser Sintering of Metallic Powders
R. Glardon, N. Karapatis, V. Romano   / G. N. Levy (1)
STC E,  50/1/2001,  P.133
Keywords: Nd:YAG laser, sintering, metals
Abstract : Compared with CW CO2 laser sources, Nd:YAG lasers with Q-switching capability offer a wider parameter range, with improved sintering control, due to the short pulsed energy delivery. In particular, thermal diffusion being strictly limited by the nanosecond interaction between the energy pulse and the powder, higher accuracy can be achieved, while caking can be minimized. By systematically varying average power, scan velocity and repetition rate, process maps are established, for various materials, such as nickel and cobalt alloys, and titanium. Sintering depth and macrostructures are determined for different parameter sets. Basic models and physical explanations are given, for the various phenomena and consolidation processes. This mapping provides a correlation between the process parameters and the structure and properties of the produced parts. Results show that roughness and density are related to the pulsed energy delivery. For example, it is shown that multi-layer Ti samples can be sintered to a density close to 80 %37;.
Modeling, Monitoring and Control in High Quality Laser Cutting
R. Poprawe   / W. König (1)
STC E,  50/1/2001,  P.137
Keywords: Laser, Cutting, Surface Quality, Monitoring
Abstract : Electrical discharge machining (EDM) and laser cutting are thermal separation processes widely used in shaping and contour cutting applications. However, there are gaps in understanding the dynamics of the process, especially issues related to cut quality. This work describes the advances in fundamental physical modeling and process monitoring of laser cutting, as well as time varying processes such as contour cutting. The onset of evaporation and the increase of capillary forces are the two physical phenomena relevant to the build-up of adherent dross. The dynamic model predicts a modulation frequency for the laser power that leads to almost complete suppression of adherent dross in contour cutting.
Micro-bending of Thin Spring by Laser Forming and Spark Forming
M. Otsu, T. Wada, K. Osakada (1)  
STC E,  50/1/2001,  P.141
Keywords: Microform, Laser, Spark, Bending
Abstract : To attain accurate bending of thin plate springs, spark forming in which a plate is bent by thermal stress due to electric spark is proposed. Experiments are performed with plate springs of 50mm or 70mm thickness made of beryllium copper, pure titanium, pure copper and 18Cr-8Ni stainless steel, and the results are compared with those of laser forming. The bending angle can be controlled with an accuracy of 1?10-4 degree by the proposed method. It is concluded that spark forming has advantages in the variety of applicable materials, efficiency of energy, cost and space of apparatus over laser forming.
Hybrid High Speed Machining (HSM): System Design and Experimental Results for Grinding / HSM and EDM / HSM
D.K. Aspinwall, R.C. Dewes, J.M. Burrows, M.A. Paul   / B.J. Davies (1)
STC E,  50/1/2001,  P.145
Keywords: Machining, grinding, electrical discharge machining (EDM)
Abstract : Point grinding and electrical discharge machining (EDM) are detailed on high speed machining centres. A Taguchi design was employed to evaluate operating parameters when point grinding (plunge) nickel-based superalloys with 15 mm diameter electroplated diamond and cubic boron nitride (CBN) wheels using speeds up to 60,000 rpm provided by an ancillary spindle. Material removal of up to 120 cm3 and roughness values down to 1.2 mm Ra were obtained when machining Inconel 718. A retrofit EDM servo head unit was designed for die sinking and workpiece surface texturing. When texturing 2D and 3D workpieces, surfaces were produced with an Ra of 1-10 mm, depending on operating parameters.
Design and Characterisation of Ultrasonic Cutting Tools
M. Lucas, J.N. Petzing, A. Cardoni, L.J. Smith   / J.A. McGeough (1)
STC E,  50/1/2001,  P.149
Keywords: Ultrasonic cutting, Tool design, Vibration
Abstract : Cutting of food products and other materials with ultrasonically assisted tools has demonstrated significant benefits including reduced wastage and improved cut quality. However, the success of the technology relies on careful design of the ultrasonically excited tools and transmission components. In this paper, the different challenges of tool design are discussed with reference to two cutting devices. The studies demonstrate that accurate characterisation of the vibration behaviour of the tool and an understanding of the effects and limitations on vibration responses of design modifications, allows tool performance to be enhanced in the design.


Enhancing performances of SHPB for determination of flow curves
P. F. Bariani (1), G. Berti, S. Corazza  
STC F,  50/1/2001,  P.153
Keywords: compression test, high strain rate, flow stress
Abstract : A compression test on a Split Hopkinson Pressure Bar (SHPB) is the most common testing method adopted to determine material flow curves in a quite wide range of high strain rates. However, in most ordinary SHPB applications material rheology can only be investigated up to a rather low strain. Furthermore, several phenomena, including friction at interfaces and radial and axial inertia, are potential sources of inaccuracy for flow stress data. The paper presents the main design-guidelines followed when developing a high-performance SHPB system for the determination of accurate flow curves. The results from hot compression tests carried out on Aluminium- and Nickel-alloys prove that with the developed system most of the limitations of ordinary-SHPBs are overcome and system performances significantly improve.
Flow Stress, Yield Criterion and Constitutive Equation of Mushy/Semi-Solid Alloys
M. Kiuchi (1), J. Yanagimoto , H. Yokobayashi  
STC F,  50/1/2001,  P.157
Keywords: Semi -solid, Yield, Deformation
Abstract : New mathematical models of yield criterion and constitutive equations of mushy/semi -solid alloys (hereinafter described as semi -solid alloys) are proposed in order to investigate their flow features and deformation characteristics in various forming and shaping processes. First, a large number of uniaxial compression tests of semi -solid alloys are carried out and their stress -strain curves are measured. Through the tests, the remarkable drop of their flow stress is observed when their solid fraction decreases from 100%37;. The second, a new formula of yield criterion of semi -solid alloys is proposed. It can express the drop of their flow stress in semi -solid state. In addition, so -called constitutive equations, which describe flow and deformation of such alloys in forming and shaping processes, are derived from the formulated yield criterion. At the last stage, the obtained constitutive equations are introduced to 3D FEM simulation of upsetting of billets.
Ironing of thin walled cans
J. Danckert (1)  
STC F,  50/1/2001,  P.165
Keywords: Ironing, Die design, FEM
Abstract : The ironing of thin walled cans has been analysed using the slab method and FEM. The results show that there exists a critical reduction ratio at which the ironing process may become unstable (or not selfcentring). The results obtained show that the critical reduction ratio is heavily influenced by the geometry of the ironing die (semi-die angle and length of the die land), the friction conditions and the strain hardening of the material. An increase in the semi-die angle and/or length of the die land decreases the critical reduction ratio. If the friction coefficient in the punch-can interface is increased compared to the friction coefficient in the die-can interface, the critical reduction ratio increases. The critical reduction ratio also increases if the strain hardening of the can material is increased.
Investigation of Ecology Friendly Lubrication in High Speed Drawing Of SSID Tubes
R. Shivpuri (2), D. Bhaskararao, S. Mukherjee, S.D. Kini  
STC F,  50/1/2001,  P.169
Keywords: drawing, lubrication, ecology
Abstract : Tubes used in the chemical and fluid power industry have special inner surface roughness requirements. To meet these requirements, it was decided to explore the mandrel drawing of carbon steel tubes to submicron surface finish and thereby reduce the need for machining and honing the inner diameter of the tube. An additional goal was to investigate the use of ecology friendly solid lubricant in the mandrel drawing process. First, a roughness model was developed which relates the interface parameters such as effective stress to roughness changes and lubrication parameters. This model was calibrated using industrial experiments on a draw bench. Then a design of experiment was carried out to relate the tube drawing phenomenological parameters such as die angles, reduction and drawing speed to the interface parameters. These two models were then integrated to predict the surface roughness changes at the inner surface of the tube during mandrel drawing. It was found that the new lubricant is able to provide good surface finish for typical tube drawing reductions with and without the conversion coating. However, for reductions larger than 40%37; it cannot prevent die pick up. At drawing speeds greater than 0.5 m/s it is effective in preventing die pick up but cannot deliver SSID surface finish in drawn tubes.
Prediction of service life and failure probability of cold forging tools
M. Geiger (1), B. Falk  
STC F,  50/1/2001,  P.173
Keywords: Simulation, Tooling, Fatigue
Abstract : Tools systems for the production of cold forged parts, especially for parts with net-shape or near-netshape attributes, can be denoted as extremely high stressed technical components. Due to this circumstance they often fail by fatigue crack initiation in surface areas, which are characterised by high load levels. Therefore, the primary goal of this publication is to present a methodology for the lifetime calculation of cold forging tools. Beside the principle demand ? the improvement of the prediction accuracy ? a so-called stochastic-deterministic method enables it to trace back the stochastic lifetime characteristics to the scatter of the primary parameters of influence and the fatigue properties of the tool material.
Development of a formulation to describe the work softening behaviour of magnesium sheets for heated deep drawing processes
E. Doege (1), G. Kurz  
STC F,  50/1/2001,  P.177
Keywords: Sheet metal, Forming, Processing
Abstract : Experimental investigations at the Institute for Metal Forming and Metal Forming Machine Tools (IFUM) demonstrate that magnesium sheets possess excellent formability, if the process is conducted at higher temperatures. The investigations are concentrated on improving the forming behaviour of commercial magnesium alloys. For the understanding of the forming behaviour of these materials a detailed evaluation using tensile tests conducted at elevated temperature is required. Because the flow stress decreases with increasing straining, which is represented by the so-called work softening, no appropriate material formulation is available. Furthermore, deep drawing tests with a locally different temperature distribution in the die and blank holder show an additional extension of the forming limits of magnesium sheet material. The obtained results lead to the conclusion that for certain applications it is possible to substitute conventional aluminium and steel sheets by using magnesium sheet metal wrought alloys.
A simple experiment to characterize material formability in tube hydroforming
L. Filice, L. Fratini, F. Micari (2)  
STC F,  50/1/2001,  P.181
Keywords: Tube, Forming, FEM
Abstract : In tube hydroforming processes an internal fluid pressure is utilized to form the material on a properly shaped die; during the process the material axial movement is favoured by the axial feeding of an active punch. In the paper a simple experiment is presented aimed to investigate the influence of the main process variables on material formability. This equipment has enabled an extensive experimental investigation; furthermore a numerical analysis based on the finite element technique has been performed and a ductile fracture criterion has been implemented to predict the insurgence of bursting defects.
Adaptive FEM Simulation for Tube Hydroforming: a Geometry-Based Approach for Wrinkle Detection
M. Strano, S. Jirathearanat, T. Altan (1)  
STC F,  50/1/2001,  P.185
Keywords: Tube HydroForming, FEM, Wrinkling
Abstract : The success of Tube HydroForming (THF) operations is largely dependent on the selection of the loading paths: internal pressure vs. time and axial feed vs. time. The Finite Element Method is often used to reduce the cost of prototyping. In this paper, the adaptive simulation concept is presented as an effective FEM approach, able to select a feasible THF loading path within a minimum number of simulation runs or even within a single run. The adaptive simulation technique is based on the ability to detect the onset and growth of defects (wrinkling, buckling, bursting) and to promptly readjust the loading paths. The detection and quantitative evaluation of wrinkles play a key role in the implementation of the adaptive simulation. Therefore, a new geometrical wrinkle indicator is introduced and evaluated with numerical and experimental evidence. The proposed wrinkle indicator is computationally inexpensive, suitable for many die shapes and sensitive to different kinds of wrinkles.
Development of Micro Punching System
B.Y. Joo, S.I. Oh (1), B.H. Jeon  
STC F,  50/1/2001,  P.191
Keywords: micro hole, micro punching, alignment
Abstract : A micro hole punching system was developed and micro holes of 100µm in diameter were successfully made on brass sheets of 100µm in thickness. A micro punch made of tungsten carbide was designed to withstand the punch load, considering the buckling and the bending moment due to possible misalignment error. The punch was fabricated by the grinding process with diamond wheel. The die was designed considering the punch load and fabricated by micro electrodischarge machining process. In this system the stripper is designed to guide punch tip to minimize the possible misalignment. The punch was installed on a vertical stepper and the die was mounted on an X-Y translation unit. The precision motion controller controlled all motions of the micro hole punching system. In this study technical difficulties and solutions in the micro hole punching process were also discussed.
Analysis of flat rolling of superconducting silver/ceramic composites
J.I. Bech, M.S. Nielsen, M. Eriksen, F. Toussaint, p. Doremus, N. Bay (1)  
STC F,  50/1/2001,  P.201
Keywords: Superconductors, Rolling, Composites
Abstract : The flat rolling process from wire to tape is presumably the most crucial link in the chain of mechanical processes leading from loose powder and silver tubes to the final superconducting Ag/BSCCO tape. In order to improve the critical current density of the superconducting filaments, one must process these to the highest possible density without at the same time introducing failures as large cracks and macroscopic shear bands. In order to analyse and optimise the process, the interaction between the involved materials and their very different mechanical properties must be taken into account. The silver is considered an incompressible von Mises material, hardening as a function of equivalent strain. The powder on the other hand is a compressible friction material implying pressure dependent ?flow stress?. In this paper particular attention is paid to stresses and strains and defects in the deformation zone. The evolution of density in the powder cores is analysed by the finite element method.
Identification of Parameters in the History Dependent Constitutive Model for Steels
M. Pietrzyk   / J. Jedrzejewski (1)
STC F,  50/1/2001,  P.161
Keywords: Metal forming, Flow stress model, Parameter
Abstract : The problem of an influence of history of deformation on material behaviour during hot forming of steels is discussed in the paper. The method of description of the yield stress, which accounts for a strain path, is pre-sented. This approach is based on an internal variable method and it uses dislocation density for a descrip-tion of the state of the material. Identification of the material parameters in this model is the main difficulty, which prevents its practical application. Therefore, an inverse analysis combined with the experimental data is used in this work for an identification of these unknown parameters. The experiment composed axisymmet-ric hot compression performed at various temperatures and at various strain rates on the Gleeble 3800 simu-lator. After identification the flow stress model was implemented into the finite element program and simula-tions of various hot forming processes were performed.
Influencing the Friction in Metal Forming Processes by Superimposing Ultrasonic Waves
K. Siegert (1), J. Ulmer  
STC F,  50/1/2001,  P.195
Keywords: ultrasonic, forming, friction
Abstract : The possibility of influencing the friction in metal forming processes by superimposing ultrasonic waves will be discussed in general. It can be shown by experimental investigations that it is possible to reduce the friction forces and to improve the surface quality of formed parts. A new friction law including the influence of superimposed ultrasonic waves and the surface and lubrication properties will be described.


Temperatures in High Efficiency Deep Grinding (HEDG)
W.B. Rowe (1), T. Jin  
STC G,  50/1/2001,  P.205
Keywords: Grinding, Modelling, Temperatures
Abstract : A thermal model is presented for deep grinding with particular relevance to the HEDG process. HEDG is defined as deep grinding at high workspeeds and very high removal rates. The contact between the workpiece and wheel is represented as a circular surface. It is found that the contact angle and also the Peclet number (widely used in heat transfer and defined below) have strong effects on the grinding zone temperatures. Experiments were carried out to demonstrate the high removal rates achievable and to measure the resulting contact temperature. It was found that high removal rates and absence of thermal damage could be achieved as predicted. The new model is shown to provide a good estimation of contact temperatures. It is also confirmed that HEDG can achieve low specific grinding energy compared with shallow grinding and creep grinding. The chips take away a substantial proportion of the heat generated in the grinding process. As in creep grinding, burn-out of the coolant causes a steep rise in contact temperature of the workpiece.
An Investigation of the Effect of Machine Loop Stiffness on Grinding of Ceramics
B. Zhang (2)  
STC G,  50/1/2001,  P.209
Keywords: machine loop stiffness, surface grinding, residual workpiece strength
Abstract : This experimental study deals with the effect of machine structural loop stiffness on grinding of ceramics. The objective of the study is to investigate how the loop stiffness affects grinding forces, wheel actual depth of cut (ADOC) and workpiece strength. A compliant workholder is specifically designed and attached to a precision grinder to simulate grinding machines of various compliances so that the effect of machine loop stiffness can be isolated under otherwise identical conditions. Silicon nitride is used as workpiece material and ground with diamond wheels of two bond types and three grit sizes at machine loop stiffness of four different levels. The ground workpieces are assessed in terms of residual workpiece strength, grinding damage, grinding forces, and ADOC. Theoretical analyses are given to indicate that machine loop stiffness can affect on normal grinding forces and workpiece strength. A discussion is provided to reveal how residual workpiece strength is affected by residual stress and grinding-induced damage.
Dynamic Behaviour of Cylindrical Traverse Grinding Processes
M. Weck (1), N. Hennes, A. Schulz  
STC G,  50/1/2001,  P.213
Keywords: Traverse grinding, Dynamic stability, Computer simulation
Abstract : Compared to cylindrical plunge grinding processes the conditions of contact in cylindrical traverse grinding processes are much more complex, so that it is hardly possible to derive an analytical stability criterion. Because of this, a numerical simulation tool has been developed, to research the dynamic behaviour in the time domain and to determine stable machining parameters of cylindrical traverse grinding processes. The simulation tool is based on a process model, including the dynamic compliance of the machine tool, the grinding normal forces, the grinding wheel wear and the surface of workpiece and grinding wheel. Special attention was paid to the conditions of contact, regarding the development of step wear of the grinding tool.
Application of AE Contact Sensing in Reliable Grinding Monitoring
J.F.G. de Oliveira, D.A. Dornfeld (1)  
STC G,  50/1/2001,  P.217
Keywords: Grinding, Process monitoring, Acoustic emission
Abstract : The low repeatability of the AE RMS level and its weak correlation with some grinding quantities has been the main problem that limits the use of this sensing technique in industrial environments. This paper presents results on the influence of some measuring conditions on the AE information. Some reliable grinding monitoring functions are proposed for production based on fast RMS analysis and binary contact detection techniques. An innovative grit mapping technique is introduced based on these new concepts. Some examples of application that include information about the topographic characteristics of a grinding wheel and its transformation during grinding are presented.
Ultraprecision Micro-Grinding of Germanium Immersion Grating Element for Mid-Infrared Super Dispersion Spectrograph
H. Ohmori, N. Ebizuka, S. Morita, Y. Yamagata   / H. Kudo(1)
STC G,  50/1/2001,  P.221
Keywords: ultra-precision grinding, grating element, electrical tool shaping
Abstract : The design of a mid-infrared high dispersion spectrograph with a resolution of 200,000 at 10mm employing germanium immersion grating elements is required for the ?SUBARU? large space telescope. The authors applied an ultraprecision micro-grinding technique using fine-diamond grinding tools whose edges have been sharpened by electrical and mechanical processes to fabricate the element, and successfully obtained the required element with a sharp and smooth V-faced grating structure using germanium. The successful fabrication of this element is expected to contribute to the production of a compact and efficient high dispersion spectrograph in the development of the most advanced image analyzer.
Development of Single Step Grinding System for Large Scale ?300 Si Wafer: A Total Integrated Fixed-Abrasive Solution
H. Eda, L. Zhou, H. Nakano, R. Kondo, J. Shimizu   / T. Nagao (1)
STC G,  50/1/2001,  P.225
Keywords: Silicon wafer, Grinding, Positioning
Abstract : This research has developed an integrated manufacturing system for ?300mm silicon wafer, using fixed abrasive instead of conventional free slurry, to provide a totally integrated solution for achieving the surface roughness Ra < 1nm (Ry < 5~6nm) and the global flatness < 0.2µm/?300mm. In addition to the space saving, this integrated system also significantly reduces the total energy consumption by 70%37;, compared with the current process used for ?200mm Si wafer. Three core technologies: the hybrid process mechanics, the GMM (giant magnetostrictive material) actuated positioning/alignment device and the ecologically friendly coolant circulation system are described in this paper. The system performance and results are then presented and discussed.
Process Analysis for the Evaluation of the Surface Formation and Removal Rate in Lapping
U. Heisel (1), J. Avroutine  
STC G,  50/1/2001,  P.229
Keywords: Lapping process, Grain motion analysis, Surface topography
Abstract : During the process of lapping, the mechanisms of surface formation and removal rate are decisively influenced by the movement type of the individual grains within the lapping abrasive. Two active movement types can be differentiated. These are the rolling and sliding of the individual lapping grains within the working gap in relation to one of the working partners as well as the passiveness of the grains, whereby varying surface topographies of the workpiece are created by active movement types. These can among others be influenced by some of the adjustable process parameters. However, the most important parameter is the significant grain form. On this basis, a simulation model for the analysis of the surface formation by the motion of grains is described in this paper, also considering collisions and break-ups of grains. It enables the quantitative specification of the individual movement types of the lapping grains under the influence of different process parameters. These are for example the lapping pressure, lapping speed, grain size, grain concentration etc as well as the qualitative estimation of these influences on the processing result.
Mechanisms of the Chemical Mechanical Polishing (CMP) Process in Integrated Circuit Fabrication
N. Saka, J.-Y. Lai, J.-H. Chun (2), N.P. Suh (1)  
STC G,  50/1/2001,  P.233
Keywords: Chemical Mechanical Polishing, Semiconductor Manufacturing, Integrated Circuits
Abstract : A contact mechanics model that describes the polishing mechanisms of copper-patterned silicon wafers in the fabrication of ultra-large-scale integrated (ULSI) circuits is presented. The model explains the die-scale variation of material removal rates due to pattern geometry, and predicts results that are in agreement with experimental observations. When the width of the copper interconnect is less than 0.5 µm, dishing of interconnects is less than 20 nm and thus does not contribute much to surface nonuniformity. However, because the overpolishing rate varies with the copper area fraction, it may contribute to die-scale nonuniformity.
Fracture Strength of Zero-Thermal-Expansion Glass-Ceramics for Ultra-Precision Components
Y. Namba, H. Takehara, Y. Nagano   / T. Masuzawa (1)
STC G,  50/1/2001,  P.239
Keywords: Glass-ceramic, Fracture strength, Ultra-precision machining
Abstract : Zero-thermal-expansion glass-ceramic is a key material in ultra-precision engineering. However, applications of this material have been limited in static components, because of a lack of data on the fracture strength of this material. We examine the fracture strength of the material by means of a 4- point bending test on samples machined using various methods. Etching technology is useful in increasing the strength, which strongly depends upon the surface roughness after etching. The floatpolished sample has a fracture strength of 546MPa, which is more than 4 times higher than that of normally machined surfaces, and also much higher than that of alumina.


High Speed Nanometer Positioning Using a Hybrid Linear Motor
H. Shinno (2), H. Hashizume  
STC M,  50/1/2001,  P.243
Keywords: Nano-technology, Ultra-precision machine, Nano-positioning
Abstract : With ever increasing demand for higher accuracy and productivity, high speed ultraprecision table positioning technology is urgently required. In order to achieve nanometer positioning accuracy and high speed feed drive of the table, it is effective to minimize error factors in the table system by using a linear motor in perfect noncontact condition. In such a linear motor-driven table system of a noncontact type, however, the force ripple of the motor directly influences the linear motion error of the table. In this study, a hybrid linear motor has been developed which has no force ripple. The proposed hybrid linear motor is constructed from a voice coil motor and a coarse driving mechanism, e.g., a wire drive. Furthermore, a hybrid linear motor-driven aerostatic table system has been developed and the performance of the table system has been evaluated.
A Study on Development of an Open Servo System for Intelligent Control of a CNC Machine Tool
M. Mori, K. Yamazaki (1), M. Fujishima1, J. Liu, N. Furukawa  
STC M,  50/1/2001,  P.247
Keywords: Open-Servomechanism, Intelligent Control, CNC Machine Tool
Abstract : An open servo control system for an intelligent CNC machine tool system has been proposed and developed. The developed system is equipped with real-time access window, through which user custom application software can monitor or modify any parameters and variables of servo system in a real time manner as a parallel session while the standard servo control is being performed. The developed system has been implemented in a CNC vertical machining center for feasibility study by integrating the software model reference adaptive control as custom application. The experimental results have successfully demonstrated the effectiveness of the open servo system.
A Process Oriented Approach to Automated Quality Control
C. Ament, G. Goch (2)  
STC M,  50/1/2001,  P.251
Keywords: Quality Assurance, Distributed Control, Holonic Manufacturing System
Abstract : To guarantee a constant quality of manufactured products, it is necessary to optimise the process parameters immediately when deviations of the workpiece quality have been observed. Established methods of quality management are only able to register quality deviations (like the statistical process control) or to analyse them offline with the help of experts (like failure mode and effects analysis). The presented approach develops a process oriented automated quality control for manufacturing in two steps: First, a local quality controller stabilises the product quality to reference values in the pace of workpiece production. In order to obtain the control law for the process parameters, a learning approach is applied. In the second step, the information exchange between the local controllers is established parallel to the workpiece flow in order to obtain an optimised global process. As an example, the method is applied to quality control in the turning process.
Attenuation of Vibrations due to Unbalance of an Active Magnetic Bearings Milling Electro-Spindle
V. Tamisier, S. Font, M. Lacour, F. Carrère, D. Dumur (1)  
STC M,  50/1/2001,  P.255
Keywords: computer numerical control, vibration, milling electro-spindle
Abstract : Among the advantages of active magnetic bearings, the absence of contact, the lifetime and the safety can be put forward. This paper presents first a new technology of milling electro-spindle equipped with a permanent magnet motor and active magnetic bearings. Then due to the use of numerical controllers, the implementation of advanced algorithms is easily performed, to ensure a numerical compensation of the rotor unbalance. The aim is to determine the value of the rotor unbalance when classical adaptive compensation methods can?t be used for stability reasons. Finally, by reducing the synchronous vibration due to the rotor eccentricity without destabilizing the system, a better resulting surface of the workpiece is expected while avoiding amplifiers saturation.
A Cutting Performance Based Template for Spindle Dynamics
S. Smith (2), J. Snyder  
STC M,  50/1/2001,  P.259
Keywords: Cutting performance, dynamic, milling
Abstract : The stable metal removal rate in milling depends on the dynamic characteristics of the tool-holderspindle system. We present a methodology for determining the permissible dynamic characteristics based on the intended cutting operation. We produce a template that bounds the tool-tip frequency response function (FRF). Measured FRFs can be compared against the template to check cutting performance. The template can be used in design to match the spindle system to the intended application. The template accounts for lobing effects, multiple modes, process damping, and static stiffness. It accounts for damping variability, producing a safe-side estimate. Experimental results illustrate the template?s use.
Improving High-Speed Machining Material Removal Rates by Rapid Dynamic Analysis
T. L. Schmitz, M. A. Davies (2), K. Medicus, J. Snyder  
STC M,  50/1/2001,  P.263
Keywords: High speed machining, Material removal rate, Sub-structure analysis
Abstract : Stability prediction and chatter avoidance in high-speed machining requires knowledge of the tool point dynamics. In this paper, three advances toward the rapid identification of the tool point frequency response and corresponding stable cutting parameters are described: 1) stable speeds determination using non-contact periodic impulsive excitation of the tool point (produced by spindle rotation and a stationary magnet) in conjunction with once-per-revolution sampling, 2) Receptance Coupling Substructure Analysis for the analytic prediction of the tool point response, and 3) once-per-revolution sampling of the audio signal during cutting to determine stability behavior.
Reconfigurable Machine Tools
R.G. Landers, B.-K. Min, Y. Koren (1)  
STC M,  50/1/2001,  P.269
Keywords: Machine Tool, Machine Tool Module, Conversion
Abstract : The uniqueness of Reconfigurable Manufacturing Systems (RMSs) is that the structure of the system as well as of its machines and controls can be rapidly changed in response to market changes (demand and products). A major component of RMSs is the reconfigurable machine tool (RMT). By contrast to conventional CNCs that are general?purpose machines, RMTs are designed for a specific, customized range of operation requirements and may be cost?effectively converted when the requirements change. In this paper, systematic design tools that have been recently developed for RMTs are reviewed, and three examples are provided to compare RMTs to traditional types of machine tools.
Development of an Intelligent High-Speed Machining Center
M. Mitsuishi(2), S. Warisawa, R. Hanayama  
STC M,  50/1/2001,  P.275
Keywords: Remote Manufacturing System, In-Process Monitoring, Thermal Deformation
Abstract : This paper describes a method for constructing an intelligent, high-speed machining system. According to the stability lobe diagram theory, there may exist a wide, stable cutting area at high spindle speeds. When cutting in this regime, it is possible to realize high productivity and efficiency and produce high quality products. On the other hand, when the spindle speed is high, the power consumption of the spindle motor is high and the prevention and control of thermal deformation is crucial. Furthermore, a machining state monitoring method in high spindle speed area should be established. The developed system has the following features: (1) active thermal deformation compensation function, (2) a real-time machining state judging function, and (3) a remote operation function using a computer network.
Performances of HSK Tool Interfaces under High Rotational Speed
T. Aoyama, I. Inasaki (1)  
STC M,  50/1/2001,  P.281
Keywords: Tooling, Machining, Finite element Method (FEM)
Abstract : The static and dynamic performance of the HSK tool interface is investigated at high rotational speed, including an experimental and numerical analysis of the influence of spindle speed on the radial stiffness of the tool interface. The behavior of the flange and taper contact of the HSK tool interface is simulated by means of the finite element method. The performance of a 7/24 tapered tool interface is also evaluated using the same spindle system, and the advantages of using HSK tool interfaces in machining are discussed.
Analysis and Improvement of Motion Accuracy of Hydrostatic Feed Table
E. Shamoto, C.-H. Park, T. Moriwaki (1)  
STC M,  50/1/2001,  P.285
Keywords: Motion accuracy, Hydrostatic feed table, Transfer function
Abstract : A new model is developed to analyze motion accuracy of hydrostatic feed tables and an algorithm is proposed to improve their accuracy. Relationship between film reaction force in a single hydrostatic pad and profile errors of a guide rail is derived at various spatial frequencies by FEM analysis, and it is expressed as a transfer function. This transfer function clarifies so called averaging effects of oil film quantitatively. Furthermore, the transfer function is utilized to estimate error motion of a multiple pad table from measured profiles of its guide rail, and to reversely estimate the profiles from measured error motion. A new method is proposed to improve the motion accuracy by lapping the rail surfaces so as to eliminate the estimated profile error. Its validity is verified analytically and experimentally in the present research, and a straight motion accuracy of 0.07 µm and 1.42 arcsec was achieved over a stroke of 250 mm after the corrective lapping.
Process Simulation and Paint Thickness Measurement for Robotic Spray Painting
M.A.S. Arikan (2) , T. Balkan  
STC M,  50/1/2001,  P.291
Keywords: Robotic spray coating, Coating measurement, Automated measurement
Abstract : A method and a computer program are developed for modeling of spray painting process, simulation of robotic spray painting, off-line programming of industrial robots and paint thickness measurement for painting of curved surfaces. The computer program enables the user to determine the painting strategies, parameters and paths. Surface models of the parts that are to be painted are obtained by using a CAD software. For paint thickness measurements, probe of the coating thickness measurement gage is attached to the wrist of the robot by using a feedback/safety adapter designed and manufactured for this purpose. Thicknesses are measured and transferred to the computer automatically. Then, obtained thickness data is processed and comparisons between simulated and measured thicknesses are made.
Design and Test of a Safe Numerical Control for Robotic Surgery
T. Bürger, U. Laible, G. Pritschow (1)  
STC M,  50/1/2001,  P.295
Keywords: NC, Safety, Hexapod
Abstract : Automated systems in safety critical applications require particularly safe control systems. This paper presents the design and test of a fail-safe numerical control (NC) for robotic surgery, which is currently assisting in a wide range of surgical treatments. The mechanical part of the robot system is based on a hybrid kinematics consisting of a hexapod and a linear axis in series. Since medical devices require a CE certification by a notified body, this paper also describes the required regulations, which build the basis for the safety concept. This multilevel safety concept is also transferable to standard NCs of machine tools.


Systematic Design of Manufacturing Systems Based on Axiomatic Design Approach
P. Gu (2), H.A. Rao, M.M. Tseng (1)  
STC O,  50/1/2001,  P.299
Keywords: Manufacturing System, Design Axioms, Design Methodology
Abstract : Rapid changes in product demand, product design and introduction of new products and increasing global competition require manufacturing systems to be highly flexible, adaptable and responsive. These characteristics of a manufacturing system must be addressed at the design stage. This paper presents a method for design of manufacturing systems by combining the axiomatic design approach and systematic design approach. The methodology explains how design axioms are used during different design stages, and also provides a step-bystep approach for the design of manufacturing systems. A case study of a furniture manufacturing system design is prov ided to illustrate an application of the method in real world manufacturing system design.
Disassembly Operation Support System with Motion Monitoring of a Human Operator
S. Takata (1), H. Isobe, H. Fujii  
STC O,  50/1/2001,  P.305
Keywords: Disassembly, support system, motion recognition
Abstract : Improving efficiency of disassembling operations is one of the key issues to facilitate part reuse and material recycling. In this paper, we propose an operation support system that provides information, such as disassembly sequence, necessary tools, and disassembly directions, using 3D product models. To provide necessary information at the proper instant, the system has a function of monitoring operator?s motion by means of 3D position sensors attached on the backs of both hands. The signals from the sensors are processed to extract features of disassembly operations. Based on the recognition of the operations, the system provides information for the operator via a head mount display. The effectiveness of the system has been verified by applying a prototype system to disassembly operations of copying machines.
Workflow management based on Information Management
D. Lutters, R.J. Mentink, F.J.A.M. van Houten (1), H.J.J. Kals (1)  
STC O,  50/1/2001,  P.309
Keywords: Information management, Integration, Workflow management
Abstract : In manufacturing processes, the role of the underlying information is of the utmost importance. Based on three different types of integration (function, information and control), as well as the theory of information management and the accompanying information structures, the entire product creation process can be formulated in terms of the information requirements of distinct processes. So-called task chains can establish the correlation between processes. Using formal representations of the information content (ontologies), a flexible resolution of processsteps is achieved. Based on this, an improved method for workflow management comes within reach.
An Autopoietic Approach for Building Knowledge Management Systems in Manufacturing Enterprises
M. Thannhuber, M.M. Tseng (1), H.-J. Bullinger  
STC O,  50/1/2001,  P.313
Keywords: Manufacturing system, Knowledge management, Intelligent processing
Abstract : This paper discusses a new understanding of knowledge at the enterprise level, which proposes to regard knowledge as a natural concept to cope with dynamic changes of market demand, process design, capabilities in diverse locations, and associated fluctuations in internal process adaptations. Knowledge is considered as a natural concept driving system behavior. Instead of focusing on individual human knowledge, we identify the ability of an enterprise to dynamically derive processes to meet the external needs and internal stability as the organizational knowledge. Based on this approach, a new knowledge management system has been developed. It consists of two key components: The ?Declarative Processing Environment?, which allows processes to be assembled goal-driven from a pool of process building blocks and the ?Autopoietic Framework? that mimics natural organisms to adapt to environmental changes, new capabilities and new technology. The framework continuously improves the pool of available process building blocks and their selection. Manufacturing applications such as process planning and supply chain management have been particularly suitable for applying this new approach.
Line-less Production System Using Self-Organization: A Case Study for BMS
K. Ueda (1), I. Hatono, N. Fujii, J. Vaario  
STC O,  50/1/2001,  P.319
Keywords: Manufacturing, Production Systems, Adaptive Systems
Abstract : The paper proposes a novel approach to the design of line-less production systems. The approach is based on the concept of biological manufacturing systems (BMS) that can deal with complexity in manufacturing using the ideas of self-organization, evolution and learning. In the line-less production systems, all production elements can move freely on the production floor using self-organization in order to adapt to fluctuations such as the diversity of production demands and the malfunction of machines. The effectiveness of the line-less production system is discussed and its feasibility is demonstrated by computer simulation. Furthermore, a mini-factory consisting of small autonomous robots is developed as a prototype of the line-less production systems.
Self-organization in a distributed manufacturing system based on constraint logic programming
A. Sluga, p. Butala   / J. Peklenik (1)
STC O,  50/1/2001,  P.323
Keywords: Optimization, Multi-agent structure, Work system
Abstract : The paper addresses the problem of self-organization of manufacturing systems. The objective is to overcome the rigidity of conventional hierarchical structures and to introduce structures that are able to adapt to a dynamic environment. The presented approach is based on the concept of Complex Adaptive Manufacturing Systems. It is characterized by a decomposition of manufacturing objectives and allocation of tasks to work systems as autonomous building blocks in a dynamic environment. The allocation is based on a market mechanism that enables self-organization and optimization of a manufacturing system by evaluation and selection among competing work systems. The approach is implemented in the Constraint Logic Programming environment Eclipse and validated in a simulation experiment.
Process planning with conditional and conflicting advice
A. Markus (2), J. Vancza  
STC O,  50/1/2001,  P.327
Keywords: process planning, sequencing, constraints, optimization
Abstract : Due to the vast amount and intricacies of technological knowledge, the process planning problem, even for relatively simple workpieces, can hardly be solved by a straightforward algorithm. The paper shows that this problem is more readily tractable as satisfying constraints that represent pieces of advice taken from experts. We de ne a generic constraint-based model for process planning that handles precedences and setup formation, as well as the mutual e ects of operation sequencing and resource assignment. We demonstrate the use of our model with examples of machining prismatic workpieces and bending sheet metal parts.
Backlog-oriented Automatic Production Control
H.-P. Wiendahl (1), J.-W. Breithaupt  
STC O,  50/1/2001,  P.331
Keywords: Automatic, Production, Control
Abstract : Conventional production control methods are normally based on static models. Therefore, they are insufficient for mastering the increasing dynamics in the companies? environment. In order to solve the problem, this paper aims to present a new general concept for dynamic modelling of job shop productions using methods of control theory. This concept for the medium-term planning level is based on a feedback control with defined reference and control variables. The developed distributed backlog controller eliminates an arising backlog as fast as possible by means of flexible capacities. Simultaneously, a central WIPcontroller guarantees a defined WIP level within the shop by controlling the total input rate into the job shop. Finally, the logistical rationalisation potentials of Automatic Production Control are pointed out by means of an industrial case study.
User-friendly Production Control Systems to Support the Flexibility of Production Organization
M. Meier, M. Baecker   / W. Massberg (1)
STC O,  50/1/2001,  P.335
Keywords: Production control, Information System Modelling, Computerized Simulation
Abstract : Due to increasing global competition, growing pressure of time and prices as well as the individualization of products, enterprises are obliged to implement structural and process organizations which are flexible and to optimise them permanently. As a result, flexible information systems which on the one hand support new forms of organization and on the other hand can be adapted efficiently by trained personnel are required. The purpose of this paper is to present a concept for a user-friendly production control system that is based on a model based toolbox.
A Spatial Scheduling System for Block Painting Process in Shipbuilding
K.K. Cho (1), K.H. Chung, C. Park, J.C. Park, H.S. Kim  
STC O,  50/1/2001,  P.339
Keywords: Scheduling, Spatial Scheduling, Algorithm
Abstract : This paper deals with a spatial scheduling problem for the painting process in shipbuilding. This problem is complicated because both scheduling and spatial allocation of the blocks in the paint shop, and the workload balance among working teams should be considered simultaneously. The spatial scheduling system for the block painting process includes an operation strategy algorithm, a block scheduling algorithm, a block arrangement algorithm, and a block assignment algorithm. This system generates the block painting schedules that satisfy due date, working space constraint, and workload balance among working teams. This system has been tested using actual scheduling data from a shipyard and successfully implemented in a paint shop in a shipbuilding company.
Parallel Disassembly Sequencing with Sequence-Dependent Operation Times
J.-G. Kang, D.-H. Lee, p. Xirouchakis, J.-G. Persson (1)  
STC O,  50/1/2001,  P.343
Keywords: Disassembly, Sequencing, Environment
Abstract : This paper focuses on the disassembly sequencing, which is the problem of determining the disassembly level and the corresponding disassembly sequence for a product at its end-of-life with the objective of maximizing the overall profit. Parallel disassembly and sequence-dependent operation times are considered by developing an extended process graph obtained from a transformation of a conventional AND/OR graph. Then, an integer programming formulation is developed with precedence constraints that allows its resolution with standard techniques. Finally, an optimal solution is obtained, with a reasonable amount of computation time, for an industrial application of a subassembly of a copy machine.
Continuous Improvement and Participative Factory Planning by Computer Systems
E. Westkämper (1), R. von Briel  
STC O,  50/1/2001,  P.347
Keywords: Digital Factory, Simulation, Virtual Reality
Abstract : Turbulent influencing factors ? based on market requirements and technological demands ? lead to a permanent change and improvement in the factory processes, manufacturing systems and layouts. New investigations in manufacturing show that the application of new machining processes and tools require a systematic and stepwise change of the layout and the organisation in order to activate the economic potentials. It is evident that continuous improvement and optimisation with the perspective to mediumterm objectives can be realised by means of new methods and new computerised systems for factory planning. Digital models and the technology of virtual reality allow the continuous planning of changes in factories. This paper includes results of the planning of future manufacturing systems and the systematics of continuous planning based on digital modelling and virtual manufacturing.
Hybrid, AI- and simulation-supported optimisation of process chains and production plants
L. Monostori (1), Zs.J. Viharos  
STC O,  50/1/2001,  P.353
Keywords: Manufacturing Systems, Artificial Intelligence, Optimisation
Abstract : The paper describes a novel approach for generating multipurpose models of machining operations, combining machine learning and search techniques. A block-oriented framework for modelling and optimisation of process chains is introduced and its applicability is shown by the results of the optimisation of cutting processes. The paper illustrates how the framework can support the simulation-based optimisation of whole production plants. The benefits of substituting the time-consuming simulation by ANN models are also outlined. The applicability of the proposed solution is demonstrated by the results of an industrial project where the task was to optimise the size spectrum of the ordered raw material at a plant producing one- and multi-layered printed wires.


Opto-tactile Sensor for 2D and 3D Measurement of Small Structures on Coordinate Measuring Machines
H. Schwenke, F. Wäldele, C. Weiskirch, H. Kunzmann (1)  
STC P,  50/1/2001,  P.361
Keywords: Coordinate measuring machine (CMM), Probe, Micro-parts
Abstract : A novel tactile probing system for dimensional measurement of small structures is presented. The measurement principle combines optical and mechanical techniques and allows probing elements below 50 µm to be realized. The measurement uncertainties achievable are in the sub-micron order. With this full 3D sensitivity on the basis of the opto-tactile concept is achieved. Some exemplary measurements show the capability of the new sensor.
Development of a Silicon-based Nanoprobe System for 3-D Measurements
H. Haitjema, W.O. Pril, P.H.J. Schellekens (1)  
STC P,  50/1/2001,  P.365
Keywords: CMM-probe, silicon, MEMS
Abstract : A small 3-D probe system was developed based on sensing the bending of elastic hinges carrying the probe stylus. The stylus platform and elastic hinges are etched in silicon. On the elastic hinges, piezoresistive straingages are integrated, including the necessary wiring. The 3-D measurement range is about one hundred micrometres in each direction and the repeatability is at the nanometre level. Several prototypes of these MEMS-type probe were realised in IC-technology successfully. Calibrations with a displacement generator based on laser interferometry reveal typical repeatabilities in the nanometre level and a 3-D uncertainty of the order of 25 nm.
A System for Measuring High-reflective Sculptured Surfaces Using Optical Noncontact Probe
G.X. Zhang (1), Y.C. Xu, Z.X. Xie, Y. Du, Z. Li  
STC P,  50/1/2001,  P.369
Keywords: Measurement, Sculptured Surface, Probe
Abstract : With the development of industry more and more high-reflective sculptured surfaces are required to be measured quickly and accurately. For solving this problem a new optical probe with three incidence lights and a receptor has been developed. Two polarizing plates with mutually perpendicular polarizations are used to eliminate the disturbance of the specular light. A system based on 3-D coordinate measuring machine, PH10M motorized head and the new developed probe has been built. The system can track and measure the unknown free form sculptured surface automatically. Measures for improving accuracy and performance of the system are studied. The effectiveness of the proposed system has been tested by experiments.
Dynamics and Control of the UNCC/MIT Sub-Atomic Measuring Machine
R.J. Hocken (1), D.L. Trumper (2), C. Wang  
STC P,  50/1/2001,  P.373
Keywords: Ultra-precision, Control, Servomechanism
Abstract : This paper reports on the design, modeling, implementation, and experimental results for the control of our Sub- Atomic Measuring Machine (SAMM), which has been jointly developed by UNC-Charlotte and MIT. This machine is intended for measuring features on planar substrates with a work volume of 25 mm ´ 25 mm ´ 100 mm, with subatomic resolution. The machine uses four linear motors to control motion in six degrees of freedom and provide magnetic suspension. We derive the commutation law for these linear motors based on a least self-heating condition. We also present modeling of the stage motion in six degrees-of-freedom and our controller design using state-space methods. The experimentally-demonstrated RMS stage positioning noise is 0.12 nm in x, 0.082 nm in y, 1.45 nm in z, 22 nrad in qx, 18 nrad in qy, and 2.7 nrad in qz over a 25 second measurement.
Compensation of Static and Transient Thermal Errors on CMMs
J.-P. Kruth (1), P. Vanherck (1), C. Van den Bergh  
STC P,  50/1/2001,  P.377
Keywords: Metrology, Thermal deformation compensation, Coordinate measuring machine
Abstract : Using CMMs under normal workshop conditions necessitates to take into account the influence of environmental temperature on the machine structure. Non-standardised environmental conditions result in temperature dependent measurement errors. The paper presents a parametric approach to describe the relation between transient temperature distributions and resulting deformation of the CMM. The focus lies on broadening the temperature range in which the original accuracy specifications can be guaranteed. Starting from a correction scheme for uniform, invariant temperature situations, an approach for transient environmental loads is developed. Based on a limited number of temperature inputs, the required correction coefficients for the probe position are calculated.
Advances in Precision Machining of Steel
E. Brinksmeier (1), R. Gläbe  
STC P,  50/1/2001,  P.385
Keywords: Ultra-precision machining, Steel, Tool wear
Abstract : Precision machining of steel with geometrically defined diamond cutting tools is handicapped by excessive tool wear. We have revisited solutions proposed in the literature and investigated some new approaches. Care has been taken to identify the mechanisms responsible for chemical and abrasive wear and to quantify tool wear in well defined cutting experiments.
Grazing Incidence Interferometry for High Precision Measurements of Cylindrical Form Deviations
A. Weckenmann (2), J. Bruning, S. Patterson, p. Knight   / J. Bryan (1)
STC P,  50/1/2001,  P.381
Keywords: Laser, Optical, Metrology
Abstract : Grazing incidence interferometers equipped with diffracting elements (computer generated holograms) are now being used to measure the cylindricity, roundness and straightness of cylindrical parts. The method is non-contact, with automatic work piece alignment and is capable of recording thousand of points on the surface in a few seconds. It incorporates parallel data acquisition of the cylindrical surfaces, so that an excellent radial resolution can be obtained. There are some questions regarding the basic theory and the accuracy when measuring workpieces with short wavelength errors. Experimental results using a CylinderMaster CM 25, and a modification for measuring blind holes are presented.
New Design of Precision CMM based upon Volumetric Phase-Measuring Interferometry
S.-W. Kim   / D.Y. Yang (1)
STC P,  50/1/2001,  P.357
Keywords: CMM, Optical metrology, Machine design
Abstract : A new design of high precision CMM is proposed by introducing a volumetric interferometer system that is capable of measuring the complete spatial motion of the probe in six degrees of freedom. This design is intended to allow the CMM measurement to be free from the Abbe offsets and angular motion errors of slide ways. The volumetric interferometer operates on the principle of phase-measuring interferometry and determines the 3-D coordinates of the probe by monitoring the interference intensity of the two spherical wavefronts emanated from two optical fibers of single mode propagation.


High Sensitivity Optical Detection of Oriented Microdefects on Silicon Wafer Surfaces Using Annular Illumination
T. Miyoshi, S. Takahashi, Y.Takaya, S. Shimada(2)  
STC S,  50/1/2001,  P.389
Keywords: Optical measurement, Surface defect, Ultra-precision
Abstract : A new optical measurement method detecting the microdefects on silicon wafer surfaces, which can be applied to in-process measurement, is presented in this paper. In our proposed method, a unique annular incident light spot is imaged by an original dark field optical system with a high-power objective lens. This annular incident light spot enables the sensitive detection of the oriented microdefects such as microscratches on the silicon wafer surface independent of its direction. In order to verify the feasibility of our proposed method, the basic and scanning experiments were performed for microgroove with sub-micrometer scale. This results showed that the proposed measurement method is effective for detecting the oriented microdefects.
Effect of Surface Oxidation on Micromachinability of Monocrystalline Silicon
T. Inamura (2), G.Y. Feng, N. Takezawa, N. Mohri  
STC S,  50/1/2001,  P.393
Keywords: Cutting, Micro machinability, Oxidation
Abstract : Microcutting experiments are carried out under an atomic force microscope (AFM) using workpieces of silicon monocrystals that have been exposed to air for various lengths of time before cutting. The results are observed under the same AFM with decreased tip force. The results show that difficult-to-cut areas appear locally after 24 hours of exposure time and these areas extend with increasing exposure time until the whole surface is covered after 120 hours. It is also found that exposure of workpieces to air produces a SiO2 surface layer in which residual compressive stress is generated and whose hardness and/or elastic constant are lower than those of bulk Si. The molecular dynamics simulations carried out based on the above results show that the deterioration of machinability of monocrystalline silicon is caused by the viscoelastic/plastic properties of SiO2.
Effects of Polishing on the Photoluminescence of Single Crystal ZnO
D.A. Lucca (1), D.W. Hamby, M.J. Klopfstein, G. Cantwell, C.J. Wetteland, J.R. Tesmer, M. Nastasi  
STC S,  50/1/2001,  P.397
Keywords: Surface, Polishing, Sub-surface damage
Abstract : The photoluminescence (PL) response of single crystal ZnO subjected to mechanical and chemomechanical polishing has been investigated. Zn-terminated and O-terminated surfaces of (0001)- oriented ZnO crystals were prepared by mechanical polishing with 1/4 µm and 1 µm diamond abrasives and by chemomechanical polishing. The spectrally resolved room temperature PL of the polished surfaces was measured, and changes in both the spectral content and PL intensity introduced by polishing were assessed. The PL results were compared to a direct measure of subsurface damage obtained by ion channeling. Room temperature PL spectroscopy is shown to exhibit potential as a sensitive tool for the characterization of subsurface damage in polished ZnO.
Method for the Analysis of Residual Stress Induced Failure in Thin Films
E. Uhlmann (2), K. Klein  
STC S,  50/1/2001,  P.401
Keywords: Coating, Residual Stress, Finite Element Method (FEM)
Abstract : PVD thin film systems are generally exposed to high intrinsic compressive stresses. These stresses are in fact desired as they are accompanied by an increase in strenght. However, they lead to a coating failure under higher loads. Therefore a method for the analysis of residual stress induced failure mechanisms in thin films has been developed. For this purpose defined turning profiles with varying roughness values were created on HSS cylinders and subsequently coated. Coating defects are the result of static loads caused by residual stresses and when a critical maximum height is exceeded in the prepared profile. Such defects can be verified by means of microscopy. By calculating the stress gradients in the test structures with a FEM model, the influences of the critical parameters can be discussed. The results permit the optimisation of coating processes.