Requirements of an industrially applicable microcutting process for steel micro-structures

 Micro-cutting offers good potentialities in order to manufacture small and medium lot sizes of micro-parts with arbitrary geometry at an economically reasonable expense. Either by direct machining or as a means to fabricate moulds for micro injection moulding, the major advantages turn out to be large removal rates, good compliance with tolerance ranges, high surface quality and a wide choice of materials which can be processed. Particularly if highly wear resistant materials are to be processes, as it is the case in mould fabrication for powder injection moulding, micro cutting of steel is a very eligible option. Consequently, the possibility to manufacture wear resistant micro structures of high aspect ratios by mechanical cutting is demonstrated with regard to its specific requirements in terms of transferability of the laboratory process into an industrial manufacturing process. Accordingly the paper focuses on repeatability of machining results and machining capabilities. Received: 10 August 2001/Accepted: 24 September 2001     

Characterisation and testing of micro specimen

Currently for the design of micro components often no reliable material data is available. Therefore in the German Collaborative Research Centre (SFB) 499 [1] metallic and ceramic micro specimen that are manufactured by different micro moulding techniques as micro casting, slip casting or micro powder injection moulding are investigated with respect to their microstructure, mechanical and tribological properties. As metal was investigated a AuAgCu-alloy named Stabilor G and as ceramic was investigated ZrO₂. Additionally the wear behaviour of mould inserts made of different materials as X38CrMoV5–1, Ni and Cu63Zn37 and the modifications of near surface microstructures due to micro milling in X38CrMoV5–1 in different heat treatment states are presented.Abbreviations R_b Bending strength of one specimen - ₀ Characteristic beinding strength of a batch after Weibull - m_corr Weibull exponent corrected by the Maximum Likelihood Method - P_F Probability of failure - Friction coefficient - W Linear amount of wear - f DeflectionThe authors are grateful for the support of the research work in the SFB499 Design, production and quality assurance of moulded micro components made of metallic and ceramic materials by the Deutsche Forschungsgemeinschaft.     

Multi-Step H∞ Generalized Predictive Control

An H generalized control law is derived which has properties in common with both the GH and GPC control laws. The stability and robustness properties are the same as for a GH optimal controller but a cost on future predictive error and control action is dealt with in the same manner as for the GPC or model based predictive control laws. This type of long range predictive control algorithm has stability and robustness problems which are much improved through the H formalism. The general two-block problem solution is considered first and this is then reduced to a novel one-block multi-step GH control law which is very attractive computationally. This latter algorithm has all the benefits of one-block H controllers and yet the equations can be written in a form where GPC type constrained solutions can be obtained.     

Y-Invalidate: A New Protocol for Implementing Weak Consistency in DSM Systems

In this work we propose and implement a new variant of the well-known write invalidate protocol called Y-invalidate. Whereas the former protocol required that every copy of a page be invalidated every time that page is updated, our variant invalidates a copy of a page at process A only at the next synchronization point which is relevant to Aand or if the copy was modified by the owner's process after the page was copied to A. We thus avoid invalidating copies of pages that were modified but never read after modification, and avoid, of course, the associated overhead. Y-Invalidate is basically a weak-consistency protocol. Its main advantage is that it implements weak consistency without the need to merge copies of a page that were updated in different machines. To the best of our knowledge, this is the first variant of weak consistency protocols which does not merge multiple copies of pages. Unlike other variants of weak consistency, Y-invalidate supports implicit synchronization points in the program by invalidating copies of shared memory pages that are referenced by while-loops. In this way, Y-invalidate approximates strict consistency. The Y-invalidate protocol was implemented in the ParC system, which is a powerful parallel extension of the C language. The ParC compiler was modified to detect some of the implicit synchronization points in the source code. Experimental results show significant improvement compared to both the traditional write-invalidate protocol and weak consistency.     

An effective fuzzy-nets training scheme for monitoring tool breakage

Recent research results show that fuzzy logic and the neural networks systems are very effective in detecting the breakage of cutting tools during machining processes. In the present study, a fuzzy-nets training procedure was developed to build the rule banks to meet the dynamic requirements of machining processes. The system is capable of responding and adapting in real-time to either shut down the machine when a tool fracture occurs or tune the process parameters on-line. The training procedure was validated in a back-up truck problem. Furthermore, two fuzzy-nets systems were combined to serve as a tool breakage detection system for an end milling operation. When the system was evaluated for end milling, the adaptive capability (of the fuzzy-nets system) was shown to enable detection of tool breakage to occur on-line, approaching a real-time base.     

Effect of workpiece springback on micromilling forces

The machining forces present in micromilling with tools in the 50–100 m diameter range are dominated by contact pressure and friction between the tool cutting edges and the workpiece. A model of the micromilling process was developed based on the elastic contact between the tool and the workpiece along the side and bottom cutting edges of the tool. Micromilling experiments were conducted on 6061-T6 aluminum to obtain machining forces in the feed and cross-feed directions during slot milling and partial engagement end milling. Comparisons with the experimental data indicate reasonable agreement for full slot milling as well as end milling with radial depths of cut in the range of 2 m to 40 m. It was concluded that this model is adequate for predicting micromilling forces with the precision needed to reduce tool breakage and workpiece clamping forces and for predicting tool deflection that affects wall slope and feature size.This work was supported primarily by the Engineering Research Centers Program of the National Science Foundation under Award Number EEC-9986866. The Engineering Research Center for Wireless Integrated Microsystems is also hereby acknowledged. All machining was performed at the Micromechanical Applications and Processes Laboratory at Michigan Technological University.     

Integration of 3-D shape construction and assembly to realize micro systems

In order to make micro 3-D structures, we are designing a table-sized factory, namely Nano Manufacturing World (NMW). In NMW, we challenged to use a new process fused by semiconductor process for preciseness and machine process for 3-dimensionality. In order to realize the new process, we designed three new mechanisms in this paper: multi-face shape making beam, co-focus rotational robot and micro mechanical tools. Through an evaluation to actually make a micro Gojunoto with the mechanisms, we confirmed their validities for functions of integration of 3-D shape construction and assembly.     

Deep sub micron high aspect ratio polymer structures produced by hard X-ray lithography

Microfabrication using X-ray lithography is a well established process in many laboratories worldwide. Radiation spectra, mask technology and process conditions are optimized for patterning resist thicknesses of several hundred micrometers with lateral dimensions of a few microns. This article provides first results as to how far these technologies can be extended to form structures with sub-micrometer lateral dimensions in resist layers of a few micrometers thickness. Available equipment and processes of the 2.5 GeV electron storage ring ANKA and the process technology of the Institut für Mikrostrukturtechnik (IMT) in Karlsruhe, Germany, have been applied. An X-ray mask with a 2.7 m Ti-membrane and 20 m thick Au-absorbers is used to expose 1.6 m PMMA resist on silicon wafers. As the smallest features on the mask are 2 m, a double exposure with an intermediate deliberate relative movement between mask and resist generated sub-micron resist test structures. Smallest feature sizes are between 300 and 400 nm. They are not yet limited by diffraction, but by different process conditions that lead to adhesion loss, resist cracking and surface rounding. It has been shown that an intermediate layer of 1.2 m thick polyimide between resist and substrate significantly enhances adhesion and reduces resist cracking. Reducing the beam power impinging onto the sample from typically 21 to 0.4 W leads to a 50% reduction of the surface rounding at the top of the microstructures. To demonstrate the capability to pattern thicker resist layers, first samples with an increased resist thickness of 4.1 m and an aspect ratio of up to 8 were processed. Finally, a metal mesh with 2 m thick Au-absorbers and 900 nm hexagonal holes was applied to pattern showpieces of sub micron features using a reduced electron energy of 1.3 GeV.The high resolution metal mesh was provided by R. Fettig of IMT.     

Restrictions of production engineering on micro-specific product development

The influences deriving from technology on the functions achievable by means of product design are typical characteristics of the development of micro-technological products. As a result, unlike the conventional design process the function attainable in micro technology due to product design appears to be less subjected to certain requirements. Multitechnological influences, resulting from production processes, material characteristics or micro-specific effects have an especially restrictive impact on the design of machine elements. On the basis of the product development process for primary shaped micro components from metallic and ceramic materials a method is presented which makes it possible to detect the know-how provided by disciplines subsequent and adjacent to the design process, having influence on the design of the machine element and interpret this relevant to design. The computer-aided availability of knowledge is accomplished with a knowledge-based design environment.The work presented is supported by the Deutsche Forschungsgemeinschaft within the collaborative research center (Sonderforschungsbereich) 499 Development, production and quality assurance of primary shaped micro components from metallic and ceramic materials. This paper was presented at the First International Colloquium Micro Production in February 2003.     

Manufacturing process performance prediction by integrating crisp and granular information

This study deals with the integration of crisp and granular information for predicting the performance of a manufacturing process. Supporting and computing a set of two If-Then rules is considered the central idea for this integration. In these rules, the antecedent part deals with the recommended ranges of the control variables of the process, while the consequent part deals with the acceptable ranges of the performance measures of the process. The rules specify that if the control variables are kept within their recommended ranges, then it is likely or unlikely to get the performance measures within their acceptable ranges. The rules are supported by using the following conditional probabilities: the probability of getting the performance measures acceptable given that the control variables are within their recommended ranges (which should be likely), and the probability of getting performance measures acceptable given that the control variables are not within their recommended ranges (which should be unlikely). The remarkable thing is that both acceptable ranges and recommended ranges are subjectively defined concepts. So are likelihood perceptions such as likely and unlikely. Therefore, all of them can be defined by using some kind of fuzzy-granular information. The usefulness of this new approach is demonstrated by solving a machining decision-making problem (select cutting conditions and inserts satisfying subjectively defined surface finish requirement in terms of roughness and fractal dimension of machined surface). Further study should be directed toward understanding these rules in the context of predictive process planning.This revised version was published in June 2005 with corrected page numbers.     

Process observation for the assembly of hybrid micro systems

The automation of micro assembly is becoming more and more important in micro technology. Especially the demands on handling and process observation of hybrid micro systems with optical and mechanical functions are quite high. Because of this process monitoring is inevitably necessary for a better understanding of what is really happening in the micro world. Process visualisation is very important in (micro electronic and mechanical systems) MEMS but does not guarantee an operative micro system. Therefore, instruments for quality control are required to secure a safe and reproducible assembly. The aim of this article is to give an overview over so far used and new devices for process observation and quality control.The authors gratefully acknowledge the financial support of the Deutsche Forschungsgemeinschaft (DFG) within the Collaborative Research Centre (SFB) 440 Assembly of hybrid microsystems.     

Metallic microgripper with SU-8 adaptor as end-effectors for heterogeneous micro/nano assembly applications

This paper presents design, fabrication, and characterization of easy-to-handle electroplated nickel microgrippers with SU-8 adaptors for heterogeneous micro/nano assembly applications. Two distinctive designs of microgrippers as end-effectors of micro/nano assembly applications have been developed in this work. The first design is 200 m thick electroplated nickel microgripper with a plastic mechanical displacement amplifier that is driven by a piezoelectric actuator. The piezoelectric actuator is capable of creating 5 m displacement which is amplified to 10 m by the plastic mechanical amplifier and finally such displacement generates 50–139 m microgripper tip displacement. The second design is 20 m thick electroplated nickel microgripper embedded in SU-8 adaptor for easy-to-handle operation. The second design is electro-thermally actuated using a set of joule-heated bent beams. With applied actuation voltage in the range of 2–4 V, the microgripper generates tip displacement of 4–32 m. Extensive thermal and mechanical finite element modeling have been carried out and measurement results were compared with the simulation results. Such developed easy-to-handle microgrippers can be used for micro/nano pick-and-place assembly applications.This work was supported by the National Institute of Standards and Technology-Advanced Technology Program (NIST-ATP 70NANB1H3021). The authors would like to thank the members of Design Engineering Group at Zyvex Corporation, Mr. Yohannes Desta from the Center for Advanced Microstructures and Devices (CAMD) at Louisiana State University for the valuable technical discussions, and the members of Micro and Nano Device and Systems (MiNDS) Laboratory and Cleanroom staffs at the University of Texas at Dallas.     

Implementation of Generalized Finite Element Methods for Homogenization Problems

The implementation of a generalized Finite Element Method (FEM) for problems with coefficients or geometry that oscillate locally at a small length scale 1 is described. Two-scale FE-spaces are combined conformingly with standard FE. Numerical experiments show that the complexity of the algorithm is independent of the micro length scale .     

The role of “craft language” in learning “Waza”

The role of craft language in the process of teaching (learning) Waza (skill) will be discussed from the perspective of human intelligence.It may be said that the ultimate goal of learning Waza in any Japanese traditional performance is not the perfect reproduction of the teaching (learning) process of Waza. In fact, a special metaphorical language (craft language) is used, which has the effect of encouraging the learner to activate his creative imagination. It is through this activity that the he learns his own habitus (Kata).It is suggested that, in considering the difference of function between natural human intelligence and artificial intelligence, attention should be paid to the imaginative activity of the learner as being an essential factor for mastering Kata.This article is a modified English version of Chapter 5 of my bookWaza kara shiru (Learning from Skill), Tokyo University Press, 1987, pp. 93–105.     

Microfabrication by hot embossing and injection molding at LASTI

LIGA process includes three processes as X-ray lithography, electroforming to fabricate metalic molds and replication, and can be fabricated nano and micro parts for various devices that it is difficult to product by conventional machining methods. A key technology which gathers mass-production efficiency in the LIGA process is micro-replication technology. We choiced hot embossing and injection molding methods for replication. For a demonstration, two kinds of Ni molds, a mesh pattern within a line width of 100 m, and an aspect ratio of 1.0 and a mesh pattern within a line width of 40 m, and an aspect ratio of 2.5, were prepared. These were produced with X-ray lithography and nickel electrofoming technique. In hot embossing, an experiment of micro-replication using polymethyl methacrylate (PMMA) and polycarbonate (PC) sheets succeeded. At injection molding, it could not transfer well with PMMA and PC, but injection temperature was set up highly, and it succeeded by cycloolefin polymer. Furthermore, we measured sidewalls surface roughness of microstructures produced at each steppes of the LIGA process, and it checked that the LIGA process had processing accuracy higher than a conventional machining method.We would like to thank Ms. A. Kitajima and Dr. R. Maeda at National Institute of Advanced Industrial Science and Technology (AIST), Mr. M. Ohtomo at Ikegami Mold Engineering Co., Ltd., and Mr. Noriaki Sato at Juken Kogyo Co., Ltd. for their valuable collaboration and contributions. This research was the contract research from the New Industry Research Organization (NIRO) supported financially by the New Energy and Industrial Technology Development Organization (NEDO).     

Specifying and executing behavioral requirements: the play-in/play-out approach

A powerful methodology for scenario-based specification of reactive systems is described, in which the behavior is played in directly from the systems GUI or some abstract version thereof, and can then be played out. The approach is supported and illustrated by a tool, which we call the play-engine. As the behavior is played in, the play-engine automatically generates a formal version in an extended version of the language of live sequence charts (LSCs). As they are played out, it causes the application to react according to the universal (must) parts of the specification; the existential (may) parts can be monitored to check their successful completion. Play-in is a user-friendly high-level way of specifying behavior and play-out is a rather surprising way of working with a fully operational system directly from its inter-object requirements. The ideas appear to be relevant to many stages of system development, including requirements engineering, specification, testing, analysis and implementation.     

Micro assembly injection moulding for the generation of hybrid microstructures

Based on the micro injection moulding process, which has been investigated at the IKV for several years, a process called micro assembly injection moulding is developed and investigated. It combines the joining of hybrid elements with the generation of functional structures. Micro assembly injection moulding is a quite diverse process with many influencing parameters. For basic studies of this process, a special mould technology with maximum flexibility and precision is used. The mould concept includes a special system for the positioning of inlay parts and complex sensor equipment (pressure, temperature endoscopic devices) for controlling and analysing the process. The processing aspects which have been investigated are the production of movable microstructures by using incompatible polymers, the generation of fluidic hollow structures by lost core technology and the overmoulding of wires and optical fibres. In all cases, the choice of the different materials, the temperature layout of the process and the mechanical strain of inlay parts play a significant role. Furthermore, the precision in positioning of inlay parts and the demoulding of hybrid structures are of great importance.The investigations are part of the SFB (Sonderforschungsbereich) 440 Assembly of Hybrid Micro Systems and were financially supported by the DFG (Deutsche Forschungsgemeinschaft).This paper was presented at the Conference of Micro System Technologies 2001 in March 2001.     

Integrative quality assurance of micro-parts using Microfeatures

The article introduces the Microfeature Catalogue as an information database that is structured by Microfeatures and can be used for preventive and non-preventive quality assurance. The Microfeature conception is adapted and evaluated in the specific fabrication environment of micro mechanical components. The production of micro parts demands a further development of the new fabrication technologies on the one hand and an appropriate development of the concomitant processes such as the quality assurance process on the other hand. A coherent information cycle between design, fabrication and quality assurance is put into practice.     

Modelling structures in generic space, a condition for adaptiveness of monitoring cognitive agent

The adaptiveness of agents is one of the basic conditions for the autonomy. This paper describes an approach of adaptiveness forMonitoring Cognitive Agents based on the notion of generic spaces. This notion allows the definition of virtual generic processes so that any particular actual process is then a simple configuration of the generic process, that is to say a set of values of parameters. Consequently, generic domain ontology containing the generic knowledge for solving problems concerning the generic process can be developed. This lead to the design of Generic Monitoring Cognitive Agent, a class of agent in which the whole knowledge corpus is generic. In other words, modeling a process within a generic space becomes configuring a generic process and adaptiveness becomes genericity, that is to say independence regarding technology. In this paper, we present an application of this approach on Sachem, a Generic Monitoring Cognitive Agent designed in order to help the operators in operating a blast furnace. Specifically, the NeuroGaz module of Sachem will be used to present the notion of a generic blast furnace. The adaptiveness of Sachem can then be noted through the low cost of the deployment of a Sachem instance on different blast furnaces and the ability of NeuroGaz in solving problem and learning from various top gas instrumentation.     

A verification tool for ERLANG

This paper presents an overview of the main results of the project Verification of ERLANG Programs , which is funded by the Swedish Business Development Agency (NUTEK) and by Ericsson within the ASTEC (Advanced Software TEChnology) initiative. Its main outcome is the ERLANG Verification Tool (EVT), a theorem prover which assists in obtaining proofs that ERLANG applications satisfy their correctness requirements formulated as behavioural properties in a modal logic with recursion. We give a summary of the verification framework as supported by EVT, discuss reasoning principles essential for successful proofs such as inductive and compositional reasoning, and an efficient treatment of side-effect-free code. The experiences of applying the tool in an industrial case study are summarised, and an approach for supporting verification in the presence of program libraries is outlined.EVT is essentially a classical proof assistant, or theorem-proving tool, requiring users to intervene in the proof process at crucial steps such as stating program invariants. However, the tool offers considerable support for automatic proof discovery through higher-level tactics tailored to the particular task of the verification of ERLANG programs. In addition, a graphical interface permits easy navigation through proof tableaux, proof reuse, and meaningful feedback about the current proof state, to assist users in taking informed proof decisions.