Supporting design of primary shaped micro parts and systems through provision of experience

Nowadays, miniaturization is one observable trend in the development of new technical systems. Based on the miniaturization of existing macroscopic production technologies e.g. powder injection molding, a new process chain for the development of primary shaped microparts and systems is being developed in the collaborative research center 499 “design, production and quality assurance of molded micro components made of metallic and ceramic materials”. Because of the constantly evolving miniaturization and growing complexity of the developed microparts and systems, new development processes and methods are needed. Because of the mostly restrictive influence of the downstream phases (production and quality assurance) over the design phase, micro-specific design processes require well-founded knowledge about micro-specific manufacturing techniques (e.g. restrictions) which may be stored in form of design rules. However, many micro-specific aspects cannot be represented in design rules. In this paper the authors propose a new approach to ensure this other kind of knowledge.     

Ensuring functional reliability of molded micro components

Microsystems technology is an emerging technology that is used in ever more technical systems, such as inkjet nozzles or accelerometers. 3D micromechanical structures became feasible by miniaturizing macromechanical elements. One big challenge in downsizing mechanical elements is to adapt conventional manufacturing technologies to the conditions of microtechnology. Integrated design and production processes must be suited to the new requirements, in-depth knowledge of production technology is required to design micromechanical components. Since 2000, the Collaborative Research Center 499 “Design, Production and Quality Assurance of Molded Microcomponents made of Metallic and Ceramic Materials” has been focusing on a continuous and stable process chain for molded micro components (Albers et al. 2005, Microsyst Technol). The aim of prior funding periods was to develop the knowledge about how components, such as gearwheels, and systems, such as micro gears, can be designed. Present research is focused on how to design functional elements, i.e. shaft-hub joints to transmit torque. This paper will introduce an approach that generates know-how via testing several plain bearings and shaft-hub joints in order to derive the necessary know-how to develop simulation tools later on.     

Statistical process and measurement control for micro production

The core challenge of an industrially applicable and economic production of wear resistant micro components and systems is the establishment of both robust and flexible manufacturing process chains. In order to guarantee those stable process chains, manufacturing processes have to be controlled and continuously improved by an effective and fast interfering operational quality assurance that is adapted to the micro-specific framework. Since tolerances of micro-structured parts are in the micro- and sub-micrometer range, geometric measurement results have to meet high requirements in terms of precision and reliability. Therefore, in order to control manufacturing processes in micro production based on measurement data the increased importance of measurement uncertainty and measurement variation has to be considered. Measurement data show an interference of measurement and manufacturing distribution and can lead to wrong decisions when deciding whether the micro manufacturing process is in or out of control. Thus, the focus of the paper lies on continuously monitoring, controlling and separating measurement and manufacturing variation in a flexible, simple and reliable manner. Therefore, a new type of a multivariate μ-EWMA control chart developed at wbk is discussed and benchmarked with traditional control charts. The paper concludes with first results of the application of the multivariate μ-EWMA chart in micro production environment.     

Quality assurance for micro manufacturing processes and primary-shaped micro components

The development of robust and flexible manufacturing processes represents the major challenge to be overcome by industrially applicable micro production. For robustness and flexibility to be ensured also for micro dimensions, the manufacturing processes need to be controlled and continuously improved by means of a quality assurance system that is fast to respond, matches the requirements of production and is tailored to the micro-specific demands. Up to now, micro manufacturing processes have been characterized by a high degree of variability resulting from an increased number of significant influencing factors. Besides, the tolerance specifications of components with micro structures are in the micro and sub-micrometer range, requiring measuring methods to meet the highest demands in terms of accuracy. For micro manufacturing processes to be controlled on the basis of measured data, the increased significance of measuring uncertainty and measurement variation in relation to the required tolerances is to be taken into consideration. Measured data will always reflect the effect of both manufacturing and measurement variation, which may lead to wrong decisions being taken on the approval or rejection of components if the most rigid tolerance specifications need to be met. Therefore, the focus of this research document, generated as part of the Collaborative Research Center (SFB) 499, has been put on the continuous monitoring, control and separation of manufacturing and measurement variation by means of statistical methods and tools. The two ideas presented and discussed are a novel design for quality control charts and a control loop for the combination of statistical process control and statistical modeling, developed as part of the SFB 499. This article concludes by giving first results regarding the use of statistical tools in the field of micro manufacturing technology.     

Elicitation of a reference process model for tool-based micro technologies for planning and controlling purposes and user support

The production of moulded micro components including design, manufacture and quality control is a highly integrated process. A lot of experts, machines, tools, etc. should be deployed meaningfully along this process. The process chain was never written down in detail or as a whole so that new products could be developed on this basis. All developments hitherto have been carried out partly intuitive and partly based on area-specific sub process chains. For an efficient and effective planning and controlling and user support during future tool-based micro product engineering processes, the authors propose a corresponding reference process model. For this purpose, implicit process knowledge must be retrieved from expert’s minds to consider area-specific sub-process chains. For implementation of the reference process model, the Integrated Product Engineering Model (iPeM) will be used.     

Supplier selection and purchase problem for multi-echelon defective supply chain system with stochastic demand

In the real production process, some members in the supply chain system sometimes cannot effectively complete their production task because of defects involving the production or purchasing of components. A supply chain system that has defects in at least one echelon is called a multi-echelon defective supply chain (MDSC) system. Most supply chain systems are MDSC systems. Determining parts or components supply quota from different suppliers with limited suppliers, factories and distribution centers capacities in the supply chain system are becoming an important issue for businesses. In this study, we propose a new heuristic (H2) which is an extension of H1 heuristic that was previously presented. The MDSC system was formed with the mixed integer linear programming by LINDO software for calculation of the lower bound. The heuristics and MDSC system were modeled by using ProModel software. The heuristics were applied to a case from the Turkish furniture industry. The heuristics were compared with each other by considering different coefficients of variation, service levels, and deviation from lower bound. Simulation experiments showed that the proposed H2 heuristic outperformed the H1 heuristic.     

Sensor-guided micro assembly of active micro systems by using a hot melt based joining technology

This article presents (the most) recent results of the subprojects B4 and B8 of the Collaborative Research Center 516—Design and Manufacturing of Active Micro Systems—which are concerned with the assembly of active micro systems. While subproject B4 investigates sensor guided assembly processes, subproject B8 develops suitable assembly techniques on the basis of non-viscous adhesive systems (hot melts). Process development focuses on the suitability for automation, process times and the applicability of batch processes. The article discusses certain hot melt application techniques that are suitable for batch production, a sensor-guided assembly system as well as different approaches for heat conduction in an automated assembly process for hot melt coated micro components.     

Micro assembly injection moulding

Injection moulding is established as one of the most common manufacturing processes of thermoplastics due to its high degree of automation and the short cycle times. Micro injection moulding is a rapidly growing technology that allows for the efficient production of very complex micro parts in high series. The “Market Analysis for Microsystems II 2002–2005” of the Nexus Task Force anticipates a yearly growth in the field of micro system technology of about 20% (Wechsung et al. 2002). This study identifies in addition to the continuous miniaturization the growing use of polymers in micro systems (Schneider et al. 2001). No other material group offers this wide range of material properties and permits to choose processing parameters and application properties according to necessities (Gächter 2000). While the production processes of micro technical components are mainly controllable, the assembly of these components to hybrid micro systems is a bottleneck to the industrial large scale production. The assembly itself represents a large fraction of the added product value and gains in importance with growing complexity and miniaturization of the systems.     

Powder injection moulding of metallic and ceramic micro parts

Industrial use of micro components is determined by the availability of efficient manufacturing techniques. While micro injection moulding of plastic is common practice, metal and ceramic powder injection moulding (PIM) still is under development. High-pressure and low-pressure injection moulding methods complement each other ideally, covering the entire spectrum from prototype to large-scale production. With high-pressure PIM, micro gear wheels with diameters <300 μm can be fabricated using LIGA mould inserts. Densities between 97 and 99% of the theoretical values are achieved. Apart from oxide ceramics, metal materials like copper or powder metallurgical steels like 17-4PH or 316L are often applied. Multi-component injection moulding requires less mounting steps and, hence, offers decisive advantages for effective production of interesting material combinations like electrically conductive/insulating or hard/ductile. Studies relating to the fabrication of immobile as well as mobile shaft-wheel components were performed. Other activities focussed on in-mould labelling with foils containing ultra-fine particles to improve surface quality and detail accuracy. Low-pressure injection moulding allows for the manufacture of small series within 1–4 weeks at low cost. However, the process has features which are not compatible with high-pressure PIM. Although use of a low-viscous feedstock is associated with various benefits, low-pressure injection moulding has not met with acceptance in micro moulding.     

On the simulation of molded micro components and systems

Regarding micro components and systems, experimental work for characterizing materials’ properties as well as components’ and systems’ behaviors have to be supplemented by numerical analyses. These analyses should cover component and system issues. On a component level, macroscopic approaches are extended by methods allowing consideration of the influence of components’ grain structures including possible defects. On a system level, the high tolerances accepted for the individual components due to production inaccuracy and their effects on the expected load distribution capability of the system are taken into account. This paper presents approaches for simulation of micro components and systems using the finite element method and multi body simulation. Methods to overcome the abovementioned issues will be shown, as well as the effects of grain structure on the stress distribution in the individual components.     

Complexity Measures for Process Evolution

The foundation for process evolution research is the modelling of process structural complexity. With such a model, process systems can be directed toward acquiring good maintainability attributes according to the principles of engineering. In this paper a process management (PM) model is developed to acquire directly from the target process codes the knowledge hidden among and within components of process systems. With the knowledge acquired by the PM model, process structural complexity measures in terms of partitioning, restructuring and rewriting criteria are developed; a systematic process remodularization schema is derived, and algorithms for scheduling process changes are presented. These criteria and mechanisms are used to guide the process production chain.     

High aspect ratio micro tool manufacturing for polymer replication using μEDM of silicon, selective etching and electroforming

Mass fabrication of polymer micro components with high aspect ratio micro-structures requires high performance micro tools allowing the use of low cost replication processes such as micro injection moulding. In this regard an innovative process chain, based on a combination of micro electrical discharge machining (μEDM) of a silicon substrate, electroforming and selective etching was used for the manufacturing of a micro tool. The micro tool was employed for polymer replication by means of the injection moulding process.     

用于微器件装配的微操作系统

微器件装配技术是微机械的关键技术之一,本文从微 器件装配系统的特性和功能出发,提出了一套用于微装配的微操作系统设计方案,并对系统 各个组成部分进行分析,介绍了系统实现的方法．     

Development and application of miniaturized scanners for laser beam micro-welding

Nowadays, flexible production systems for laser joining of micro parts require high dynamics and precision, as well as increased flexibility regarding the working space. The combination of miniaturized scanner-based laser joining systems and high-performance assembly systems is a new approach for a high accuracy compact micro assembly system with an increased flexibility. Using highly dynamic oscillation techniques leads to a stabilization of the welding process of difficult-to-weld materials, e.g. of zinc-containing alloys on the one hand, and to an increased process velocity and reduction of the joining geometry, e.g. for the welding of plastic materials on the other. Hence, a miniaturized laser processing optics is being developed featuring an integrated beam deflection for laser beam micro welding of metal as well as plastic materials. The requirements on this laser processing optics, the choice of a suitable beam deflection system and the design and simulation of the miniaturized optics are presented and discussed. Furthermore, results of laser beam micro welding applications are presented. These results directly influence the design of new miniaturized laser processing optics. By means of the integration of highly dynamic scanner devices further process improvements can be achieved for laser beam micro welding.     

Fabrication of drive and guide components for micro motors

This paper provides a contribution to the technology and fabrication of functional components for micro motors based on an electromagnetic principle. The focus of this research is on components for the drive, guide and bearing for magnetic actuator systems. The technology and fabrication process of an electromagnetic guide is presented in detail. Its active principle is based upon repellent magnetic forces. Furthermore, the components of a linear variable reluctance micro motor are described. An improvement of driving forces has been achieved in comparison to the first prototype by determined optimizations. In addition, the weight of the traveller could be decreased. The fabrication of compact coil designs for the electromagnetic guide as well as the optimization of components for the reluctance motor are mainly attributed to the implementation of new fabrication technologies and new materials like inorganic insulation layers and electrodepositable photo resists.     

Parallel precision alignment of multiple micro components

Micro components are available in a variety of shapes sizing from 1 mm down to 0.01 mm. Today, their mass production is quite common using state of the art production technology. Micro spheres for example, are on the one hand available in lot sizes up to some thousands in a constant quality within micron accuracy. On the other hand they are quite commonly provided as bulk material with diameter variations of up to 10% in each lot size Brandau (Chem Ingenieur Tech 75:1741–1745, 2003). In both cases, the bulk micro components are usually arranged in incoherent batches which are packed in plastic bags or small jars for handling and shipping. The decollating of the single components for follow-up micro assembly processes is complicated by the well-known effects in micro handling such as dominating adhesion and friction forces (Petersen 2003). These effects limit the post processing of bulk micro components to manual work in order to sort and align the single micro components prior to their exposure to an automated assembly line. To enable a sophisticated and automated handling of the single micro components, automated sorting and alignment mechanisms are necessary to arrange the bulk micro components in a well defined pattern structure which is essential to realize an efficient automated micro assembly.     

Optimizing the operating conditions in a high precision industrial process using soft computing techniques

This interdisciplinary research is based on the application of unsupervized connectionist architectures in conjunction with modelling systems and on the determining of the optimal operating conditions of a new high precision industrial process known as laser milling. Laser milling is a relatively new micro‐manufacturing technique in the production of high‐value industrial components. The industrial problem is defined by a data set relayed through standard sensors situated on a laser‐milling centre, which is a machine tool for manufacturing high‐value micro‐moulds, micro‐dies and micro‐tools. The new three‐phase industrial system presented in this study is capable of identifying a model for the laser‐milling process based on low‐order models. The first two steps are based on the use of unsupervized connectionist models. The first step involves the analysis of the data sets that define each case study to identify if they are informative enough or if the experiments have to be performed again. In the second step, a feature selection phase is performed to determine the main variables to be processed in the third step. In this last step, the results of the study provide a model for a laser‐milling procedure based on low‐order models, such as black‐box, in order to approximate the optimal form of the laser‐milling process. The three‐step model has been tested with real data obtained for three different materials: aluminium, cooper and hardened steel. These three materials are used in the manufacture of micro‐moulds, micro‐coolers and micro‐dies, high‐value tools for the medical and automotive industries among others. As the model inputs are standard data provided by the laser‐milling centre, the industrial implementation of the model is immediate. Thus, this study demonstrates how a high precision industrial process can be improved using a combination of artificial intelligence and identification techniques.     

甲醇精馏变负荷操作优化技术研究及应用

粗甲醇的精馏提纯是甲醇合成生产过程中十分关键的一环,具有很强的非线性和时变性.目前的绝大部分研究都是针对精馏塔设计与塔结构的研究,而对实际投入运行的精馏系统的操作型节能研究较少.研究对已实际投入生产的精馏系统,当进料负载和组分因实际生产情况或者市场需求而改变时,如何确定最佳操作参数达到节能优化的目的,并提出系统的解决方案.     

Decision-based process planning for wire and arc additively manufactured and machined parts

The conventional manufacturing of aircraft components is based on the machining from bulk material and the buy-to-fly ratio is high. This, in combination with the often low machinability of the materials in use, leads to high manufacturing costs. To reduce the production costs for these components, a process chain was developed, which consists of an additive manufacturing process and a machining process. To fully utilize the process chain’s capabilities, an integrated process planning approach is necessary. As a result, the work sequence can be optimized to achieve the economically most suitable sequence. In this paper, a method for a joint manufacturing cost calculation and subsequent decision-based cost minimization is proposed for the wire and arc additive manufacturing (WAAM) & milling process chain. Furthermore, the parameters’ influence on the results and the magnitude of their influence are determined. These results make it possible to design an economically optimal work sequence and to automate the process planning for this process chain.     

Micro ultrasonic welding: joining of chemically inert polymer microparts for single material fluidic components and systems

This paper presents a novel powerful micro joining process—the ultrasonic welding of real micro polymer parts. It seems to be especially suited for the manufacturing of single material, chemically inert plastic microfluidic components and systems for applications in the field of pharmaceutics, biotechnology and life sciences as well as for high temperature polymer fluidic microdevices. The performance of this ‘micro ultrasonic welding’ process, alone using a pneumatic standard ultrasonic welding machine, is demonstrated by the example of covering and sealing microchannels and assembling a piezo-driven micropump.