Quality assurance in micro production

Quality assurance is essential for an efficient support of all developing and manufacturing processes and activities with the forefront objective to reach robust processes with a high throughput of parts meeting their functional requirements. Due to the lack of a broad base of experiences regarding the still developing manufacturing technologies in micro production an adequate quality assurance plays an even more important role in order to efficiently support the transition of micro production processes from non-robust to stable processes. Thereby, quality assurance faces particular challenges in micro production, which render a reasonable application of common quality methods difficult or even impossible. Consequently, it is essential to develop new concepts or adjust widely applied quality assurance methods in order to support and continuously improve the development- and manufacturing processes in micro production. Within the scope of the Collaborative Research Center (SFB) 499 “Design, production and quality assurance of primary shaped micro components manufactured in ceramic and metallic materials” the approach of the subproject working on the topic quality assurance is threefold: (i) An efficient and process-accompanying information management has been implemented and will be enhanced further on. (ii) Specifically adjusted preventive methods of quality assurance have been developed and applied. (iii) In order to implement an efficient operational quality assurance performance data of the manufacturing processes has been collected and provided. In the future this supply of data will be used to control and improve the manufacturing processes.     

Replication processes for metal and ceramic micro parts

To cover the demand for effective manufacturing of metal and ceramic micro components two process technologies are described. The first one can be regarded as a special variant of micro powder injection molding (MicroPIM): inmold-labeling using powder filled feedstocks. Its basic procedures are the backfitting of powder filled foils by an injected PIM-Feedstock and the subsequent co-debinding and co-sintering steps. For example, two-material ceramic parts with microstructured surfaces could be produced and compacted with mostly tight interfaces. The second process conduct combines two-component and insert injection molding with an electroforming process. Since all process steps involved are based on technologies suitable for series production, low product costs per unit will be realistic. Surface qualities and dimensional accuracies are comparable or even better than achieved if applying alternative processes like MicroPIM.     

Quality assurance and testing for safety systems

In this paper we identify special quality assurance and test requirements of software for safety systems and show that even the best currently available practices meet these requirements only at very high cost and by application of empirical rather than technically rigorous criteria. Redundancy can help but is expensive and the reduction in failure probability due to software redundancy is uncertain. We identify a qualitative approach to test data interpretation, particularly the examination of rare events in the conditions that precipitated an observed failure, as a possible avenue for a more economical reliability assessment. This can be used as an alternative or as a supplement to redundancy for meeting the reliability requirements for software in safety systems. Further research in this area is recommended.     

Design and manufacturing of micro milling tools

The actual geometrical design of micro milling tools has been adopted from macro tools, assuming that the effects during the milling process are analogical. Experience has also proved that micro tools respond to influences in a very different way than macro tools do. So it is very important to achieve a comprehensive understanding of the entire process by taking a structural, mechanical and cutting technological approach to micro milling tools in order to be able to optimize them. Oftentimes, structural details such as the rake angle and the twist angle impede further miniaturization and are impossible to achieve with conventional manufacturing techniques. This paper deals with an alternative method to manufacture structural optimized milling tools, namely Electro Discharge Machining (EDM). The present state of research already puts the deficits of the currently available tools on display. Manufacturing tolerances of ±10 μm on a micro tool are insufficient to ensure constant cutting conditions for the commonly used lateral infeed or feed per tooth of a few micrometers. Sometimes, only one cutting edge is engaged, which results in increased wear, increased cutting forces, minor surface quality and a higher risk of milling cutter breakage. That is why a single-edged micro milling tool has been developed. It guarantees clear adjustment of the process parameters, feed per edge and lateral infeed. For that purpose, stability analyses of simple stylus geometries have been conducted by means of FEM simulations. Corresponding to the results of the simulation the geometry of this tool was optimized in several steps. The resulting tool with a diameter down to 30 μm was machined on the EDM-machine (Sarix SX 100) at the wbk—Institute of Production Science. Initial tests have been carried out and showed the ability of these tools to optimize cutting process.     

Integration framework for intelligent manufacturing processes

In this article, we describe a new approach to applying distributed artificial intelligence techniques to manufacturing processes. The construction of intelligent systems is one of the most important techniques among artificial intelligence research. Our goal is to develop an integrated intelligent system for real time manufacturing processes. An integrated intelligent system is a large knowledge integration environment that consists of several symbolic reasoning systems (expert systems) and numerical computation packages. These software programs are controlled by a meta-system which manages the selection, operation and communication of these programs. A meta-system can be implemented in different language environments and applied to many disciplines. This new architecture can serve as a universal configuration to develop high performance intelligent systems for many complicated industrial applications in real world domains.To whom all correspondence should be addressed.     

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.     

Assembly and measuring technique for the manufacturing of active micro systems

This paper presents the current results of the development of an assembly equipment with integrated measuring system that will permit a high position accuracy. The kernel of the work is an parallel robot, an innovative optical sensor for 3 dimension and an micro gripper.     

微流程的建模与分析

业务流程管理技术是组织实施信息系统的重要使能技术.为确保微流程能正常运行,提出了一种建模与分析微流程的方法.首先,该方法以Petri网为形式化基础,对微流程以及微流程间的同步组合和异步组合进行建模.其次,基于Petri网的分析技术,该方法对组合微流程进行了合理性分析.实验结果表明,该方法能建模微流程,并检测出组合微流程...     

Methods for simulating and optimizing molded micro components and systems

Casting production of metallic and ceramic micro components is still in the research phase, and the components obtained with the current technologies are suffering of a certain lack of reproducibility. Within the scope of Collaborative Research Center 499 “Design, Production and Quality Assurance of Molded micro components made of Metallic and Ceramic Materials”, basics in a persistent process chain for micro components are acquired. The development, process preparation, mass production and material and components behavior investigation is understood under consistent chain. This work presents computer simulation based methods that contribute to optimize micro molded systems on both a component and a system basis. The introduction of such methods allows studying the behavior of components and systems with regard to their grain structure and the wide geometric tolerances required.     

Hybrid evolutionary optimization for nutraceutical manufacturing processes

In this paper, an intelligent approach, called HERON (hybrid evolutionary optimization for nutraceutical manufacturing), is proposed to optimize a variety of manufacturing processes in the nutraceutical field. The approach integrates the Taguchi method, an artificial neural network (ANN), and a genetic algorithm (GA). The Taguchi method is used to cost-effectively gather the data on the process parameters. Data obtained by the Taguchi method are divided into input and output data for an ANN’s input and output parameters, respectively. The ANN trains itself to develop the relationship between its input and output parameters. The trained ANN is then integrated into a GA as the fitness function, such that the GA can evolutionarily obtain the optimal process parameters. The HERON is validated through a manufacturing process on soft-shell turtle soft-capsules. The objective is to minimize the soft-capsule defect rate. Compared to the defect rates obtained by the empirical and Taguchi methods, the HERON reduces the defect rate by 43.75 and 32.5 %, respectively. In addition, compared to the manufacturing costs obtained by the empirical and Taguchi methods, the HERON reduces the manufacturing cost by 11.81 and 25.29 %, respectively.     

Internet-based CDSS for modern manufacturing processes selection and justification

To select the right process technology for a business is related to strategic goals, resource availability and market conditions. Such dimensions must be included in an evaluation process of technology choice. Although various approaches have been suggested for evaluation of the modern manufacturing processes, still, there is a need for a decision aid to assist companies in selection and justification of the most suitable technology to their operations and business objectives. In this study, we designed an Internet-based Collaborative Decision Support System (CDSS) consisting of three stages: strategic justification, operational justification, and economic justification. For decision-making process in each stage, knowledge-based systems, simulation, and activity-based costing models and methods are used, respectively. A unique feature of this system is that it not only combines the capabilities of various decision-making methods, but also takes into account the objectives and operating characteristics of individual companies in the evaluation process. The other characteristics of the CDSS are easy to use, understandable, and less time consuming.     

Metal-ceramic-composite casting of complex micro components

Metal-ceramic-composite casting has a huge potential as a new manufacturing method for the production of complex-shaped micro sized parts or microsystems consisting of different metals and ceramics. The fundamental advantage of this method is the capability of multi-component part fabrication in one step avoiding first time consuming joining or assembling techniques; second the used material combinations can fulfill complex functionalities and enhanced mechanical properties. One of the most challenging factors in micro composite casting is a stable mechanical bonding between the used individual materials. But under consideration of the different physical properties like thermal expansion coefficient as well as of the wettability of the ceramic inserts and of the applied metal casting material it is possible to manufacture form and force fitting microsystems. Within the framework of this feasibility study complex metal-ceramic micro composites have been realized successfully using the lost-wax casting process. Casting experiments were performed at different muffle preheating temperatures with Al-bronze of the type CuAl10Ni5Fe4 as casting material. The ceramic parts, respectively inserts cast around by metal are micro gear wheels (2.5 mm diameter) consisting of ZrO₂ and Al₂O₃.     

Quality assurance evidence collection model for MSN forensics

Instant Messaging (IM) applications have become an important tool for business and social communication. However, when using IM, individuals and companies expose themselves to many security threats. Collecting all available data and preserving the integrity of evidence is a challenging task to perform IM forensics. In particular, under resource constrained situations, a good evidence collection mechanism is required to provide effective event collection in a network environment with heavy traffic. The emphasis of this paper is on the development of an effective evidence collection control mechanism that achieves an optimal outcome with a reasonable forensic service requests acceptance ratio and tolerable level of data capture loss. In this paper, we propose an evidence collection control model used in network forensics, called Quality Assurance Evidence Collection (QAEC). QAEC dynamically adjusts the amount of data to be collected on an evidence flow according to the storage capacity level. QAEC is firstly modeled as the Continuous Time Markov Chain (CTMC) and is realized by a cost function that comprises both flow-level and packet-level components to reflect the efforts on the evidence reconstruction process. We also present a prototype system (known as the MSN-Shot) as a MSN forensic system which uses QAEC to select an appropriate evidence collection strategy to maximize the given cost function. With the numerical analysis and prototype results, this study confirmed that the QAEC model meets cost-effective requirements and provides a practical security solution and guarantees a high level of quality assurance for network forensics.     

Design and manufacturing of mobile micro manipulation system with a compliant piezoelectric actuator based micro gripper

This paper presents a new design of mobile micro manipulation system for robotic micro assembly where a compliant piezoelectric actuator based micro gripper is designed for handling the miniature parts and compensation of misalignment during peg-in-hole assembly is done because piezoelectric actuator has capability of producing the displacement in micron range and generates high force instantaneously. This adjusts the misalignment of peg during robotic micro assembly. The throughput/speed of mobile micro manipulation system is found for picking and placing the peg from one hole to next hole position. An analysis of piezoelectric actuator based micro gripper has been carried out where voltage is controlled through a proportional-derivative (PD) controller. By developing a prototype, it is demonstrated that compliant piezoelectric actuator based micro gripper is capable of handling the peg-in-hole assembly task in a mobile micro manipulation system.     

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.     

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.