Fraunhofer IPK

Institut für Produktionsanlagen und Konstruktionstechnik

Digital Transformation - Englische Ausgabe 2017
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Process Chains for Micro-Production

CIRP Keynote Advances the State of the Art

The ability to manufacture high-precision components with micro-features is of growing importance for companies in many industries. The production spectrum ranges from manufacturing individual parts for specific applications, e. g. astrophysics, to large-scale manufacturing of items for medical technologies. Manufacturing technologies must meet comprehensive requirements in terms of quality and costs. In this context, meeting standards for accuracy, reliability and reproducibility of processes is of the utmost importance. For the first time, scientists working in Germany and the USA have investigated topics in micro-production technology comprehensively in context with manufacturing technologies, mechanical engineering and measuring techniques. The result of this collaboration is a summary of the current state of the art for the production of micro-components, which goes far deeper than previous research and has attracted international attention.

Manufacture of a molding tool for the production of blood plasma separators based on micro-fluid principles with a minimal structural dimension of 15 µm.

Products

Research of the international team focused on four major topics, namely applications, manufacturing procedures, machine systems and measuring technologies, as well as process chain. Initially, the examination of industrial application examples became the basis for product classifications and for discussions about how to establish production chains to manufacture these products. In the course of their discussions, the team elaborated on the fact that the classic process chain model »from rough to intricate« does not directly fit the addressed applications. Instead, a continuing changeover between precise, highly precise and ultra-precise processing and measuring must take place in process chains to accurately meet the requirements for the structure and component.

Manufacturing Technologies

This realization is a prerequisite to the proper analysis of high-precision components with microstructures, which must conform to the international state of the art in manufacturing. Here, micro-cutting is of utmost importance. Manufacturing technologies using geometrically defined and geometrically undefined cutting edges are improving constantly so that they are fit for precision cuts in the micrometer range with submicrometer precision. The team recognized advances particularly in the modeling of processes or process steps for the prediction of process results. Ultra-precise micro-cutting is also now available for processing very hard materials. Procedures involving geometrically undefined cutting edges make the grade when new technologies are used such as vortex processing and the use of new tools for producing microstructures. The team also found improvements in non-conventional and forming processes for the addressed applications. Electrical discharge machining of ceramic materials and metal as well as the stamping of lattice textures are only two of the many examples for these developing trends.

Machine Systems and Measuring Technology

Worldwide, the required machine technology shows a clear development toward serviceable and flexible hybrid machine systems with the highest possible integration density. Aside from the integration of various manufacturing procedures, the integration of high-quality measuring technology into processing equipment is of increasing significance. Research and development work in the past ten years reveals comprehensive efforts to combine maximum resolution of measured data and maximum measuring field size with the highest measuring accuracy. New kinematic implementations of Abbé's Principle, which demands that the physical representation of a measuring device should be linearly aligned with the test object, as well as the optimization of existing tactile and optical measuring methods, lead to crucial advancements in the accuracy of workpiece measurements. Standardization of optical measuring procedures especially increases the reproducibility and traceability of measurements. In addition, newly introduced process control measures lead to increased process stability. The produced structures are very small and require very small tools, in most cases. Because of this and because the point of action is often hard to reach, engineers must use non-conventional high-resolution procedures. An example is the use of solid-borne sound sensors to monitor especially micro-cutting tools.  

Process Chain

Finally, the team used an actual component as an example to evaluate the theoretical insights gathered in recent years. More than 20 international institutes participated in the execution of the experiment: Engineers at the institutes were asked to create a component with precisely specified dimensions. Each team was free to design the component. The variations in dimensions and tolerances of the used sample component corresponded to actual industrial demands. Most of the ditch structures, ridges, faces and cylindrical surfaces of the component find their close match in the areas of precision tool design and construction for molding and casting processes such as injection molding and hot embossing. The evaluation objective was to verify the published state of the art regarding flexible manufacturing of precision structures and creation of process chains for manufacturing components of various structures and specifications in the one-digit micrometer range. Then, standardized processes were deduced from the results and verified by the participants.

Convincingly, the evaluation indicated that manufacturing high-precision components with microstructures in process chains is feasible. The process chain is not limited to the production in a hybrid machine system, but also works across borders and continents. To a large degree, the process results depend on the used machining and measuring techniques, the environmental conditions and the specified standard parameters. With these results, the team of researchers proved that high and ultra-precision technologies are controllable even though many parameters may influence the results.

Miniaturized modular machine concept for manufacturing high-precision workpieces with microstructures: in this case, dry EDM.

Keynote Paper 

This research was carried out in close cooperation with leading international scientists and presented in a Keynote Paper for the International Academy for Production Engineering (CIRP). Koordiniert wurden die Arbeiten am Fraunhofer IPK has coordinated the research and its publication. Co-Authors are:

  • Prof. Dirk Biermann, Technische Universität Dortmund
  • Prof. Ekkard Brinksmeier, University of Bremen,
  • Prof. Tino Hausotte, Friedrich-Alexander-Universität Erlangen/Nürnberg, 
  • Prof. Brigid Mullany, University of North Carolina at Charlotte, USA
  • Prof. Kamlakar P. Rajurkar, University of Nebraska, Lincoln, USA
  • Prof. Eckart Uhlmann, IWF TU Berlin, Fraunhofer IPK

Your contact

Prof. Dr. h. c. Dr.-Ing. Eckart Uhlmann

Phone: +49 30 39006-100

eckart.uhlmann(at)ipk.fraunhofer.de

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