MICRO-TECHNOLOGIES AND SPECIAL MATERIALS FOR THE DEVELOPMENT OF MECHATRONIC MICRO-NANO SYSTEMS FOR ULTRA PRECISE MEASUREMENT PROCESSES

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1 8th International DAAAM Baltic Conference "INDUSTRIAL ENGINEERING April 2012, Tallinn, Estonia MICRO-TECHNOLOGIES AND SPECIAL MATERIALS FOR THE DEVELOPMENT OF MECHATRONIC MICRO-NANO SYSTEMS FOR ULTRA PRECISE MEASUREMENT PROCESSES Gheorghe, Gh. I. & Despa, V. Abstract: This scientific work deals with new technologies that apply laser microsintering of special materials with structures based on nickel, titanium and cobalt, for new high precision linear and angular mechatronic micro-displacements micro-nano-systems. Scientific work is based on experiments and tests of laboratory micro-technology and micro-nano-systems used in the advanced areas of micro-engineering and micro-medicine. Key words: advanced micro-technology, mechatronic micro-nano-systems; microsintering; micro-engineering. under the action of various powers laser beams. Through this micro-technology, parts, subassemblies and assemblies are obtained, with any geometric complexity of mechatronic micro-nano-systems for ultraprecise measurement processes. Selective laser sintering advanced microtechnology for metal micro-powders was implemented and used in INCDMTM Bucharest in advanced research for hightech micro-engineering, micro-medicine fields, and so on. 2. SELECTIVE LASER MICRO- SINTERING 1. INTRODUCTION Currently, are known and applied various advanced micro-technologies using conventional operating principles and especially advanced unconventional operating principles. Of these, the most advanced and effective is the advanced micro-technology of selective laser sintering based on the new principles of integrated design - 3D design - execution of micron layers made from nano-grained powders, successively deposited and solidified. Selective Laser Sintering - SSL - is a family of methods that can build a solid body from various types of material - plastic, metal, ceramic very rare methods or physical, mechanical and biocompatibility properties, made from special powder material by solidification, by exposure of successive layers of powder 280 Selective laser micro-sintering is based on the intelligent mechatronic equipment type EOSINT M 270 and the rapid prototyping process based on three-dimensional CAD data and micro-powders of various alloys, and bronze-based alloy, martensitic steel, stainless steel, super alloy cobaltchromium, titanium alloy and so on. The intelligent mechatronic equipment type EOSINT M 270 (Fig. 1) with the schematic diagram shown below (Fig. 2) represents the technical and technological infrastructure of the advanced microtechnology and laser sintering. Micro-powder metallic materials as used in the selective laser sintering technology, have special physical and micromechanical qualities, have properties of biocompatibility and corrosion resistance and are suitable for biomedical, aerospace, mechatronics, robotics, and automotive industry and so on.

2 equipment and expanding technological research on some other group of materials with mechanical and technological properties closer to the needs of MEMS and NEMS constructions and functional assemblies. Fig. 1 EOSINT M 270 Legend: 1. Processing room 2. Scanner lid 3. Left hood of the optical system (Only for EOS service personnel) 4. Xtended installation mode only: release key 4. Right hood of the optical system (Only for EOS service personnel) 6. Screen 7. Xtended installation mode only: Signal light 8. Emergency stop button 9. Keyboard and mouse 10. Operating table (pivot) 11. Laser 12. Front door 13. Xtended installation mode only: Protective gas shift indicator 14. Xtended mode installation: Shielding gas control unit 15. Process computer 16. Final stage engine 17. Air maintenance unit 18. Anti-state carpet connection 19. Cable shielding 20. Control cabinet 21. Front cover (Only for EOS service personnel) Selective laser sintering processes is based mainly on the experience gained in the design of intelligent steno-lithographic 281 Fig. 2 Schematic diagram Legend: 1. Horizontal work section 2. Active surface of the working board 3. Section through piece 4. Laser generator 5. Focused laser beam 6. Beam deflection device 7. deflected laser beam 8. controller 9. base plate work 10. Adjuster 11. Direction indicator 12. Board receivers 13. Opening 14. Watertight door 15. Container for disposal 16. Container door seal 17. Inert gas supply means 18. Heating 19. Download device 20. Powder coating applicator 21. Powdery material 22. Powder supply 23. Radiator heating 24. Central control device 25. Fixing layer powder device 26 to 28. Container In the rapid prototyping project, we have succeeded in demonstrating that a thin

3 layer (of approx. 18 μm) of certain mixtures of powders under the action of the laser beam can reach locally, based and duration of exposure, the melting temperature of the transition of the powder layer to liquid state. Based on the physical properties of powders, immediately after the laser action has ceased, almost always local solidification is attained, obtaining a compact layer, placed on the direction of molecular chains, surrounded by a volume of powders exposed to laser light. The explanation of solidification is essentially based on the same mechanism of steno-lithographic procedures, installing chemical bonds forming linear molecular chains, or three-dimensional trees. For these states, state transitions, which imply a significant local heating device, can be accelerated by initializations and controlled by inhibitory substances and the energy can be obtained by concentrated heat sources in the working place, laser radiation, and so on. All these sources must be adapted and adjusted on the fly, so as to give additional heat to reach the melting temperature which provides favourable thermal and kinetic conditions and development process by establishing molecular chains and partial crystalline structure, with the transition from liquid to the solid state, strengthened, that marks the sintering process. In terms of energy, industrial powders / micro-powders, with a wide range of melting temperatures, require a different heat input from the concentrated source of energy. Choosing the activation energy required is possible by selecting fast heating regimes under dynamic sintering process. The diversity of these regions has attracted finally the selective sintering denomination. In conclusion, this phase is better than the earlier period when stereolithography technology and equipment were researched, designed and approved, by the following elements of technical progress, as follows: stereo-lithography processes are limited to use acrylic or epoxy photo-polymers which could be generate a small range of products; selective laser sintering processes are based on a lot of material such as plastics, ceramics and metal powders, which will result in even more products at a higher layer of performance, i.e. with physicmechanical properties closed to the requirements of used equipment parts. 3. SPECIAL MATERIALS AND TYPES OF SINTERING Due to fundamental and applicative research conducted it was concluded that the sintering mechanism explanation is more complex because it is different from conventional sintering due to the flowing features, as follows: - selective sintering is initiated prior to making powders, although powders are pressed by roller compaction (Fig. 3); Fig. 3 Roller compaction - the variety of powders with different melting temperatures pretends power laser devices with continuous emission for melting. Therefore, instead of He-Cd lasers, are adopted higher power CO2 lasers; - the universal character of SLS equipment, resulting from the initial set of materials that can be processed with a CO2 laser facility. Because of its selectivity, the device can provide power emission. 282

4 In continuous regime, at the level of automated regulations, that provide: - low intensity when melting wax; -higher intensities for melting metal powders; Sintering achieves high performance when using a powder mixture consisting of two groups of material; Types of particles used in selective laser sintering technology in the laboratories of INCDMTM Bucharest, Romania, are mainly as follows: a. metal powders, category A: o EOS CobaltChrome MP1 o EOS CobaltChrome SP2 o MaragingSteel EOS MS1 o StainlessSteel EOS GP1 o StainlessSteel EOS PH1 b. metal powders, category B: o EOS Titanium Ti64 o EOS Titanium TiCP Geometric peculiarities of metallic powders are shown in Figure 4. Fig.5 and Fig. 6 Applications obtained in the field of high accuracy are based on the CAD software and specialized software for rapid prototyping, as follows: o SolidWorks 2009 SP3.0, RapidWorks 2.3.1, NextEngineHD o PR-EOS Tools o EOS PSW offline o EOSTYLE, that represents a specialized element micro-motor gas turbine, shown in Fig. 7. Fig.4 Geometric peculiarities of powders 4. EXAMPLES OF INDUSTRIAL APPLICATIONS OBTAINED IN THE LABORATORY OF INCDMTM Biomedical applications obtained are based on DICOM files to build a bone structure and is subjected to FEM analysis (Fig. 5 and Fig. 6). Fig. 7 Micro-motor gas turbine Applications obtained for the aerospace field are based on the piece made from 283

5 L EOS CobaltChrome MP1, are shown in Figure 8. Fig. 8 EOS CobaltChrome MP1 Applications obtained for the field of finite implant elements in the laboratory of INCDMTM are shown in Figure 9, Fig. 11 and Fig. 12 In all applications obtained in the laboratory of INCDMTM and presented above, schematic representation of the data stream are shown in Fig. 13. Fig. 9 Implant elements whose pre-execution phase, which is prior to physical execution, is the 3D design shown in Figure 10 The applications obtained in new concepts and developed by INCDMTM in the rapid prototyping laboratory, are shown in Figures 11 and 12. Fig. 13 Scematic of data stream. Legend: 1 CAD data generation 2 Data preparation 3 Process computer 4 Laser 5 Scanner 5. CONCLUSION New perspectives for the development of selective laser sintering technology, concern, immediately: o development of the triad: engineerclinician - IT specialist;

6 o design of new advanced research technologies and biomedical devices, implants, 3D scanning, CT scan, MRI scan, DICOM handling, 3D design, e- Manufacturing (Rapid Prototyping, Rapid Manufacturing, Rapid Tooling),etc.; o creation of a centre of excellence in research for new technologies related to CT and MRI medical imaging, 3D geometric modelling of osteo-articular structures, FEM mechanical and parameterization analysis (Finite Element Method -), Computer assisted surgery and Micro-surgical and orthopaedic corrective methods quantitative assessment. 6. REFERENCES [1] M. Shellabear: Trends and Prospects for e-manufacturing using Laser-Sintering, PR 24th Seminar, Tokyo, June [2] Shellabear M., Lenz J., Junior V.: e- Manufacturing with Laser-Sintering - to Series Production and Beyond, Lane, Erlangen, September 2004 [3] Thomas, W., Wolf,: Marks' Standard Handbook for Mechanical Engineers, Section 13.5 "Surface Texture Designation, Production, and Control", 2009 [4] Yan, M., Gu, P., Huang, X., Zhang, X.: Analysis of Accuracy machine for rapid prototyping of quality components, Proceedings-of-SPIE, The-International- Society-for-Optical- Engineering, V3517, ADDITIONAL DATA ABOUT AUTHORS Authors: Prof. univ. dr. eng. Gheorghe Ion Gheorghe; PhD student eng. Veronica Despa Manuscript Micro-technologies and special materials for the development of mechatronic micro-nano systems for ultraprecise measurement processes National Institute of Research and Development in Mechatronics and Measurement Technique (INCDMTM) 6-8 Sos. Pantelimon, District 2, Bucharest, Romania Phone /69 Fax cefin@cefin.ro Valahia University of Targoviste Blvd Carol I, Nr. 2, , Targoviste, Dambovita, ROMANIA Tel. +40/245/ Fax. +40/245/ rectorat@valahia.ro Corresponding Author: Gheorghe Ion Gheorghe, geocefin@yahoo.com. 285