MICROMACHINIG

RAJKUMAR MSRIT BANGALORE

1. Presented by: RAJKUMAR S WAGMARE 1MS15MSE10 1 st sem. M.Tech MSE M.S.RAMAIAH INSTITUTE OF TECHNOLOGY BANGALORE ( AUTONOMOUS INSTITUTE,AFFILIATED TO VTU)

2. MICRO MACHINING Presented by RAJKUMAR S 1MS15MSE10

3. MICRO MACHINING

4. Introduction Micromachining  is the basic technology for fabrication of micro-components of size in the range of 1 to 500  µm . Their need arises from miniaturization of various devices in science and engineering, calling for ultra-precision manufacturing and micro-fabrication.

5. MICRO MACHINING Figure : Micro Machining Definition Definition: material removal at micro / Nano level with no constraint on the size of the component being machined.

6. MICRO MACHINING Removal of material in the form of chips having the size in the range of microns. Creating micro features or surface characteristics (especially surface finish) in the micro / Nano level.

7. Why Micro Machining? Final finishing operations in manufacturing of precise parts are always of concern owing to their most critical, labour intensive and least controllable nature. In the era of nanotechnology, deterministic high precision finishing methods are of utmost importance and are the need of present manufacturing scenario. The need for high precision in manufacturing was felt by manufacturers worldwide to improve interchangeability of components, improve quality control and longer wear/fatigue life.

8. Why Micro Machining? Present day High-tech Industries, Design requirements are stringent. Extraordinary Properties of Materials (High Strength, High heat Resistant, High hardness, Corrosion resistant etc.) Complex 3D Components (Turbine Blades) Miniature Features (filters for food processing and textile industries having few tens of microns as hole diameter and thousands in number) Nano level surface finish on Complex geometries (thousands of turbulated cooling holes in a turbine blade) Making and finishing of micro fluidic channels (in electrically conducting & non conducting materials, say glass, quartz, &ceramics)

9. What is Micro Fabrication? Fabrication of products deals with making of machines, structures or process equipment by casting, forming, welding, machining & assembling. Classified into: Macro & micro Macro: fabrication of structures/parts/products that are measurable /observable by naked eye( ≥ 1mm in size) Micro: fabrication of miniature structures/parts/products that are not visible with naked eye(1 µm ≤ dimension ≤ 1000 µm in size) Methods of Micro Fabrication : Material deposition & Material Removal

10. 1. Classification of micro manufacturing techniques.  

11. Classification of Micro fabrication Figure: Classification of Micro Machining

12. Achievable Machining Accuracy

13. Laser Micromachining in Medicine Ø 0.08 mm Ø 0.02 mm

14. WORKPIECE MATERIAL FOR MICRO MACHINING Figure 5. Typical workpiece materials used in micromachining  

15. MICRO CUTTING TOOLS

16. Different micromachining Techniques Photolithography Etching Silicon Micromachining LIGA Mechanical Micromachining

17. Photolithography Photolithography , also termed  optical lithography  or  UV lithography , is a process used in  micro fabrication  to pattern parts of a thin film or the bulk of a  substrate.  It uses light to transfer a geometric pattern from a  photo mask  to a light-sensitive chemical "photoresist", or simply "resist," on the substrate.

18. Photolithography

19. Photolithography Process description

20. etching Etching is used in micro fabrication to chemically remove layers from the surface of a wafer during manufacturing. Etching is a critically important process module, and every wafer undergoes many etching steps before it is complete. It is characterized by etch rate , etch selectivity and etch uniformity

21. Process variations : 1 . Wet etching   Etching processes used liquid-phase ("wet") etchants. The wafer can be immersed in a bath of etchant , which must be agitated to achieve good process control. For instance, buffered hydrofluoric acid (BHF) is used commonly to etch silicon dioxide over a silicon substrate. 2. Dry etching Modern VLSI processes avoid wet etching, and use plasma etching instead.  plasma etching operates between 0.1 and 5  Torr The plasma produces energetic free radicals, neutrally charged, that react at the surface of the wafer. Since neutral particles attack the wafer from all angles, this process is isotropic

22. Bulk micromachining Bulk and surface micromachining are processes used to create microstructures on micro-electromechanical (MEMS) devices. Micro-Electro-Mechanical Systems (MEMS) is the integration of mechanical elements, sensors, actuators, and electronics on a common silicon substrate through microfabrication technology While both wet and dry etching techniques are available to both bulk and surface micromachining, bulk micromachining typically uses wet etching techniques while surface micromachining primarily uses dry etching techniques. Bulk micromachining selectively etches the silicon substrate to create microstructures on MEMS devices.

23. Surface micromachining Unlike Bulk micromachining, where a silicon substrate (wafer) is selectively etched to produce structures, surface micromachining builds microstructures by deposition and etching of different structural layers on top of the substrate  Generally polysilicon is commonly used as one of the layers and silicon dioxide is used as a sacrificial layer which is removed or etched out to create the necessary void in the thickness direction The main advantage of this machining process is the possibility of realizing monolithic microsystems in which the electronic and the mechanical components(functions) are built in on the same substrate.

24. Process description

25. Liga process An important technology of MST Developed in Germany in the early 1980s LIGA stands for the German words Lithography (in particular X-ray lithography) Galvanoforming (translated electro deposition or electroforming) Abformtechnik (plastic molding) The letters also indicate the LIGA process sequence

26. Processing steps in liga Apply resist, X-ray exposure through mask, remove exposed portions of resist, electrode position to fill openings in resist, strip resist for (a) mold or (b) metal part

27. Advantages in liga LIGA is a versatile process – it can produce parts by several different methods High aspect ratios are possible (large height-to-width ratios in the fabricated part) Wide range of part sizes is feasible - heights ranging from micrometers to centimeters Close tolerances are possible

28. Disadvantages in liga LIGA is a very expensive process Large quantities of parts are usually required to justify its application LIGA uses X-ray exposure Human health hazard

29. Manufacturing Facilities IN CMTI –BANGALORE MACHINES FOR MICROMACHINING 1. Ultra Precision 5-Axes CNC Micro Machining Centre – KERN Evo Machine Features: The machine is built with Polymer Concrete bed for high rigidity and damping. The spindle rpm is 50,000 with inbuilt cooling system to avoid thermal expansion. The positional accuracy of the machine ± 0.001 mm. Infrared touch probe facility for tool and work piece setting. Minimum size of the drill and milling cutter that can be used are 30 μm and 50 μm respectively. Micro Machining Centre – KERN Evo Application Examples: Application Areas: Micro surgical tools Optical fiber connections Watch parts Micro parts for Bio medical applications

30. 2. Micro Wire Electro Discharge Machine – AGIE Excellence 2F Machine Features:- Submerged machining. Temperature controlled dielectric Dual measuring system for X and Y axes Minimum wire diameter: 30 μm. Maximum taper angle: 30º/ 100 mm. Auto process parameter selection facility. Profile accuracy on machined component: ± 4 μm . Taper accuracy on the machined component: ± 5 Arc min. Surface finish on machined component: < Ra 0.4 μm Application Examples: Application Areas: Dies & Punches for Electronic & Horological Applications Micro surgical tools & Bio medical devices Thin walled structural parts fro Aerospace application Precision form gauges

31. 3-Excimer Laser Micromachining System Machine Features: Wavelength: 193 nm and 248 nm Repetition rate: 1 Hz to 100 Hz Accuracy of positioning: 2.5 μm Repeatability: ± 0.25 μ m Minimum Feature Size: ≤1.5 μm Application Areas: Capability to machine various types of polymers like Polyimide, Poly carbonate, SU-8, Liquid Crystal Polymer (LCP), Polyester, HDDA, PVC, PET, PMMA etc Micro lenses MEMS Bio-absorbable medical stents Micro fluidic channels etc

32. 4. Hard Turn-Mill Centre – HARDINGE 8/51SP Hard Turn-Mill Centre can do machining of materials of hardness > 45HRC with an accuracy & surface roughness comparable to grinding. Machine Features: Polymer composite machine base Hydrostatic linear ball guide system High dynamic stiffness Higher material removal rate compared to grinding Positioned accuracy: 5 μ m Repeatability: 2 μ m Application Areas: Bearing industries Die and Mould industries General Engineering industries

33. OTHER PRECISION MACHINS IN CMTI

34. References 1 -Wikipedia for micromachining 2. -WWW.Cmti-india.net(journal published in APRIL-2004 VOL-3 NO-4) 3-NICMAP-National information centre for tools and production 4-Etch Rates for Micromachining Processing Kirt R. Williams, Student Member, IEEE, and Richard S. Muller, Life Fellow, IEEE 5-Vogler, M. P., DeVor, R. E., and Kapoor, S. G., 2004, “On the Modeling and Analysis of Machining Performance in Micro-Endmilling, Part II: Cutting Force Prediction,” ASME J. Manuf. Sci. Eng., 1264, pp. 695–705. 6-Lee, K., and Dornfeld, D. A., 2002, “An Experimental Study on Burr Formationin Micro Milling Aluminum and Copper,” Trans. NAMRI/SME, 30, pp. 255–262. 7- Vogler, M. P., DeVor, R. E., and Kapoor, S. G., 2004, “On the Modeling and Analysis of Machining Performance in Micro-Endmilling, Part I: Surface Generation,”ASME J. Manuf. Sci. Eng., 1264, pp. 685–694. 8-Weule, H., Huntrup, V., and Tritschle, H., 2001, “Micro-Cutting of Steel to Meet New Requirements in Miniaturization,” CIRP Ann., 50, pp. 61–64. 9-Yuan, Z. J., Zhou, M., and Dong, S., 1996, “Effect of Diamond Tool Sharpness on Minimum Cutting Thickness and Cutting Surface Integrity in Ultraprecision Machining,” J. Mater. Process. Technol., 62, pp. 327–330.

35. Thank you