Lapping Machine Process and Application

GMT started manufacturing lapping & polishing machine in 1971. It was built for in-house use and until then hand lapping process was used for finishing surface plates. Critical parts for our workholding devices required a finishing and buffing machine. There was demand in the market for valve lapping and lapping plates. Since GMT had a captive ferrous foundry, castings for lap plate and lapping machine were easier to source.
Since then GMT has become one of India's largest lapping machine manufacturers and suppliers with over 350 installations throughout India mainly to the valve and pump industry. When a buyer in Japan wanted a super finishing machine for lapping large granite plates, GMT designed and supplied a 3000mm dia flat lapping machine.
Pump manufacturers, electronic industries, valve manufacturers, etc., have found a sure way of obtaining positive sealing.

1. The Lapping Process An ISO 9001:2008 & EMS 14001 Company 10/2011 1

2. What is Lapping? Lapping is a mechanical precision finishing operation done to achieve high dimensional accuracy Diagram of the lapping process in action 2 An ISO 9001:2008 & EMS 14001 Company 10/2011

3. What is Lapping? It helps achieve positive sealing by obtaining high degree of flatness and surface finish A typical example would be lapping automotive pump seals An ISO 9001:2008 & EMS 14001 Company 3 10/2011

4. The Lapping Process Lapping improves surface finish by reducing peaks & valleys on a surface Surface finish of 0.2 µ Ra achievable with GMT Lapping machines 4 An ISO 9001:2008 & EMS 14001 Company 10/2011

5. Advantages of Lapping Accessible flat surfaces of parts of any shape & size and any type of material can be lapped Improves service life of the moving parts which are subject to wear Improves geometrical & dimensional accuracies Absolutely no distortion in the component after lapping since no clamping devices are used The lapping process generates minimal heat so hardened parts will not have to be hardened again Reduction of peaks and valleys results in maximum bearing area between mating surfaces - This ensures tight seating of seals 5 An ISO 9001:2008 & EMS 14001 Company 10/2011

6. Typical Applications & Industries that Make Use of Lapping Valve Manufacturers Air Compressor Industries Automotive industries Pump Manufacturers Electronic Industries 6 An ISO 9001:2008 & EMS 14001 Company 10/2011

7. Carbon What Can be Lapped? A wide variety materials, hard or soft can be lapped. A partial list includes: Cast Iron Tungsten Plastics Ceramics Stainless Steel Bronze Silicon (Eg.wafer) Rubber 7 An ISO 9001:2008 & EMS 14001 Company 10/2011

8. GMT manufactures flat lapping machines both single side & double side 8 An ISO 9001:2008 & EMS 14001 Company 10/2011

9. Single Side Lapping Machine Consists of a rigid rotating spindle with a lapping plate, and three or four conditioning rings GMT’s single side lapping machines provide flatness to a precision of one light band (0.0003mm) on 75mm diameter with a surface finish of 0.2 µ RA 9 An ISO 9001:2008 & EMS 14001 Company 10/2011

10. GMT has supplied lapping machines to over 300 customers all over India Sizes range from 300mm to 3000mm diameter 10 An ISO 9001:2008 & EMS 14001 Company 10/2011

11. Our Customers Include: 11 An ISO 9001:2008 & EMS 14001 Company 10/2011

12. Range of Lapping Machines Manufactured by GMT Single side lapping machines 300mm - 400mm diameter Model 06-01, 06-02 12 An ISO 9001:2008 & EMS 14001 Company 10/2011

13. Range of Lapping Machines Manufactured by GMT Single side lapping machines 610mm diameter Model 06-13 13 An ISO 9001:2008 & EMS 14001 Company 10/2011

14. Range of Lapping Machines M anufactured by GMT Single side lapping machines 900mm diameter Model 06-03 14 An ISO 9001:2008 & EMS 14001 Company 10/2011

15. Range of Lapping Machines M anufactured by GMT Single side lapping machines 1200mm diameter Model 06-05 15 An ISO 9001:2008 & EMS 14001 Company 10/2011

16. Range of Lapping Machines M anufactured by GMT Single side lapping machines 1500mm diameter Model 06-06 16 An ISO 9001:2008 & EMS 14001 Company 10/2011

17. Range of Lapping Machines M anufactured by GMT Single side lapping machines 1800mm diameter Model 06-07 17 An ISO 9001:2008 & EMS 14001 Company 10/2011

18. Range of Lapping Machines M anufactured by GMT Single side lapping machines 2100mm diameter 18 An ISO 9001:2008 & EMS 14001 Company 10/2011

19. Range of Lapping Machines M anufactured by GMT Single side lapping machines 3000mm diameter 19 An ISO 9001:2008 & EMS 14001 Company 10/2011

20. Range of Lapping Machines M anufactured by GMT Double side lapping machines/Planetary lapping machines Model 24-01 To maintain: Flatness Surface finish Parallelism 20 An ISO 9001:2008 & EMS 14001 Company 10/2011

21. Range of Lapping Machines M anufactured by GMT Double side lapping machines/Planetary lapping machines Model 24-02 with pneumatic lifting arrangement 21 An ISO 9001:2008 & EMS 14001 Company 10/2011

22. Range of Lapping Machines M anufactured by GMT Double side lapping machines/Planetary lapping machines Model 24-11 22 An ISO 9001:2008 & EMS 14001 Company 10/2011

23. Range of Lapping Machines M anufactured by GMT Double side lapping machines/Planetary lapping machines Model 24-11 with 4 way lapping (rotating top & bottom lap plates) 23 An ISO 9001:2008 & EMS 14001 Company 10/2011

24. Accessories Hand lap plate To correct minor imperfections and for small batches Cupboard To store polishing paper, pad, hand tools etc, (can be used as a machine stand for 300 and 400mm diameter bench model lapping machines) Straight Edge To check the flatness of lap plate Monochromatic Light & Optical Flat Used for measuring the flatness. Sodium Vapour Lamp used with a wavelength of 0.00058 mm Polishing Stand Fitted with 4/0 emery paper to achieve reflective surface after lapping for light band interpretation (for flatness checking) 4/0 Emery Paper 24 An ISO 9001:2008 & EMS 14001 Company 10/2011

25. Measuring Flatness Unit for flatness measurement is half the wavelength i.e. λ / 2 = 0.000589 / 2 = 0. 0002945mm  (rounded off to 0.0003mm i.e. 0.3 micrometer) Monochromatic Lamp Optical Flat Flatness is measured using GMT make Monochromatic lamp & Optical flat  The GMT Monochromatic lamp unit provides light source with sodium vapour lamp.  The wave length of Sodium light in air (λ air):  0. 000589mm i.e. 0. 589 micrometer)  An ISO 9001:2008 & EMS 14001 Company 25 10/2011

26. Measuring Flatness An imaginary tangent intersects one interference band immediately above it Imaginary tangent line This shows the flatness to be below one band or 0.0003mm Point of contact An ISO 9001:2008 & EMS 14001 Company 26 10/2011

27. Measuring Flatness Optical flat is in contact with the surface being tested , usually where pressure is applied causing the air film to be squeezed thin at that place When light is reflected from the surface under test, interference occurs and is visible as a pattern of light & dark bands The width of each band = λ / 2 ( (i.e.) 0.0003 micrometer) Point of contact or line of contact  Point of contact Straight, parallel and equally spaced bands show that surface is perfectly flat within 0.0003mm An ISO 9001:2008 & EMS 14001 Company 27 10/2011

28. GMT also offers optional features like: Water cooling for lap plate, Variable speed drive, Pneumatic lift arrangement, Lapping fluid recycling 28 An ISO 9001:2008 & EMS 14001 Company 10/2011 Accessories for Lapping

29. Guindy Machine Tools Limited www.gmt.co.in 29 An ISO 9001:2008 & EMS 14001 Company 10/2011