GMT started manufacturing lapping machines in 1971. They were developed for lapping silicon wafers for Bharath Electronics. Later, when demand for large quantities of surface plates arose, the machines were modified to lap surface plates.

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 superfinishing machine for lapping large granite plates, GMT designed and supplied a 3000mm dia flat lapping machine.

Hence, pump manufacturers, electronic industries, valve manufacturers, etc., have found a sure way of obtaining positive sealing.


  • A wide variety of materials can be lapped.
  • Flatness to one light band (0.0003 mm) on 100 dia can be achieved.
  • Surface finish to less than 0.2 µRA can be achieved.
  • Parts of different materials, thicknesses and shapes can be lapped.
  • Because the flatness of the lap-plate is maintained continuously by means of conditioning rings, there is no interruption in production.
  • Appropriate diameters of the conditioning rings result in optimum lapping area.
  • Finally, automatic and adjustable digital display times control the lapping cycles.


  • Cast iron, Stainless Steel, Aluminium, Bronze
  • Plastics, Tungsten, Ceramics
  • Silicon, Carbon, Alumina, Ferrite, Stellite


300mm and 400mm DIA

300mm and 400mm dia lapping machines are bench models and are robust. The lap plate and conditioning rings are of special, close-grained cast iron. Taper roller bearing supports the lap plate for maximum stability.

610, 900 & 1200 DIA

The structure for these sizes are heavy duty and with heavy ribbing. The design of the main spindle bearings gives great axial load capacity, maximum stability, long life and smooth performance even under heavy eccentric loading. Lap plates are manufactured from close-grained alloy cast iron, stress relieved after pre-machining and finally finish-machined and lapped in position.

1500, 1800 and 2100 DIA

Sizes 1500, 1800, and 2100 mm dia machines are massive with robust bases. Large heavy-duty roller bearings take care of eccentric and other radial loads.

The drive is through the main motor through ‘V’ belts through a fluid coupling to ensure smooth working. The drive to the lap plate is through a heat-treated pinion and a high tensile spheroidal cast internal gear. Variable speed drive for lap plate, the reverse mechanism for conditioning ring is a standard supply. Water cooling for the lap plate is optional.



With GMT Monochromatic Lamp, one can measure flatness within 0.6 microns quickly and easily. These attractive and self-contained units use sodium lamps to produce a brilliant glare-free light of known wavelength. You can observe contrasting light and dark bands on most reflective or semi-reflective surfaces. As a result, when used with GMT optical flats, they measure surface flatness within 0.3µ on parts up to 75mm dia.


GMT optical flats are made from clear fused quartz. Flats made of quartz are superior due to their very low thermal expansion and greater abrasion resistance. GMT optical flats are available in 50, 75, 100 and 150mm dia sizes.


In order to obtain the highest reflectivity from a lapped surface for light band interpretation, it is generally required to hand polish sample parts briefly after work has been lapped. GMT polishing stands effectively handle a fine grade polishing paper,  holding it tight to prevent rounding the edges of the work, yet permitting easy access to a new section of paper when desired. The stand uses a standard roll of polishing paper.

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