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India is a country rich in natural resources. There are large reserves of mineral ores, petroleum and building stone">stone. We have a long history of global trade with near and distant countries of the world. In ancient times, Indian spices and finely spun clothes were famous all the world over. Today, as one of the industrialized countries, we are exporting everything available under the sun; raw ores, finished products, building stone">stones. Indian marble and granite have been exported to all parts of the world. Conventionally rough blocks of marble/granite have been exported. Being unprocessed these do not attract good price. Export of decorative granite articles has not been in bulk quantities for any length of time. This is so because of poor quality of goods produced. If a large variety of quality decorative articles could be thrown at competitive prices in international market, a huge untapped source of foreign exchange could be made available.

After extensive development/trial testing, we have perfected techniques/machines to produce granite articles of endless variety and consistent quality at competitive prices for international market.

The process starts at core-drilling, using diamond segmented core drill, on Core drilling machine, with ample water as coolant. Cylindrical core is cut to required length, forming raw-stock. Centre-points are drilled on both faces by carbide drill, on pillar drill machine.

Job is now held between centres of VSK CTC 475 profile Turning machine. A very light pressure on the driving centre is required as the cutting forces generated are very light. Job is rotated slowly at about 15 to 20 rpm.

A number of roughly equi-distant circumferential gashes are cut along the length of job by 250/300 dia. segmented diamond cutter by pulling the cutter carriage at right angles to the job axis. A template precisely controls the depth of gashes within 1 to 1.5 mm from the intended profile. Thin discs left between gashes are then broken, one by one starting from one end, by lightly tapping with a small hammer. This leaves a rough profiled job.

The profile is finished by plunge cutting with diamond cutter, the form and dimensions or profile controlled by carriage stopped against the profile template. A number of cuts, if needed,are taken advancing cutter axially in small increments, thus giving a smooth accurate profile. Job rotates at 30 to 50 rpm depending upon diameter of job.

Polishing is done on VSK-BTC-475 Polishing Machine. Job is held between centres, driven by driving dogs. Resin bonded diamond lapping sticks are used for polishing. Operator forces the diamond stick against the revolving job by pushing a wooden bar, about 450 mm long, one end of which is anchored in a hole of plate. By traversing this bar sideways, the profile is polished. Sticks of 200, 400, 800, 1500 & 3,000 mesh grit are needed to complete polishing operation.

Flower vases, flower pots, candle stands, table-legs balusters fountains etc. are a few out of endless list of articles that have been made using above process on VSK machines. Special mention may be made of 240 mm dia, bowls as thin as 3 mm. On the other end solid granite sphere of 600 mm dia. Is also feasible.

The application of the process/machines has been extended to produce architectural pieces like pillars and pillar claddings. Pillars of 600 mm base dia. and 4,000 mm long have been executed. Four segment, 700 mm long claddings cover an existing/new constructed pillar to make 500 mm dia. granite pillar of any height.

It would be appropriate to highlight the advantageous features of our process/machines at this point.

The profile produced by gashing and copy turning from the template is as exact as the template and independent of operator skill.

From this profile which is highly accurate in forms and dimensions, insignificant material.Not exceeding 0.5 mm is removed during diamond polishing. This results in minimum distortion to the original copy turned product. The end products are. therefore dimensionally and formwise accurate, all being almost identical.

Rejection is minimum as surface cracks produced by chisel hammer which open-up in polishing are eliminated by use of core drilling and copy turning.

Light cutting force and smallest possible material removal in diamond polishing under very light pressure reduce operator fatigue to bare minimum.

There is no limit to section thinness. Section as thin as 3mm and sharp edges can be produced. There is no limit on the profile too; cup-saucer and fruit bowl is feasible.

It can be concluded from above that the techniques/machines perfected by us will give necessary improvements in techniques for making decorative architectural granite articles. These will ensure dimensionally accurate and formwise true articles. Intricate profile and thinnest possible sections have been produced economically. Polishing by diamond sticks, will produce articles of quality which will be economically competitive in internal and export markets.