A great variety of high precision tools now enable men to cut, shear, slice, hive, split and shape stones for all kinds of uses. A look by M.A. Siraj
From Stone Age tools to stone-cutting tools, the journey has been indeed long for mankind. Stones that were the stuff of tools for primitive men are today themselves at the receiving end. A great variety of high precision tools now enable men to cut, shear, slice, hive, split and shape stones for all kinds of uses.
Marble and granite stones are expensive commodities and chipping them to size could lead to considerable waste. Over the last few years, the granite and marble industry has incorporated new machines that can cut them with precision to the extent of a fraction of a millimetre. Italy has consistently maintained excellence in manufacturing such machines.
The latest technologies in the field provide solutions not merely to cut the marble and granite slabs to thin slices but also to round off the sharp edges, create grooves that run uniformly into them, dress the surfaces of the huge blocks and even to etch geometrical patterns over the slabs or blocks. The huge, rough blocks of stones that arrive from mines can now be processed with machines that are capable of producing 20 mm thin slices of an eight cubic metre block within eight hours.
Two major technologies that are deployed are Gang-saw and Diamond Wire-saw. The first is more suitable for mass production of thin slabs. In fact, normally a unit should deploy two (or four, or eight) machines in order to guarantee a continuous material output to the polishing line.
Gang-saw machines use heavy steel blades while wire-saw use diamond bead cutters studded over wires. Gang-saw machines require nearly two weeks to install as it involves elaborate civil work while wire-saw machines are easy to install but are expensive, yet highly efficient.
Apart from block-squaring for fitting them into the gang-saws without losing space, the application of a diamond wire saw is more for the production of a few slabs, of more expensive material and different thickness. This would absolutely not be economical to do with a gang-saw.
Therefore, if there is a frequent need of few slabs or thick slices in short time, one uses a stationary wire-saw. But if one needs a lot of thin slabs continuously, a gang-saw is the ideal option. Bigger establishments deploy both the systems which complement each other.
Even the speed of the two machines varies greatly. A gang-saw cuts at a speed of five centimetre an hour while a diamond wire saw at about 100 centimetre an hour. But wire-saw machines have a few more advantages.
These create less noise and vibration and in case of spares, wire-saw cutters entail less shipping cost as they are wires studded with diamond cutters whereas gang-saw cutters are heavy steel blades.
Wire-saw machines also save power consumption to the extent of 85 per cent and require far less manpower for operation and maintenance.
Bejoy A.J., manager for engineering services at Intertech Services, a firm dealing with imported stone cutting machines, says ‘Gaspari Menoti’, the latest multiwire-saw machines from Italy, can cut a stone block with each side measuring 3.4 metres and height of 2.2 metres into 140 slabs of two centimetres each. The machine costs Rs. 5.30 crore and uses several wire-saws with diamond beads.
Bangalore is a major centre for granite and stone processing in India as out of the 65 such units in the country, 15 are located in and around Bangalore.
Italian firm Breton is also a leading manufacturer of stone processing machines. H.C. Manjunath from Paradigm Granite installed a multiwire-saw machine from Breton which can cut an eight cubic metre granite block into 20mm thin slices.
Chima Impex, a stone processing unit from Ongole, processes almost 4,000 sq. ft of slabs each day after having imported Breton machines from Italy.
A majority of the stone processing units (50 out of 65 in India) are located in the four South Indian States as more mines have opened in this region, especially in Andhra Pradesh and Karnataka during recent years.
According to Satish Gopal, Sales and Project Manager at Ferromech Industries, ‘EC800’, the first indigenous stone cutting machine, is being manufactured at the Devanahalli-based unit. He says the machine can be customised for each individual buyer according to specific needs of the units.
The machine is capable of slicing rough blocks of stone, can do edge cutting and can dress the stone for all kinds of requirement. It is operated by a 20HP disk motor and moves on a bridge by means of a sliding support on oil bath cast iron guides. The maximum cutting sizes are 350 x 350 cm. According to Gopal, the machine is receiving encouraging response from stone units in India.
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