Due to its unique properties, black granite in recent years, has been used extensively in the field of measuring instruments, both for traditional ones (surface plates, parallels, set squares, etc…), as well as modern ones: CMM machines, physic-chemical process machine tools.
Suitably lapped black granite surfaces are not only extremely precise but also ideal for use in conjunction with air bearings.
The reason of the choice of black granite in manufacturing of precision units are the following:
- DIMENSIONAL STABILITY: black granite is a natural aged material formed over millions of years and therefore displays great internal stability
- THERMAL STABILITY: the linear expansion is much lower than the steel or cast iron ones
- HARDNESS: comparable to good-quality tempered steel
- WEAR RESISTANCE: instruments last longer
- ACCURACY: the flatness of the surfaces is better than the one obtained with traditional materials
- RESISTANCE TO ACIDS, NON-MAGNETIC ELECTRICAL INSULATION RESISTANCE TO OXIDATION: no corrosion, no maintenance
- COST: working the granite with state-of-the-art technology prices are lower
- OVERHAUL: Eventual servicing can be carried out quickly and cheaply