At present, we use the granite components, are the use of high-quality natural granite material by mechanical processing, hand-made. Black luster, the structure of precision texture uniformity, good stability. Strong strength and high hardness. Because of the non-metallic materials of granite, there is no magnetic reaction and no plastic deformation. Its hardness is 2-3 times higher than that of cast iron (equivalent to HRC), so it has good accuracy. In the use of rock tools, even if the heavy bump, at most a few pieces of ballast, but not as metal tools, because of deformation and damage precision. The precision measuring datum parts of high quality cast iron and steel can obtain high and stable precision.
The machining and using precision of granite component can be applied to the measurement of industrial production and laboratory, and the granite component face must not have the defects such as sand hole, shrinkage, scratches, bruise, blowhole, crack, slag rust and so on. The concave or falling corners on the non working surface of granite members are allowed to be repaired. Granite component is a precision datum measuring tool made of natural stone material, which is an ideal datum for instrument, precision tool and mechanical workpiece inspection.