GMT metrology specials

Apart from complete range of standard granite and cast iron metrology dimensional inspection equipment, GMT's Metrology Division also manufactures custom built metrology products like master square for alignment of machining center, large size granite plates and granite base structures for Special Purpose Machines.

Granite for Metrology


Certain minerals present in the granite are the cause of its typical colour. The presence of these minerals on the working surface of a surface plate, or other metrology artefact, can cause problems. If they are very hard and brittle (quartz for e.g.) they can wear quickly leaving pitted areas on the surface.

It is an acknowledged fact that pure black granite from the Deccan plateau in the South India is most resistant to wear. This does not mean that other colours do not have metrology characteristics. As granite is a natural material and its properties can vary from vein to vein in the quarry, it is best to get the stone periodically tested for its properties. Experts from GMT visit quarry to select the granite best suited for metrology.

Granite Surface Plates are made from select granite with uniform distribution of light and dark constituents. In such granite the minerals are evenly distributed resulting in a homogenous appearance.
Texture : Fine
Specific Gravity : 3.08 g/cm3
Hardness : Scleroscope over 90
Modules of Elasticity : 9.0 to 12.0 x 105kg/cm2
Moisture of absorption : Nil