Advantages of granite in Metrology is multi-fold. Granite is the best material for providing an accurate surface reference in Metrology.
PROPERTIES OF GRANITE
Our mission is to be the premier provider of precision granite and other mediums in this metrology field, by delivering superior value as measured by customer service and responsiveness, product quality, technical expertise and innovation. We manufacture Surface Plates, Straightedges, Master Squares, Master Angles, Cubes and other related items. The sizes are based on the Indian (ISI) and German (DIN) standards. We also undertake special sizes on customers’ request. Further we can certify to the customer’s choice of standard.
As a material for Metrology, granite is a very hard natural igneous rock formation of visibly crystalline texture, formed essentially of quartz and orthoclase/microcline. Due to its high quartz content, granite provides greater resistance to wear and damage. Its anti-glare property results in less eyestrain for the person using the products. Due to its hardness and wear qualities, non-denting property, smoother action, greater precision, and, low maintenance cost, granite is used often for manufacturing of DImensional Metrology Reference equipment like surface plates, measuring prisms, guideways of precision instruments and other metrology aids.
ADVANTAGES OF GRANITE IN METROLOGY
- High degree of hardness (High quartz- high hardness)
- Low heat conductance
- Low temp sensitivity
- Electrically Non-conductive
- Rust and acid resistance
- Matt surface, non-reflective surface
- Low water absorption
- High modulus of elasticity- Torsionally rigid, sag-free
- Dolerite – a better scratch resistance
SOME SPECIFICATIONS OF GRANITE WHICH ARE RELEVANT FOR METROLOGY
|Modulus of elasticity||55 GPa|
|Compressive strength||286 MPa|
|Tensile strength||17.7 Mpa|
|Co-efficient of thermal expansion||2- 4 x 10-6 K-1.|
Another major advantage of granite is that any small impact or scratch is made on the granite surface plate, it results in crushing of localized zone. The broken piece or powder comes out without harming the surface accuracy.
However, in the case of cast iron or steel surfaces, under similar circumstances a bulge would result. This affects the surface accuracy and often these are hard to notice by the naked eye.
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