Precision Granite Straight Edge for CNC and Metrology

A:

It is important to note that color alone is not an indication of the physical qualities of the stone. In general, the color of granite is determined by the presence or absence of minerals which may have no bearing on the qualities that make good surface plate material. There are pink, gray, and black granites that are excellent for surface plates, as well as pink, gray, and black granites that are totally unsuitable for precision applications. The critical characteristics of granite, as they pertain to its use as a surface plate material have nothing to do with color, and are as follows:

Stiffness (deflection under load - indicated by Modulus of Elasticity).

Hardness

Density

Wear resistance

A:First, it is important to keep the plate clean. Airborne abrasive dust is usually the greatest source of wear and tear on a plate, as it tends to embed in work pieces and the contact surfaces of gages. Second, cover your plate to protect it from dust and damage. Wear life can be extended by covering the plate when not in use, by rotating the plate periodically so that a single area does not receive excessive use, and by replacing steel contact pads on gauging with carbide pads. Also, avoid setting food or soft drinks on the plate. Note that many soft drinks contain either carbonic or phosphoric acid, which can dissolve the softer minerals and leave small pits in the surface.

A:This too depends on the plate usage and environment. We recommend that a new plate or precision granite accessory receive a full recalibration within 1 year of purchase. If the plate is going to receive heavy use, it may be advisable to shorten this interval to six months. Monthly inspection for repeat measurement errors using a Repeat-o-Meter, or similar device will show any developing wear spots and only takes a few minutes to perform. After the results of the first recalibration are known, the calibration interval may be extended, or shortened as allowed or required by your internal quality system.

A:The answer is 'yes' for almost every application. The advantages of granite include: No rust or corrosion, almost immune to warping, no compensating hump when nicked, longer wear life, smoother action, greater precision, virtually non-magnetic, low co-efficient of thermal expansion, and low maintenance cost.