What is the best material for my dimensional artifacts, such as, gage blocks, balls, and cylinders?
Every gage material has some niche, or it disappears from the market. To choose a material depends on what it will be used for and how it will be used. The main properties to consider are cost, thermal expansion, thermal diffusivity, stability, wear, and wringing properties. Cost: This is a major driver for many uses, particularly shop use. Most calibration labs have few gages and very high accuracy calibrations may cost more than the gage. The least expensive gage material is usually steel. Thermal Expansion: Steel has long been a favorite gage material because most parts are made of steel in many industries. If the gage and part have the same thermal expansion, then the temperature where they are compared is not so important. If the thermal expansions are very different, the metrologist must calculate correction factors, or put correction factors on the drawing. If you make parts that are not steel, steel gages are no advantage, of course. Thermal Diffusivity: If a block is warmer or
