In factory floor metrology there is a seemingly endless supply of external factors that can impact the accuracy and repeatability of a gauging system. Temperature is one such factor that when not properly addressed can have you second guessing every other measurement.
When we were reviewing the requirement and specifications for this gauge, one note really stood out from the rest: “Non-temperature controlled, open air factory. Daily temperature swings between 30 and 50 degrees Fahrenheit.”
The thermal expansion coefficient of steel is 7.2 x 10^-6 per degree F.
If you were to measure an 8″ diameter at 77° F and then the temperature dropped just 10 degrees, that part would now measure 7.999″.
When working with tolerances of 0.0005″, even the smallest change in temperature will have a substantial impact on the operation of the gauge.