Temperature changes can cause materials to contract or expand and, as a result, cause the dimensions of parts to show small changes when you measure the same dimensions at different temperatures. To prevent errors that such changes cause, and to measure closely-held dimensions more accurately, make sure that the parts, gages, and gage masters agree with these conditions:

Do a check for the calibration sticker. Be sure that it is not expired.

Examine for defect conditions that you can see. These include burrs, nicks, and other indications of misuse. These defective conditions can prevent correct function of the gage.

Do not use gage or equipment with an expired calibration sticker, no inspection due date that shows, or for other reasons that prevent the correct function of the gage or equipment.

Obey all special instructions to correctly use each gage.

Make sure that the gage has protection from temperature changes when you use it.

When you measure dimensions, use a gage that has a greater accuracy than the total tolerance specified. A gage with the smallest minimum (tightest) tolerance will give greater accuracy than a gage with larger minimum (wider) tolerances.

When more than one gage is applicable, think about the type of dimension you need to examine and how easy the instrument is to use.

If the part tolerance is such that the specified gage does not give the necessary accuracy, it is permitted to use an alternative gage or inspection method that has the necessary accuracy.

When a gage is not practical, not available, not specified in technical data, or not listed on work instructions, the alternative gage or inspection method must have the same, or better, accuracy than that specified.