# Impact of Temperature on Steel Measurement Instruments

Thickness steel gauges are measuring instruments that are used to determine the thickness or gage of an object. There are several different types of thickness gages, each that function in a slightly different manner depending on the intended application for the gage.

We know that changes occur in material things as temperatures vary. It is a common phenomenon which quite well-known to engineers, metrologists, and common people alike. Although these are very subtle changes that are usually invisible to the naked eye, you can see its application in the gap in the railway tracks between its two lengths. You can also notice the expansion joints in bridges, as a bridge’s span length changes with the varying temperature in various seasons. In an industrial environment where measurement is important and tolerances are low, even a small difference in measurement becomes critical and must be accounted for.

## Thermal Expansion

Whenever a material is heated, then its temperature rises due to the increased vibrations in the atoms. The distance between the individual atoms also increases resulting in the expansion of the material. This change is dependent on the material, although the most common change to occur is an increase in volume.  Since the heat affects all atoms in the material depending on their location, the change in length occurs which is proportional to the increase in temperature.

The Coefficient of Thermal Expansion is a constant specific to a material that defines the change in relation to the temperature. It simply means materials expand or grow a certain length when heated, and contract when the temperature is reduced and this constant gives us how much this expansion or contraction occurs.

An increase or decrease in the length of a steel ruler with the variation of length with temperature to the naked eye cannot be detected. Even when performing certain measurements the difference is negligible. However in the case of pin sets, micrometers, or calipers, gage blocks, plugs, or rings there is a significant difference. That is because of the difference in accuracy and amount of steel.

In the case of gage blocks, plug gages, ring gages, and other more accurate and thicker dimensional gages, the acclimation time is quite critical. These types of gages are kept in a temperature-controlled environment for 24 hours for accurate measurements. On the other hand, ceramic gages take much longer to acclimate as compared to steel gages, so these gages may take up to 48 hours to stabilize.

The standard dimensional laboratory calibration temperature is 20 °C (68 °F). This is the temperature that gage blocks and other more accurate gages are calibrated when they are manufactured. In a dimensional lab environment, extreme care is necessary. All possible sources of heat must be eliminated. The heat from the human body, hot air from breathing, and heat generated from the electronic instruments, and heat radiated by the electric room lighting must be accounted and taken care of.

Ultimately then, an understanding of thermal expansion is needed to provide highly accurate measurement results. Therefore we at e2b calibration laboratory set the ambient temperature at a constant 20˚C resulting in the perfect environment to provide customers guaranteed precise metrology solutions. Our laboratories use the latest technology, offering a full range of measurement, and calibration services. You will receive the measurement information that your customers need for product verification and quality control to the highest degree of accuracy. We perform calibrations in a temperature-controlled clean room environment to help minimize factors that contribute to measurement uncertainty, such as thermal expansion.

e2b calibration provides reliable and cost-effective calibration services for your gages. Our verifiable and traceable services are unmatched in the industry.  We are ISO-17025: 2017 compliant and registered with ANAB. We are also ANSI/NCSL Z540-1-1994 certified. We are NIST Traceable Wide scope of ISO/IEC 17025 accreditation. Contact e2b calibration for more information about our on-site calibration services.

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