ASTM E4 Practices for Force Calibration and Verification of Testing Machines

ASTM E4 includes the force calibration and verification of tension or compression, or both, static and quasi static testing equipment using force measurement standards. These procedures are not meant to represent comprehensive purchasing standards for testing equipment. The SI units are to be taken as standard.

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Scope:

Force-applying and -indicating machines are employed in a variety of industries and applications. They could be used to assess material qualities in a research lab or to qualify a product for distribution on a production line. The testing equipment can be calibrated using the techniques in Practices E4 so that the measured forces can be traced back to the SI. Those that use, manufacture, and provide calibration services for testing machines and related apparatus can follow the processes in Practices E4.

Procedure:

Practiced at various calibration forces, ASTM E4 calibration involves comparing the testing machine’s stated force (or the testing machine’s applied force in the case of testing machines without force indicators) to a force measurement standard. These Practices E4’s metrological criteria account for measurement uncertainty by restricting the key contributors to measurement error, such as the force measuring standard utilized, resolution, repeatability, and measurement accuracy. Practices E4 verification entails using force measurement errors, as well as resolution and return-to-zero readings, as proof that a testing machine’s force indicator(s) indicates values, or that the testing machine applies forces, that meet the requirements of these Practices E4 in terms of percent error of force, repeatability, resolution, and return-to-zero at the calibration forces directed by these Practices E4.

Video 01: ASTM E4 Calibration of Force Machines

Specimen size:

Elastic force measurement standards must only be used within their Class A validated range of forces for calibrating testing devices.

Data:

The percent error of forces, EP, and the force measurement error, E, is determined in ASTM E4 as follows:

E = A – B

Ep = [(A – B)/B] × 100

Where:

A = force indicated by the testing machine being verified, N

B = value of the applied force, as measured by the force measurement standard, in the same units as A

Conclusion:

ASTM E4 includes the force calibration and verification of tension or compression, or both, static and quasi static testing equipment using force measurement standards.