How To Choose The Best CMM Calibration Artifact

Calibration artifacts are critical to the performance and quality of your CMM. They also help to ensure your measurement data are precise, accurate, and reliable. However, there are numerous calibration artifacts to calibrate different measurements.

Likewise, there are different types of CMMs and they can have errors anywhere along the 21 different measurement axes. Using the proper calibration artifact allows you to fix the corresponding measurement error and address any anomalies or discrepancies in the measurement data. Here are some tips to choose the best CMM calibration artifact.

Level of Precision

Before attempting to calibrate the CMM, you should first assess the level of precision required for the calibration. Is it simply to calibrate the faulty height measurements of the CMM? Is it to calibrate the probe angle of the CMM? Understanding the level of precision will give you a better analysis as to which calibration artifact to use.

This is because some calibration artifacts are better suited for high-level precision calibration while others are used for simple and daily calibration. For example, the swift check calibration artifact performs simple and quick checks on the CMM and delivers easy and clear results.

It consists of a length bar, ring gauge, and sphere that comprises all the geometries and directions required to check for the performance of the CMM. It helps to check for the daily measuring accuracy of every part of the CMM and has a standard precision level for calibration.

However, in cases where a higher level of precision is required in the calibration process, a laser interferometer is used. The laser interferometer is a calibration artifact that utilizes a laser with a beam splitter to make extremely precise measurements based on the reflected laser light.

Calibration Process

There are numerous CMM calibration processes and they require different calibration methods and artifacts depending on what you wish to measure. All calibration processes measure an artifact against a fixed measurement plan and the data points act as a reference base to be compared against the known dimensions of the artifact.

From there, the faulty measurements are rectified and the CMM is calibrated to remove any errors that would prevent it from accurate measurement. For example, if you wish to perform a coordinate calibration process or calibrate the height measurement of the CMM, you may choose a KOBA step gauge calibration artifact.

To perform a dimensional measurement calibration process, a rectangular gauge block would be used due to the vast selection of gauge blocks available.

Probe Material

The probe material is another important consideration in choosing the best CMM calibration artifact. When performing a CMM calibration, you want the artifact to be pretty similar in hardness to the material being measured.

This is because there will be contact force from the measuring probe to the artifact, thus if they are both similar in hardness, it will prevent any inconsistency or error in calibration results due to material or probe damage. Significant errors occur when the hardness of the material varies widely and this will affect the measuring accuracy of the CMM and the calibration process.

by George Chitos