A coordinate measuring machine (CMM) calibration artifact is used to ensure that the measurement data created by the CMM is accurate through regular calibration. The CMM calibration artifact also includes an ISO-17025 accredited certification and most CMM calibration can be accomplished through the use of a calibration artifact.
Importance of CMM Calibration Artifact
The CMM calibration artifact is an important tool that helps to gauge any inconsistencies or errors in the CMM measurements. This helps in providing accurate calibration data and in fixing or integrating any inconsistencies into the data. A CMM machine can have errors along 21 different measurement axes, thus depending on the severity of the errors, calibration may or may not be required more often.
The calibration artifact may be attached differently to the CMM depending on the type of calibration being done and the type of probe used. Some artifacts require a mounting bracket to be held in place for the calibration process while others can be mounted directly onto the CMM.
The calibration process involves measuring the artifact along with a fixed measurement plan and comparing the data points against the known dimensions of the artifact to check for consistency. By doing so, any error that prevents the CMM from accurately performing its function and measuring the inspected parts would be removed.
Different Artifact Types
Calibration artifacts help to measure the accuracy of measuring machines and this is done through the artifact containing a variety of geometry types such as spheres, cones, circles, and many more. Some common calibration artifacts include the ball plate, KOBA step gauge, end bar, hole plate, and swift-check gauge. Different artifacts may be chosen for the calibration of the CMM depending on the type of measurements being performed and the probe used.
Reminders when Using Calibration Artifact
When choosing a calibration artifact, it is best to choose an artifact that is similar in hardness to the material that is being measured. This is to prevent any inconsistencies due to material or probe deformation. Moreover, once the calibration artifact is installed in the CMM, it has to be given time to cool down and disperse its heat as the artifact is temperature sensitive and will react to the body heat transferred from the technician’s hands.
Sometimes when the CMM involves very precise measurements, the environment can also affect the calibration process. For example, differences in temperature or air currents in the lab can affect the calibration process. It is thus best to strictly control conditions when attempting to calibrate the CMM using an artifact to minimize any discrepancy.
Artifact Form and Material
The calibration artifact may differ in form and material depending on the kind of probe you are calibrating. The stiffness of the artifact material is also an important consideration when deciding which artifact to use as the contact force of the measuring probe may dent or deform the artifact. CMM calibration artifact forms also do not follow any specific rules due to the broad range of uses for CMMs.