A number of measurement devices come equipped with internal or user calibration functions. Allowing the user to calibrate their measurement equipment on a more frequent basis gives greater control over the quality process; however, with great control comes great responsibility. There are a number of considerations that must be taken into account to ensure that the operator is not invalidating the certified calibration of their equipment by utilizing such functions.
Before going further, it is important to note that calibration does not mean verification. There is no issue with a user regularly verifying the operation of their equipment, as long as no adjustments are made. An example of verification would be placing test weights on a balance before using it daily, in order to ensure the scale is functioning correctly and reading within tolerance.