Werth Messtechnik Measuring machines with temperature compensation
Germany – Correcting temperature-induced measurement deviations is critical for many users.
Temperature-induced measurement deviations on a 100 mm aluminium workpiece at ambient temperature of 25°C are about 7 µm. For plastics, the deviation under similar conditions can be as much as 50 µm. Temperature deviations can, in some cases, equal dimensional tolerance.
Measurement uncertainty can be caused by the measuring machine itself, the operator, the workpiece, features to be measured and environmental conditions. In order to ensure accuracy, both the measuring machine and the workpiece must typically maintain a temperature within a few degrees of 20°C. Automatic correction of measurement deviations resulting from differences between ambient and reference temperatures is standard for all Werth coordinate measuring machines. The effects of the measuring machine itself (e.g., expansion of the scale) are determined and corrected. The thermal expansion coefficient of the measured object is treated as 11µm/K m (a typical value for steel). Objects made of steel and materials with similar thermal expansion coefficients can thus be measured with very low measurement uncertainty, both in production and maintenance activities. When measuring workpieces in a poorly controlled environment, correction of the workpiece temperature should be made to compensate for its expansion coefficient.