A measuring artefact for true 3D machine testing and calibration

A new measuring device is introduced that allows fast testing and calibration of machine tools, robots and coordinate measuring machines with three linear movements with a measurement uncertainty of less than 5 pm. Errors are measured in the three degrees of freedom X, Y, Z at measuring points forming a regular three dimensional grid, thus allowing space error compensation. The device consists of a standard 2D-ball plate that can be relocated square to the plate. Kinematic couplings ensure defined and repeatable relative locations of the ball plate - thus forming a three dimensional grid. The main concept, the calibration of the kinematic artefact, the probing method and uncertainty estimation are explained in the paper. The application of the kinematic artefact on a three axes machine tool is shown. Measurement uncertainty and robustness against imperfect environmental conditions are very competitive compared to the current state of the art in machine tool metrology.