Error compensation method for machine tool and machine tool

An error compensation method for a machine tool for compensating a motion error of a translational axis in accordance with a compensation parameter in the machine tool, wherein

• the machine tool includes two or more translational axes, a table configured to hold a workpiece, and a main spindle configured to hold a tool, the translational axes enable a relative motion of two degrees or more of translational freedom of the tool held onto the main spindle with respect to the workpiece, and the machine tool includes an output unit,
• the error compensation method comprising:
• outputting at least one of a plurality of calibration-master conditions to the output unit, the calibration-master conditions including a type of a calibration master that includes a plurality of targets, an installation direction of the calibration master, and an installation position of the calibration master;
• installing the calibration master on the table in accordance with the output calibration-master condition;
• obtaining measurement values of positions of the targets by detecting the positions of the plurality of targets under the calibration-master condition using a sensor mounted to the main spindle;
• calculating an error value using the measurement value obtained under the calibration-master condition and a calibration value of the position of the target;
• approximating a relation between the measurement values and the error values by a curve and a straight line, calculating the compensation parameter of a positioning error of the translational axis based on an approximate curve in a partial range of a stroke of the translational axis, and calculating the compensation parameter of the positioning error based on an approximate straight line in another range of the stroke of the translational axis and
• wherein the approximating includes obtaining one of the approximate curve or the approximate straight line for the error values and the measurement values obtained under the calibration-master condition.