Method of assessing three dimensional volumetric errors in multiaxis machine tools

A method of assessing three-dimensional volumetric errors in a multiaxis machine tool, comprising:

• setting up a first radial error equation according to error in distance between commanded nominal coordinates of a spindle of the multiaxis machine tool and actually moved coordinates of the spindle with respect to a fixed center point to measure the volumetric errors of the multiaxis machine tool in three-dimensional working space;
• modeling first positional error components along each of three orthogonal axes as a dimensionless polynomial function with corresponding positional error coefficients;
• modeling second positional error components due to backlash along each of the three axes with corresponding amount of the backlash in the three axes;
• modeling third positional error components along each of the three axes with corresponding amount of squareness errors between two nominally orthogonal axes among the three axes;
• setting up three-dimensional volumetric error equation depending on kinematic configuration of the multiaxis machine tool;
• setting up a second radial error equation by substituting the three-dimensional volumetric error equation, the first positional error components, the second positional error components, and the third positional error components for the first radial error equation;
• solving the second radial error equation and calculating the positional error coefficients, the amounts of the backlash, and the amounts of squareness by means of an approximation technique and coordinates data.