Improvement of positional accuracy of precision micro milling centre using pitch error compensation

An experimental procedure was performed on precision micro milling centre to improve positional accuracy and keep tolerances within the required range for precision manufacturing in tool and die industry. The micro milling processes play an important role in tool and die industry, which is facing increasing demands on global market, namely demands related to positional accuracy and repeatability. Laser interferometer was used for measurements of 3-axis machining centre, where the values for positional accuracy and repeatability were calculated according to ISO 230-2 standard for all three axes. Values of positional accuracy for X- and Y-axes were out of manufacturer's tolerance (3 μm), while positional repeatability was satisfactory and below 0,7 μm for all axes. Based on determined positional errors, correction of pitch error compensation table was performed. The improvement of positional accuracy was significant, with values around 1 μm and below. Finally, measurement uncertainty for accuracy and repeatability was estimated for all axes according to the same standard.