When combined with high-end servo actuators, precision rackand- pinion drives can hold less than 1 arc-min of backlash, true running of 10 μm, and 98.5% efficiency. Such drives are employed in many precision applications, including high-speed metal cutting, laser cutting, grinding machines, and woodworking machines. Other applications include automatic assembly equipment and gantries.
Rack-and-pinion questions & answers
Q: How is accuracy maintained?
A: The accuracy of a precision rack-and-pinion system is around 12 μm per 500-mm rack. By matching sections — each section is checked and marked — lengths of any size can be created with no more than 40 μm of position error.
Q: What qualifies as “high precision?”A: Tight tolerances, wearresistant treatments, and individually deburred gear teeth are good signs when looking for a high-precision rack-and-pinion drive. Tooth-to-tooth error, though a factor, is not as important as total cumulative pitch error. With rack-and-pinion drives, it is possible to have relatively high tooth-to-tooth error and still achieve the desired cumulative accuracy.
