High-speed precision numerically controlled tapping using dual predictive control

We explain an algorithm to do numerically controlled tapping. This dual predictive control algorithm achieves both high speeds and precise positioning. By predictively controlling z-axis motion and also predicting spindle-axis positions, we ensure good synchronization between these two motions. An experiment achieving tapping with 6,000 rpm/160 ms acceleration/deceleration, 6,000 rpm rotational speed and 20 micrometer precision is reported.