The single axle straightness, the X, Y verticality and the system return difference are the main reasons for creating error.

All of the high-speed wire cutting machines have not realized the closed-loop control; the return difference of mechanical drive system has become the most important target for the precision of coordinating machine, the return difference roughly comes from the following five aspects:

1 The gear gap, which mainly refers to the transmission gear between the stepping motor and the lead screw.

2 The connecting key gap, especially the gearwheel on lead screw. The influence of motor shaft key gap not only has the return difference, but also accompanied with the noise.

3 The gap between lead screw and nut, the axial transmission gap of lead screw usually is below 0.003 after

leaving from the factory, the product which has bad quality do not have too much guarantee.

4 The lead screw bearing gap, the elimination of this gap depends on adjusting the inner and outer ring axial of bearing, but if the quality of bearing is inferior, it will rotate extremely inflexibly after the gap elimination, once it rotated livelily the gap is existing, therefore this place’s bearing may not be careless.

5 The integral rigidity transferred by moment is worse, creates the flexibility distortion of delicate spot and make the movement slow and lag, also appears by gap.

The above five aspects together created the system return difference, in actual processing, even if the simplest seal graph, also need to remove the return difference at least for two times, therefore the actual processing precision is generally about two times of return difference which can’t be eliminated. If the system return difference is 0.006, then it’s possible that the processing precision is 0. 012.

The two axes’ verticality and each axes’ straightness is another main reason which causes the distortion of displacement. This error quantity is stochastic, and is difficult to be estimated.