What is Backlash?
The term "Backlash" originated from gear engineering discipline. In JIS terminology, this word is described as: Play that exists between a pair of engaged gears' tooth surfaces. When described as a distance of an arc on the engagement pitch circle, it is called "Circumference Direction Backlash", when described as the shortest distance between two opposing tooth surfaces is called "Normal Line Backlash".
Causes for ball screw backlash are:1)Axial clearance
2)Axial elastic deformation of nut
3)Elongation and contraction of screw shaft
4)Axial deformation due to tortional forces
The entire drive train mechanism must be taken in consideration when considering the subject of Backlash.
There is a method of backlash reduction caused by axial clearance and deformation of the contacting surfaces. It is called "Preloading" and is applied during ball screw assembly. This "Preload" is not to be confused with applied load on the system, but should be understood as internally built-in load.
