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Ball Screw Accuracy Improvement
How to improve the accuracy of Ball Screw

In the past, in order to obtain high positioning accuracy, mainly by improving the ball screw assembly it's own accuracy to achieve, therefore, Ball Screw lead accumulated error demand is very high, make it difficult to manufacture ball screw, and increase the ball screw production costs. Especially the high-precision ball screw, only through the CNC thread grinding machine or laser feedback thread grinding machine to achieve.

With the continuous development of science and technology, people mastered the CNC compensation technology, therefore, no need great grinding of ball screw, can achieve high positioning accuracy. In order to meet the requirements of the CNC compensation technology, international standards and departmental standards have requirements on the ball screw stroke change quantity, installation such as the stroke change quantity in effective stroke, stroke change quantity in any 300mm stroke, stroke change quantity in 2π radians. Its purpose is to control the linear of ball screw stroke error, that the error linearization of ball screw stroke, to create conditions for CNC error compensation.

In order to minimize the friction, the isolation balls and the bearing balls should be alternate from each other. However, some of the load and stiffness requirements may require every three bearing balls with a isolation ball. The isolation ball diameter slightly smaller than the bearing ball acts as an idler, they along the bearing balls in the opposite direction rotation, and to reduce contact friction. An unfavorable consequence of the use of isolation balls or reduce the number of bearing balls is the reduction of the bearing capacity of the ball screw, which must be compensated by decreasing the working load or increasing the ball screw size.

The resistance caused by lubrication will increase the friction torque, especially at high speed, most of the ball screws are used far less than 5 m/min. However, the speed of modern machine tools required is more than 10 m/min, the speed of some system applications up to 30 m/min. The lubricant type of minimum resistance is determined by the axial rotation speed of the ball screw. Generally speaking, the speed of 500 rpm/min or moving speed less than 3 m/min, the best use of grease lubrication. In this lower speed is mainly boundary lubrication. Speed of more than 500 rpm/min, mainly oil film lubrication, oil is the best lubricant.

In the case of very high temperature, the individual cooling system can be installed in the ball screw, air or oil mist is sprayed on the screw shaft. Usually, air cooling is more effective, and will not be like that loss. Cooling can also be carried out by using the method of making the pressure water through the hollow shaft of the ball screw, using such system, ball screw temperature hardly rises.