NSK Develops Technology to Reduce Machine Tool Quadrant Glitches in Circular Interpolation Motion by Stabilizing Friction in Ball Screws

NSK Ltd. has developed a ball screw technology to significantly reduce quadrant glitches*1 arising during circular interpolation machining operations in machine tools by stabilizing friction when the ball screw reverses the direction of motion. This is the world's first technology of this type for ball screws.

NSK will exhibit this new technology at JIMTOF 2020 Online (The 30th Japan International Machine Tool Fair), to be held from November 16-27, 2020, and plans to bring ball screws incorporating the new technology to market in April 2021.

*1:Quadrant Glitches: When machining in a circular interpolation motion (orthogonal with two axes), irregular friction arising when the motion of the ball screw reverses directions causes a deviation from the intended path resulting in a streak or protrusion on the workpiece.

Development Background

In recent years, there is increasing demand for higher accuracy machining and higher finish quality in die machining performed by machine tools such as 5-axis machining centers. This means there is a need for further improvements in machine tool feed performance.

In particular, motion errors called quadrant glitches (reversal spikes), which are caused by variation in friction during reversals in the direction of ball screw motion, leave streaks on the workpiece surface resulting in a lower quality finish.

Remedy via software compensation has attempted to address this issue, however, the frictional variation that occurs when the ball screw reverses direction is difficult to predict and cannot be fully compensated for through software, so more fundamental improvements are needed in ball screw technology.

New Technology

Reduced frictional variation when the ball screw reverses direction of motion

Utilizing in-house proprietary friction control and high-precision evaluation and measurement technologies, NSK developed improvements that significantly reduce the frictional fluctuations that inherently occur in ball screws when the direction of motion is reversed.

Benefits

Contributes to improving machine tool feed performance of and protecting the environment

Significantly reducing quadrant glitches achieves a higher quality finish on the workpiece surface. This shortens the finishing process, ultimately contributing to energy savings and increased machine tool productivity.

Applications

Ideal for die machining, high precision component machining, wire-cut electrical discharge machining (EDM) and any machine tool or machining center performing precision work requiring high-accuracy positioning.