Ball Screw Equations Under Scrutiny

Researchers at the University of Duisburg-Essen in Germany are investigating whether the load-life calculations for ball-screw actuators used routinely by engineers are applicable in machine designs that involve repetitive moves, short strokes, and quick thrust build-up over a fraction of revolution. "The equations were developed several decades ago when there were less sophisticated techniques available to determine the behavior of rolling elements and their impact on wear," says George Jaffe, Executive Vice President of Steinmeyer, Inc., a maker of ball screw actuators and motion systems. "Now we have the tools to develop more refined models that take into account things like the impact side loads, ball spacers, and various lubricants have on ball screw life." To support this effort, Steinmeyer is providing sample products and technical assistance to the research team. "Engineers can still use the existing equations, they just need to recognize that they're making a 'best estimate,'" says Jaffe.