A supplier asked NSK for its expert advice to help to reduce the downtime frequency in production of automotive brake systems. A team of NSK specialists duly investigated the raceways and lubrication conditions in three faulty linear drives in order to determine failure causes. The result: a combination of high loads, penetrating cutting fluids and high ambient temperatures was responsible for the short lifespan.
NSK recommended using ball screws that have been specially developed for high speeds and loads. This product range features a customer-specific nut that is tailored exactly to the application and provides greater axial stiffness, not just of the ball screw, but the entire powertrain, thus increasing machine precision. Moreover, as preload is spread over several balls, service life is increased considerably. As recommended by NSK, the ball screws were equipped with the company’s proprietary X1 high-performance seals. These seals prevent any cutting fluid from penetrating the linear system and stop the ball screw lubricant from contaminating the machining centre's cutting fluid or coolant. The X1 seal also has excellent grease-retention capabilities. Optimal lubrication of the ball screw in tough operating conditions is assured by using the K1 lubrication unit, which enables the lubricant's useful life to be considerably prolonged, again contributing to lower maintenance costs. The results were highly successful: ball screw lifespan increased by a factor of six. Furthermore, since installation, there have been no more failures.
The automotive supplier can now benefit from lower spare part costs and, above all, from significantly less production downtime: total yearly cost savings of approximately €266,000 have been achieved. Ball screw upgrades, which are performed by NSK experts, can be made at no great expense and without altering the surrounding structure of the machine tool.