The linear drives of the latest injection-moulding machines have to operate with higher accelerations and faster feed rates to meet the growing demand for shorter cycle times. The two new ballscrews – extensions to NSK’s HTF series of high-load ballscrew drives, which it launched in 1996 – have been developed to satisfy this demand.
In the first development, NSK has expanded its HTF-SRD series of ballscrews, designed for clamping duties in injection-moulding machines, by adding versions with larger leads. The high-load ballscrews, with top feed speeds of 2–3m/s, result in shorter cycle times and increased productivity for end-users. In addition, ball circulation has been optimised, reducing noise levels by up to half compared to conventional systems.
In the second development, NSK has added has added small and medium diameters (starting from 50mm) to its HTF-SRE series ballscrews, which were previously offered only in relatively large spindle diameters of 140–200mm. The new sizes will help to satisfy the high dynamic performance requirements of the latest injection-moulding machines. In addition, these ballscrews have much smaller nuts, with outer dimensions compatible with those of NSK’s HTF-SRC ballscrews, which are used in many injection-moulding machines around the world.