Linear Motion Control - 2017-08-14
As machines for the semiconductor industry operate with cycle times of one second or less, pick-and-place units must offer very high dynamic performance. A case in point can be seen at a manufacturer of chip-mounting systems, where NSK recommended a combination of its ball screw and miniature linear guide technologies to replace the existing linear motor and significantly increase dynamic capability.
Assembly machines in the semiconductor industry put high demands on pick-and-place units. (Photo: Arijit Modal/ Shutterstock)
With regard to the process, the pick-and-place unit of the assembly machine grips a semiconductor chip and inserts it inside a package. During this operation, the facilitating 40 mm stroke is executed at a speed of 2.5 m/sec.
The linear motor used previously was performing this task at the limit of its capability, which prompted the OEM to approach NSK for an alternative solution. After a comprehensive assessment of the application, NSK’s engineers proposed the use of a BSS Series ball screw in combination with PU Series miniature linear guides.
NSK’s PU miniature linear guides are purpose-designed for demanding applications such as those found in semiconductor manufacturing equipment and medical devices. Smooth ball recirculation enables effortless motion, while an enhanced seal prevents friction dust from entering the surrounding environment. This makes PU miniature linear guides suitable for use in clean room applications with an appropriate lubricant.
Another advantage of the PU Series is low weight: the carriage is approximately 20% lighter than comparable systems on the market, which makes a considerable difference in highly dynamic applications. The drive unit of the pick-and-place system now weighs only 1 kg, while its operating speed is 2.5 m/s (with an acceleration of 40 g). In addition, it offers a 40 mm stroke and a maximum ball screw rotational speed of 5000 rpm.
Thanks to this high-performance capability, the NSK solution delivers much higher dynamics than the linear motor it replaced. Furthermore, the manufacturer of the chip mounting systems says it is fully satisfied with the reliability and lifespan of the PU Series miniature linear guide and BSS Series ball screw.
The NSK PU Series of miniature linear guides was developed for demanding applications such as semiconductor manufacturing equipment.
NSK’s BSS Series ball screws ensure exact positioning with short cycle times.
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