High-quality ball screws replace planetary roller screws

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NSK ball screws have achieved a manufacturer of welding guns to reduce costs by 40 per cent.

High-quality ball screws replace planetary roller screwsWith its experience in high-load ball screw applications, NSK has achieved a 40 per cent cost reduction in the manufacture of a product for a manufacturer of automated welding guns. This has been achieved by replacing the manufacturer's existing actuation mechanism, using planetary roller screws, with high-quality, silent-running NSK ball screws that offer maximised efficiency and load carrying as a result of integrating a greater number of load-carrying balls.

NSK was called in as part of a cost-reduction strategy introduced by the welding gun manufacturer, and was tasked with providing a lower-cost alternative to the planetary roller screws currently used. However, the alternative had to meet stringent operating demands: it must not reduce performance, nor increase energy consumption or maintenance requirements.

NSK had to take into account the fact that in welding guns a very high load is applied in a very short time, and always in the same point of the stroke. Therefore, reliable operation requires the maximum number of load-carrying balls, with an equal load distribution.

With its experience in high-load ball screw applications, NSK proposed a SFD3605-12 ball screw that offered the key benefits of conforming to the same dimensions as the existing design, plus reductions in operating friction and temperature as a result of changing from rollers to balls. Moreover, these benefits have been achieved with a ball screw that shows a 40 per cent cost saving, thereby improving competitiveness for the welding equipment manufacturer.

Key to the all-round improved performance of the NSK ball screw is a new ball recirculation technique. This employs a deflector at each end of the ballnut to ensure that the load-carrying balls are picked up tangentially, thereby eliminating the direct ball-to-ball contact that causes noise and vibration. In addition, the improved design provides smoother and more stable running at low speeds; these qualities are important in ensuring high levels of reliability and accuracy in machine tool and other precision equipment applications.

NSK's precision ball screws are included in a newly produced pocket-sized guide detailing the company's range of linear motion equipment. Suitable for use by design engineers, the pocket guide contains useful information encompassing everything from linear guides to high-technology Megatorque motors for precision direct-drive applications.

Free copies of the pocket guide are available via NSK's Freephone service: +44 (0)500 2327464. Callers should quote the catalogue reference LIN/B/E/06.11, and also the title of the publication: Pocket Guide Linear Motion. For more information about NSK's precision ball screws, go to

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