xxx 2012-09-06

IMTS 2012: New planetary screw assemblies are stronger and quieter

IMTS 2012: New planetary screw assemblies are stronger and quieter

The new planetary screw assemblies move heavy loads quickly.

With newly developed planetary screw assemblies, Rexroth is expanding the range of applications for electro-mechanical solutions by a solution that allows for heavy loads to be moved quickly. The drive elements are available in five sizes. They reach a static load capacity of up to 475kN, while at the same time requiring less installation space than ball screw assemblies having the same capacity. The high performance drive elements are especially well-suited for intermediate and heavy engineering applications, such as pressing, machine tools and plastic injection-molding machines.

The design principle of planetary screw assemblies with large contact areas improves the load bearing capacity significantly without increasing the dimensions. Planetary gears with a defined contact profile rotate inside a nut parallel to the axis around a bolt. The numerous contact areas lead to a high axial rigidity and load bearing capacity, thereby allowing for a long service life. The new screw assemblies achieve a high level of positioning and reproduction precision even with minimal movement.

Contrary to ball screw assemblies, where the balls are continuously fed back through the return passage into the load bearing area, the planetary bolts rotate inside the nut. This makes them run very smoothly, with noise emissions remaining clearly below those of ball screw assemblies.

Rexroth's sealing technology in the planetary screw assemblies allows for long lubrication intervals. As a result, lubricant consumption is reduced, which in turn means lower maintenance costs and less pollution.

The product range initially includes screw diameters of 20, 30 and 48 mm and leads of 5 and 10 mm. Compact cylindrical single nuts and flange single nuts grant a high degree of freedom for designers. With the new planetary screw assemblies, Rexroth covers dynamic load capacities of up to 231kN and static load capacities of up to 475kN. In addition, a split flange single nut allows for the assembly to be preloaded for zero clearance.

In manufacturing the screws, Rexroth benefits from its experience in the economical roll-forming process. This technology, which has proven successful in large series production, achieves the same accuracy levels as the more expensive grinding process. Rexroth supplies the planetary screw assemblies ready-to-install with machined ends.

For a list of specifications as well as available features and accessories please visit

Bosch Rexroth AG is one of the world’s leading specialists in the field of drive and control technologies. Under the Rexroth brand name, the company supplies more than 500,000 customers with tailored solutions for driving, controlling, and moving. Bosch Rexroth is a partner for Mobile Applications, Machinery Applications and Engineering, Factory Automation and Renewable Energies. The company provides customized solutions tailored to the needs and specifications of each individual market. As The Drive & Control Company, Bosch Rexroth develops, produces, and sells components and systems in over 80 countries. As part of the Bosch Group, Bosch Rexroth and its 38,400 associates generated approximately 6.4 billion euros ($8.9 billion) in revenue in 2011.

To learn more, please visit

In the U.S., Canada and Mexico, the Bosch Group manufactures and markets automotive original equipment and aftermarket products, industrial drives and control technology, power tools, security and communication systems, packaging technology, thermotechnology, household appliances, solar energy, healthcare telemedicine and software innovations. Having established a regional presence in 1906, Bosch employs over 22,500 associates in more than 100 locations, with sales of $9.8 billion in fiscal year 2011, per preliminary figures. For more information, visit

The Bosch Group is a leading global supplier of technology and services. According to preliminary figures, more than 300,000 associates generated sales of 51.4 billion euros ($71.5 billion) in the areas of automotive and industrial technology, consumer goods, and building technology in fiscal year 2011. The Bosch Group comprises Robert Bosch GmbH and its more than 350 subsidiaries and regional companies in some 60 countries. If its sales and service partners are included, then Bosch is represented in roughly 150 countries. This worldwide development, manufacturing, and sales network is the foundation for further growth. Bosch spent more than 4 billion euros ($5.5 billion) for research and development in 2011, and applied for over 4,100 patents worldwide. With all its products and services, Bosch enhances the quality of life by providing solutions which are both innovative and beneficial. Further information is available online at and


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Susan  Strauss
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