Corrosion-resistant linear motion products from stock

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Corrosion-resistant linear motion products from stockCorrosion-resistant linear motion systems are required in many industries, including food, beverage, electronic, medical products and pharmaceutical production, as well as nuclear engineering and research and development. While most manufacturers make provision for this need, HepcoMotion says that it goes one important step further: the company's policy is not just to offer a stainless steel or corrosion-resistant option, it is to provide this choice within its standard range. From a specifier's point of view, this brings important benefits; instead of being a 'special' that is subject to long lead times, popular sizes of the HepcoMotion corrosion-resistant linear motion systems are available ex-stock.

The HepcoMotion range also provides technical advantages too. There is, of course, a trade-off between corrosion resistance and long life. Non-magnetic stainless steel is the most corrosion-resistant type, but it is also relatively soft and, therefore, generally unsuitable in linear systems under load or subject to high duty cycles. In designing its various systems, HepcoMotion has been highly selective in the materials it chooses to achieve the best compromise between corrosion resistance and durability.

Although many components are made from AISI 400 series stainless steel, HepcoMotion also uses other materials too. For example, it offers lightweight aluminium carriage plates and flange clamps that have a special anodised surface treatment that is claimed to provide corrosion resistance as good as that of stainless steels. This finish is approved by the US Department of Agriculture for use in food processing machinery. Various coatings are also available for applications where an alternative to stainless steel is practicable.

The slideways in HepcoMotion's corrosion-resistant systems are typically machined from martensitic stainless steel conforming generally to AISI 420, but HepcoMotion says it has the edge on corrosion resistance here too. The company has invested heavily in capital equipment to provide a superior surface finish and, in simple terms, the better the finish, the less likely surface corrosion will be evident. Slideways ground all over for maximum corrosion resistance are also highly durable; V-edges are typically hardened to 52 HRC.

Maintenance-free for arduous operating conditions

For those seeking maximum corrosion resistance in a linear motion system, HepcoMotion offers its SL2 stainless steel range. These products use many of the standard slide options in the company's flagship GV3 series for general automation but in ground stainless steel. The system is designed to be maintenance-free and is therefore suitable for use in arduous conditions.

The proven Hepco V concept and the quality of the manufacturing process provide the SL2 system with its inherent smooth-running and low-friction characteristics. These qualities enable it to operate dry, without lubrication, for sensitive applications. In most circumstances, however, the system can be equipped with cap seals that prevent the ingress of dirt, provide positive lubrication and extend service life. Greases used can be high-temperature resistant, food-compatible or to a suitable nuclear engineering application specification.

All bearing assemblies are of stainless steel construction and available in either twin-bearing or double-row format. They are hardened and precision ground to special tolerances and raceway conformity to suit the application. The double-row assembly has a high radial load capacity and is eminently suitable for harsh environments and high-speed conditions where extra long life is required. Both types are supplied lubricated for life but, for applications where low-level radiation is a consideration, they can be supplied with special grease lubrication internally. Special bearing greases for high-temperature and food-compatibility can also be provided similar to the lubrication products used in the cap seals.

Of course the corrosion-resistant options are not just restricted to basic X-Y linear systems. HepcoMotion offers standard ground rings up to 1.6m diameter. The choices extend from small sizes for light load applications to high-capacity rings for heavy indexing requirements. Complete ring and track systems with multiple carriages are available for packaging, medical device manufacture and for filling lines. Heavy-duty single- and double-edge systems complete with stainless bearings up to 95mm in diameter may be specified for high-load applications where corrosion resistance is required.

There are also various driven options too. Corrosion-resistant products are contained in the standard DLS belt-driven product programme for high-speed applications in hostile conditions. And consistent with the company's commitment to integrating corrosion resistance within all its new product programmes, there is also an appropriate version of the small and highly cost-effective belt-driven system, the PDU (profile driven unit), that was recently introduced.

For HepcoMotion corrosion resistance is as much a standard consideration as load or speed and its products can be supplied as individual elements or complete assemblies and systems. The choice is extensive but it enables the company to provide the optimum requirements for both the application and the budget.

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