Machine elements for use in vacuum conditions and clean rooms

Increasing miniaturisation of manufactured products means that both front-end research and development and downstream production and assembly processes have to be performed under clean room conditions.

A clean room is an environment that has a low level of environmental pollutants such as dust, airborne microbes, aerosol particles and chemical vapours. These rooms are normally fitted with sophisticated air conditioning systems, airlock entry and exit  systems for personnel, as well as certified monitoring instruments. Clean rooms are used extensively in semiconductor manufacturing, biotechnology, liquid crystal manufacturing, medical and life sciences, as well as other processes that are sensitive to environmental contamination.

A clean room has a controlled level of contamination that is specified by the number of particles per cubic metre at a specified particle size. For example, the ambient air outside in a typical urban environment may contain as many as 35 million particles per cubic metre, each particle being 0.5µm and larger in diameter, corresponding to an ISO Class 9 clean room.

Schaeffler UK offers a range of rolling bearings, linear guidance systems, direct drives and lubricants for use in clean room environments.

By working closely with independent research institutes, Schaeffler’s industrial laboratories are able to classify the company’s bearings, linear guidance systems and lubricants for clean room environments, certified for particle emissions according to ISO 14644-1.

Extensive analysis is carried out on these products, including outgassing behaviour, electrostatic discharge (ESD) and mechanical efficiency. Most of the analysis is performed in cooperation with the Fraunhofer Institute based in Stuttgart, Germany. Measurements are carried out on Schaeffler products in clean rooms according to ISO class 1. This involves maintaining a displacement flow with low vertical turbulence under consistent operating conditions.

John Loonam, Linear Product Specialist at Schaeffler (UK) Ltd comments: “Whereas clean rooms themselves are classified according to international specifications based on airborne particulate concentration, machine elements such as rolling bearings and linear guides do not have their own air volume or air supply system, and so are not classified into clean room classes.”

“Measurement of particle emission is therefore used to determine the clean room suitability of machine elements. However, such measurements are not covered by international standards. The method used at Schaeffler is extremely thorough and measures particle emissions over a fixed period at positions with the highest particle emission.”

Schaeffler’s range of monorail guidance systems comprise linear recirculating ball bearing units that are available in two-, four- and six-row versions. All metal parts can be made from corrosion-resistant martensitic steel. The customer can also choose units with a very low magnetic permeability. Where robust construction is required, the customer can specify end pieces that are made from corrosion-resistant steel, which provides resistance to gamma radiation and is suitable for use in vacuum and clean room applications.

Schaeffler also offers a range of lubricants that are suitable for use in linear guidance systems and rolling bearing clean room applications.

Based on a synthetic oil and polyurea thickener, Schaeffler’s Arcanol CLEAN M multi-purpose grease offers significantly lower particle emissions in linear guides and rolling bearings compared to standard grease. Arcanol CLEAN M is also suitable for moderate vacuum conditions and enables longer service intervals and reduced maintenance of guides and bearings.

For more information, please visit or telephone the marketing department on 0121 351 3833.

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