Innovations offer smoother movement

Tom Shelley reports on state of the art developments with regard to bearings and achieving smooth linear movement

All mechanical mechanisms depend on bearings. Crucial to maintaining low friction and long life is ensuring continue integrity. Recent developments include new surface coatings that insulate the bearings from damage caused by the passage of electric current in large motors, and intelligent lubrication systems.

To provide electrical insulation, Schaeffler's 'Isotect A' can be applied to the external surface of the inner or outer rings. Depending on operating temperature, resistance can be up to 10Gohm. Capacitative impedance for bearings used with motors attached to variable speed drives, which often work at high frequencies, can be ensured by choosing appropriate layer thicknesses. If greater protection is required, the company offers ceramic rolling elements across most of its bearing range.

But, much benefit can be obtained by merely ensuring continued lubrication. Austrian manufacturer, Hollitzer Baustoffwerke Betriebs-Gesellschaft, believes it is saving up to €450,000 a year in maintenance costs and production downtime by installing FAG Motion Guard Concept 6 lubrication systems on the vibrating screens at its quarry. Previously, bearing failures at the site averaged between four and six a year, each of which cost €20,000 in machine downtime and €70,000 in lost production.

For linear bearings, THK has brought out its LG guided ball bushing that greatly increases load capacities and includes an integrated anti-twist feature. Four raceways with circular arc grooves are evenly positioned round the circumference of the shaft and inside the nut. In comparison with a conventional product using point contact, load capacity is increased by a factor of 2.4 to 3.8. The new products are initially available with shaft diameters of 4, 6 and 8mm.

Swiss based bespoke bearing manufacturer Jesa specialises in the manufacture of steel ball bearings which are over moulded with plastic. It has produced a special bearing that includes an innovative solution for large sliding doors. It was originally conceived by the company's UK managing director, Roger Cornwell. It uses a double over moulding of softer plastic onto hard plastic, with metallic elements to reduce noise and improve surface adhesion.

"We have produced many variations on the basic design to meet specific project needs," says Cornwall. "We produced elegant ones for home use, high tech versions for avant-garde architects and motorised ones for really big industrial doors."

Heason Technology has launched a new modular actuator range for pick and place and other sample dispensing applications for life science and other analytical equipment. The PLA range has an extruded anodised aluminium housing that uses a stepper motor to drive a leadscrew and recirculating ball linear guide bearings. The range is supplied with microstepping drives and a motor controller.

For designers of heavier duty machines, Linear Motion Systems based in New York has announced its TechnoMod Gantry Machines. These are multi axis motion platforms complete with controls, cabling, software and enclosure, all fully assembled. The platforms are available in three different sizes and can be used for pick and place, dispensing, assembly, drilling, routing, welding and general automation applications.

Author
Tom Shelley

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