Ball screws in circuit breakers

An important circuit breaker manufacturer, looking for a totally reliable drive solution to instantly separate the heavy metal contacts in circuit breakers, turned to the Swiss company Eichenberger Gewinde that provided its robust Carry cold-rolled ball screws. These screws indeed prepare the mechanical power-on and power-off operation in the circuit breaker using helical springs. The Carry ball screws are being produced in large numbers using a cost-effective thread rolling process at the Eichenberger’s factory in Burg. In fact, during thread rolling, the material’s longitudinal fibres are not cut but diverted. The result is a compressed and extremely resilient surface which has been rolled smooth. This is essential for the long service life of a screw. In particular, the rolling friction co-efficient is 0.003 to 0.001 compared with sliding friction of steel on steel (lubricated) of 0.1 to 0.05. The excellent sliding properties of cold-rolled ball screws ensure minimal friction and provide little scope for contamination.