For dimensional metrology with uncertainties in the sub-urn range, micro-tactile sensors are used. Due to their fragile structures, severe damage can occur as a result of overtravel in the order of millimetres after probe and workpiece have come into contact with each other. A new design of a safety clutch is introduced, which is based on miniaturised rolling element bearings. If the forces are sufficiently low, such a bearing will act like a spring in the sub-μm travel range. Forces exceeding several mN yield a complete rolling over several millimetres with almost constant friction. Hence, no overloading of the probe occurs. For verification, a new apparatus was designed to determine the pre-rolling behaviour of the bearing in one dimension. A dynamic friction model can be deduced. In the experiments, sub-um displacements show a high repeatability over thousands of motion cycles. In combination with a 3-D micro-tactile sensor, a bearing-based 2-D clutch shows a good functionality and repeatability.
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