Jewel-bearing specialist improves metrological inspection with new measurement system

Swiss company La Pierrette has been a supplier of jewel-bearings to prestigious watchmakers since 1914, with quality, precision and reliability being its ‘key watchwords’.

The company produces a broad range of synthetic sapphires and rubies for luxury watch movements at its base; and the main purpose of jewel bearings is to reduce metal-on-metal friction

“The manufacturing of jewel bearings is a complex process because diamond is the only mineral harder than the gems that we cut. As a result, diamond machining is the only possibility, which makes for very tight manufacturing tolerances. Depending on the target characteristics, the tolerance intervals are between 2 and 8 µ, meaning that production is possible only with specially engineered machines. All this also requires many metrology operations,” explains Romain Conti of La Pierrette’s R&D department.

The company carried out its inspections using manually operated stands but because many dimensions have to be characterised repeatedly on each bearing, this process was long.

As a solution, the company is now using Keyence‘s IM Series image dimension measurement system to improve the repeatability and rate of its tests. Thanks to the system, the process is more automated and faster. Not only can the company inspect a series of pieces at the same time, but its measurements are more complete because it is possible to check for flaws in shape.

The time saving was essential at La Pierrette as it turns out several million pieces each year.

“We have to inspect every visible piece both in terms of conformity and appearance. However, our production volume allows us to inspect only a small fraction of the other pieces. The IM Series enables us to increase the number of inspections and thus improve the quality of our products. That, coupled with the fact that the IM Series allows us to directly view measurement statistics, helps us to identify production deviations much faster,” said Conti.

The image dimension measurement system makes it possible to obtain high-accuracy, reliable measurements in a minimum of time. Simply place a target on the stage and press the button. Up to 99 points are measured in a matter of seconds with a high degree of accuracy. Its automatic operation and repeatability of ± 1 µm eliminate inter-operator variability problems.





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