Monthly Archives: May 2014

The clever ball bearing selection process with this Sigma workstation is our new Data I/O card

A Load of Balls for Sigma

Could this be our most intriguing Sigma application? Okay, some of you may ask “What’s Sigma?” as it is perhaps our best-kept secret. Despite our secretiveness, there are quite a few Sigma workstations being pressed into service in the marketplace. This particular application sees the hand assembly system selecting ceramic ball bearings for precision ball races.

The real power behind the clever ball bearing selection process with this Sigma workstation is our new Data I/O card. This accessory permits Sigma to be programmed to offer parts based on live incoming data – in this case a measurement being made of the precision ball race cage. Once this fine-tolerance measurement is passed to Sigma, the workstation presents the assembly operator with the best matched set of ceramic ball bearings from the appropriate tray of a single motorised carousel. It then guides the picking process using a suction cup, allowing the operator to take eight ceramic balls.

These ceramic ball bearings vary minutely in size, due to the natural tolerance of the manufacturing process. However, when each ball is accurately measured, sets of the same size (strictly gauged within very tight tolerance parameters) can be grouped into a carousel tray segment. Sigma knows the exact measurement of each of these ball sets and offers them up according to the incoming measurement via Sigma’s Data I/O card. It’s essentially blue-printing – a procedure used widely in the performance automotive sector, especially for sports car and motorcycle engines. In this way, the assembly operator can only build a ball race to the exact measured quality.

Talking of performance, these premium ball races make their way into turbocharger units, where rotational velocity can exceed 150,000 rpm! At these speeds, any slack or play in the ball race could cause catastrophic vibration. Similarly, while ceramic balls are less prone to thermal expansion, a bearing race that is too tight can seriously degrade rotational performance. That’s why the precision measurement and matching process is so critical. And that’s also why the Sigma workstation with its new Data I/O card is so important.

The turbo units manufactured by this Sigma customer are used in top-brand German performance cars.