Bosch Rexroth saves costs with integrated measuring systems

24 July, 2017

The plant, which manufactures high-precision linear motion components such as profiled rails, runner blocks and ball screw drives, as well as entire linear motion systems, has not experienced a single instance of machine downtime, while producing materials with a repeatability of +/- 0.25 µm.

‘Total Cost of Ownership‘

Bosch Rexroth has now converted its cost savings into a ‘Total Cost of Ownership‘ tool, which allows manufacturers to calculate their own savings, as well as the potential savings for mechanical engineers and end users.

Linear motion systems require a high level of accuracy in order to function properly. For example, the highest accuracy class, UP, has a height and parallelism tolerance for profiled rails over 1000m of just 3µm. By meeting minimum tolerances, manufacturers can ensure their products are interchangeable with others of the same size.

Until 2014, Bosch Rexroth relied on optical position sensors, or glass scales, to achieve the desired accuracy with its metal-cutting equipment. These solutions were expensive because they required regular cleaning and maintenance. At times, they were even responsible for machine failures because they were prone to introducing contaminants.

Optical position sensors can cause substantial downtime because they have to be physically removed in order to be cleaned thoroughly, before being reinstalled, realigned and recalibrated. They also halt production once a year because the measuring signal of each optical system must be tested, costing more hours in downtime.

Bosch Rexroth installed integrated measuring systems (IMS) into its ball and roller runner blocks. The IMS, which can detect the absolute position of an axis down to +/- 3 µm/m, are integrated completely into each machine, saving on installation space. They are resistant to vibration, shock and magnetic interference, and do not wear over time because they measure using induction.

Unlike optical sensors, they also function without sealing air systems, saving time and costs in the maintenance of oil separators and particle filters, and reducing the risk of contamination to the machine.

Any downtime is significantly reduced because each component can be replaced individually, with any repairs taking less than an hour. The measuring systems also integrate seamlessly into a wide range of automation systems, including DRIVE-CliQ , HIPERFACE , and SSI and TTL interfaces.

Stefan Dorn, head of advanced engineering and technical product management for linear motion technology at Bosch Rexroth, said: “Accuracy requirements are becoming more exacting in virtually every metal machining sector and application. This also increases the degree of accuracy required for linear motion technology and measuring systems. To meet this challenge, Bosch Rexroth has been using its maintenance-free IMS solutions in upgraded machine tools for more than two years.

“Since replacing the glass scales, we have achieved five-figure savings in terms of maintenance costs and availability. IMS also have the potential to decrease system and assembly costs for machine manufacturers.”

1 DRIVE-CLIQ is a registered trademark of Siemens.

2 HIPERFACE is a registered trademark of SICK STEGMANN GmBH.