Co-ordinating the micron

Paul Boughton

High performance linear actuators from THK are being used in a new co-ordinate measuring system to provide exceptionally high levels of accuracy, with a measuring frequency of 1kHz and a resolution that is less than 30nm, and a maintenance-free operating life of up to 10 years.

The VC-10 co-ordinate measuring machine is designed and built by the German company, Optacom, and have been developed for use in a wide range of industries, from aerospace and motorsport to electronics and medical devices, where high levels of precision are required for both one-off and volume production parts.

The VC-10 measuring machine has two precision linear axis, in the X and Z directions, offers a large measuring area of 170 x 175mm and self-calibrates in under three minutes.

In addition, the system is the first of its kind to feature a fully automatic contour recognition system, making analysis much faster, reliable and precise than was previously possible.

Key to the success of the new VC-10 is the use of THK's advanced linear motion technology, with the company's latest SKR linear actuators being used in both axes to provide exceptionally high levels of resolution and repeatability.

SKR linear motion actuators offer a unique combination of rigidity, accuracy and reliability in compact, maintenance-free units. This is achieved through the use of THK's patented Caged Ball™ technology, which is incorporated within each actuator to improve overall performance, with the load-bearing ball races being arranged in such a way that the capacity load is spread uniformly in the radial, reverse-radial and lateral directions.

Perhaps most importantly, the use of Caged Ball technology reduces levels of friction, heat and noise to an absolute minimum, significantly enhances both positional accuracy, to within ±0.02mm, and positional repeatability, to ±0.003mm, while allowing the coordinate measuring probes to be moved smoothly at high speeds.

For Optacom a further important factor in the choice of THK linear motion technology was the durability of the SKR guides, which have to last without maintenance for the projected 10 year lifetime of each machine.

Additionally, Optacom needed a supplier that could ensure product availability worldwide, so that even if a guide did develop a fault it could be replaced locally in the minimum of time.

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