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Product category: Actuators, motion systems, etc
News Release from: HepcoMotion | Subject: GV3 linear motion system
Edited by the Manufacturingtalk Editorial Team on 03 March 2004

Linear motion system keeps tapes in
check

Linear motion system enables a fully automatic Class 1 laser tape measurement bench to measure within +/-20 microns with a base accuracy of 1.1 micron per metre.

The UK's leading measuring tape manufacturer, Fisco Tools has moved into a quality assurance league of its own with the in house installation of a purpose built, fully automatic Class 1 laser tape measurement bench The system is the only one of its type in the world

This investment allows the automatic verification and calibration of Fisco's steel measuring tapes up to 50m in length to EC Class 1, a standard that demands an accuracy of +/-.2m in the first metre, which is the same degree of accuracy that is provided by a rigid steel ruler.

Achieving Class 1 is a two stage process.

The first step is to print to Class 1 accuracy and that is assured by Fisco's in-house developed inkjet printing system.

"However, we cannot sell a product as Class 1 unless we can prove it," explains Engineering Manager, Stan Burton.

"So we needed a system capable of measuring to +/-20 microns." To put this into perspective, a human hair is 70 - 100 microns and a grain of talcum powder, 10 microns! In fact, the machine base accuracy of the final installation is 1.1 micron per metre - around 1/75th the thickness of human hair.

Central to the measuring apparatus hardware is a 32m long Hepco GV3 linear motion system that has been laid to 0.1mm level and 0.1mm straightness and is guaranteed to maintain this accuracy for a minimum working life span of ten years.

The GV3 is the main rail system for transporting the tape blade unwind/rewind carriage and camera carriage that houses the laser reflector.

"During a measuring cycle when the carriages are at rest, we have total stability of less than 1 micron," Burton explains "This is thanks to Hepco's variable pre-loaded bearings that give better rigidity than even the most expensive ball bearing systems.

Although high accuracy journals are available from Hepco, this was achieved with its standard components.

During an early trial, an alternative linear slideway was tested on a one metre long test bed.

"Despite being very expensive, we couldn't adjust the pre-load," Burton continued.

"I could push the carriage and move it by microns." This performance was not good enough for Fisco.

The Hepco linear slides were supplied in 4m sections, manufactured in consecutive numbered lengths, finally totalling 32m.

"One extra length needed to be added in much later in the building phase," Burton continued.

"And even though it was a matched section, the lengths joined exceptionally well." Any out-of-true joints were unacceptable.

Even a variation of just 10 microns would be sufficient to cause the laser reflector carriage to vibrate, losing the beam and data.

Another major advantage of the Hepco Generation slideways cited by Fisco was the machineable edge opposing the hardened vee runners.

This proved invaluable for mounting sub-components directly to the slide sections.

"Other manufacturers were considered but they could only offer systems that were much more expensive and far less flexible." Burton concluded.

The new laser system is located at Fisco's factory in Rayleigh, Essex in its own temperature controlled room.

National Weights and Measures accredited, it is also approved and used by Trading Standards to verify other manufacturers measuring tapes. Request a free brochure from HepcoMotion ...

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