Torque monitoring equipment used for 100% inspection of automotive assemblies

July 2000
INA Bearings is the third largest bearing manufacturer in the world and has factories throughout employing over 24,000 people. The Llanelli, South Wales, site produces engine tappets, rocker shaft assemblies and cam belt tensioners for virtually all of the European automotive manufacturers. It also produces ball bearing inner and outer rings for heavy duty and military vehicle applications.

When a new production line was brought on stream to produce self-adjusting belt tensioners, the company realised that it would need 100% torque testing to ensure that the tensioners would provide the full range of adjustment required in service. To enable this, INA invested in TMAC (torque monitoring and control) equipment from Crane Electronics.

Once assembled, the tensioners are located on a test rig where the TMAC ensures that each assembly is free to pivot within a closely defined torque range of between 1Nm and 2Nm. At the same time, the TMAC records the properties of every torque test, and there is a facility to download the relevant statistics if required for conformance with the quality assurance regime.

Connected to the TMAC is a Crane CheckStar rotary transducer. Drive from the tool is transmitted to the tensioner assembly through the CheckStar, which measures the applied torque properties of every test operation.

Keith Prescott, a Production Engineer at INA, comments:

“When we started production of the new self-adjusting cambelt tensioner, we identified the need for critical torque testing of every assembly before delivery to customers. I had used Crane TMACs and CheckStars previously on other applications and was aware of the system's capabilities. I was confident that they would suit this application.”

INA also utilises a Crane TorqueStar digital data collector for general torque testing on various applications. The TorqueStar is used in conjunction with another CheckStar rotary transducer for measuring, recording and calculating the dynamic capability of all types of nutrunners. Furthermore, being completely portable, the TorqueStar is ideal for use on different production lines throughout the factory.

“Since we have been using the Crane Electronics equipment on the new belt tensioner line, we have been confident that we are ensuring the highest standards of quality control for every product”, confirms Mr Prescott. He adds: “We are now planning to use similar equipment for 100% torque checking of nuts on rocker shaft assemblies.”