Electronics Manufacturer benefits from fastener torque monitoring and in-house Calibration

August 2000
As manufacturers of navigational equipment, Raytheon Marine needs to ensure that all of its products will give reliable service, even under the most arduous of conditions. Radar and depth reading equipment, as well as auto-pilot systems, form some of the standard range of equipment produced by the Portsmouth-based company. To ensure that the threaded fasteners are tightened to the correct torque settings, Raytheon always uses and Crane Electronics’ digital torque testers for their regular electric torque drivers calibration.

With threads as small as M2 used in plastic parts, it is imperative that every torque driver is calibrated correctly to prevent over-tightening and thread-stripping. The use of Crane digital torque testers for calibration of its torque drivers means that Raytheon can be certain that they are giving the correct output at all times. Around 200 torque drivers are used by the company, all of which are calibrated by just two digital torque testers.

Raytheon Marine has an operator in each production cell who is designated with responsibility for calibration. As the Crane torque tester is so easily portable, the operator can take the unit to the production area and do all of the testing there without disrupting production. Screws as small as 2mm are used to hold PCBs on to plastic mouldings, so the fastening torque is very critical. “The Crane testers ensure that our equipment is always performing to the required standards,” says Mr. Richard Johnson, Production Engineer at Raytheon Marine.

The digital readout gives a HI, OK or LO indication, which makes the Crane instruments very easy to use. Up to 200 readings can be stored and printed, with all readings having a date and time stamp. Available with capacities of 1, 2, 4, 12 and 30Nm, the torque testers are fully portable and are suitable for spot-checking of electric and pneumatic screwdrivers and nutrunners, as well as impulse tools and hand torque wrenches.

To ensure consistency, Raytheon calibrates each of its torque drivers on a monthly basis using the Crane digital torque testers. However, the torque testers need to be calibrated every 12 months and the company carries out its own annual calibration in-house. Richard Johnson continues: “We need to calibrate our drivers all of the time, so we went to see how Crane calibrated the torque testers. They were very helpful to us and now we do our own calibration in-house using beams and weights.”