“Click” “type wrenches are the most widely used torque product in the world. When the set torque is reached, a click wrench typically emits an audible “click” and a slight moment of release of up to three degrees, before going positive. After the “click”, an operator should stop pulling as torque is achieved and the tool becomes positive. If not, the assembler will over torque the fastener. Even a couple extra pulls on the handle is not good. Proper use and training is required so that operators stop pulling the moment the click sound is heard or felt to prevent the fastener being over tightened.
A torque wrench is a precision tool and should be treated and maintained like a measuring instrument. A torque wrench must be properly calibrated and maintained on a regular preventative maintenance and calibration schedule.
When calibrating a click wrench it is recommended following the ISO6789 International Standard requirements. The standard covers items such as calibration methods, design requirements, and tool types. For calibrating a torque wrench, either use a torque tester or torque sensor within the range of the torque wrench.
Torque Calibration Process for a Click Wrench
- To begin, you must pre-load the torque wrench 5 times to the tool’s maximum torque capacity without taking a torque measurement. Make sure to use a calibration device that is within the proper range.
- Next set your click wrench at 20% of the torque range, and record a total of 5 torque readings.
- Next adjust your click wrench to 60% of torque range, and again record 5 readings.
- Complete final 5 torque readings with the click wrench set to 100% of the maximum torque range capacity.
- Check that all readings are within the allowable tolerance. If they are outside the accuracy limit, then adjust the wrench in accordance to the manufacturer’s instructions. Repeat torque calibration process until all torque values are acceptable.
- Now your click wrench is ready for use. It is recommended to check calibration every 5,000 cycles to ensure the best performance.
After being used, adjustable click wrenches should be turned back to the minimum scale value. This helps to preserve the spring and ensures a longer product life cycle with high precision and maintain the best accuracy.
Some manufacturing companies own torque calibration equipment and calibrate their tools “in-house”, while other companies send their tools out to a calibration lab. Be selective when choosing a lab. A facility needs to comply with quality standards. A lab that is ISO 9001 certified and ISO 17025 accredited is a good starting point.
Mountz Inc. features an experienced calibration and repair staff. Our trained technicians can calibrate and repair most any tool. Mountz provides rapid service with quality that you can trust as we offer two state-of-the-art calibration lab and repair facilities that can calibrate up to 20,000 foot-pounds.
Since 1965, Mountz’s in-depth knowledge of torque is reflected in our tool’s craftsmanship and our ability to provide solutions to both common and uncommon torque applications. We perform calibrations in accordance with ANSI/NCSL-Z540. Mountz is dedicated solely to the manufacturing, marketing and servicing of high quality torque tools.
Using a quality torque wrench makes a safer world through accuracy and precision. Controlling torque is essential for companies to ensure their product’s quality, safety and reliability isn’t compromised. The failure of a three-cent fastener that isn’t properly tightened can lead to catastrophic or latent failures. Fasteners that are insufficiently fastened can vibrate loose and excessive torque can strip threaded fasteners.