Torque Wrench Calibration 101

Posted by Ellen Smith on Aug 29, 2016 11:00:00 AM

A ruler. A measuring cup. A stop watch. What do all of these things have in common? These measuring devices are part of everyday life whether we’re doing routine home improvement projects, cooking, or participating in sports. To ensure that a newly purchased refrigerator fits in the kitchen, a cake successfully rises or the fastest swimmer is awarded the Olympic gold medal, it’s important that measuring devices are accurate. The Merriam-Webster Dictionary defines accurate as able to produce results that are correct: not making mistakes. The importance of accuracy is even greater when the measuring device is used to design, build and maintain aerospace engines and aircraft and safety is at stake.
Wrench_with_Drill_Adapter.jpgWhat is Calibration?
To ensure accuracy, measuring devices are calibrated on a regular basis. Calibration is defined as the setting or correcting of a device by adjusting it to match a dependably known and unvarying measure. It compares the reading from the device that is being calibrated to a standardized measure, and the results are presented on a calibration certificate. A torque wrench, which is used to precisely apply a specific torque to a fastener such as a nut or bolt, is an example of a tool that requires regular calibration. When used in aerospace applications, an inaccurate wrench may over-torque or under-torque a bolt which could lead to aircraft failure and the increased likelihood of an accident resulting in injuries or even fatalities. Regular calibration reduces the possibility of inaccurate measurements and reduces the period of time in which an inaccurate tool could be used. To maintain the accuracy of these tools, the industry recommends that a torque wrench is calibrated every 12 months, at a minimum. For wrenches that have very high accuracy specifications or are used on highly critical fasteners, the calibration window may be narrowed to 6 months or less.
How is a Torque Wrench Calibrated?
Environmental conditions and processes for calibration services are tightly regulated and must be followed closely by service providers. Any company providing these services must use specialized equipment, trained staff and defined processes. Calibration equipment must be at least four times more accurate than the wrench that it is being calibrated and requires regular calibration itself. The calibration lab’s environment must be kept at controlled temperature and humidity levels which are then recorded on the calibration certificate. A standardized calibration process ensures accurate results and a rapid turnaround to reduce time out of the field. Calibration certificates issued are traceable to the National Institute of Standards and Technology (NIST), a non-regulatory federal agency within the U.S. Dept. of Commerce which promotes U.S. innovation & industrial competitiveness by advancing measurement sciences, standards and technology.

Standard data provided on Advanced Torque Products' calibration certificates include:

  • Wrench model and serial number
  • Equipment used to calibrate
  • Maximum capacity of wrench
  • “As Found” Clockwise and Counterclockwise torque readings at multiple forces throughout the scale of the wrench
  • “As Left” Clockwise and Counterclockwise torque readings at multiple forces throughout the scale of the wrench
  • Angle Verification values, if applicable
  • Calibration technician’s name
  • Room temperature and humidity
  • Calibration date
  • Calibration frequency
  • Next calibration due date

Advanced Torque provides calibration services for Click-Out and Hand-Held wrenches, TruCheck Torque Checkers, and ATP Digital Torque Wrenches. In addition to our ATP products, we also provide calibration services for many other brands on the market. Calibrations are done at our Newington, CT location by an experienced calibration team knowledgeable on a wide range of products. The importance of regular and timely calibration services for torque tools cannot be underestimated when these tools are used on highly critical aerospace applications. To schedule a torque wrench calibration, visit the ATP website and complete the online Customer Request Form or call 860-828-1523.

Topics: Torque Wrench Calibration