Whether mechanical or electronic, precision torque wrenches require calibration because the internal mechanisms can wear, fatigue, or become jolted out of accuracy by a drop or a misuse.
How does a Calibration System Work?
A torque wrench, set at a specific value, is placed in the calibrator with the handle held stationary.
The square drive is placed into a transducer.
By use of a mechanical loader (either motorized or hand crank), rotational force (load) is applied to the torque wrench square drive. This load is very accurately measured by the system’s transducer, which sends data to the digital monitor.
Accuracy- All CDI Torque Calibration Systems have an accuracy of ±0.25% of indicated value, CW & CCW, from 10% to 100 of full scale. DTT testers are ±0.5% of indicated value, CW & CCW, from 10% to 100% of full scale. DTC checkers are ±1% of indicated value, CW &CCW, from 10% to 100% of full scale.
A.S.M.E- American Society of Mechanical Engineers. ASME sets codes and standards for mechanical & electronic devices, including torque wrenches.
Calibration Arms – Certified arm or wheel that attaches to a transducer for calibration purposes.
Calibration – The act of adjusting a torque wrench in order to bring it back within spec. ASME specifications call for wrenches to be calibrated at 3 points; 20%, 60% and 100% of their full scale.
Calibration Tray – Certified weight tray used to hang dead weight on a calibration arm for calibration purposes.
Certification (or “Cert”) – Written document included with all CDI adjustable torque wrenches and all testers and calibration systems. All certs are traceable to N.I.S.T.
Compression Gauge – This is also called a “force gag.” This is a mechanical or digital device that measures the amount of push, or compression between two forces.
Extension Arm – A mechanical arm designed for only the 2000 ft. lb. loader that allows for the testing of torque wrenches over 45” long.
Force Arm – System can perform force testing such as push-pull gages, cable tensionmeters, and dynamometers with additional components sold separately.
17025 – Laboratories use ISO/ IEC 17025 to implement a quality system aimed at improving a quality system aimed at improving their ability to consistently produce valid results. Since the standard is about competence, accreditation is simply formal recognition of a demonstration of that competence. A prerequisite for a laboratory to become accredited is to have a documented quality management system. The usual contents of the quality manual follow the outline of the ISO/ IEC 17025 standard.
Joint Rate Simulator – A mechanical device used to test power tools on transducers. The device allows the power tool to spin and simulate soft and hard joints before taking the torque reading.
Loader – A loader is the common name of the gearbox device that applies force to the torque wrench for purposes of testing or calibration. The loader applies the load by rotating the transducer while the torque wrench is held stationary. Calibration systems have either a mechanical (hand crank) or motorized loader.
Mode (First Peak) – For Micrometer & Split Beam wrenches, captures and holds the applied torque at the “click”. Used for “click” type torque tools.
Mode (Peak) – Holds and displays just the maximum torque value applied. Used for digital and dial wrenches, and torque screwdriver testing.
Mode (Power Tool) – Displays final peak average torque. Used for power tools.
Mode (Track) – Displays continuous real-time torque values as force is applied (similar to dial wrench function). Used for electronic or dial type testing.
N.I.S.T. – National Institute of Standards and Technology is a non-regulatory agency of the U.S. Department of Commerce. They are a federal agency that sets standards for weights and measurements in the U.S. All CDI torque products are calibrated with weights and arms that are traceable back to N.I.S.T.
NIST Traceable – All weights, arms and trays are certified and traceable through serial numbers back to equipment that meets N.I.S.T. accuracy standards.
Tension Gauge – Also called the “force gage.” This is a mechanical or