Calibration of Torque Wrenches
Calibration of Torque Wrenches
(OP)
We recently had our AS9100 audit and something came out of it that we didn’t expect. Torque wrenches not calibrated. Now granted, we only use them to tighten machining fixtures on certain CNC jobs but we were still told they needed to be calibrated.
I have no idea what sizes of torque wrenches we have in the plant, but I need to get started somewhere.
1. Does anyone know of any NIST traceable torque standards to test the wrenches against?
2. What is an acceptable tolerance for torque wrenches?
3. If it is out of tolerance can our in-house calibration team repair one (like we do with mics or calipers for instance)?
Any information or incite will be greatly appreciated!
I have no idea what sizes of torque wrenches we have in the plant, but I need to get started somewhere.
1. Does anyone know of any NIST traceable torque standards to test the wrenches against?
2. What is an acceptable tolerance for torque wrenches?
3. If it is out of tolerance can our in-house calibration team repair one (like we do with mics or calipers for instance)?
Any information or incite will be greatly appreciated!





RE: Calibration of Torque Wrenches
2. To do it right you really should work that in with an overall fastener preload control strategy for the facility. Or just go for +/- 5%.
3. Yes.
RE: Calibration of Torque Wrenches
Having said that, and dependent on the type of tooling-manual clicker/beam/dial type, hydraulic or pneumatic types, or even the planetary gear powered torque multipliers, are all generally 'calibrated' against something like a Skidmoore unit or the newer electronic versions. You might want to ask you tooling supplier about re-certification of your tools to meet your audit requirements.
Rick
RE: Calibration of Torque Wrenches
For dial indicating types you are comparing the reading of the wrench's dial to the reading on the calibrator. Calibration varies by manufacturer, but generally involves turning an eccentric, moving a pivot in a slot, or carefully bending a tiny part.
For beam types you are also comparing the reading to the calibrator. There is really no way to adjust the calibration, but then again there really isn't much that can go out of calibration either.
RE: Calibration of Torque Wrenches
RE: Calibration of Torque Wrenches
Here is what my friend said , "" Oh yes, those damned torque wrenches! xxxxx finally listened to me and got ours done, even got some new ones that read correctly!
You need to have the wrenches calibrated/tested through a reputable calibration Lab. xxxxx uses DZ Calibrate from El Cajon.
Torque wrenches should be within 1 increment +/- or less for accuracy.
He-he, it is such a fun adventure going through the audit process. We officially have our certificate now.""
This is from a person who has just spent 9 months getting a company up to speed on AS9100
B.E.
RE: Calibration of Torque Wrenches