How to find Uncertainity in a Torque Wrench?

[berlinmony]

Dear All,
My company has set up a torque wrench calibrating unit for our Internal Purpose.
We have a Master Gauge.
With the guidelines form ISO 6789:2003 i was confused how to find the Uncertainity for Torque Wrench.
However after googling I couldnot find an easy way to acheive the uncertainity Value..(All the softwares i tried or more complicative and confusitn)?
Is there any easiest way to find the Uncertainity Value?
Pls help.ur answers ASAP will be unforgottable!
in Advance!

 

[Miner]

See MSA - Torque Wrenches - Statistical studies that cover requirements of MSA, Post #16. I realize that you are asking an Uncertainty question, but the responses that I made to the MSA question are relevant here.

A torque wrench is not a gauge. Therefore, uncertainty is not an issue.

A torque wrench is a process. Therefore, capability is a issue.

A torque analyzer is a gauge, and uncertainty is an issue.

A torque wrench may be set using an torque analyzer. The ongoing output is capability. A torque analyzer measures the output of a torque wrench. Therefore, it is a gauge, and uncertainty is an issue.

 

[berlinmony]

Dear Sir,
Thanks for the reply.But why 80% of the torque wrench carries the test results Uncertainity Value +/- 1% k=2

Pls answer for this..

Berlin

 

[Miner]

That is a good question to which I do not have the answer.

I can speculate two possible reasons. First, the belief that a torque wrench is a gage is very widespread. Second, it might be a measure of the inherent variability (capability) of the wrench to produce a given torque.

 

[AndyN]

Dear Sir,
Thanks for the reply.But why 80% of the torque wrench carries the test results Uncertainity Value +/- 1% k=2

Pls answer for this..

Berlin

Possibly for a couple of reasons (or combination of reasons):-

As Miner says a torque wrench is not a gauge but many people believe it is, so maybe they have asked the supplier/makers for uncertainty and this is what they publish, based on a study someone did.

Maybe the supplier/maker doesn't know any different. This is what I've found to be the case.

I do know a very good study was done by a client of mine on their torque wrenches - they use a lot of them - and they did capability studies and found that the more you pay for a specific type of torque wrench (better quality ones tend to cost more) the better it holds a value over time/use.

 

[harry]

An interesting read: Uncertainty of measurement in torque wrench calibration