Verify Calibration of instron load cell.

[seesaw]

is there a way of doing a sanity check that a load cell is still in calibration. some one mentioned putting load cell upside down and placing a known calibration weight on it? is there a better way?

 

[unclesyd]

We had quite a number of instruments made by Instron and always sent the load cells back to Instron for calibration/certification.

 

[seesaw]

ya, its due for calibration in a month or two but i need to do some testing in the mean time and just want to make sure my results are pretty accurate. I perform the automatic calibration with the bluehill software but thats all. is there a simple check?

 

[gfbotha]

Don't see much wrong with your proposed sanity check, as long as the weight is such that you reach well into the load cell range. And, load it slowly.

Cheers

 

[MintJulep]

Check the entire measurement chain (cell, amplifiers, display/recorder), not just the load cell.

Applying a known force is what Instron will do at their lab, so nothing wrong with just putting a known weight on top.

Check more than one point.

Instron should give you "as-found" and "as-returned" cal plots. So you could correct your recorded data if it was way off.

 

[CoryPad]

As stated by others, you can use objects with known mass (and assume ~ 10 m/s² gravitational acceleration) and compare that force with the force the software displays. You should use the Instron-provided fixtures that connect into the force cell to "couple" your object to the cell, although there shouldn't be any need to turn things upside down as long as you can suspend the objects from the fixture(s).

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[gfbotha]

Regarding MintJulep's 1st comment: It's good advice - just 3 months ago we had "a problem" with quite an old Instron load cell - after a lot of time & effort it turned out to be a bad connection further on.

As mentioned by CoryPad: it might be more representative and also more stable to rather suspend/hang the weight.

Regards
G

 

[Mattest]

2 questions:

1) Is your query regarding tensile or compression?
2) What is the capacity of the load cell?

You will need to check it in the same direction and depending on the capacity you may be able to check with weights.

It may be that the cell has been overloaded and then you can get different results in each direction.

 

[seesaw]

It regarding compression. Its a 100 Newton Load cell.

 

[GregLocock]

spring, tape measure.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Mattest]

seesaw,
No problem you need to turn the load cell upside down and load the end stud with weights to simulate the compression mode. Ensure that the weight is centred on the load cell stud (some load cells are sensitive to off-centre loading.)

Max 10kg will be enough (100N / 9.81). I would suggest using different weights to check for linearity.

Testing machine load cells should normally be accurate from 0.2% of the maximum capacity upwards, but if you make a check at aprox 20%, 50% and 100% this will be enough for a confidence check.