Question on Scales and Accuracy Required

Hello -- we have a recurring problem with calibration of a scale in manufacturing.  The scale is capable of reading to thousandths place (e.g. 1.000), but it is in a harsh environment, and is always found out of calibration by our service.  It is not enough off to cause an issue with out label weight, but it means I have to write up an OOS report every time, and it looks bad on audits.  Our packaging label weight is only to hundredth place (e.g. 1.00). 

Question - what level of accuracy do we have to calibrate to?

Thanks!

Robyn

Can you get a different scale that is not so sensitive?  

No ... but I think it's more of the level we require the calibration service to calibrate to.  They are happy to certify the scales to a lower accuracy, but I am not sure if the norm is to be more accurate (sensitive) than required.

If the scale company can certify it to the hundredth place and you can get an accurate reading (i.e. it's not bouncing around)  I see no reason that you can't use that.  I'm not an expert in weights and measures though so hopefully more people will comment.  

Also, what makes the environment 'harsh'?  Can you build a protective cover around it possibly?  

I normally use 1% of my "target" value as the minimum level of calibration/verification necessary. Anything further is just gravy, and in your case it may be more of a headache. Come up with realistic tolerances in which you are "out of calibration". You can still have them certify the scale to a tighter precision, but your daily "verification" or test weight activity can have a larger range than the actual calibration event provided it doesn't impact how you're using the scale.

Thanks - I'll work with the calibration service to see what their allowed variances are.  daily verifications are good (since we are not checking to the accuracy that the calibration service is).