Weighing (Weight) Scales Verification - Blank weight of material

Q

qalsang

Hi

There are many weighing scales in our production floor. We use them to weigh the blank weight of material before the moulding process. The blank weights must be within a set range as specified in the process sheet.

We use a set of standard weights (certified by accredited laboratory) to
verify our scales at a weekly interval. As long as the weighs are within the
set range , we will consider the scales acceptable. Records of verifications
are kept.Weighing scales will only be sent for repair & calibration when found
faulty or inaccurate during verification.

Question : Is the above verification practise meet the requirement of TS16949,7.6 - Control of monitoring & measuring devices??
 

Stijloor

Leader
Super Moderator
Re: Weighing Scales Verification

Hi

There are many weighing scales in our production floor. We use them to weigh the blank weight of material before the moulding process. The blank weights must be within a set range as specified in the process sheet.

We use a set of standard weights (certified by accredited laboratory) to
verify our scales at a weekly interval. As long as the weighs are within the
set range , we will consider the scales acceptable. Records of verifications
are kept.Weighing scales will only be sent for repair & calibration when found
faulty or inaccurate during verification.

Question : Is the above verification practise meet the requirement of TS16949,7.6 - Control of monitoring & measuring devices??

Yes.

Stijloor.
 

AndyN

Moved On
Re: Weighing Scales Verification

As Jan said - yes!

Don't forget that once you have sufficient data to support the decision, you could reduce the frequency of the check. My experience is that the equipment is usually robust enough and cared for that you can do the checking less frequently.

You'll certainly have enough data to help you with that decision, if you record more than a 'check' or 'tick' mark to say it was done. If your people have recorded the actual indicated weight, this can be plotted to show how accurate and consistent the scales are.
 
T

trainerbob

Re: Weighing Scales Verification

Good comment on the answer. We tend to not look at our frequency of calibration once the interval has been originally determined. Even though it takes a little bit of time, it can be a big time and money saver for our organizations, which helps transform our efforts into bottom line savings.
 

BradM

Leader
Admin
Re: Weighing Scales Verification

Good comment on the answer. We tend to not look at our frequency of calibration once the interval has been originally determined. Even though it takes a little bit of time, it can be a big time and money saver for our organizations, which helps transform our efforts into bottom line savings.

That's right; it can save money both directions. If you instrument is performing below some trigger point (<25%) each calibration, you can save money by extending (without a quality loss).

Too, so many times we forget the cost of investigation. If an instrument is running along the line, the frequency needs to be shortened, or the instrument replaced.
 
B

Bangun Purba Samosir

Re: Weighing Scales Verification

Make sure that your Internal lab already met requirement:
- Adequancy of the labolatory procedures,
- Qualification of the labolatory personnel conducting tests,
- Testing of the commodity (ies),
- Capability to performthese tests correctly, traceable to he relevant process standard (e.g.ASTM),and
- Review of the related quality records.
- temperatur and Humidity

Make sure that range that you evaluate covers actual range when the weighing used, example: Your product has range 20 gr up to 500 gr, so that the calibration should cover that min that range.
If you only check at 350 gr, it does not inform your weighing condition.

Make sure calibration result have correction value below than max correction value, commonlly max correction value is from the tolerance of product. Example: Product weighed has standard tolerance +/- 3 Kg, so the calibration result should has correction below than 3 Kg, or better 1/10 x 3 = 0,3 kg (MSA).

Par bangun purba Samosir
 

Hershal

Metrologist-Auditor
Trusted Information Resource
Hi

There are many weighing scales in our production floor. We use them to weigh the blank weight of material before the moulding process. The blank weights must be within a set range as specified in the process sheet.

We use a set of standard weights (certified by accredited laboratory) to
verify our scales at a weekly interval. As long as the weighs are within the
set range , we will consider the scales acceptable. Records of verifications
are kept.Weighing scales will only be sent for repair & calibration when found
faulty or inaccurate during verification.

Question : Is the above verification practise meet the requirement of TS16949,7.6 - Control of monitoring & measuring devices??

Couple of things to watch.....

Make SURE people are wearing gloves when handling the weights, finger oil will change their value.....

Watch essentricity.....that is, you can try to hit the exact center every time but you will not.....so build in a tiny bit of room for that.....

Take the uncertainty of each weight into account also.....and remember if you put more than one weight on your scale the uncertainty is a straight add (unlike wringing in gage blocks).....

Hope this helps.
 

WCHorn

Rubber, Too Glamorous?
Trusted Information Resource
Just an add-on question regarding the scope of the requirement for calibration. Section 7.6 of the standard establishes that scope as "monitoring and measuring devices needed to provide evidence of conformity of product to determined requirements."

Qalsang's description is of blanks that are shaped into the final product in a molding process. Since the scales are not being used to provide evidence of conformity of the product, I believe the scales are outside the scope of the requirement.

I still recommend calibrating them for the company's own benefit, but if an auditor found them not calibrated, I don't think he'd have the basis for a nonconformity. What do you all think?
 
T

trainerbob

Scales or any gauges used in a "for reference only" instance are still measuring and comparing the result to some standard, requirement, or reference. Collecting data just to collect data dosen't make sense. If it makes sense to use a measuring device we want to know that that device is accurate - I would want to see verification of calibration!
 

WCHorn

Rubber, Too Glamorous?
Trusted Information Resource
Section 7.6 does not seem appropriate to me. I understand what you want to see, but I can only justify an observation, not a finding. In your nonconformnace report, what section of the standard would you cite as the requirement?
 
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