Scales Checks

IFSQN Hi,

What are peoples opinions on scales checks and the weights used to test them along with justification. Ive joined a buisness where they use 4 different weights to check each scales, using either one or a combination. You could spend half a day just doing all the combinations!  I come from a buisness that just used 2 different weights to check the scales, each corner and centre for each type of weight.

Your thoughts please.......

Thanks

DW

Hi DW,

I would suggest that you have a daily check with the weight placed at the centre of the platter. Use weights that reflect the weight of the product used, so if your products are all 80  - 120g, then a 100g weight will suffice. If you have a 400g product using the same scales, then also use a 500g weight.

Monthly (or weekly) checks will use a wider range of weights at all 5 points on the platter (4 corners and the centre). I suggest from 1/10th to 2 - 5 times the expected weights (10g - 500g for 100g expected weight etc). Use 1g tolerance. Anything out of tolerance at any point should be considered broken and therefore unusable.

Hi DW,

 

I would suggest that you have a daily check with the weight placed at the centre of the platter. Use weights that reflect the weight of the product used, so if your products are all 80  - 120g, then a 100g weight will suffice. If you have a 400g product using the same scales, then also use a 500g weight.

 

Monthly (or weekly) checks will use a wider range of weights at all 5 points on the platter (4 corners and the centre). I suggest from 1/10th to 2 - 5 times the expected weights (10g - 500g for 100g expected weight etc). Use 1g tolerance. Anything out of tolerance at any point should be considered broken and therefore unusable.

Thanks BrummyJim, we are on the same page. I like the idea of a daily and a monthly check which i hadnt considered

Cheers

DW

Your check must cover the 'working range' e.g. 100 - 600g for a 1kg scale, you must at least check a point <100g, 300g (optional), 500g (optional) and 700g.

Yong.

Hi Yong,

BRC doesn't specify how scales are calibrated, just that they should be (on a risk assessed basis of course!!!). Do other standards differ? In all the sites I've worked (only 4) we've taken the above approach - check your target value.

IFSQN Hi,

 

What are peoples opinions on scales checks and the weights used to test them along with justification. Ive joined a buisness where they use 4 different weights to check each scales, using either one or a combination. You could spend half a day just doing all the combinations!  I come from a buisness that just used 2 different weights to check the scales, each corner and centre for each type of weight.

 

Your thoughts please.......

 

Thanks

DW

Hi DW,

I go along with most of previous basic ideas. I tend to daily use one checkweight close to intended target and, similar to Brummy, 2-3 checkweights bracketting the target at weekends.

I find most of the IT documents on this topic statistically incomprehensible but the 2 "simple" prodecures below looked reasonably complete and  understandable.

From a quick look the quoted weight error tolerances are mostly around +/- 0.1-0.2 % of the reference weights >100g or so (there are some noticeable differences in the two example tables given though).

IMEX the possibilities/tolerances also operationally relate to what you are packing/guaranteeing, eg pieces weighing 5g each may necessitate a rethink.

May also need some flexibility if balance is located underneath an air-conditioner.

SOP 1 - balance calibration.pdf   978.76KB   104 downloads

SOP 2 - balance calibration.pdf   210.76KB   68 downloads

Your variance will also depend on the LEGAL requirements of your packaging type in your country. If you are packaging catch weight (i.e.pack says 100 grams, you pack anything from 100 to 110g per pack), you need to be sure what the law allows for variance. In Canada, there is a federal division for weights and measures that you also must comply with. The governing body for weights and measure may also have a calibration requirement and it is being used for trade.