Justifying an Analogue Weighing Scale for Compounding Industry

K

KCIPOH

#1
Hello everyone,

I'm in the pvc compounding industry, meaning we are doing pvc pelletize as our end product which is the raw material for our customer.

We are using analogue weight scale (max weight of the scale unit is 10kg) to weigh the weight of the liqiud chemical and lately, one the weight scale has broken, so i manage to get a spare unit from the other side of factory which is very bad condition.

Existingly, we have a unit of digital weight scale for weight the weight of the pvc pelletize for packing. In order for me to justify whether the spare unit can be use and accurate, i took a paper bag (net weight is 25kg), put it on the digital scale and pour in the pvc pelletize start from 1kg and the bag i transfer to the spare unit to see it would give me the same reading and back to digital scale, add another 1 kg and transfer again to the spare unit scale to see the reading continually until max 10kg.

I would like to seek advice from the cove members whether my method is correct when i want to justify the scale to be use in my production.

Thanks and appreciate :confused:
 
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S

Sturmkind

#2
Re: Justify an analogue weight scale for compounding industry

KCIPOH;

You are certainly on the right path! Make sure that the scales are linear across the expected operating range as will. If you are only using 10 kg and your process is OK with a 1-2 kg error, then this approach is OK.

Two roads to go would be to do 16 iterations for a formal regression analysis or just do a formal GR&R with 2 people, 5-10 Bags, 2 trials.

Hope this helps!
 
K

KCIPOH

#3
Re: Justify an analogue weight scale for compounding industry

Hello Sturmkind,

Thanks for your verification and i know at least what i do is on track, but currently, we only weigh the liquid chemical weight, base on the formulation and no tolerance been set till now, 1-2kg is totally out of requirement as few grams different will result in a huge difference in the pelletize hardness and color as well.

What is the meaning of 'iteration', 'regression analysis', can you explain further on what is the meaning of 'to do 16 iterations for a formal regression analysis' as i haven't come across this method before.

Thanks and appreciate.
 

BradM

Staff member
Admin
#4
Re: Justify an analogue weight scale for compounding industry

Hello everyone,

I'm in the pvc compounding industry, meaning we are doing pvc pelletize as our end product which is the raw material for our customer.

We are using analogue weight scale (max weight of the scale unit is 10kg) to weigh the weight of the liqiud chemical and lately, one the weight scale has broken, so i manage to get a spare unit from the other side of factory which is very bad condition.

Existingly, we have a unit of digital weight scale for weight the weight of the pvc pelletize for packing. In order for me to justify whether the spare unit can be use and accurate, i took a paper bag (net weight is 25kg), put it on the digital scale and pour in the pvc pelletize start from 1kg and the bag i transfer to the spare unit to see it would give me the same reading and back to digital scale, add another 1 kg and transfer again to the spare unit scale to see the reading continually until max 10kg.

I would like to seek advice from the cove members whether my method is correct when i want to justify the scale to be use in my production.

Thanks and appreciate :confused:
If I understand what you are saying, you are making comparisons from the digital scale with the analog scale. First, I do admire you resourcefulness.:agree1: However, I'll take it that since you placed this in the calibration forum, that you are trying to make some calibration statement in regards to the analog scale. I guess I'm asking, what are you trying to do here? What kind of "qualification" are you trying to make on the analog scale?

What you're doing may be fine. But there might also be a lot of potential errors associated with this comparison. I don't think I would make any accuracy statements on the analog scale based on this comparison.

Sorry:eek:; another question. What is the purpose of using the analog scale? Why not just use the digital scale?

What is the meaning of 'iteration', 'regression analysis', can you explain further on what is the meaning of 'to do 16 iterations for a formal regression analysis' as i haven't come across this method before.

Thanks and appreciate.
It's great that you asked. :agree1: Sturmkinds suggestions is that you should do this comparison (from digital to analog) a number of times and record the readings that you are getting (iterations). Then, you can take these numbers and perform a regression analysis based on all the variables. What you will be doing is giving yourself a "prediction" tool of sorts.

If I use this bag, with these pellets, and place it on the digital scale just so, weigh it, and then place that bag on the analog scale, based on previous values, it should yield X result on the analog scale. Does that make any sense?
 

Al Rosen

Staff member
Super Moderator
#5
Re: Justify an analogue weight scale for compounding industry

What is the meaning of 'iteration', 'regression analysis', can you explain further on what is the meaning of 'to do 16 iterations for a formal regression analysis' as i haven't come across this method before.

Thanks and appreciate.
16 iterations = perform the test 16 times.

Regression analysis = Method to determine how the dependent variable behaves in relation to the independent variable. For more information on this you can GOOGLE "Regression Analysis".
 
K

KCIPOH

#6
Re: Justify an analogue weight scale for compounding industry

Hello BradM,

First of all, thanks for your explanation and question. Well, basically what i'm doing are just to qualify the old analogue scale which i think can be use to replace another spoiled analogue scale. so i do a comparison of reading between the digital scale and analogue scale to see if they yield the same reading for each kg i weighted.

For your information, the analogue scale are use to weigh the weight of the liquid chemical which will splash a bit when come out from the metal drum and because of this reason, we only use analogue scale instead of digital scale.

And your last sentence 'If I use this bag, with these pellets, and place it on the digital scale just so, weigh it, and then place that bag on the analog scale, based on previous values, it should yield X result on the analog scale. Does that make any sense', yes, this is what i'm doing, compare the reading of analogue scale with digital scale to justify whether the scale can be use or not.

I'm always welcome for any further suggestion from you guys.

Thanks and appreciate:thanx:
 
K

KCIPOH

#7
Re: Justify an analogue weight scale for compounding industry

Hello Al Rosen,

First of all, what is the best way to address you? Thanks.

Thanks a lot for your explanation on the iteration, but i still need more simple explanation to understand the 'regression analysis', i'll try to go through the site you recommended and see how first.

Thanks and appreciate :thanx:
 
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