Checkweigher Calibration
The company that built the machine have created a rather bespoke machine to suit our pack range and the size of the production line. Also the software was created by "a n other" company and I am struggling to get precise information, I am assured it will all come together and it is a while off being finished yet.
To clarify, I am after the calibration tolerances not the T1 and T2 figures used for average weight systems.
We pack a range of pack weights all as average weight systems from 200g to 2500g
Thanks in advance, Mike
I can understand your frustrations as most of the checkweighers out there do not carry the same manufacturer of the actual machine and software. I am pretty good with the different types of software, but I would need to know which it is before I could assist you in calibration techniques. Please include the names and program version.
A.McCreary
programme.
I was hoping somebody would give me some + or - weight % or maybe the was an industry guidline etc!
Mike
I was hoping somebody would give me some + or - weight % or maybe the was an industry guidline etc!
Mike
Well in regards to this, each country has its own weights and measurement acts. You must check the guildlines for your country, usually it invovles package declared weight for each particular product you intend to weigh. Typically you must meet or exceed the declared weight.
Definitions of units of measurements and the provision of the technical equipment relating to weights and measures in the UK are provided by the National Weights and Measures Laboratory, an agency of the Department of Trade and Industry. I would start there.
Hopefully this helps.
Well in regards to this, each country has its own weights and measurement acts.
You are quite correct. This was the significance of caddyshacks mentioning the t1,t2 system which is standard within the EC. USA no idea
@Caddyshack - Clearly the tolerances utilised must be adequate to deliver compliance with the existing regulations. I realise this does not answer the original question but i fear a meaningful operational answer may require knowledge of the specific process, eg typical size of pieces of product etc.
Rgds / Charles.C
Can anybody help me on the formula for calculation of the "ZOI" (Zone of Indecision) for my checkweigher?.
Is it simply the range the machine displays when a known weight is passed over the machine several times?
I was told once that the ZOI should be 6 x the SD (Standard deviation) although this doesn't stack up on my machine, my local trading standards office could not help either!!
Regards
Caddyshack
Is this what you want ??
11 Annex F Checkweighers and other automatic instruments
F.1 The place of checkweighers in the average system
F.1.1 The requirements to be met by checkweighers in order to be usable for the checks made by the
packer under the Directive are dependent on the type that is used and their manner of use. There
are no restrictions on the precision of measurement required in the use of checkweighers, but
conditions are laid down for allowances covering tare weight variation of containers and the ‘zone
of indecision’ of the set point.
The ‘zone of indecision’ is the extent, expressed in units of mass, of the zone within which the
machine may take two contrary decisions with respect to the same load. The value of the zone of
indecision is taken as equal to 6xstandard deviation of the accept/reject distribution.
The ‘set point’ is the value, in units of mass, at which the instrument is set to accept/reject product.
http://www.welmec.or...cations/6-5.pdf
Rgds / Charles.C
PS looks like this document is the (original) standard item but my guess is you hv already. It knows yr problem but all my attempts to find the appendix D referred below led to dead links
http://www.nmo.bis.gov.uk/Docs/Legislation/Packaged%20Goods/Packaged%20Goods%20Regulations%202006%20issue%202.pdf7. Set points need to be set to ensure that all three packers’ rules are complied with
continuously, and needs to take into account the zone of indecision and variability of the
weight of packaging (tare).
8. Where the zone of indecision (ZoI) is greater than 0.25 TNE then the set point
should be increased by 0.5ZoI – 0.125TNE.
9. Where the tare variability (standard deviation) exceeds 0.1 TNE then a simple
way to address this is to add an allowance of 0.85s on to the set point.
10. For further information on determining the zone of indecision and establishing
appropriate set points see Appendix D of the Packers’ Code.
PPS - some very nice maths in first refs !
yu might also find this set of typical specs (inc yr ZOI) for a Sartorius interesting
http://www.sartorius...sheet-SYNUS.pdf
Dear Caddyshack,
Is this what you want ??
http://www.welmec.or...cations/6-5.pdf
Rgds / Charles.C
PS looks like this document is the (original) standard item but my guess is you hv already. It knows yr problem but all my attempts to find the appendix D referred below led to dead links
http://www.nmo.bis.g...20issue%202.pdf
PPS - some very nice maths in first refs !
yu might also find this set of typical specs (inc yr ZOI) for a Sartorius interesting
http://www.sartorius...sheet-SYNUS.pdf
Cheers Man!!
Nice to see you posting again.
Hope everything OK post delivery.
Rgds / Charles.C