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#1 Prasant

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Posted 20 January 2014 - 04:04 PM

Hi All,

 

I need some help here. I had my SQF audit and got a Major non conformance with my Metal Detection which is my CCP. Here is what happened :

 

The auditor wanted to check the CCP. The test wand when passed alone were detected. Then he passed the Test wands with the product in different way such as under, above, front, back etc. It was detected every place except the Non Ferrous not being detected in one out of the three occasion. I understand there is weak point in every metal detector and its not always possible to target the weak point in your test.

 

He gave me a major non conformance for this and asking me to re validate my metal detection.

 

I have the below questions

 

1) Is this a major or minor non conformance ? Please give me your inputs.

 

2) What is the best way to test the metal detector ?

 

3) How do I re-validate my metal detector. I validated my metal detector with the Health Canada and Supplier guidelines on the metal detection.

 

Your valuable input and expertise would be highly appreciated.

 

Thanks in advance.


Edited by mapry2, 20 January 2014 - 04:06 PM.


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#2 cazyncymru

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Posted 20 January 2014 - 05:18 PM

 I re validate my metal detector each year. Mind you, mine is more for Tesco & BRC rather that SQF.

 

I write a report laying out what I'm going to do. This includes

 

  • Taking into consideration packet size and contents
  • Tabulation of all the metal detectors on site, together with identification of rejects mechanisms to be verified to ensure that it is correct.

  • Confirmation that all test pieces used in the business are recorded against each metal detector.

  • Confirmation that each test piece is certificated

  • Equipment that has an air line fail safe to be identified.

  • Confirmation that the air line fail safe is functional (Checked Daily by QA)

  • Memory test carried out as per the above guidelines. (Carried out daily by QA)

  • Confirm audible or visual alarms on lines are functional

  • Confirmation that metal detector boxes are locked. (Checked By QA/ Supervisor daily)

  •  Information from service reports including set up sensitivities etc. (Calibration Folder)

  • Trending product rejects for metal contamination

  • Trending Customer Complaints for metal contamination.

  • Confirmation that belt speeds can only be altered by an engineer via key access.

  • Sensitivity is set up by the engineer on service and cannot be altered

  • Checks were carried out with the test piece at various positions in the pot, and also with the test piece in the middle of the pot. They were also checked at various positions on the belt (ie to the sides and in the middle)

  • The metal detectors were also checked with product at various temperatures, including mixing temperature, packing temperature and chill temperature.

  • Confirmation of the metal detectors have a bin full or reject confirmation alarm.

 

 

I reference

Guidance from Mettler Toledo - “Reduction of Metal Contamination – Building an effective programme “, Tesco COP 375 – Metal Detector & XRay Systems and Loma “A Guide to Metal Detection in the Food Manufacturing Industry”

 

Hope this helps

 

Caz x



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#3 Snookie

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Posted 20 January 2014 - 06:18 PM

What type of product are you running and what size test pieces are you running?


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#4 Prasant

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Posted 20 January 2014 - 06:27 PM

Thanks Caz.

 

Snookie,

 

We pack frozen fruits and our test wands are 2.5 Fe, 2.5 Non Fe and 3.5 SS



#5 Nara

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Posted 21 January 2014 - 01:50 AM

validate the metal detector must be do every week until 3 month. after that you can do verification metal detector with metal test card everyday



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#6 Charles.C

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Posted 21 January 2014 - 05:14 AM

Dear mapry,

 

Unfortunately the SQF viewpoint on "validation" is well-proven on this forum to be inconsistent in various possible ways. And one of them is between SQF auditors.

 

As I read it, yr OP omitted to mention your own routine (?)  validation procedure  (eg test / frequency) in the audit  which then led to the NC?

 

I'm also not entirely clear as to the meaning of yr tem  "re-validation" in current context ? Do you mean that the auditor simply wanted you to modify yr existing routine  "validation" procedure ?

 

Some people would certainly interpret re-validation as per Caz's detailed post #2  but I suspect that is not what you (terminologically) meant ?

 

IMEX (not SQF), many auditors do not (in routine production) expect a  "full", eg Tesco style, repertoire for "validating" a MD and nor do all the equipment manufacturers include such detailed recommendations either.

 

But, unless yr standard says/implies otherwise, the auditor usually wins, or paraphrasing American Football, wins "in the event that no good reason can be offered to change it". Based on previous threads here, for SQF, the auditor always seems to win. :smile:

 

@Nara, Maybe i misunderstand yr post but it seems to imply that you are prepared to risk a recall of 1week's production in the event of a "validation" failure ? This is unusual.

 

Rgds / Charles.C


Kind Regards,

 

Charles.C


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#7 Prasant

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Posted 21 January 2014 - 03:40 PM

Thanks all.

 

Charles, thanks again for the valuable information. In my verification procedure, I pass the test piece with the product every hour. I never had any issue when passed with the product.

 

The auditor wanted to verify the metal detector and asked me to pass on many different location. When he put on the product, then I had this issue. This is because of the weak point in the metal detector.

 

So the auditor feels that my metal detector not working which is not 100% true. He wants me to start over again with my metal detector.

 

I wanted to change the sensitivity of Non Ferrous from 2.5mm to 3.0mm to cover this weak point.

 

Any guidance how to incorporate this change ?

 

Thanks.



#8 Mr. Incognito

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Posted 21 January 2014 - 03:47 PM

Well if your going to change the sensitivity it would be good to discuss it at a food safety team meeting so that it's documented and then you'll have to change your work instruction / form as applicable.  And of course you are going to need to run some testing to make sure it works properly.

 

I think that's a pretty high level of sensitivity if I remember right I've never seen them higher than 2.0mm.  If you use any recycled packaging I'd make sure your not looking at a sensitivity too much stronger than they are or you may kick off due to packaging.


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#9 Prasant

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Posted 21 January 2014 - 03:59 PM

Thanks MerleW.

 

In my situation I have frozen product in laminated bags. And my Metal Detector head has an aperture size of 450mm wide x 250 mm high.

 

Mu supplier recommendation is 2.5-3.0mm Non Ferrous. I read somewhere that there is a relation between Aperture size to Sensitivity limit. It says one you have more than 200mm high, then the recommended sensitivity should be 3.0 for Non Ferrous.


Edited by mapry2, 21 January 2014 - 03:59 PM.


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#10 cazyncymru

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Posted 21 January 2014 - 04:02 PM

Mapry2, get hold of a copy of the Mettler COP. I'm sure you can download it. It explains it all in there, brilliant document.

 

Alternatively, you can down load the whitepaper from Safefood 360

 

Caz



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#11 Snookie

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Posted 21 January 2014 - 08:18 PM

I had auditor want to test a product not on the product line.  We were happy to accommodate him.....after all he's the auditor, but when we went to adjust the machine for that product: he was going to give us a critical finding for a non-working CCP.  After a long intense discussion it was changed to a finding which I disputed (the only time I ever disputed audit findings). I eventually got most of our points back. 

 

IMHO, metal detectors are tricky and a pain in the lower posterior region and too many people do not understand them (this does not include the many knowledgeable people here). 

 

 

You may want to check with the maker of your equipment.  Machines are often built for specific products and frequencies so even if your customer wants a specific sensitivity, your machine may not be capable of it,  especially based on the food type, packaging and many other factors.  In the fresh produce industry 2.5 Fe, 3.0 non-Fe and 3.5 SS is about the lowest achievable and based on pack size it still can be darn tough with some of the best equipment.  Based on your machine, product and specifications you need to determine where your machine is the most stable (this will most like necessitate a factory trained technician), as many things can set them off.  Many customers want as small as possible, but as long as your under 7 your under choke hazard and if it is sharp, any size is a risk.  We all want it safe, but we can be limited by the technology. 


Edited by Snookie, 21 January 2014 - 08:19 PM.

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#12 Simon

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Posted 21 January 2014 - 09:24 PM

Maybe take a look at this webinar presented by Mettler Toledo at Food Safety Live 2013: 

 

Designing & Implementing a Robust Foreign Material Prevention Program


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#13 Charles.C

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Posted 21 January 2014 - 10:48 PM

Dear mapry,

In my situation I have frozen product in laminated bags. And my Metal Detector head has an aperture size of 450mm wide x 250 mm high.

 

Mu supplier recommendation is 2.5-3.0mm Non Ferrous. I read somewhere that there is a relation between Aperture size to Sensitivity limit. It says one you have more than 200mm high, then the recommended sensitivity should be 3.0 for Non Ferrous.

 

 

I agree with Snookie, can be a real PITA.

 

There seem to be 2-3 issues –

 

(1) Choice of wand-sphere diameter with respect to sensitivity.

(2) Understand the auditor’s method of checking

Plus perhaps one Canadian aspect –

(3) AFAIK, Canada defines significant metal hazards as >2mm. whether this is relevant to yr MD situation I do not know. I assume (hope) it is not.

 

I am in no way a MD expert but here is one suggested solution (IMO).

 

I assume 3.0mm for non-Fe fully works for you ?

 

Re – (1)

AFAIK, yr product will be categorised as wet.

You are using a  substantial aperture size (250mm).

Both of the above reduce the sensitivity.

Assuming the above, numerous publications / tables will support yr use of  3.0mm non-ferrous wand, for example –

Attached File  met1, Tesco.doc   631.5KB   529 downloads

Attached File  met2,Loma.pdf   701.96KB   514 downloads

Attached File  met3,Fortress.pdf   90.67KB   419 downloads

 

Re – (2)

 

Again there appear to be 2 issues –

 

(a) front and back

(b) above and below

 

Regarding (a). The reason for front/back does not seem to be explained in either the Tesco or Safefood white paper as far as I could see. (The Mettler 60+ page document mentioned by Caz appears only available by post (!?) but looks impressive from the on-line preview). Perhaps the b/f logic is supposed to be obvious but it wasn't to me. :smile:

Here is a previously contributed explanation (credit Alan Johnson) which at the time seemed plausible to me. However  I hv yet to see any further explanations to compare –

 

In terms of placing metal test wand at the front and rear of the pack, most UK retailer codes of practice recommend this in one form or another. Primarily it is because a metal detector on its own does not know the position of the test wand in the pack. It can only sense (not very accurately) the position of the metal sphere as it passes through the coils. To ensure accurate rejection of the product on a conveyor based system there normally has to be a photo eye that senses the leading edge of the pack and this is wired so that the pack is positively rejected wherever the test wand is positioned. Metal detectors have been known not to reject positively without photo eyes or if the reject timing has been set badly, so the test is worse case. There are even additional test routines that check the functionality of these additional failsafe devices at the start of a production shift

 

 

http://www.ifsqn.com...tor/#entry45817

(post #21)

 

Regarding (b) the typical response with height is theoretically something like –

Attached File  met4,fortress.pdf   190.73KB   284 downloads

I assume the curve shown is (in total) "symmetrical" so if MD detects OK in the middle, should also work above and below but not necessarily vice-versa. Hence the methodology suggested in most texts to test close to the centre-line.

 

This is all approximate logic due sensitivity is governed by a host of factors additional to the above, eg as stated in the previous attachment   –

 

 

Product effect, metal free area, type and orientation of contaminant and other factors can affect the practical sensitivity in any application.

 

Accordingly the above suggestions are  welcome to be criticised by any experts around (or non-experts for that matter :smile: ).

 

Rgds / Charles.C


Kind Regards,

 

Charles.C


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#14 Tony-C

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Posted 24 January 2014 - 07:31 AM

Thanks all.

 

Charles, thanks again for the valuable information. In my verification procedure, I pass the test piece with the product every hour. I never had any issue when passed with the product.

 

I wanted to change the sensitivity of Non Ferrous from 2.5mm to 3.0mm to cover this weak point.

 

Any guidance how to incorporate this change ?

 

Thanks.

 

Hi Mapry,

 

If the detector works at 3mm then that is what I would do. There have been many debates on sizes of foreign bodies on the forums, in particular people have been looking for scientific literature to justify things like size of sieves or sensitivity of metal detectors. From memory I think the USDA recommended < 7mm but also consider special groups of consumers. Quite often this can be down to customer requirements/customer codes of practice.

 

Regards,

 

Tony



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#15 Prasant

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Posted 24 January 2014 - 04:56 PM

Thank you all for the valuable technical input here. The Admin is doing a great job here.

 

A big thank to Tony and Charles.



#16 moskito

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Posted 25 January 2014 - 12:24 PM

Hi mapry2,

 

we do similar in bakery (boxes and pouches) to what caz describes. We are driven by M&S and Tesco guidelines, especially related to test procedure and fail safe checks. Our test pieces are 1,2 FE, 1,5 non-FE and 1,8 SS.

 

Rgds

moskito



#17 Patchanzu

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Posted 19 June 2015 - 04:45 PM

The intended use of the product and the targeted consumer profile also play an important role in the determination of the  Metal detector sensitivities.e.g hard candy is not expected to be consumed by toddlers, while ice cream/cookies can be consumed by toddlers 



#18 Tony-C

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Posted 19 June 2015 - 04:58 PM

The intended use of the product and the targeted consumer profile also play an important role in the determination of the  Metal detector sensitivities.e.g hard candy is not expected to be consumed by toddlers, while ice cream/cookies can be consumed by toddlers 

 

:welcome:

 

So what do you think the difference in sensitivities should be between a product for adults compared to a product that will be consumed by children?

 

Regards,

 

Tony



#19 Petronela

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Posted 11 May 2016 - 07:30 AM

 I re validate my metal detector each year. Mind you, mine is more for Tesco & BRC rather that SQF.

 

I write a report laying out what I'm going to do. This includes

 

  • Taking into consideration packet size and contents
  • Tabulation of all the metal detectors on site, together with identification of rejects mechanisms to be verified to ensure that it is correct.

  • Confirmation that all test pieces used in the business are recorded against each metal detector.

  • Confirmation that each test piece is certificated

  • Equipment that has an air line fail safe to be identified.

  • Confirmation that the air line fail safe is functional (Checked Daily by QA)

  • Memory test carried out as per the above guidelines. (Carried out daily by QA)

  • Confirm audible or visual alarms on lines are functional

  • Confirmation that metal detector boxes are locked. (Checked By QA/ Supervisor daily)

  •  Information from service reports including set up sensitivities etc. (Calibration Folder)

  • Trending product rejects for metal contamination

  • Trending Customer Complaints for metal contamination.

  • Confirmation that belt speeds can only be altered by an engineer via key access.

  • Sensitivity is set up by the engineer on service and cannot be altered

  • Checks were carried out with the test piece at various positions in the pot, and also with the test piece in the middle of the pot. They were also checked at various positions on the belt (ie to the sides and in the middle)

  • The metal detectors were also checked with product at various temperatures, including mixing temperature, packing temperature and chill temperature.

  • Confirmation of the metal detectors have a bin full or reject confirmation alarm.

 

 

I reference

Guidance from Mettler Toledo - “Reduction of Metal Contamination – Building an effective programme “, Tesco COP 375 – Metal Detector & XRay Systems and Loma “A Guide to Metal Detection in the Food Manufacturing Industry”

 

Hope this helps

 

Caz x

Hi caz x,
 

I know this post a year ago but I hope you or the others can help me because our company has just started BRC certification.

I want to ask about "Confirmation that each test piece is certificated"
Do you mean all the test piece has certification?? for example thermometer should have certificate of calibration so does the test piece as well right???

 

Sorry, My English is not very good so I just want to get clear information about test piece certification so I can talk to my boss to buy it because my boss wants to make it by himself.  :smile: 

Thank you... 



#20 Petronela

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Posted 11 May 2016 - 08:17 AM

Hi caz x,
 

I know this post a year ago but I hope you or the others can help me because our company has just started BRC certification.

I want to ask about "Confirmation that each test piece is certificated"
Do you mean all the test piece has certification?? for example thermometer should have certificate of calibration so does the test piece as well right???
 

Sorry, My English is not very good so I just want to get clear information about test piece certification so I can talk to my boss to buy it because my boss wants to make it by himself.  :smile: 

Thank you... 

I want to ask one more question, Our Auditor told us that he need the photos to prove that we had bought 3 testing pieces for metal detector. Do we have to buy the testing pieces or we can just use a third party for our metal detector testing??

 

thank  you :smile:






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