7 replies to this topic

[SauceManinKS]

Hey Everyone,

First timer post, i had an auditor tell me i should have my magnets tested annually for a pull test. they are not used as a CCP only as a back up / extra security in our MAYO lines. What are your thoughts and experiences with this? My facility is in food sector category 18 and 21 in the SQF category system. 

[SauceManinKS]

Sorry First timer mistake, Title should not be Raw but Rare Earth Magnet. typo whoopise

[Bansal]

Hi,
As per standard if the equipment is used for safety, quality, legality, it should be documented and calibrated.

and if your documentation shows them that you have this, you have to have the calibration done.

Hope this helps!

Thanks

[jfrey123]

Magnets are usually deemed too ineffective to be a CCP, as they only capture ferrous metals; but once you've determined they have a job to do in your process, you do need to verify that they are doing it effectively.

 

Magnets do lose their strength over time.  The pull test can be done with a simple kit in house.  It's been close to 10 years since we did one, but in my first spice plant we did this every 6 months on all the magnets.  The company had a procedure written with limits for each magnets (I wish I could remember how we established the strength limits, I think the manufacturer can provide you with the initial strength rating).  I think for that program, if magnets were outside spec by 10%, we replaced them.

[SauceManinKS]

this is great info team. thanks for all the feedback. im in contact with the manufacturer to get the details 

[Charles.C]

Magnets are usually deemed too ineffective to be a CCP, as they only capture ferrous metals; but once you've determined they have a job to do in your process, you do need to verify that they are doing it effectively.

 

Magnets do lose their strength over time.  The pull test can be done with a simple kit in house.  It's been close to 10 years since we did one, but in my first spice plant we did this every 6 months on all the magnets.  The company had a procedure written with limits for each magnets (I wish I could remember how we established the strength limits, I think the manufacturer can provide you with the initial strength rating).  I think for that program, if magnets were outside spec by 10%, we replaced them.

Re ^^^^(red) - Ahem.

 

Non-ferrous means does not contain iron.

 

What metals will a magnet not stick to?

 

Most of them, actually. The only metals that magnets DO stick to are called “ferromagnetic,” and these are iron, cobalt, and nickel, a few of the “rare earth” metals (and so you’re not likely going to encounter those), and many of their alloys (such as most steels). But none of the other common or familiar metals, such as aluminum, copper, lead, silver, zinc, platinum, tin, chromium, uranium, titanium, tungsten, etc., etc., are attracted to a magnet .

https://www.quora.co...-ferrous-metals

 

Magnets can be CCPs when they are the only, significant, hazard-remover present or possibly when part of a combination CCP with a MD (latter maybe misses small particles).

 

IIRC from earlier threads the minimum effective "power" is 10,000 Gauss.

[jfrey123]

Re ^^^^(red) - Ahem.

 

Non-ferrous means does not contain iron.

 

I think I'm missing the point your apparent correction here.  In my experience, people using magnets in their food safety programs commonly refer to ferrous and non-ferrous metals, and acknowledge that stainless steel is technically a ferrous that's unlikely to be captured on a magnet.  So when I stated ferrous metals stick to magnets, you highlight it, and link to a quora article stating the exact same thing (except to refer to it as ferromagnetic), what were trying to show me?

[Charles.C]

I think I'm missing the point your apparent correction here.  In my experience, people using magnets in their food safety programs commonly refer to ferrous and non-ferrous metals, and acknowledge that stainless steel is technically a ferrous that's unlikely to be captured on a magnet.  So when I stated ferrous metals stick to magnets, you highlight it, and link to a quora article stating the exact same thing (except to refer to it as ferromagnetic), what were trying to show me?

Hi jfrey,

 

Sorry if my comments were unclear. Was just trying to point out that magnets only capture magnetic materials. This includes some  non-ferrous metals as indicated in my Post.

 

Although typical magnets (unlike metal detectors) are not sensitive to non-magnetic material they may have (HACCP) significance  In some circumstances/hazards and be associated with  CCPs (eg Post 6).

 

JFI here is some background material on metal/magnetic features.

 

Using basic definitions -

Metals which contain iron are classified as "Ferrous" . And, conversely, for "Non-Ferrous".

 

Briefly -

Many/Most Ferrous metals are magnetic. But some are not.

Many/Most Non-Ferrous metals are not magnetic. But some are.

 

Examples of all 4 permutations are illustrated in the following Excel -

 

 Magnetic Characteristics of Some Ferrous,Non-Ferrous Metals.xlsx   9.02KB   8 downloads

 

Some relevant links -

 https://en.wikipedia...re-earth_magnet

https://www.thyssenk...-steel-magnetic

https://www.magnetmf...u-need-to-know/

https://blog.thepipi...steel-magnetic/

(contentious)

https://www.meadmeta...ls-are-magnetic

https://www.mtm-inc....ess-steels.html

 

Regarding some roles of Magnets in food processing/HACCP -

 

https://amrconsultin...etal-detectors/

https://www.magnatta...etal-detectors/

 

Magnets/CCP are discussed a few times on this Forum, eg -

 

https://www.ifsqn.co...magnets-as-ccp/

https://www.ifsqn.co...critical-limit/

https://www.ifsqn.co...et-trap-as-ccp/

https://www.ifsqn.co...ts-and-sieving/

(based on above, one common magnet problem if categorized as a CCP is  to define an associated Critical Limit. The latter is often handled (arguably fudged) via criteria based on magnet strength).

 

 

PS - just to example the type of "arguments" that exist  in the Magnetic Literature-

https://blog.thepipi...nferrous-metal/

 

PPS - trivial quiz question - if 316 Stainless Steel is guaranteed non-magnetic, then how do Process Metal detectors detect it ???

 

@SMKS - this Post details material on evaluating magnet strength -

 

https://www.ifsqn.co...ry/#entry150040

 

yr use of a "backup" magnet might be interpreted as implying you consider that there is a significant chance of (magnetic) metallic hazards occurring in yr process flow/output. This belief could prompt some auditors to query why the magnet is not a CCP  or possibly why no MD ? (such risk logic has often been used to support associating a post-Packaging MD location as a CCP).

Edited by Charles.C, 22 May 2023 - 01:54 PM.
edited