Investigating Metal Detection Issues: Testing Metal Samples

During our magnet checks, we have been finding small pieces of metal; this has been happening on and off for a few weeks. We've been investigating the issue by going through our production processes, etc., but haven't found the source. Is there a way to "test" the metal or compare it to samples of metal? Any advice would be helpful as we are confused about where it comes from.

Thanks!

What are you checking with the magnet? 

and what is your process flow chart? 

It is not uncommon to find metal swarf on magnet wand. Has your MD been rejecting such samples? 

We run power material through our magnets. We don't have a MD. 

I would take a look the equipment leading up to the magnets and examine them for damage. If you're finding actual little chunks of metal then there should be some wear visible. Things like Mills, Pumps, Augers, etc can all be common sources of FM when they become damaged. You may have to disassemble equipment pretty thoroughly to find the source of the damage.

If all your equipment seems undamaged then you should turn your focus to the product itself, perhaps your ingredients have been contaminated by FM. If you're buying powder for instance, the supplier's equipment may be introducing metal.

To answer your question though, "testing" metal for its source isn't something I'm aware of. Most food equipment is made of stainless steel, so I guess if you determined that the metal was something that equipment couldn't possibly be made of then that could rule somethings out...but to me that's an unorthodox approach to this problem.

What type of power or powder? 

I meant powder....things like sugar, salt, acidulants 

we've tried going back to the suppliers regarding the metal source and they deny that it's from them--so that is a dead end. 

All of the equipment we use is stainless steel. It is hard to tell what metal and from where it could be without having "samples" to compare the metal from. 

Thanks for your help!

So the powder does not go through further processing at your facility? You test them in the same state you received them? 

Well, stainless steel is an iron alloy and will be picked up by magnet. 

Do you wipe the magnet after each use? How is it stored? 

From my first job at a spice company when we had these situations in powders and granulated product, we would setup a magnet in a hopper direct feeding into a fresh package (poly lined box 99% of the time), then we would dump product over the magnet to evaluate the raw material.  Pull some random cases of the product, run it, record the findings.  If you're finding the metal in raw, that's a pretty slam dunk case to say the supplier is on the hook:  document the evaluation with pictures and a solid write-up of the process/findings, deliver it to them and demand a CAPA.  If nothing is found, process the material/lot as normal and see what you get in your process.  I will say we were pretty notorious for powdered metal in our product after milling, just a side effect of mill blades and mill liners wearing out from the friction.  We ran multiple magnets throughout the process to reduce the powder and would investigate when larger metal shavings were discovered.  Most of the time the larger metal shavings was from raw inputs (dried slice vegetables from the previous manufacturing step), but in one instance I remember we started discovering metal from a new screw conveyor that the owners bought.  Ran fine when empty, but it was large enough that the weight of product on the auger would cause it to shift and strike the sides.  That whole deal was a nightmare...

There is equipment out there that can tell you what kind of metal it is then could narrow it down to what in your system is made of that metal.  Of course you'd need to know what all type of metal is used in the equipment to help narrow that down.

We talking metal dust, flakes, or bigger pieces?

I meant powder....things like sugar, salt, acidulants 

 

we've tried going back to the suppliers regarding the metal source and they deny that it's from them--so that is a dead end. 

All of the equipment we use is stainless steel. It is hard to tell what metal and from where it could be without having "samples" to compare the metal from. 

 

Thanks for your help!

I think you really need a metal detector.

Frankly, we can then provide quite specialised equipment and services.

There is a piece of equipment called an X-ray Fluorescence Spectrometer that may be what you need, but it is expensive and I believe your sample may be too small.

Metal detectors are widely used, simple, reliable and inexpensive.