A few comments
Placing a magnet on a clean surface and wiping clean with a clean cloth to remove any material works well with older magnets. I have heard of a brush being used but this could end up being a risk with loose fibres. If you use water remember to dry effectively if this may impact your product.
With new installations consider having a non magnetic section for cleaning eg with a pole magnet a small section at the end (not in the process stream) can be non magnetic, this would allow the use of a pushing tool to move the material to this spot at which point it would drop off. This method is a lot easier than the cloth method.
Avoid dropping the magnet or subjecting it to high temperature cleaning as this can reduce the strength of the magnet
Consider having a findings classification guide with different corrective actions eg milling processes often have low levels of fine metal powder as normal. This could require a different corrective action to high levels of fine powder or coarse findings.
Consider testing the magnet periodically using a gauss meter or by doing a pull test. I have not heard of defined critical limit but from experience tend to plan to replace at 6K gauss.
Consider modifying the magnet that cannot be removed so it can be. How can you effectively clean a magnet when you cannot fully access it?
It is worth considering using magnetic stainless steel prior to the magnet if deemed needed. An example could be on a wire screen. Keeping in mind magnetic stainless steel does not lend itself to all processes.
Whilst I don’t consider magnets good enough for a final inspection they serve their purpose as a good early indicator and they are cheap enough compared to other FM devices.
Hope this is of some help.
hello QLD,
Since you have cleaning procedure for magnet? Do you have any record / form to fill-up by your personnel (operator) as a proof of evidence during cleaning activity?
Can u send me a draft / format of the form / record for me to adapt.
Hope you would respond and share u're ideas.
Thank you!
Regards ,
Christine :)
Edited by QAD_Rebisco, 09 October 2013 - 03:23 AM.