Magnets being destroyed

[KPHYDRA]

Hi,

I work with Hydraulics and we're having problems with a magnet on the piston.
The magnet is being destroyed, probably because we're using 350 bar pressure and the piston stops instantly, the pressure destroys the magnet. Magnet measurements: Ø24/Ø10 x4 mm.

Pictures:

http://imgur.com/ChYsKDE,ZKmubgB

Do you guys have any suggestions what to do? Is it possible to get magnets in a more "robust" material, something that does not break upon impact?

Regards,

Kenneth

 

[MagMike]

Practically all permanent magnets are brittle. You could look into flexible ferrite magnets (fridge magnets), but I doubt they would be strong enough for your application.

The best solution is to protect/isolate the magnet from the pressure.

 

[BrianE22]

Do you know how strong a magnet you need? Maybe you could magnetize a piece of low carbon steel.

 

[EdStainless]

You need to re-design so that the load is carried by a steel pole piece, and that the magnet just provides field.
Magnets are not suitable structural materials.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[StoneCold]

Maybe you could switch from a hall effect sensor to a proximity sensor and then just have a raised steel section that is detected when the cylinder reaches the set point.
Assuming it is cylinder location you are interested in and not something else. Different cat.

Regards
StoneCold

 

[hacksaw]

Please clarify your picture. It is not clear what part of the image displayed is the magnet.

 

[mikekilroy]

not sure what I see either, but would kevlar banding over the magnet help?

http://www.KilroyWasHere<dot>com

 

[hacksaw]

The OP might consider submitting his query to the forum dealing with with mechanical seals.

 

[hacksaw]

The valve pix included in the original post appears to be a cartridge, axial orifice style of hydraulic valve.

The wetted parts are likely austenetic stainless and only weakly magnetic, but the greatest concern appears to involve elastomer seal failure.

Perhaps the OP might consider reposting his question in the valve forum or the one dealing with mechanical seals or better yet contact the manufacturer.

 

[djhurayt]

Not sure but my interpretation of the photo is that the crumbled looking material to the lower right of the photo (between the two flanges) is the magnet that KPHYDRA is having issues with. And is not an elastomer seal as it seem hacksaw may have interpreted it.

If that is correct, KPHYDRA, do you think it is the pressure or the sudden stop (repeatedly I assume) that is causeing the magnet to impact the flanges on each side as the piston fires one direction or the other?

Not sure how this piston/magnet is assembled but if it is a multiple piece assembly, would it be possible the place a wave washer on each side of the magnet to give it some cushion when coming to an abrupt stop ???

david

 

[hacksaw]

It would help a great deal in the discussion if the valve model number was included.

I have to say that I've never seen magnets included in the wetted parts of any valve design, and am curious as to how a permanent magnetic on a valve stem would benefit the operation of the valve.