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Machining Magnets

Hi guys. I need to machine away the corner of a neodymium magnet that needs to go into a hole in a mold. One of the passages for a core intersects the hole the magnet is going to get pressed into. There really isn't any other place to put the magnet, and the core is a necessary part of the casting.

Any tips or suggestions?

The best thing I can think of is to just use the little bench top belt grinder.

The problem is if the prototype is satisfactory I may find myself making a bunch of these molds. Hand grinding one is no big deal. 20 or a hundred... well that could be pretty time consuming.

I know they are fragile. That's why I think grinding is the best option for just one. I do not want to put a grinding wheel on one of my mills, and the little no-name mill drill still comes in handy from time to time (I used it today), so I'm not crazy about filling it up with grit either.

Reply to
Bob La Londe
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What I've read about those magnets is that they aren't recommended for machining as the dust is easy to ignite. Also if using to hold a core in a mould IIRC the magnetic properties are lost at low temperature of less than 100C so you may be better off looking for another solution.

Reply to
David Billington

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"Machining the magnets will generate heat, which if not carefully controlled, can demagnetize the magnet or even ignite the material which is toxic when burned."

Reply to
Jim Wilkins

What I've read about those magnets is that they aren't recommended for machining as the dust is easy to ignite. Also if using to hold a core in a mould IIRC the magnetic properties are lost at low temperature of less than 100C so you may be better off looking for another solution.

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Igniting dust could be an issue. Thanks.

If it holds until the mold closes its fine. No its not holding the Teflon (or sometimes brass) core pin in place. ;^) They just both need to occupy the same space at the same time, and since I have not yet mastered phasing matter, then grinding some away is the next best option.

Using a magnet in this type of application is a tried and true technique. Most just don't use it because they are mass producing and time is money. For custom its well worth it. Maybe less so if every magnet has to be customized.

Reply to
Bob La Londe

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"Machining the magnets will generate heat, which if not carefully controlled, can demagnetize the magnet or even ignite the material which is toxic when burned."

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Well since it looks like ordering a shorter length magnet to go in the hole is a better option I looked and found that KJ magnetics has rare mags rated for high temperature use. Now to see if there is somebody who can get them here in a day or so for less than $74 shipping.

Reply to
Bob La Londe

formatting link
"Machining the magnets will generate heat, which if not carefully controlled, can demagnetize the magnet or even ignite the material which is toxic when burned."

*********

Well since it looks like ordering a shorter length magnet to go in the hole is a better option I looked and found that KJ magnetics has rare mags rated for high temperature use. Now to see if there is somebody who can get them here in a day or so for less than $74 shipping.

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McMaster to the rescue. LOL. They were typically outrageously more expensive, but they had some much higher temperature neodymium mags that will work ok, and I needed to order some fill in drill bits, teflon rod, and a couple other things from them anyway.

Reply to
Bob La Londe

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