Milling useing a magnetic plate

[forrey45]

Hi
I originally posted this question on another site that should remain nameless and had no response.
Maybe I should have just come here first?.

I have two jobs to do;
1: A1011 steel 4 x 2 x ¾ machined all over one face removing about .35 in places.
2: 44W plate steel 3 x 1.5 x .100 machined all over one face and in places only leaving .01 thickness.

I would normally do this type of thing on the vacuum plate but there are thousands of them and I was thinking a magnetic plate would do the job, having looked on the net there are permanent styles which seem to be for grinding. Electromagnets I am not sure of in a VMC, and then the Electro-Permanent which seem ideal apart from plugging and unplugging to change parts.

Has anyone used any of these in production runs?
Would a strong fine permanent do the trick?
Thanks
Forrey.

[Boots]

I've been machining for about 40 years and I have never heard of using a Magnet to hold onto a part being machined. I can think of all kinds of reasons NOT TO DO IT. And can't think of any reasons to do it. I've only used Magnets to hold parts in a surface Grinder and sometimes use a mag base to take out the harmonics when turning on a manual lathe. But in a milling machine you are asking for trouble. Worst thing I can think of is the part moving. It would have to be such a strong magnet that you couldn't move the part with a sledge hammer. Make sure there is a strong barrier (like bullet proof) between you and the part if you are going to try it.

[Bent]

I have used a permanent magnet for face milling lots of times. It is very do'abel. A electro
permanent magnet can be used for milling on 5 sides. The side towards the magnet has to have good contact. NO AIRGABs

Regards Bent

[ImanCarrot]

What happens if you get a power cut to the electromagnet or a fuse blows? Big spinning things in contact with a (now not held) thin sheet of metal... just a thought!

[thebodger@roger]

I would like to give you some info on this. Yes it is possible. We have 10 CNC finishing mills doing hard milling with magnetic tables. They are made by "SCHUNK". Their web site will have info on them. We use them because they can be milled flat to match the machine geometry exactly. We require this in the parts we make. They do have tremendous holding power. The parts do not fly off at power loss, in fact we disconnect the power after the magnet is enegized. The residual magnetism will hold the part for days or more. To remove the part, the power is reconnected, and the magnet controller performs a de-magnetization cycle. Never had a part move, even with some agressive cutting. Only thing I don't like about them is the steel chips and swarf stick to the magnet.