how is magnetism induced without an electric field
how is magnetism induced without an electric field
(OP)
Hi
I am involved in a manufacturing procses utilizing stainlees steel needles (dia approx. 0.3mm, parts are partially shotblasted to a depth of approx. 5 microns). The needles are contained in a metal hopper and moved back and forth over a steel plate with slots machined in to them. The needles are supposed to drop into the slot but we are having a lot of problems with magnetism getting induced into the base of the hopper, this creates problems with the needles dropping into the slotted steel plate.
The magnetism is very localised in the edges of the hopper and as far as we can determine there is no electrical field to induce the magnetism.
I am hoping someone can help me discover where the magnetism is coming from and maybe how we can prevent it building up. We can remove the magnetism with a demagger but it causes a lot of down time removing the apporpriate parts and we are desperate for production at present so all help gratefully received,
Clive
I am involved in a manufacturing procses utilizing stainlees steel needles (dia approx. 0.3mm, parts are partially shotblasted to a depth of approx. 5 microns). The needles are contained in a metal hopper and moved back and forth over a steel plate with slots machined in to them. The needles are supposed to drop into the slot but we are having a lot of problems with magnetism getting induced into the base of the hopper, this creates problems with the needles dropping into the slotted steel plate.
The magnetism is very localised in the edges of the hopper and as far as we can determine there is no electrical field to induce the magnetism.
I am hoping someone can help me discover where the magnetism is coming from and maybe how we can prevent it building up. We can remove the magnetism with a demagger but it causes a lot of down time removing the apporpriate parts and we are desperate for production at present so all help gratefully received,
Clive





RE: how is magnetism induced without an electric field
We commonly take steel that has no RM and stamp it into flat cutout parts using mostly carbide tooling. After a good run most of the tool has developed RM and almost all the pieces coming out the other end do to.
we de-mag parts several times throughout our processing. They often like to stick together and that can be rather annoying.
RE: how is magnetism induced without an electric field
RE: how is magnetism induced without an electric field
You might consider putting an insert plate in the bottom of your feeder. I would suggest a stainless alloy that does not become magnetic when work hardened.
I suppose that you need this plate hard to prevent wear. There are a number of stainless grade avaialble as cold rolled hard sheet that are completely non-magnetic.
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