- #1
Cbowen546
- 3
- 0
Hey everyone, I am trying to develop a small electromagnet to pick up (relatively) large amounts small shavings which are roughly 70-80% Fe in composition and are roughly 10-40 microns in size. This device needs to be powered by a maximum of two D-Cell batteries (maybe we can look into alternate power sources of similar sizes).
We went through a few iterations of magnets before coming here. I am using a 1018 full annealed (slow cooled in normal atmosphere) steel rod 0.25 in diameter rod for cores. We started with a straight core with a ~250 turn binary coil of 24ga magnet wire. We wound a few different coils and determined pole to pole distance was too great and these would not work for our application.
Next iteration was a U shaped core to bring poles closer together (1.0in apart) with same specs as above (.25” 1018 steel core, 24ga magnet wire, ~250 turns). For these we wound two parallel coils, one on top of the other with ~250 turns total. These picked up some of the particles but not nearly enough. We then moved poles even closer on these EM’s with somewhat better results but still nothing to report on.
Now we are looking at developing a scaled down version of a suspended electromagnetic separator like they use in coal mining. I built a case from mild steel tube and two end plates of mild steel (see mspaint drawing) all components have a light press fit (so I can take it apart if need be and so we don’t deform the parts too much). This “separator” does not work at all. No attraction to anything. This makes sense due to the complete flux path but then how do the mining units work? Do the components need to be welded together and should there be a small air gap from one pole if the coil to the case?
What am I missing here? There has to be a good way to make an electromagnet pick up small shavings like these. A good neodymium magnet picks up enough of the dust to make it worth while but we really need the on-off capabilities of an EM for this process…
Any input is greatly appreciated!
Chris
We went through a few iterations of magnets before coming here. I am using a 1018 full annealed (slow cooled in normal atmosphere) steel rod 0.25 in diameter rod for cores. We started with a straight core with a ~250 turn binary coil of 24ga magnet wire. We wound a few different coils and determined pole to pole distance was too great and these would not work for our application.
Next iteration was a U shaped core to bring poles closer together (1.0in apart) with same specs as above (.25” 1018 steel core, 24ga magnet wire, ~250 turns). For these we wound two parallel coils, one on top of the other with ~250 turns total. These picked up some of the particles but not nearly enough. We then moved poles even closer on these EM’s with somewhat better results but still nothing to report on.
Now we are looking at developing a scaled down version of a suspended electromagnetic separator like they use in coal mining. I built a case from mild steel tube and two end plates of mild steel (see mspaint drawing) all components have a light press fit (so I can take it apart if need be and so we don’t deform the parts too much). This “separator” does not work at all. No attraction to anything. This makes sense due to the complete flux path but then how do the mining units work? Do the components need to be welded together and should there be a small air gap from one pole if the coil to the case?
What am I missing here? There has to be a good way to make an electromagnet pick up small shavings like these. A good neodymium magnet picks up enough of the dust to make it worth while but we really need the on-off capabilities of an EM for this process…
Any input is greatly appreciated!
Chris
