Electromagnet: lamination vs. solid core
Electromagnet: lamination vs. solid core
(OP)
Right now I am using a coil that is wound onto a bobbin that is .300x.300" footprint and .200" window height. the core area is about .100x.100. The coil is wound to 30ohms and has about 600 turns. I am pulsing 500-800ma upon activation. Currently I am using silicon steel laminations as a core material. From what I have read, laminations help mainly with eddy currents in AC operation. This coil is strictly DC. My question is will I see any increase in field strength with a solid soft iron core as opposied to the laminations?
RE: Electromagnet: lamination vs. solid core
RE: Electromagnet: lamination vs. solid core
RE: Electromagnet: lamination vs. solid core
The annealing recipe generally calls for baking in a vacuum or dry hydrogen atmosphere at 1650degF (900degC) for 1 hour minimum. You'll also get a 5 to 10% improvement with annealing. Again, economics will determine if that is cost effective for you.
RE: Electromagnet: lamination vs. solid core
What is the width of your pulse?
For short pulse widths (Say under 8 millisecond) a laminated core is usually advisable.
RE: Electromagnet: lamination vs. solid core
RE: Electromagnet: lamination vs. solid core
CarlPugh raised a good point (and kudos to him for catching that in the original post). A 60ms pulse is not DC. It takes a finite amount of time for iron to respond to a magnetizing pulse. I don't think you'll get maximum output from iron in that time-frame. You can experiment to find out, but you'll probably have to stay with the silicon steel laminations.
RE: Electromagnet: lamination vs. solid core
RE: Electromagnet: lamination vs. solid core
That is a good way to put it.
RE: Electromagnet: lamination vs. solid core
In the last 30 years I have developed low and high force and low and high speed ON-OFF DC solenoid valves. In addition I developed many electromagnets using only solid core low carbon alloys. I have never needed pure iron (ingot iron) and never laminated core.
Valve speed ranged from 1 msec to 100 msec (mechanical plus electrical) response time and valve and electromagnet forces ranged from 100 gramf to 100 kgf.
The disadvantage of a low carbon alloy is the residual magnetism when the current is reduced to zero. However, the much higher saturation flux density than silicon steel lamination steel more than compensates this disadvantage.
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RE: Electromagnet: lamination vs. solid core
Regards,
RE: Electromagnet: lamination vs. solid core
Another reason that a solid core will give you higher field is that there is more metal. Laminations have a packing factor, the air between them does not help you.
There are multiple reasons to anneal. It will raise saturation (slightly), it reduces residual field (important if you really need the device to turn off), and it results in more uniform behavior (Depending on how sensitive you unit will be to field stregnth variations). If you don't need it , don't do it.
There is low carbon steel available that is not special magnet steel. There are commercial uses for 1002 and 1005 out there. I don't have any contacts for you, it has been too long.
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RE: Electromagnet: lamination vs. solid core