I am currently working on a project where I am building an electromagnet that works over an air gap. Specifically a gap of about 0.3 inches. The electromagnet type was selected because I need to be able to turn it on and off based on input sensors to my micro-controller. Also all of my design work has been done in solid works using their Emag plugin.
How for the real grit. The essential problem I am having is that to make the electromagnet strong enough, I have to increase the size to a point where it is becoming too heavy for my project (too heavy is roughly over 3 lbs). Also the magnets should have a pulling force of about 50 lbs over the air gap from before. Furthermore I have dabbled into designing electro-permanent magnets but they, one also become to heavy, and two do not entirely turn off.
So here is my questions for you all:
- Has anyone had experience making electromagnets that work over air gaps that could give me pointers?
- Or has anyone had experience making electro-permanent-magnets that work over air gaps that could give me pointers?
The magnetomotive force required is calculated below. It takes into account the reluctance of the core, the air gap, and the material it is attracting. The material is 1008 12 guage steel. The core is either Vacoflux 27, which is 27% cobolt and 73% iron, or we may use high purity Iron, around 99.98% purity. Currently we have been using SolidWorks EMS plug in to do FEA analysis of the magnetic fields instead of using equations. N=number of turns; I=current; F=desired physical force; Lm=length of magnet; Lp=length of plate; Z=length of airgap; Uo=permiability of air; Up=permiability of plate material; Um=permiability of core material; Sm=cross sectional area of magnet core; Sp=cross sectional area of plate;