As you read through our website, you’ll see a measurement called Pounds Pull listed for most items, but what does that really mean?
Pounds pull (also called breakaway force or pull strength) is the force required to vertically detach a magnet from ferrous material. We measure it in pounds, using very specific conditions to create uniformity. If your application conditions are different, you will get different results.
HERE’S HOW WE MEASURE POUNDS PULL:
We use a 3/4” thick, completely flat, solid steel plate. It is larger than the magnet being tested, so the magnet makes complete contact with the plate. A pull force gauge measures the force required to pull the magnet vertically away from the steel plate.
WHAT IF YOU’RE NOT USING THE MAGNET IN A VERTICAL APPLICATION?
If you’re using a magnet in vertical placement, then shear force comes into play. While the magnetic force pulls the magnet horizontally towards the steel surface, gravity tries to pull the magnet down, and the friction between the magnet and the steel prevents it from sliding. Why don’t we publish shear strength numbers? We can’t because the friction coefficient varies dramatically depending on the two materials and any surface inconsistencies. Paint, rust, even fingerprints can make a difference!
WHAT ABOUT GAPS, DISTANCES CREATED BETWEEN THE MAGNET AND THE STEEL?
The distance between your magnet and the steel substrate to which it is trying to attract can make an almost unbelievable difference in pull strength. Although this distance is commonly called an air gap, anything that comes between the magnet material and its ferrous mate will cause a variance in strength, including paint, coatings, paper, even grease. Uneven surface areas cause gaps too, such as rust.
SO WHAT’S THE BEST SOLUTION?
Talk to us, get our recommendation, and then try it out! In most cases, we’ll send samples for prototypes at no charge.