What is the difference between adhesive force and displacement force/shear force?
Or: Why won’t my magnet on the wall hold the maximum weight?
- Our specified adhesive force applies to a holding strength vertical to the contact surface.
- If the holding strength acts parallel to the contact surface (shear direction), its maximum value is much smaller (approx. 15-25% of the specified adhesive force).
- These values may be improved with the use of special products from our shop and by experimenting with different surfaces.
Holding strength vertical to contact surfaceThe maximum theoretical adhesive force that is specified for each magnet applies, among other factors, when the holding strength is at a right angle to the contact surface (see FAQ for other factors "How strong is this magnet?").
Holding strength diagonal to the contact surface
- Roughness of both contact surfaces: The rougher both surfaces, the higher the maximum frictional force. The uneven contact surfaces interlock (see picture below).
- Contact pressure: The higher the force that presses both contact surfaces together, the higher the maximum frictional force.
Holding strength parallel to the contact surface: shear force / moving force
Rules of thumb for shear force / shifting force
|Magnet material||Material combination||Magnetic adhesive force (a)||Holding strength (b)|
|Neodymium magnets||Iron - Iron||100%||approx. 15%|
|Ferrite magnets||Iron - Iron||100%||approx. 15%|
|Magnetic tapes and sheets||Plastic - Iron||100%||approx. 25%|
- Glue our rubber tape to the backside of the magnets.
- Use magnets with rubber coating or silicone discs on the bottoms side of the magnets.
- Use appropriate rubber caps or metal discs with rim on the bottom side of the pot magnets.
- Experiment with rough or smooth metal surfaces to figure out the optimum.
1 pc. 2,50 EUR ea.*Rubber tape self-adhesive
10 pcs. 1,48 EUR ea.*metal discs with an edge and countersunk hole M3
10 pcs. 0,26 EUR ea.*Rubber caps Ø 21 mm
1 pc. 4,17 EUR ea.*Disc magnet rubber coated Ø 16,8 mm, height 9,4 mm, holds approx. 3,7 kg
1 set 4,12 EUR/set*Rubber discs self-adhesive Ø 12 mm
1 set 3,39 EUR/set*Rubber discs self-adhesive Ø 15 mm