Holding Force
Holding force and rated lifting capacity of MRP-46 can only be applied when the forces are per-
pendicular to the magnet's gripping surface.
The following factors affect magnet’s holding force:
-Material properties
-Thickness of the load
-Distance between gripping surface and attached load (airgap)
-Object diameter when lifting round part
Holding force and lifting capacity of MRP-46 pneumatic magnet are rated with steel EN S355. Most
other steel materials produce lower holding force. Also hardened steel produces lower holding
force.
Material’s capacity to conduct magnetic field depends on its thickness. A thinner material has
weaker capacity compared to a thicker material. Increasing material thickness increases the mate-
rial’s capability to conduct magnetic field until the magnet’s specific maximum value is reached.
See figure 2: MRP-46 holding force in proportion to plate thickness. Figure 2 is made for plate, but
same principle is valid also for pipe wall thickness when round parts are lifted.
Any material that separates the magnet's gripping surface from the surface of the load reduces the
total magnetic holding force. Reduction can be caused by non-magnetic materials or by materials
with weak magnetic qualities, such as, zinc or paint or similar coating, rust, frost or air. The dis-
tance between the surfaces caused by materials above is commonly called as airgap.
Surfaces must be clean and the airgap zero to achieve rated holding force. The load surface must
also be flat and it must occupy the gripping surface of the device completely. See figure 3: MRP-46
holding force in proportion to airgap.
In case of round parts, the magnet’s holding force depends also on part’s diameter. Rated holding
force can be achieved with ø ≥ 120 mm. See figure 4: MRP-46 holding force in proportion to round
part diameter. Round part is assumed to be a solid material.
Figure 1. The gripping surface and magnetic poles of MRP-46.
