Other factors aside from the magnet material and the size of the magnet affecting the magnetic pulling force are:
an air gap (magnetically non-conductive materials act like an air gap)
the quality of the surface (roughness and shape)
the temperature
the content of ferro-magnetic material in the steel; the components must also be sufficiently thick to be able to absorb the entire magnetic flux.

The magnetic pulling force can also be impaired by alternating thermal stress and by chemical factors (aggressive baths, gases, etc.).

The diagrams and graphs below show guide values relating to the impact on the magnetic pulling force caused by different mechanical specifications.

The nominal magnetic pulling forces shown in the tables of the standard pages are minimum values which are achieved at:
room temperature
perpendicular "tear-off" under full surface contact of the magnet
workpieces made of low-carbon steel with a minimum thickness of 10 mm

Force Measure

1 Newton (N = .225 lbs.