The magnets used for the SL motors produce a significant amount of force.
The amount of attractive force produced by the magnets depends on the distance from the material in which it is being attracted to. The force increases exponentially the closer the magnet is to iron.
At the specified operation air gap, the magnets produce 12 lbs per magnet. This number is used for sizing the bearings to the forcer.
If the forcer comes in contact with the platen, the magnets produce 15 lbs per magnet. There is still a gap between the magnet and the back-iron of the motor.
If the magnets comes directly in contact with iron, they will produce about 75 lbs per magnet.
If magnets come in contact with each other, they produce almost 150 lbs of force.
The SL063 platen has only one magnet covering the width of the forcer. The SL140 platen has three magnets covering the width of the forcer. The forcers cover as many rows of magnets in length as they have number of poles. For example, an SL14012 (a 12-pole forcer) will use three magnets in width and twelve magnets in length for a total of 36 magnets that attract the forcer to the platen.