Design and description
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01.00 | EGM | Assembly and Operating Manual | en | 389539
4.4 Factors influencing the holding force
Apart from the magnetic characteristics of the workpiece material,
the attainable holding force is dependent on the following
influencing factors:
Dimensions
The contact surface of the workpiece must be large enough to
cover at least two poles on the product with different polarity.
Only then can the magnetic circuit be closed and the holding force
generated.
Contact surface
The attainable holding force is greatest when the contact surface
of the workpiece is a least as big as the magnetic surface of the
product.
Air gap
Uneven or dirty contact surfaces increase the distance (air gap)
between the workpiece and the product. The attainable holding
force is greatest when the air gap or its distribution over the
contact surface is kept as small as possible. Air gaps also need to
be taken into account if, due to production reasons, a higher
surface quality cannot be achieved.
Workpiece thickness
For very thin workpieces (e.g. metal sheets) the maximum
available holding force cannot be used due to physical reasons.
Bending can also reduce the usable contact surface and thus the
effect of the holding force. The resulting peeling effects can also
counteract the holding force.
Heating
Each activation increases the internal temperature of the product.
Overheating reduces the magnetic characteristics and can destroy
the product. The following criteria must therefore be met:
• The residual heat of the workpiece corresponds to the
permissible ambient temperature,
15].
• The number of activations per minute is set in such a way that
the maximum permissible product temperature is not reached.
Movement energy
When moving the workpiece, acceleration forces counteract the
holding force. The forces exerted by the machine/system must be
significantly less than the holding force attainable with the
respective workpiece.
Note:
if you have questions about the holding force, contact
SCHUNK.
