Robur 8134 Manual De Uso E Instrucciones página 12

OPERATION MANUAL AND INSTRUCTIONS ISTRUZIONI PER L'USO
FACTORS INFLUENCING THE LOAD CAPACITY
Air gap
The air gap is the space between the active poles of the magnet and the load. It is caused by several factors, including surface
roughness and the presence of paint, burrs, oxidisation, etc. For example, an oxidised hot rolled product has an air gap of 0.1 to 0.3
mm. The roughness of a forged object may reach 0.5 mm. The magnet load capacity is reduced as the air gap increases (figs. 8 to 11).
Always check the air gap before using the accessory, and reduce the load or assess whether or not it can be used
as a consequence.
An excessively long plate section generates an air gap (fig. 6) as it tends to bend. In such a case, a number of magnets should be
used to reduce or prevent bending (fig. 7). Care should also be taken in the case of surfaces which are initially curved, rounded
or in any case not perfectly flat, as there will be an air gap which will reduce the load capacity or make it impossible to use the
accessory.
Thickness and contact surface
Excessively reduced thickness or a small or incomplete contact surface will prevent the magnetic circuit from closing effectively
and limit the load capacity of the magnet (figs. 8 to 11).
Always check the thickness of the surface before using the accessory and reduce the load or assess whether or
not it can be used as a consequence.
Rounds
Contact between rounds and the poles will always be partial. The load capacity should always be reduced, as shown in figs. 8 to 11.
Graphs showing the influence of the air gap, the thickness of the plate and the surface curve can be found on the labels at
the side of the accessory, as well as in figs. 8 to 11.
Any special, complex or combined situations not covered by the graphs in figs. 8 to 11 have to be assessed by a skilled
operator.
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Fig. 6
Fig. 8
Fig. 7
Fig. 9
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