Version 1.0
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56
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SAV 244 .70 / .71 / .72 / .73 /
.74 / .76 / .99
3 TECHNICAL SPECIFICATIONS
Holding force and surface quality
Surface quality is very important for the holding force of a workpiece as it rapidly decreases with increasing
roughness. The best values are achieved with a finely polished surface without air gap.
workpieces
magnet
holding forces perpendicular to the magnet:
20 % – 50 %
50 % – 70 %
70 % – 80 %
80 % – 90 %
R
a
1.6
R
a
3.2
BLANK
R
a
0.8
Fig. 6: Influence of the workpiece surface on the achievable holding forces (R
a
= calculated mean roughness value)
Holding force and air gap
Air gaps cannot always be avoided on workpieces. They can be generated, for example, during upstream pro-
cesses, due to cavities and uneven areas on cast parts, roughness from machining, paint layers and non-magnetic
surface layers. As air has a very high magnetic resistance, only few field lines can be generated with larger gaps
and the holding forces decrease rapidly, as shown in the example in the diagram.
The air gap sensitivity is largely dependent on the workpiece size relative to the magnet size, the material com-
position and the pole pitch of the magnet. It can be generally stated that magnet systems with a larger primary
pole pitch have a better bridging capacity. Compared to electro permanent magnets, deeper magnetic fields and
therefore greater resistance can be achieved with electromagnets.
Air gap characteristics for magnetic circular chucks
EP
SAV 244.70 / .71 / .72 / .73 / .74 / .76
magnetic circular chucks
air gap in mm
ho
ld
ing f
or
ce i
n N
/c
m
2
SAV 244.73
SAV 244.74
SAV 244.72
SAV 244.70
SAV 244.71
50
100
150
200
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
SAV 244.76
Содержание 244.70
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