Yaskawa Sigma-5 User Manual: Setup for Linear Motors - Manual (Page 48)

2 Installation
2.2.4 SGLC Linear Servomotors (Cylinder Type)
2-26
(4) Others
 Magnetic Attraction between Moving Coil and Magnetic Way
Because the steel yoke is embedded in the moving coil to generate force, magnetic
attraction generates between the moving coil and the magnetic way. When the gap
between the moving coil and the magnetic way is uniform, the magnetic attraction on
the moving coil is offset.
A uniform gap is difficult to obtain, however, because it depends upon the precision
of the moving coil and the magnetic way products, deflection of the magnetic way,
precision of the equipment of the customer, and assembly error at the time of mount-
ing the motors. In case of non-uniform gap, the attraction shown in Table 2.3 is gen-
erated. When designing the equipment, take into account the attraction.
∗1. Indicates the gap of the machine when a dislocation of approximately 70% in comparison
to the designed value occurs.
∗2. Indicates the magnetic attraction at the time of maximum force.
Note: For the conditions other than those mentioned above, contact Yaskawa representative
separately.
Table 2.3 Magnetic Attraction (calculated value)
Moving Coil Model
SGLCW-
Design Value of
Gap
(mm)
Gap G1
*1
(mm)
Gap G2
*1
(mm)
Difference of
Attraction
F1-F2
*2
(N)
D16A085
1.0 0.3 1.7
20
D16A115 30
D16A145 40
D20A100
1.25 0.4 2.1
25
D20A135 38
D20A170 50
D25A125
1.5 0.5 2.5
50
D25A170 75
D25A215 100
D32A165
1.75 0.5 3.0
80
D32A225 120
D32A285 160
Moving coil
Magnetic way
G2
G1
F2
F1
The figure shown on the right is an example in which a
non-uniform gap occurs. Actually, magnetic attraction may
be generated and extended in all directions because of an
assembling error or other reasons.