(1) Bushing structure and features
Both straight (Photo 1) and flanged (Photo 2) follow similar structural
design. Main advantage of Flanged Linear Bushing lies in its compact design (Figure
1):
- Value of friction coefficient can influence the capacity of actuator and heat generation
during movement. Oil Free Bushings are inappropriate because of heat dissipated
by continuous high-speed operation.
- In the case of using Air Cylinders, speed control of the start / stop is not possible.
Mechanisms such as Shock Absorption Dampers need to be set to stop the speed softly.
It can shorten the cycle time.
(2) Using straight and flanged types
The following should be considered when making Linear Bushing selection.
- Decide whether force will be applied to the Linear Bushing ⇒ Choose a flanged
type if the Linear Bushing must bear to force.
- Decide how much space is available on the surface to which the Linear Bushing is
to be attached. ⇒ Refer to part (3)
As shown in Figure 2, depending on the design, Linear Bushings can either
move while Shafts are fixed, or be stationary (fixed) while Shafts are in motion.
The Linear Bushing in the component a) receives inertia force from the moving component,
therefore the Linear Bushing must be firmly screwed to the housing. As for component
b), an Air Cylinder moves the Shaft in the Linear Bushing. The Retaining Ring fixing
the Linear Bushing only receives the frictional force from the Shaft. Therefore
a compact design using a straight type is fine. The same can be said for c).
(3)Installing Linear Bushings
- Fixing a Straight Linear Bushing, using Retaining Ring or Stopper Plate(Fixing Plate)
(Photo 3) is shown in Figure 3.
- Notes on installation angle
Load rating of Linear Bushing varies according to the load position on the circumference.
Linear Bushing, usually has 4-6 rows/ball tracks, that are set on even angle. When
installing, if possible avoid positioning Linear Bushing so that the ball track
is under direct load (Figure 4), otherwise that row will directly bear the
load (Figure 4a).
For example Figure 4 shows a Linear Bushing with 5 rows. The variance of
dynamic load rating is as follows. (right figure ÷ left figure). Therefore, angle
should be installed as in the right picture.
Static Load Rating
(Right figure a ÷ left figure b)=1.46
Dynamic Load Rating
(Right figure a ÷ left figure b)=1.19
MISUMI USA, INC.
1105 Remington Road, Suite B
Schaumburg, IL 60173
www.misumiusa.com
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