Here, the differences of Linear Bushing shapes (straight and flanged types) , applications, and mounting cautions.

(1) Straight and Flanged Linear Bushings

[Photo 1] is the Straight Type, and [Photo 2] is the Flanged type. The Flanged Type [Photo 2] has the following advantages.

[Fig.1] is a graphical explanation of a MISUMI Flanged Linear Bushing. Adding a flange on a straight bushing will increase the housing diameter and length, but the flanged linear bushing is compact since the bushing and an outer cylinder are integrated into one structure. A compact design is possible while retaining load bearing capacity.

(2) Usage Differentiation of Straight Type and Flanged Type

Following are the points to consider when selecting Straight or Flanged bushings.

Linear bushings can be used as the moving structure or as stationary bearings where the shafts move. [Fig.2] below is a multi-axes X-Y-Z-θ stage, and each axis can be analyzed as follows.

In the illustrated case, the X-axis moving linear bushings on section a) will need to be mounted securely since they bear the inertial forces of the moving mass. On the section b), the housing mounted linear bushings only receive the reaction forces of the friction from an air cylinder driven shafts. Therefore, a compact design using the Straight Bushings is adopted. Furthermore, the opposing layout of dual shafts against the rotary moments of the θ axis enables the use of Straight Bushings with sufficient rigidity. The c) section can be considered as the same as the b) section in terms of the shaft moving direction, and no large forces apply.

(3) Installation of Linear Bushings and Notable Points

(1) Installation of Linear Bushings

Straight Linear Bushings are mounted/secured using Retaining Rings or Fixing Plates. (See [Photo 3] & [Fig.3])

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(2) Notes on Linear Bushing Mounting Angle

Linear Bushings have varying number of ball rows depending on types and shaft diameters. They typically have 4~6 rows of ball circuits and are placed in equally spaced angles. In horizontal motion applications, placing a ball row at 12 o'clock position (left illustration in [Fig.3]) should be avoided since the balls would have to bear concentrated loads.

In the [Fig.4] with 5 ball row type, the load capacity ratio (Right divided by Left) would become as shown below. Therefore, it is recommended to mount the bushings as shown in the illustration on the Right.

Static Load Rating (Right divided by Left) = 1.46

Dynamic Load Ratin (Right divided by Left) = 1.19