iglide® plastic bushings: surface pressure, load

Figure 1.4: Maximum recommended surface pressure at 68° F

Surface pressure

The load a plastic bushing can withstand is defined in terms of surface pressure (psi). For this reason, the permissible radial load is determined by the projected surface area of the plastic bushing. Radial bushing: p = F/(d1 x b1)

For axial bushings, the load is produced accordingly.

Axial bushing: p = F/(d2² - d1²) x π/4

In this process:

F	Load (lbs)
d1	Inner diameter of the plastic bushing (inches)
b1	Plastic bushing length (inches)
d2	Outer diameter of the plastic bushing (inches)

Maximum recommended surface pressure

A comparative value of the iglide® plastic bushing material is the permissible static surface pressure (p) at 68°F. The values of each individual iglide® plastic bushing differ when it comes to this.

The value (p) indicates maximum load of a plastic bushing. The plastic bushing can continuously tolerate this load without any damage occurring. The given value applies to static operation; only very slow speeds up to 1.97 fpm are tolerated under this load. Higher loads than those indicated are possible if the load is only applied for a short period. For a few minutes, the load can be more than doubled, depending on the material. Please contact us if you have any questions.

Load and temperature

Figures 1.4 and 1.5 above show the permissible static surface pressure (p) of an iglide® plastic bushing versus temperature.

When using a plastic bushing, the bushing's temperature can become higher than the ambient temperature due to friction. Take advantage of the predictability of iglide® plastic bushing to record these effects beforehand or during testing.

Load and speed

With decreasing radial load on the plastic bushing, the permissible surface speed increases. The product of the load (p) and the speed (v) can be understood as a measurement for the frictional heat of the bushing. This relationship is shown by the p x v graphs for each iglide® plastic bushing material.

Figure 1.6: Graphs to show the wear of iglide® plastic bushings at low loads

Figure 1.7: Wear of iglide® bushings at medium and high loads

Load and wear

The load of the iglide® plastic bushing influences its wear behavior, as shown in the graphs below left. It is evident that, for every load, there is an optimal plastic bushing available.

Load and coefficient of friction

With increasing load, the plastic bushing's coefficient of friction typically decreases. In this context, shaft materials and their roughness or smoothness are also significant.