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iglide® plastic bushings: The Self-Lubricating Effect

iglide® plastic bushing

Figure 1.1: iglide® plastic bushings are homogeneously constructed. Composite materials and lubricants complement each other.

 
plain bearing

Figure 1.2: The traditional solution: a plain bearing shell layered with lubricant and coating.

 
FDA compliant plastic bushing

Picture 1.4: A plastic bushing made from the FDA compliant iglide® A180 plastic

 
Base plastics

Picture 1.5: Base plastics with reinforcing fibers and solid lubricants. Magnified 200 times and colored.

 
Base plastic without fiber reinforcements

Picture 1.6: Base plastic without fiber reinforcements and solid lubricants. Magnified 50 times and colored.

 
Low wear rate bushing

Figure 1.3: Over time, the wear rate reduces significantly.

 

Features of iglide® plastic bushings

Every iglide® plastic bushing material possesses a set of special features making it suitable for different applications and requirements. However, all iglide® plastic bushings have certain general properties in common. They are made from materials that:

1. Can handle high loads over an extended period of time
2. Have low coefficients of friction
3. Have low wear rates resulting in a longer service life

The Self-Lubricating Effect

iglide® plastic bushing materials consist of:

Base plastics

Fibers and filling materials

Solid lubricants

These components are not applied in layers, but homogeneously compounded. The advantage of this construction becomes clear if you consider the following:

1. The coefficient of friction, determined by the surface of the plastic bushing, should be as low as possible

2. The surface must not be pushed aside by forces acting on the plastic bushing

3. The plastic bushing should be particularly resistant to wear forces acting on its surface.

There is no universal material available that can fulfill all these tasks equally well.

The traditional solution

The traditional solution is a hard shell with a soft coating. Traditionally, every lubricated bushing works according to this principle, including a number of maintenance-free bearings equipped with special sliding layers. However, this soft sliding layer is not strong enough; with high edge loads or oscillations it is stripped away.

iglide® plastic bushings function differently

One component of the iglide® plastic bushing material acts for each function:

The base plastics are crucial for wear resistance

Fibers and filling materials reinforce the bushing so that it can withstand high forces or edge loads

Solid lubricants automatically lubricate the bushings and reduce friction in the system.

Integrated lubrication

The solid lubricants are embedded as microscopic particles in millions of tiny chambers in the fiber-reinforced material. From these chambers, the plastic bushings release tiny amounts of solid lubricant during movement.

They are embedded in the tiny chambers, they can not be pressed out. They are always there as soon as the plastic bushing or shaft is set in motion. They help to lower the coefficient of friction.

Base plastics and technical fibers

The radial pressure acting on the bearing is taken by the plastic base material. It provides shaft support at the contact surface. The plastic base material ensures that the solid lubricants do not receive a surface pressure that is too high. The base material is also reinforced by technical fibers or filling materials. These additional materials stabilize the bushing for applications involving continuous stress.

The start-up phase

In the initial phase, the shaft and the iglide® plastic bushing become mated to one another. During this period, the surfaces of both partners are fitted to each other. The specific load of the system lowers as the contact surfaces of the shaft and plastic bushing expand during start-up. Simultaneously, the wear rate lowers and approaches a linear curve. In this phase, the coefficients of friction continue to change, until finally assuming a value that is - for the most part - constant.

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