Maintenance-free plastic rollers

To the user reports:

FAQ

Plain bearing as a roller? Is it really that easy?

At first glance, the benefits of plain bearings for use as rollers appear very attractive. They take up significantly less space than ball bearings, are lubrication-free depending on the version and less susceptible to dust and cleaning agents. Bearings made of plastic are corrosion-free and are also generally less expensive and lighter.

A plain bearing is usually installed in such a way that it is firmly pressed into a housing bore. A shaft then rotates in this fixed bearing. We speak of a roller when the plain bearing moves around the rigid shaft, which is then called an axis, as it does not transmit torque. Then it rolls around along the outer diameter. For example, on a guide rail, link roller guide or any other surface.

Rolling instead of sliding. Or rolling and sliding?

A practical example is a sliding door on a cabinet that is mounted on rollers. Rollers are attached to the door, which in turn roll on rails. Viewed in detail, we have small locked axes on which the rollers rotate. Ideally, the rollers rotate about their axes when the door is pushed. The situation is different if the roller does not unroll but stops and slides over the rail instead. The door would become stiff, as the resistance would be higher. After all, the weight of the door rests on the very small contact surface between the roller and the rail.

Here are some helpful tips for designing one-piece plastic rollers:

• Choose the largest possible outer diameter with the smallest possible inner diameter.
• Increase the friction between the outer diameter and the rolling surface.
• Use rollers with roller adapters.

Choosing the right material

While a plain bearing is designed to carry a load applied by the shaft and to generate as little heat as possible with as little friction as possible when moving, the whole thing looks a little different in a roller application. As the bearing does not sit "comfortably" in a housing bore, which in the best case supports half the bearing circumference, only the support point on the roller track is available for a roller. The resulting surface pressure on the outer diameter is high. It doesn't really matter what material the roller is made of. The so-called "Hertzian compression" forces pretty much every material to its knees to varying degrees. The result is a flattening. Reinforcing fibres in the plastic provide a remedy here.