Plastic Bearings Have Staying Power

During the past three decades there has been an evolution in the advancement and use of highly engineered plastics in bearing applications. Plastic bearings are no longer designed like their dime-a-dozen, injection-molded nylon ancestors. Today, plastic bearings cost and weigh less than their metal counterparts, but what many design engineers still do not realize, is that they also often last longer in unforgiving environments.

High-performance plastic bearings are working to shed their negative image and continue to forge a path into almost every industry; from packaging machines and medical devices, to automotive, farming equipment, textile machinery, and many more. Plastic plain bearings are an economical replacement for needle, ball, and plain metal bearings. However, they are often not considered a viable choice in the engineering community due to the common misconception that plastic is inferior or weaker compared metal.

The truth is that composite plastic bearings can outperform their metal counterparts in countless rotary, oscillating, and linear-motion applications. In addition, plastic bearings are readily available in many different styles, sizes, materials, and colors to meet the demands of almost any application.

The argument for plastic. igus designs and develops its high-performance, cost-effective plastic bearings for almost any application. The company’s plastic bearings are an offthe- shelf solution, and are available in more than 120 different plastic compounds. Each is comprised of three parts:

Base polymers, which are responsible for the resistance to friction and wear

Reinforcing fibers and filaments, which make the bearings ideal for high forces and edge loads

Solid lubricants, which are blended into each material and eliminate the need for any external oils or grease

While most plastic bearings, like the ones from igus, can endure extreme temperatures, heavy loads and high speeds, it is still important to understand both the advantages and disadvantages of the different options available.

iglide plastic bearings vs. bronze bearings. Maintenance- free plastic bearings regularly deliver a longer service life and a cost savings of up to 40 percent when compared to oil-impregnated sintered bronze bearings. Plastic bearings not only outlast their metal counterparts, but prove more economical because no grease or oil lubricants are required, eliminating the need for routine maintenance.

With sintered-bronze bearings, oil is drawn from the bearing as it rotates on the shaft (minimum speed of 200-feetper- minute). The oil creates a thin film that then separates the bearing and shaft, preventing wear and shaft damage.

At high speeds, a low COF is achieved. Shaft oscillation, slow speeds, irregular use or uneven loads can impede film lubrication from being maintained. As a result, the COF and wear rates increase. In addition, if movement stops completely, the oil on the bearing surface dries up and cause higher friction and squeaking. High temperatures can also break down the oil. In addition, oil film on the shaft can act like a magnet for dust, dirt and airborne debris, which can seize up the bearing or contaminate a product or process, especially in food or medical applications.