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xiros® polymer ball bearing design, applications, development and testing

The range of xiros® polymer ball bearings includes a wide array of product versions. All of these share one common feature: they do not require any additional lubrication. This results in considerable advantages as, whatever the application, no lubricants pollute the environment, are washed out or decompose due to external influences.
Further advantages, depending on the design, are:

  • Maintenance-free
  • Lightweight
  • Non-metallic (due to the use of glass and plastic balls)
  • Non-magnetic
  • Chemical resistance
  • Corrosion-resistant
  • Electrically insulating
  • FDA-compliant
  • Predictable service life

The former mentioned predictability of xiros® polymer ball bearings is one of the most important advantages. Based on the results of many wear tests, the user can calculate the service life of the xiros® polymer ball bearings reliably and interpret the application


The xiros® polymer ball bearings are single-row deep groove ball bearings based on DIN 625. The lubrication-free and maintenance-free ball bearings consist of four components:

A = outer race

B = inner race

C = cage

D = balls

xiros info graphic

Structure of the series according to DIN625
Installation sizeInner ØOuter ØWidthSeriesLoad capacity
670112184Thin ring bearinglow
680112215Thin ring bearinglow
690112246Thin ring bearinglow
600112288Standard bearingmedium
6201123210Standard bearingmedium
6301123712Thick-walled bearingshigh

Outer- and inner ring

The suitability of a xiros® polymer ball bearings is largely determined by the materials of the two races. These are made from igus® tribopolymers to maximise service life and minimise friction. You can currently choose from three different materials. They allow different values of application temperature, media resistance and price. The table with material data gives exact information.
Colour overview



The cage

The material of the ball bearing cage must fit well to the application. The various material options have quite different chemical and temperature resistance values. The cage materials are compatible with all the different race options within xiros®.
Colour overview


The balls

The ball materials differ most significantly. In addition to steel, glass or plastics are used. This produces a large difference in mass, which in turn affects inertia, weight and chemical resistance. Steel balls (stainless steel) are cost-effective, chemical-resistant, but with the highest weight. Glass balls are used to give a metal-free solution. They are also very resistant to chemicals and have an average weight. Polymer balls have significant advantages in weight, size and quiet running characteristics. Depending on the polymer used, plastic balls they can have excellent chemical resistance.
ES stainless steel (1.4401)
GL glass (soda lime glass)
PAI plastic "PAI"
POM plastic "POM"

Pillow block and flange bearings

The use of xiros® polymer ball bearings together with igubal® pillow block and flange bearings gives you greater flexibility while installing the ball bearings The ready-to-install bearing housing makes it easy for users to use these maintenance-free elements. Both flange and pillow block bearings are offered as rigid or pivoting version. The difference here lies in the compensation of misalignments, which is a typical function of the igubal® bearing unit. In the pivoting version, the xiros® polymer ball bearings with spherical outer contour are assembled in an appropriate housing. f necessary, the inner bearing can be pivoted in all directions. Possible misalignment of two bearing points lying together can thus be compensated. The rigid version dispenses with this pivoting possibility in favor of cheaper price.

Application areas

In contrast to metallic ball bearings, xiros® polymer ball bearings manage absolutely without lubrication. For this reason they are suited for a multitude of applications that depend not on extreme rotary speeds or loads, but just on lubricant-free application in contrast to permanently lubricated metallic ball bearings. These areas are for example food, packaging and medical industries, packaging and textile industries, or the chemical industry and cleanroom applications as well as electronics and office technology. Their applications are where freedom from metals and non-magnetic property are required. Here the applications are mainly in medical and measuring technology.

Development and testing

The materials of the races could be further improved through numerous tests. Thereby polymer ball bearings that allow higher speeds, more loads and longer life could be developed. But the development continues: We think that the topic of the polymer ball bearing hasn't been exhausted for a long time yet. With our long years of experience in tribologically optimized plastics and our testing potentials, we believe polymer ball bearings can advance a lot further. Contact us and tell us about your applications where you think you can draw benefits from the polymer ball bearings.

The xiros® polymer ball bearings are tested for service life and wear at the igus® test laboratory. In addition to the actual material comparison tests, these trials also spell out the impacts of external influences such as temperature, humidity or dust.

N = 500 rpm, F = 20 N, T = +23 °C
Y = Wear [μm/km]
A = xirodur® B180
B = alt. Polymer ball bearings I
B = alt. Polymer ball bearings II
D = xirodur® A500
Figure 01: Wear test at the igus® laboratory
N = 500 rpm, F = 20 N, T = +23 °C
Y = Wear [μm/km]
A = xirodur® B180
B = alt. Polymer ball bearings I
B = alt. Polymer ball bearings II
D = xirodur® A500
Figure 02: Wear test at the igus® laboratory
n = 1.000 rpm, F = 50 N
Y = life time [h]
X = temperature [°C]
A = +23 °C
B = +80 °C
C= +150 °C
Fig. 03: Service life of xirodur® A500 polymer ball bearings in different ambient temperatures, dry
Picture 01: Test stand for xiros® polymer ball bearings in the igus® laboratory
Picture 02: Test stand for xiros® polymer ball bearings in the igus® laboratory

The material combinations for bearing rings, balls and cages are tested in the igus® test laboratory by a variety of load and speed trials. Thus, the application-specific selection of the suitable bearing and a service life assessment is possible.


In the scope of the development of the xiros® polymer ball bearings, continuous tests are carried out. An extensive amount of wear data are available from the numerous test results, whereby the service life of the bearings can be predicted. Thus, a concrete statement on the service life can be made both in the framework of a new development and in an existing structure.
As soon as the data is entered, the lifetime is calculated and displayed. Here it is important to know that the statement on the service life is based on real experiments conducted and evaluated under controlled conditions and therefore absolutely reliable.