iglidur® plain bearings in pivoting comparison tests of needle bearings

To carry out a test series in the igus® laboratory, the customer provided the shafts used in the application. The tests were conducted in the on-site test laboratory with a standard testing machine (Picture 1). In the customer application, a high ingress of dirt is partly possible. Therefore, lubrication is not desired and in addition, the lubrication necessary for the needle bearings can only be guaranteed within limits for the entire operating time. Hence, the plain bearings were tested in normal operation, i.e. dry without lubrication, and the needle bearings with and without lubrication. In the first step, all tests were carried out without dirt ingress.With the iglidur® plain bearings, wear was determined via the internal diameter change in load direction. For this, the internal diameter was measured with an outside micrometre before and after the tests. The difference is the wear. By means of the cycle frequency, the running performance was determined to compare the wear. The internal diameter of the needle bearings could not be measured with the means provided in the laboratory. Here the wear and tear was determined via the mass loss.

The wear test was carried out under the following parameters:

Paramenter

value

bearing

iglidur® P210

iglidur® Q

iglidur® Q2

Needle roller bearing

needle bearing

shaft

Customer shaft (nitrided)

Customer shaft (nitrided)

Customer shaft (nitrided)

Customer shaft (nitrided)

Customer shaft (nitrided)

load

4 MPa

4 MPa

4 MPa

4 MPa

4 MPa

Type of movement

Swivelling

Swivel

Swivel

Swivel

Pivot

Swivel angle

60°

60°

60°

60°

60°

velocity

0.01 m/s

0.01 m/s

0.01 m/s

0.01 m/s

0.01 m/s

lubrication

no

no

no

no

OKS 400 (one-off)

Target number of cycles

600000

600000

600000

600000

600000

Figure 2: iglidur® P210 bearing tested without lubrication with associated shaft

Figure 3: iglidur® Q bearing tested without lubrication with associated shaft

Figure 4: iglidur® Q2 bearing tested without lubrication with associated shaft

Figure 5: Needle roller bearing tested without lubrication with associated shaft

Result:

The non-lubricated needle bearings failed after approx. 1/10 to 1/3 of the nominal running time. The shaft was also severely damaged. The lubricated needle roller bearings have become heavier. This is probably due to the grease that has settled in the bearing and bound abrasion and dirt. Nevertheless, there seems to have been only very little wear on the bearing. All iglidur® bearings have reached their target service life and are still fully functional, just like the lubricated needle bearings. The shafts also show only minor signs of wear. The plain bearings made of iglidur® P210 achieved the best wear results and the running pattern on the shafts also looks best in combination with the iglidur® P210 plain bearings. based on these results, the recommendation for an unlubricated bearing in the application is a plain bearing made of the material iglidur® P210. Additional tests with dirt ingress can also be carried out in the next step as required.