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, wear was determined via the loss of mass, among other things.
Levers for force transfer2
|Bearing||iglidur® P210||iglidur® Q||iglidur® Q2||Needle bearings||Needle bearings|
|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|
|Speed||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-time)|
|Target cycle number||600000||600000||600000||600000||600000|
Picture 2: iglidur® P210 bearing tested without lubrication with corresponding shaft
Picture 3: iglidur® Q bearing tested without lubrication with corresponding shaft
Picture 4: iglidur® Q2 bearing tested without lubrication with corresponding shaft
Picture 5: needle bearing tested without lubrication with corresponding shaft
Unlubricated needle bearings failed after only approx. 1/10 to 1/3 of the target operation time. In addition, the shaft had considerable damage. The lubricated needle bearings have become heavier. This is probably due to the particles that accumulated in the bearing and adhered via the lubrication. However, only very low wear of the bearing seems to have occurred. All iglidur® plain bearings have reached the target service life and are still fully functional, just like the lubricated needle bearings. The shafts also only show a very slight run marks. Thereby, the plain bearings made of iglidur® P210 achieved the best wear results and the run on the shafts also looks best in combination with iglidur® P210 plain bearings. Due to these results, we recommend using a plain bearing made of the material iglidur® P210 for a lubrication-free bearing in the application. Additional tests with dirt ingress can also be carried out as needed in the following step.