Fraunhofer Institute for Surface Engineering and Thin Films IST
A pin-on-disk tester in use at the Fraunhofer IST.
Pin-on-disk: Friction and wear measurement of material pairings
The Pin-on-Disk Test (DIN 50324-07, ASTM G99-05, ISO 18535)
Tribometers can be used to investigate the friction and wear behavior of material pairings. A test material, e.g. a steel ball or a pin, is moved on a circular path over the specimen with a defined standard force (approx. 5 N) (pin-on-disk). During the test, the friction force or the coefficient of friction is measured continuously. The wear is subsequently determined by measuring the wear track and the abrasion of the test specimen.
How the Pin-on-Disk Test is used
Friction and wear are not material values.In addition to the material pairing, they also depend on the test parameters:
- Mode: oscillating or rotating
- Load: 1 - 10 N
- Duration: 10 - 100,000 cycles
- Frequency: 0.5 - 5 Hz
- Counterbody: steel, carbide, ceramic, special materials
- If applicable, media (e.g. air, water, oil)
We will be pleased to advise you on the optimum choice of test conditions.
Coefficient of friction of different material pairings
DLC coatings containing metal have a significantly reduced frictional resistance to steel compared to uncoated surfaces. Even when operating under oil, metal DLC coatings still improve the coefficient of friction compared to steel against steel.
Friction comparison during dry running against steel
A TiN coating is generally harder than a DLC coating and therefore offers good wear protection compared to uncoated steel. In moving components, however, a DLC coating offers a coefficient of friction that is many times lower than that of TiN or uncoated steel, especially when running without lubrication.