Wear measurement and testing
A number of new capabilities have been developed to expand the range of applications which can be simulated using the MTM2.
Sliding speed 1 m/s with varying entrainment speeds Blue = bi−directional speed control
The bi-directional capability is fitted as standard on the MTM2. This allows the ball and disc motors to be driven in opposite directions, whilst still accurately controlling the speed. With this feature slide/roll ratios (SRR’s) can be greater than 200%. Keeping a low entrainment speed maintains the contact in the mixed lubrication regime, while the high sliding speed accelerates the wear rate. This capability is particularly useful when evaluating lubricant anti-wear properties or scuffing resistance.
The MTM2 is fitted with a high precision on-line wear measurement system. A wear sensor automatically logs the displacement of the ball shaft with a one micron resolution during the test.
A stationary ball or pin loaded against the disc may be more appropriate to some test applications. With this option the ball shaft is fixed and the pin holder enables a wide range of upper specimen geometries to be loaded against the disc. Read more...
ECR equivalent circuit, Wear sensor and pin specimen
The ECR option gives an indication of in-test film thickness. The disc drive is electrically insulated from the ball and the electrical contact resistance between the two specimens is logged during the test. Read More...
The MTM2 has been successfully used to assess the scuffing resistance of different oils. Both the friction coefficient and film thickness are measured against increasing load at high sliding speed. As the load increases, the friction initially drops and then rises significantly as the film collapses.
When scuffing occurs, both friction and ECR film signals show an abrupt change
For some applications particularly when studying the behaviour of a lubricant under dynamic conditions an oscillating motion is more representative than a continuously rotating disc. The reciprocating option changes the rotation of the disc (lower specimen) into a reciprocating cycle, expanding the range of test conditions available on the MTM2. Read More...