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Application Note: AN8071

PIN/BALL ON DISC TEST WITH INLINE IMAGING FOR WEAR AND FRICTION

INTRODUCTION


The MFT5000 is a versatile multi-functional
mechanical property tester capable of simulating a
vast number of tribology and wear tests on the
same platform. This application note shows how the
MFT5000 is used to run a very common tribology
and wear test – pin/ball on disc. This test method
covers a laboratory procedure for determining the
wear and friction of materials, liquid and lubricants
etc. during sliding using a pin on disk or ball on disk setup.

Pin on Disc Tribometer

MATERIAL & METHOD

Materials are tested in pairs under nominally non-abrasive conditions. For the pin or ball on disk wear test, two specimens are required. One, a pin or ball that is positioned perpendicular to a flat circular disk. The universal upper and ower sample holders are used to mount the samples. Common test specimens are 10mm diameter 100Cr6 steel ball or 6.3mm ss pin and 100Cr6 disk. Samples of other materials and diameters can also be easily accomodated in the tool. The surface flatness and roughness of both materials are critical to get repeatable results.


The tribometer causes stationary pin/ball to press against the rotating disk at a known force and speed. During the test coefficent of friction (COF), friction force, wear and several other parameters are measured and reported. The setup for dry conditions is shown in Figure. This set up is ideal for characterizing tribological properties of alloys, ceramics, polymers, bulk materials, coatings, solid lubricants etc. with respect to a counter material in non-lubricated conditions. Figure shows the set up
in lubricated conditions with the samples submerged in lubricant.

Pin on Disk Tribometer

ANALYSIS

Ball Image


Figure shows the ball wear mark after the test.
Figure shows the comparison of coefficient of
friction w.r.t. time for four specimens under
same load and rotation speed against a Cr6 ball
of 10mm diameter at 200C. The coating on
sample 1 breaks the fastest while sample 2
shows low friction throughout the test. At the
MFT platform it is possible to do such tests at
room or at high temperatures.

Pin on Disc Wear Testing Graph

Automatic Inline Imaging – roughness, wear, volume vs time

Rtec multi-function tribometer comes with an optional inline 3D Profilometer. The profilometer automatically measures the surface topography of the wear track at pre-set intervals defined by the user e.g. after a certain number of cycles, duration of time or at the on-set of an event such as increase in friction. The XY stage is equipped with advanced encoders to automatically move the sample between the test and image area. The ability to quantifiably characterize the change in surface topography and wear track with time and combining it with friction data makes the analyses extremely powerful.

The initial 3D image acquired using the profilometer also allows to account for machining marks, grain boundaries and can be useful to explain difference in friction, stick slip, wear etc. between specimens. Figure shows the wear mark created vs time for an alloy steel sample during a 75 minutes ball on disc test.
Pin On Disc Wear Testing 3D Image
Figure shows the friction data w.r.t the time stamp. It also points out to when the surface images were taken during the test. It is clear from the data that test stops and starts from same location. Figure shows the 3D images of surface wear vs time/test step. The friction, wear and image correlation are very powerful information all generated automatically.
Pin on disc Graph Compare

CONCLUSION

MFT5000 rotary module is an excellent option to run tests in pin/ball on disc mode. The tool can be operated in dry or lubricated mode with options to do the tests at high temperatures. High loads up to 5000N can be applied to achieve high contact pressure for suitable samples. The anti-splash containers allow to run these tests under liquid media. The inline profilometer makes this tester a very powerful tool in the hand of the researcher or QC engineer. 

REFERENCES & KEYWORDS

ASTM G99, Pin on Disc, Ball on Disc

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