Four-Ball Automatic Test Machine

The Four Ball test machine is used to determine the relative wear preventing properties of lubricating fluids and greases in sliding steelonsteel applications, Extreme Pressure properties (EP) and friction behavior. During a four ball wear test a rotating steel ball is pressed against three balls firmly held together and immersed in lubricant under test. The test load, duration, temperature and rotational speed are set on the four ball tester in accordance with standard test methods. In Wear Preventive (WP) tests the average scar diameter on the bottom three balls is reported. The size of the scar shows the ability of the lubricant to prevent wear. A larger diameter indicates poor wear preventive property. While a smaller diameter indicates superior wear preventive property.

Wear scars on each of the bottom three balls are individually measured after a four ball wear test. Users can do this manually using an optical microscope. Those results can be added to the analysis report to complete the final test documents. A digital image analysis can be used to acquire image and measure the scars diameters improving repeatability and reproducibility. The acquired image can be attached to a report of the four ball wear test.

In Extreme Pressure (EP) tests the lubricant is subjected to a load that is increased in specific steps after every run of the four ball test machine. This increased load is continued until the load is reached where the lubricant fails. The failure of the lubricant is indicated by welding of the bottom three balls to the top ball. The load at which welding occurs in the index of extreme pressure property of the lubricant.

The Four Ball Test Machine permits measurements of actual load, RPM and temperature.Frictional torque during the test is also measured. All of these parameters, displayed during thetest, are acquired for displays and analysis, the data can be transferred via USB/LAN Datatransfer.