Working Principle:Four ball machineUnder pressure, a steel ball rotates and rubs against three horizontally fixed steel balls of the same size. The standard friction pair method is to fix three steel balls on the lower sample, and fix the upper sample steel ball on the rotating shaft to rotate. The initial contact mode of the friction pair is point contact, and the sample is completely immersed in a liquid lubricating medium. The frictional performance of the lubricating medium is determined by measuring the friction coefficient between the rotating steel ball and the fixed steel ball, as well as the size of the wear spot of the fixed steel ball.

Core functions and testing indicators:

Capacity assessment

*Large non card bite load（PB）Lubricants do not get stuck in friction pairs*High load reflects the initial load-bearing capacity of the oil film.

Sintering load（PD）Gradually increase the load until the critical load at which the friction pair undergoes sintering, reflecting the extreme pressure performance of the lubricant.

Comprehensive wear value（ZMZ）The average value of the load borne by the unit relative to the abrasion mark,ZMZThe larger the value, the stronger the wear resistance of the lubricant.

Wear resistance performance test

Grinding spot diameter（WSD）The average diameter of wear spots on the surface of the bottom ball,WSDThe smaller the size, the better the anti-wear performance of the lubricant.

Long term anti-wear test: Continuously operate under fixed load and speed to evaluate the long-term anti-wear ability of lubricants.

Determination of friction coefficient

Real time friction coefficient is calculated through friction torque to reflect the anti friction performance of lubricants. The lower the friction coefficient, the more significant the energy-saving effect of the lubricant.