Load Wear Index for Lubricating Greases

Description

An analogue of the fluid test, determining the ability of thick lubricating greases to protect assemblies from scuffing and welding under shock loads.

When it comes to lubricating excavators, cranes, agricultural machinery, or open gears, liquid oils are powerless. Thick lubricating greases work here. But how can you verify that this grease will not be squeezed out of the bearing upon the first heavy impact of the bucket? The Load Wear Index (LWI) analysis for lubricating greases at the RENA laboratory provides a comprehensive answer. This test ensures that the "blue", "red", or "black with molybdenum disulfide" grease you have chosen truly lives up to its price and will protect joints from metallic crunching and premature failure. The grease load wear index test (ASTM D2596) is technologically identical to the fluid test (ASTM D2783) but requires a different approach to sample preparation and cleaning of the four-ball tester (FBT-3). The friction node is subjected to sequential 10-second dynamic impacts at a rotation speed of 1770 rpm at room temperature. Before each new load step, the lab technician carefully applies the thick grease with a spatula to avoid forming air pockets, which can lead to false welding. Gradually increasing the weight from 40 kgf to critical values (sometimes over 600 kgf for extreme greases with molybdenum disulfide or graphite), we record the sizes of the wear scars. The process continues up to the Weld Point, when the electric motor's power cannot overcome the strength of the welded metal. The final Load Wear Index is calculated by the microprocessor based on the array of collected data.