Load Wear Index for Lubricating Fluids

Description

A comprehensive indicator (LWI) that determines the ability of a lubricating fluid with EP additives to withstand stepwise increasing loads up to the weld point.

Heavy mining dump trucks, wind turbines, and marine gearboxes require lubricants capable of performing miracles under pressure. The Load Wear Index (LWI) according to the ASTM D2783 standard is the highest level of tribological expertise in the RENA laboratory. This analysis doesn't just show the wear area; it mathematically models the behavior of the lubricating film throughout its entire journey of «suffering»: from the first micro-scuffs to complete catastrophic failure (welding). With this report, you receive a guarantee that your gear fluid contains state-of-the-art sulfur-phosphorus EP additives and will not allow gear jamming even under critical overloads. The methodology for determining LWI on the four-ball tester (FBT-3) is one of the most complex and time-consuming. Unlike the wear test (1 hour under a low load), here each cycle lasts exactly 10 seconds at room temperature and a speed of 1760 rpm. The instrument applies a series of strictly regulated stepwise loads (for example, 40, 50, 63, 80, 100 kgf, and so on). After every 10 seconds, the operator replaces all four balls with new ones, pours a new portion of oil, and increases the weight. After each step, the wear scars are measured with a microscope. This brutal procedure is repeated until the "Weld Point" is reached — the load at which the oil completely disappears from the contact patch and the steel balls are firmly welded to each other by friction. Then, using the results of the last 10 successful measurements prior to the weld point, the computer calculates the final Load Wear Index using a complex logarithmic formula.