Wear Scar Diameter by GOST

Description

A classic method for evaluating the anti-wear properties (wear index) of lubricants on a four-ball tester (FBT) according to CIS standards.

Many units of heavy industrial equipment and machinery operated in the post-Soviet space have clear requirements for lubricants written in classic DSTU and GOST standards. Wear scar diameter analysis according to GOST 9490 in the RENA laboratory allows oil manufacturers to confirm their products' compliance with these strict local specifications, and enterprises to legitimately use modern oils in old but reliable equipment. This test is the legal and technical basis for replacing outdated lubricants with innovative products. The GOST 9490 methodology is conceptually similar to Western standards (the same FBT-3 friction machine is used) but has fundamental technological differences in testing conditions. A pyramid of four balls (SHH15 steel) is immersed in the test oil. The load (P) is set at 196 N (20 kgf). The main difference is that the test is conducted at the ambient temperature of the fluid (20±5 °C) without additional thermal heating. The test duration is exactly 60 minutes at a top ball rotation speed of 1420-1470 rpm. Under these conditions, it is precisely the basic ability of the oil and its surface-active substances to form a protective film on cold metal that is tested. After 1 hour of operation under load, the balls are removed, and a specialist measures the wear diameter (Dz) using a microscope. This indicator (in millimeters) is the evaluation criterion.