Weld Load by GOST

Description

The absolute ultimate strength of a lubricant. Records the load at which the oil is completely squeezed out of the assembly, and the parts weld together.

What happens to your gearbox or bearing if the load exceeds all conceivable norms? Will the machinery have time to stop, or will it seize tight? The weld load analysis (Pz) in the RENA laboratory provides a comprehensive answer to this question. This extreme test is intended for top-class greases and oils containing powerful extreme pressure (EP) complexes. It proves that the product is capable of preventing emergency seizure of mechanisms (welding of parts) even under conditions of brutal overloads and shocks. This is a decisive argument for mining equipment and heavy metallurgy. Testing is conducted on a four-ball friction tester (FBT-3) and logically continues the scuffing index test. The friction node is subjected to a series of short (10-second) dynamic runs with a step-wise increase in load. After overcoming the normal wear zone and the scuffing zone, the pressure on the steel balls reaches colossal values (sometimes over 600-800 kgf). At such pressure, the temperature at the contact point instantly soars to thousands of degrees, the lubricating film (even protected by sulfur-phosphorus additives) is completely destroyed and evaporates. Direct contact of bare metal with metal occurs, as a result of which friction instantly turns into the physical welding of the steel balls into a single monolith. The machine's electric motor stops abruptly (or a protective clutch engages). The load at which this catastrophic process occurred is officially recorded as the «Weld Load» (Pz).