Development of a Laboratory-Scale Test Methodology for Performance Evaluation of Lubricants for Hot Stamping of an Aluminium Alloy

In hot stamping of aluminium, the need for efficient methods to evaluate, compare, and rank lubricants based on their tribological performance is critical in the early stages of selection. Pilot and simulative testing can be costly, time-consuming, and complex, making it inefficient for initial benchmarking. This work aims to develop a test methodology to assess lubricant performance for hot stamping under key operating conditions without fully simulating the forming process. The proposed method distinguishes the impact of temperature on lubricant degradation, friction, wear response, and cleanability. The tests utilised a conventional hot work tool steel and a 6010S aluminium alloy with two commercially available lubricants: a polymeric lubricant and a lubricant containing graphite. The tribological tests involved a reciprocating, sliding flat-on-flat configuration at two temperatures (100 °C and 300 °C). The methodology showed that the graphite-containing lubricant exhibited over a four times lower friction coefficient than the polymer-based lubricant at 10 wt.% concentration and 300 °C. At 100 °C, both lubricants provide lubrication and can be cleaned, but increasing temperature led to a significant decline of both aspects. The observed temperature range where the lubricants degrade was between 120 °C and 170 °C.