Effects of lubrication and die radius on the friction behavior of Pb-coated sheet steels

Using a strip tensile friction simulator, the influence of lubricant properties (viscosity and extreme pressure) and pin radius on the interfacial friction and the surface quality of Pb-coated sheet steels is investigated. Nine distinct testing conditions are examined by varying the lubricants (three oils and two greases) and pin radii (10 and 20 mm). Friction coefficient curves are generated as a function of sliding distance for each condition examined and the surface quality of the sheets are evaluated from surface roughness and micrographs taken before and after testing. From the experimental results, tendencies for the interfacial friction and surface finish of Pb-coated sheet steels are established with respect to lubricant properties and pin radius. Specifically, the results indicated that the friction coefficient increases with both the viscosity and extreme pressure (oils only) of the lubricants. In addition, it was determined that the lubricant properties had little influence on the final surface roughness of the deformed sheet. Considering the influence of pin size, the results showed that the friction coefficient increased with decreasing pin radius values.