The effect of lubricant viscosity in cold work forward extrusion

Abstract

In cold work extrusion, lubricants play an important role in lubricating the tool and workpiece surfaces, preventing metal-to-metal contact and reducing sliding friction, so that the workpiece can be extruded smoothly without severe wear due to lubricant starvation. In this paper, the influence of lubricant viscosity in cold work forward extrusion was investigated. The lubricants were additive-free, paraffinic mineral oil, which may have low, medium or high viscosity. The workpiece material was pure aluminum A1100, extruded with extrusion ratio of 3. The analysis focused on extrusion force, workpiece surface roughness after the extrusion process and the metal flow in the deformation zone of the workpiece. Using the visioplasticity method, the sliding velocity was calculated from the metal flow. Results showed that, the higher the lubricant viscosity, the lower the extrusion force generated. However, a high-viscosity lubricant produces coarser workpiece surface conditions after the extrusion process.