Alternative lubrication and lubricants for the cold extrusion of steel parts

Lubrication is very important in cold extrusion of steels, mainly regarding to the reduction of extrusion load and tool wear. Lubrication processes used in industries are time consuming and present high costs and important environment impact. The lubricant is generally represented by layers of phosphate (zinc or magnesium) coated to the billet and associated with soaps of sodium or calcium stearate. Those layers can also be associated with MoS2 lubricant. The proposal of this work is to develop an alternative lubrication process to the cold extrusion associated to lubricants, which are alternative too, less pollutant and that present similar results in terms of extrusion load and product quality. Therefore, four lubricants were analyzed (one mineral oil and three semi-synthetic oils), two lubrication methods were applied (immersion and hydrostatic), with billets in two metallurgical conditions and with three surface finishing. Statistical methods applied to the results of the experimental tests indicated that some processes and lubricants could be used as substitutes for common lubricants used in industry, since they presented results of extrusion load and product quality similar to those obtained in the industry with the conventional lubrication.