Increasing formability in sheet metal stamping operations using environmentally friendly lubricants

In the present investigation, an alternative environmentally friendly lubricant is introduced for sheet metal forming processes. This lubricant is based on a combination of boric acid and canola oil, both of which are natural, environmentally friendly, and have independently demonstrated good lubrication potential. In order to evaluate the interfacial friction characteristics of the canola oil and boric acid lubricant in a forming operation, a strip tensile friction simulator was utilized. This apparatus has been shown to effectively model the strain behavior encountered in a deep drawing process and accurately replicates the frictional effects experienced during sheet bending. By means of the testing apparatus, the friction coefficient between the die and a 3.175 mm thick steel sheet was measured for four different lubrication conditions: unlubricated, canola oil, transmission fluid, and a combination of boric acid and canola oil. Based on the experimental results, the boric acid and canola oil lubricant significantly outperformed the other lubrication conditions with respect to the measured friction coefficient, the final sheet surface properties and the overall sheet formability. These results indicate that the boric acid and canola oil lubricant has substantial potential for providing the manufacturing community with a commercially viable and environmentally friendly alternative that will allow the forming of complex parts. (c) 2006 Elsevier B.V. All rights reserved.