Environmental and economic evaluation of the sheet metal stamping process using alternative lubricants

Sheet metal forming of tribologically difficult materials (e.g. stainless steel) or forming in tribologically difficult conditions (e.g. ironing, punching, deep drawing) require the use of environmentally hazardous lubricants, such as chlorinated paraffin oils in order to avoid galling. The present paper describes an environmental and economic evaluation of two alternative sheet metal stamping processes. The forming of a sheet metal component for boiler burners has been taken as case study for the analyses. In particular, two different lubricants (standard mineral versus polymer matrix-based lubricant) have been tested and compared. However, the differences among the two processes involves not only the lubrication phase, but also the electric energy consumption during the stamping and degreasing, as well as the typology of solvent (perchloroethylene versus water). Results obtained with the economic analysis show that the use of the alternative lubricant leads to a 16% reduction of the total manufacturing cost, mainly due to the optimization of the degreasing. Concerning environmental results, instead, no relevant differences can be observed for almost all the considered impact categories (ReCiPe midpoint and endpoint), since the optimized phases are not the most critical ones.