Surface quality enhancement of warm incremental forming process using solid lubricant with varying etching period

Abstract

The warm incremental forming process is an effective and flexible approach for forming magnesium alloy (AZ31B) sheets, which usually is difficult to deform at room temperature. However, friction increases drastically at elevated temperatures during the forming process. In order to reduce friction, liquid lubricants are generally applied on the sheet’s surface; however, the liquid lubricant usually thins out during the warm incremental forming process. To address this problem, solid lubricants such as graphite and molybdenum disulfide have been used as better alternative lubricants for forming the parts at elevated temperatures. In addition, an increase in surface roughness, either by depositing porous film or by creating micro or nanostructures, can help better the surfaces’ lubrication by solid lubricants. In this work, a facile etching method is used to treat a pre-formed sheet and solid lubricants to improve the surface quality and reduce the part’s wear during the warm incremental forming process. The combined effect of the type of solid lubricant and etching time is studied in detail. The quality of the magnesium alloy sample and its morphology before and after the forming process has been examined using various characterization tools, including a surface roughness tester, a tribometer, and scanning electron microscopy (SEM). The results reveal that the magnesium alloy sample etched for 5 min and lubricated with graphite powder showed significantly low weight loss and better surface quality. Overall, the results revealed that the etching of samples could be highly beneficial for the warm incremental forming process.