Lubricant-Free Thermoforming Mold Using Pulse Electrochemical Polishing

Abstract

Thermoforming (TF) is a process used for fabricating products by applying heat and vacuum pressure to a plastic film or plate. Typically, TF molds require post-processing, resulting in additional costs and time consumption. Furthermore, continuous application of lubricant is necessary to prevent corrosion and facilitate mold release. Electrochemical polishing (ECP) is a technique used to achieve a polished surface on metal through an electrochemical reaction. In this research, a novel approach is proposed as a solution to the need for lubricants and manual post-processing in mold preparation, utilizing pulse electrochemical polishing (PECP). A comparative analysis is conducted on the reproducibility of products and the forces required for mold release among molds prepared using PECP, lubricated molds, and unpolished molds. To assess product reproducibility, the radii of curvature of all mold steps and grooves are determined and compared. Furthermore, peeling tests are conducted to estimate the forces required for mold release. Product surface evaluation is performed using atomic force microscopy, while lateral force microscopy is employed to measure the reductions in surface frictional force achieved by PECP.