A Study on Single Mode Laser Based Plastic-Metal Joining Process

Abstract

Especially in the automotive industry, the use of plastic and metal joints is preferred for weight savings. Generally, a method called “over molding” is used, where the joint strength is obtained with the plastic material that completely surrounds the metal parts, because plastic and metal cannot be bonded or welded together due to their chemical and physical differences. Today, it is used in the bonding process of joining plastics and metals, but the connection is weak. In order to overcome these problems, a promising approach has been explored by researchers in recent years. In this approach, a two-stage process is used. In the first processing step, laser radiation is applied to form microstructures on the surface of the metallic bonding partner. In the next step, the plastic is mechanically locked to the microstructures with the plastic injection method. A fast beam movement is realized by a galvometric scanning system, which allows scanning variable patterns on the metal surface. Because the process is based on a combination of sublimation and melting, the processing time is much shorter compared to conventional structuring processes. However, this study was done in slow cycles away from mass production in the laboratory setup. In this study, metal-plastic hybrid bonding experiments were carried out in 2 stages consisting of laser micro treatment of the metal surface and plastic injection process. After the injection process, the plastic is mechanically locked onto the processed surfaces.