A Closer Look at the Bonding Capacity of Thick Metal-Plastic Hybrids

Metal-plastic hybrids have a lot of advantages compared to purely metal or purely plastic parts. A good design for metal-plastic hybrids can help to save weight, for example in automotive applications. Therefore, it is important to understand the joining mechanisms between both materials. Aluminum AlSi9Cu3(Fe) and polyamide 6.6 with 35 % glass fibers were used as joining partners. The materials were joined by enclosing the metal part at least partially with plastic right inside the injection molding tool. Afterwards, the tensile strength of the metal-plastic hybrids was tested under a quasi-static load. This article provides a short overview of publications related to this topic, and compares their conclusions with our own results. The focus is on the influence of the surface treatment on the metal part (shot-peening) and also the effects of different joining geometries within the bonding area. Statements made in other publications were able to be confirmed and expanded for shot-peened surfaces and particular joining geometries. In most cases, shot-peening the surface of metal parts is advantageous for the joining strength. If the strength of the bond is not important, but, instead, the achievable displacement is, a shot-peened surface is not always advantageous. In addition, the joining geometries have a large influence on the behavior of the part under static load.