2.2.2 Choice of Assembly Type

2.2.2 Choice of Assembly Type

Various joining techniques are used to assemble materials in a wide range of ways. As some of these methods join components permanently and others create temporary joints, joining is divided into two groups: permanent and temporary. Permanent (non-demountable) joints are separated only by destroying either the joined substrates or the connecting element. As the name suggests, these joints are permanent and usually offer noise, vibration and harshness (NVH) improvements and leak-proof joining. Since permanent joints are not disassembled easily, inspection, repair and replacement are complex and costly. Often non-destructive testing is carried out on permanent joints for inspection of assembly. Permanent joints are suitable for applications in which disassembly is usually not required during service life. Welding is a prime example in this category. Riveted joints, soldering, brazing and adhesive bonds are also permanent joints. However, riveted joints and spot welding can only provide an NVH-optimised and leak-proof joint in conjunction with an adhesive. Figures 27 and 28 show two types of permanent joints.