Fastening & Joining Methods

Introduction

Every joining technique has particular design requirements, while certain joint requirements may suggest a particular joining technique. Design for assembly, automation, and fastener selection impose their own requirements.

Bolting is a common fastening method, for example, but welding may reduce the weight of an assembly. Naturally, joints designed for the two techniques would differ greatly. However, all joint designs must consider characteristics such as load conditions, assembly efficiency, operating environment, overhaul and maintenance, and the materials used.

Welding is often a cost-effective way to fabricate. It does not require overlapping materials, so it eliminates excess weight caused by other fastening means. Fasteners do not have to be bought and kept in inventory. Welding also can reduce costs associated with extra elements, such as angles fastened between parts.

Welded joints distribute operating stresses evenly. However, design of a welded joint significantly affects the welding processes that are used. Many design options permit excellent welding performance. Nevertheless, designers who are unaware of the range of technology and methods available may fail to realize welding's potential.

There are a variety of joining methods that do no use fasteners. Alternative methods are especially important for some materials.

Methods to join materials without the use of fasteners include adhesives, welding, brazing, soldering, clinching, and injected-metal assembly. In addition, materials such as plastics, composites, and metal-ceramic combinations may indicate the use of certain joining methods.