Russell Davison

The range of plastic snap-in fasteners is classed as permanent or semi-permanent, as they can be removed with the aid of special tools. It is not feasible to repair products with these permanent joints. This leads to 'throw away' products, upon a fault occurring, unless self-contained sub-assemblies are used in standard modules.

Parts integration dictates that groups of components should, where possible, be manufactured as a single part by chip-less forming, e.g. precision die-casting, precision plastic moulding, powder metallurgy, investment casting, fine blanking, and high energy rate forming. These methods produce, in one single operation, the features of a number of parts without the use of fasteners. Also, features for identification by the automatic bowl feeder tooling can be cast into the part.

Each part in an assembly serves a purpose with the aid of functional features. The designer should group a number of parts together to form a single part with multi-functional features.

Create a precedence diagram for the assembly operations. Identify redundant areas of the operation and incorporate the functional parts of these operations into other operations.