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
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.