Monday, 29 May 2006

Automatic Assembly (9/16)

The product designer must analyse the product and consider if it can be economically assembled in it's present state, or decide if design changes are necessary for automatic assembly.  In practice, the majority of products assembled manually require design changes to make automatic assembly viable.  The product designer must consider what further benefits can be gained from more re­designing of design features, assembly operations, or even the elimination of parts.  The process of design for automatic assembly is best effected by a systematic approach. A structured method for evaluating designs to identify inefficient features has been developed by UMass and other organisations.

An automatic feeding device and, at least, one workhead is required for each component to be automatically assembled into a part-built product.  A significant reduction in cost is achieved by eliminating a part from a product.  Designers should strive for the irreducible number of separate components per assembly, consistent with its performance and fitness for purpose.  An investigation into the function of the product exposes redundant parts and these should be eliminated.

Fasteners, which are separate from the component being secured, should be avoided.  Fastening technologies of the future are based on adhesives, ultrasonic welding, soldering, resistance welding, clip fastening, and twisted tab joining.  Fasteners can be classed as being permanent or semi-permanent. Permanent fasteners do not permit removal, e.g. adhesives.  Semi-permanent fasteners do permit removal, e.g. screws.

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