Abstract:
This thesis presents product complexity as a criterion for the optimisation of
product design in the light of an Assembly-Oriented Design and Design for
Assembly implementation. It takes a holistic approach to the evaluation of the
product architecture by presenting a set of indicators that help examine the product
structure at two different levels: Assembly and Component complexity. Assembly
complexity assessment is further sub-divided into Structural and Sequence
complexity. The latter is a well-known and thoroughly studied area in assembly
sequence evaluation, whereas the former gives a novel and original approach to
drawing attention to those areas in the product configuration that will consume more
resources (i.e. time and tooling required). Component complexity, on the other hand,
is sub-divided into manufacturing and process handling/manipulation complexity.
The first area has been addressed by the manufacturing analysis section of most
Design for Assembly and Manufacturing methodologies, but it has been traditionally
addressed as a manual and chart-based evaluation. This is a rigid approach that
leaves little room for expansion and has no connection with the product structure.
The metrics presented in this work embody a new approach that takes into account
the component-to-component interactions and allows the analysis of component
shape by extracting its geometry characteristics and comparing them with particular
traits of the manufacturing processes available to the designer.
Additionally, the metrics presented in this work can be used to make an
assessment of the product complexity at a particular point (static complexity) in the
development cycle. They can also be registered over a period of time to provide an
estimate of the possible consequences of the decisions made during a part of the
development cycle (dynamic complexity). By using the methods developed,
designers could reduce production costs and increase the reliability of their products.
