Ethical issues in engineering design - 3TU.Centre for Ethics and ...

Engineering ethics and design processes
As the example of the bolt and the new transportation device suggests,
engineers are confronted with different degrees of external constraint in different
design processes. According to Vincenti [Vincenti, 1992], this degree of external
constraint depends mainly on two dimensions: the level of design hierarchy and
the type of design (normal versus radical). 6
Design hierarchy
Most modern products consist of several parts, subassemblies and subsystems. 7
In many cases these subsystems and parts are more or less independently
designed. Depending on how the design process is organised, different teams
and engineers work on different parts of the product. There is communication
and co-operation between the teams or at least there usually is. These design
teams can be from the same or from different companies. The parts,
subassemblies and subsystems are ordered hierarchically. The complete product
is designed at the highest levels of the design hierarchy; subsystems and parts are
designed at lower levels. Vincenti divides the design hierarchy of the design
process of an airplane in the following levels.
‘1. Project definition: translation of some usually ill-defined military or
commercial requirement into a concrete technical problem for level 2.
2. Overall design: layout of arrangement and proportions of the airplane to
meet the project definition.
3. Major-component design: division of project into wing design, fuselage
design, landing-gear design, electrical-system design etc.
4. Subdivision of areas of component design from level 3 according to
engineering discipline required (e.g., aerodynamic wing design, structural
wing design, mechanical wing design).
5. Further division of categories in level 4 into highly specific problems e.g.
aerodynamic wing design into problems of platform, airfoil section and
high-lift devices).’ [Vincenti, 1990, 9].
There are similarities between Vincenti’s ideas of design hierarchy and the
design hierarchy levels defined by Disco et al. [Disco et al., 1992]. Disco et al.
distinguish the following levels of hierarchy:
• systems, like a plant, electricity or cable networks
• functional artefacts, like cars, etc
• devices like pumps, motors etc
• components, like materials, nuts, condensers etc
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6
Vincenti uses the term “technical constraints” instead of external constraint, but this is a
misleading term in my view since some of the constraints mentioned by Vincenti are not
technical but rather social in nature. Vincenti seems to use the term technical constraints for all
constraints that the engineer s of a design team cannot change [Vincenti, 1992].
7
Walton, for example, estimates that there are about 30.000 parts in the Ford Taurus [Walton,
1997].
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