Page 110 - Design for Six Sigma a Roadmap for Product Development

Product Development Process and Design for Six Sigma 85

3.4.3 Creating lean product
In Yang’s recent book Voice of the Customer Capturing and Analysis
(Yang 2008), it is stated the product development process is an infor-
mation creation process. The consumer of this information is the prod-
uct. If you design a high-end, complicated product such as commercial
airplanes, it consumes a lot of information. You need an enormous
amount of design, drafting, testing, simulation, and tooling design to
generate enough information that you know how to build the aircraft
successfully. Axiom 2 of the axiomatic design principles says that the
best design is the design that delivers all product functions and has
the lowest possible information content, or complexity level. It makes
a lot of sense here. For example, in an automobile design project, if you
end up using a lot of specially designed parts, extremely high part
counts, and a lot of new and immature technologies, then you need to
spend a lot of engineering hours to design, analyze, test, and trou-
bleshoot these parts and subsystems. Overall, you need to generate a
lot of information in these design tasks. So this design will consume a
lot of information that were created by hard work. However, if you
adopt the right design principle, you can use off-the-shelf parts to
replace specially designed parts, use value engineering and design for
manufacturing practice to reduce a large number of parts, and reduce
the number of immature technologies introduced into this product. If
the product still can deliver the same functions as the previous design,
by doing all these, you reduce the information content in the design
greatly, so you don’t need to generate all that information any more,
and you save a lot of engineering hours.
In Yang’s book, it is stated that the ideal product development
process is such that it creates information and knowledge at the high-
est efficiency, speed, and quality, but the consumption of information
for each good quality product is minimum.
In this subsection, we discuss the strategy to reduce the information
consumption for each product design. The information consumption is
proportional to the complexity of the product design. So we need to
trim all unnecessary complexities out of product design. A product
design that is free of unnecessary complexities is called a lean product.
The complexity in engineering design is related to
■ Number of functions and parts
■ Complexity in product architecture (how different modules and
design parameters are related to one another)
■ Uncertainty (such as uncertainty caused by variation, quality, and
technical immaturity)
■ Complex relationship between design parameters and product
performance