Page 579 - Design for Six Sigma a Roadmap for Product Development

Design Optimization: Advanced Taguchi Robust Parameter Design 537

transformation. For example, in using an automobile, energy conver-
sion is the main transformation.
In technical designs, the main transformation is usually accompa-
nied by a second type, and quite frequently, all three transformations
come into play. There can be no transformation of material or signals
without an accompanying transformation of energy, however small.
The conversion of energy is often associated with conversion of mater-
ial. Transformations of signals are also very common in the form of
control and regulate energy and/or the material transformation
process. Every signal transformation is associated with transforma-
tion of energy, although not necessarily with material transformation.
Technical systems are designed to deliver functions. A technical sys-
tem delivers a main function in order to accomplish the main task of
the system, namely, the task that the system is supposed to accomplish
for the user. The system also delivers auxiliary functions, or support-
ing functions, which contribute indirectly to the main function.
In a DFSS context, technical systems are designed to deliver func-
tional requirements as derived by the zigzagging process. A technical
system delivers high-level functions in order to accomplish the attrib-
utes of the voice of the customer. The system also delivers low-level
functions in the physical structure.
Phal and Beitz (1988) use the notations and symbols shown in
Fig. 15.2 to model the physical and process structures in a block
diagram to effect some visual translation above the mathematical
mappings obtained via the zigzagging process (Chaps. 5, 6, and 8).

Example 15.1.Tensile Testing Machine (Phal and Beitz 1988) A tensile test-
ing machine is a measurement device that measures tensile strength of

Flows

E M S

Flow of energy Flow of material Flow of signal

Function

Main function Auxiliary function
Figure 15.2 Symbols for design synthesis.