Page 580 - Design for Six Sigma a Roadmap for Product Development

538 Chapter Fifteen

E power Measure
Change energy force S
into force and force measurement
S control movement S deform measurement
Measure
deformation
E deformation
Load
specimen
Specimen Specimen deformed
Figure 15.3 Functional diagram of a tensile testing machine.

materials. The tensile strength of a material such as wire, rope, or stone is
its ability to support a load without breaking. In a tensile strength test, a
piece of specimen is loaded and fixed at the fixture of the testing machine;
then a mechanical force is applied on the specimen and the magnitude of the
force is gradually increased until the specimen is “broken” or has “failed.”
Both the “force at breaking point” (tensile strength) and the deformation of
the specimen will be measured and recorded. Figure 15.3 is a rough func-
tion diagram for the tensile testing machine using the symbols defined in
Fig. 15.2. It gives a good idea of design hierarchy and the roles of these three
kinds of transformation on each level.
Figure 15.4 gives a more detailed block diagram for the tensile testing
machine.
Clearly, in each block, several transformations can occur simultaneously,
but there is usually one main type of transformation; this could be any one
of the three transformation types. When the main mode of transformation
is energy, or material transformation, signal transformation is often accom-
panied with it in the form of control (design parameter). The functions are
accomplished by the transformation process.
The following checklist is helpful in identifying, recognizing, and
designing different modes of transformation in the technical system:
Energy transformation:
■ Changing energy (e.g., electrical to mechanical energy)
■ Varying energy components (e.g., amplifying torque)
■ Connecting energy with signals (e.g., switching on electrical energy)
■ Channeling energy (e.g., transferring power)
■ Storing energy (e.g., storing kinetic energy)
Material transformation:
■ Changing matter (e.g., liquefying a gas)
■ Varying material dimensions (e.g., rolling sheetmetal)
■ Connecting matter with energy (e.g., moving part)