Page 331 - Design for Six Sigma a Roadmap for Product Development

Theory of Inventive Problem Solving (TRIZ) 301

the product, but cold elsewhere. One way to keep the product hot during
coating is by applying an electric current for inductive heating during the
coating process.

Example 9.7. Separation in Space (Fey and Revin 1997)
Problem. A rotor link has to satisfy mutually exclusive requirements. It
should be light (for a given shape) to reduce driving motors and/or to allow
for larger payloads. However, light materials usually have reduced stiffness.
On the other hand, it should be rigid to reduce end-of-arm deflection and the
setting time in start/stop periods. However, rigid materials are usually
heavy.
Contradiction. The link must be light in order to carry large payloads, but
it must be heavy for good rigidity.
Solution. A simple analysis reveals that the end-of-link deflection is
determined by the root segment of the link (the highest bending moment),
while the inertia is determined mainly by the overhand segment. Thus the
contradictory requirements are separated in space. The root section, which
does not significantly influence the effective mass of the link but deter-
mines its stiffness, is made of a high Young’s modulus material such as
steel, while the overhang section, which does not noticeably contribute to
stiffness but determines the effective mass, is made of something light
(such as aluminum).

Rotor Link

Inertia Force

Moment
distribution