Page 292 - Design for Six Sigma a Roadmap for Product Development

262 Chapter Eight

P-diagram

Device # 1: Ring Rotor x 1.3.1-1 x 1.3.2-1 Close tolerance
Clearance to Chamber Close Clearance Material Coating lubrication
y 1.3.1 -1 Minimize
leak (loss of flow) from high A 11
pressure to low pressure Ring rotor Leakage
y 1.3.2-1 Lubricate A 0 A clearance
running surface of chamber 21 22 Lubricate
to chamber
chamber surface

Cover flatness
Pocket flatness
Cover deflection
Fluid temperature
Fluid condition
Figure 8.17 The P-diagram of sealing device 1 with DFSS.

This parameter also should be smartly introduced, yielding uncoupled
or at least decoupled designs. This parameter should deliver one of the
FRs without adversely affecting the other FR. Using TRIZ, these char-
acteristics fit the coating to be declared as x 1.3.2 in the sealing 1 mapping.
Coating will help the lubrication by surface tensions of the hydraulic
media keeping the surfaces wet and lubricated. Coating does not affect
leakage, allowing the tolerance to be tightened to minimize the leakage.
The resulting mapping and the P-diagram are given in Fig. 8.17.

8.6 The Implications of Axiom 2
Axiom 2 deals with design information content (complexity), which in
essence is a function of the number of FRs and DPs (solution size) and
their inherent variation. Shannon entropy can be used to quantify the
information content. In a study on digital signal communication,
Shannon (1948) defined a level of complexity, called the entropy, below
which the signal can’t be compressed. The principle of entropy was
generalized to many disciplines and used as a measure of uncertainty.
In the design context, Suh (1990) proposed information as a measure
of complexity in axiom 2.

8.6.1 The complexity paradigm
Complexity in design has many facets, including the lack of trans-
parency of the transfer functions between inputs and outputs in the