Page 283 - Design for Six Sigma for Service (Six SIGMA Operational Methods)

252 Chapter Nine

39. Inert atmosphere
• Replace a normal environment with an inert one.
• Add neutral parts or inert additives to an object.
40. Composite materials
• Change from uniform to composite (multiple) materials.
Example 9.5: Using 40 Principles and the Contradiction Matrix to Improve
Wrench Design
When we use a conventional wrench to undo an overtightened or corroded nut
(as shown in the following picture), one of the problems is that the corners of
the nut receive a concentrated load, so they may wear out quickly. You can
reduce the clearance between the wrench and nut, but it will be difficult to fit
the wrench onto the nut. Is there anything we can do to solve this problem?

Clearly we want to reduce the clearance between the wrench and nut to improve
operation reliability; however, this leads to the deterioration of operations.
From the TRIZ standpoint, a technical contradiction is present when a useful
action simultaneously causes a harmful action.

A problem associated with a technical contradiction can be resolved either by
finding a tradeoff between the contradictory demands or by overcoming the
contradiction. Tradeoff or compromise solutions do not eliminate the technical
contradictions, but rather soften them, thus retaining harmful (undesired)
actions or shortcomings, in the system. An engineering problem becomes an
invention one when it has a technical contradiction that cannot be overcome by
conventional means and tradeoff solutions are not acceptable. The 40 principles
and the contradiction matrix are important tools for overcoming contradictions.

Step 1. Build contradiction model: Look into the problems and find a pair of
contradictions. The contradiction should be described using 2 of the 39
parameters for technical contradictions. In this problem, the contradiction is
• Things we want to improve: Reliability (parameter 27)
• Things are getting worse: Ease of operation (parameter 33)
Step 2. Check contradiction matrix: Locate the parameter to be improved in
the row and the parameter to be deteriorated in the column in the contra-
diction matrix for inventive principles. The matrix offers the following
principles 27, 17, and 40 (see the following partial matrix).