Page 343 - Design for Six Sigma a Roadmap for Product Development
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Theory of Inventive Problem Solving (TRIZ) 313
It is clear that we want to reduce the space between wrench and nut to
improve operation reliability, however, this led to the deterioration of oper-
ations. From a 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 trade-off between the contradictory demands, or by overcoming
the contradiction. Trade-off or compromise solutions do not eliminate the
technical contradictions, but rather soften them, thus retaining harmful
(undesired) actions or shortcomings in the system. A trade-off solution in
this example would be to make the clearance neither too big nor too small.
An inventive solution for this problem can be found if the technical contra-
diction can be overcome completely. Forty principles and the contradiction
table are important tools for overcoming contradictions.
1. Build contradiction model. Look into the problems and find a pair of con-
tradictions. The contradiction should be described using 2 parameters of
the 39 parameters for technical contradictions. In this problem, the con-
tradiction is:
Things we want to improve: Reliability (parameter 27)
Things are getting worse: Ease of operation (parameter 33)
2. Check contradiction table. 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 partial matrix show below).
What is deteriorated?
25. Waste of time 26. Quantity of substance 27. Reliability 28. Measurement accuracy 29. Manufacturing precision 30. Harmful action at object 31. Harmful effect caused by the object 32. Ease of manufacture 33. Ease of operation 34. Ease of repair 35. Adaptation
What should be improved?
25. Waste of time 35 38 10 30 24 34 24 26 35 18 35 22 35 28 4 28 32 1 35 28
18 16 4 28 32 28 18 34 18 39 34 4 10 34 10
26. Quantity of substance 35 38 18 3 3 2 33 30 35 33 3 35 29 1 35 29 2 32 15 3
18 16 28 40 28 29 31 40 39 35 27 10 25 10 25 29
27. Reliability 10 30 21 28 32 3 11 32 27 35 35 2 27 17 1 11 13 35
4 40 3 11 23 1 2 40 40 26 40 824
28. Measurement accuracy 24 34 2 6 5 11 1 28 24 3 33 6 35 1 13 1 32 13 35
28 32 32 23 22 26 39 10 25 18 17 34 13 11 2
29. Manufacturing precision 32 26 32 30 11 32 26 28 4 17 1 32 25 10
2818 1 1036 3426 3523