TECHNIQUE 49 Mistake Proofing

Your first objective with axiomatic design is to make your design as independent as possible with reference to functionai requirements. After this you wouid make it as robust as possible, as per the information axiom, using such techniques as Robust Design (Technique 38), Design FMEA (Technique 40), and Mistake Proofing (Technique 49). 

While the purpose of Design Scorecards is to prevent problems, defects, and errors through superior design, they also enable better problem detection after a new solution (design) is implemented. If you are in detect-and-fix mode, any number of process-optimization techniques may help, such as Process Behavior Charts (Technique 52), Cause Effect Matrix (Technique 54), Mistake Proofing (Technique 49), and Design of Experiments (Technique 50). 

Use DFMEA during your preliminary, initial, and detail design reviews to uncover any potential failure modes. Then your first priority is to prevent these modes by improving the design itself (see Mistake Proofing, Technique 49). If you can t mistake-proof your solution (as in the foot-on-brake example), your next priority is to detect a failure mode before it occurs and prompt the user to take action. The oil warning light in a vehicle is an example of this approach. 

Use Poka-Yoke (mistake-proofing) techniques to help reduce operator assembly errors by prescribing component features and/or assembly procedures to aid correct assembly. 

After processes are documented, they have to become as fast, efficient, and flawless as possible. This means you optimize the processes that generate all the value for your new solution. Several techniques will help you do this, but you should start with Measurement Systems Analysis, because it ensures the validity of any data you use in optimization studies (see the Design of Experiments, and Conjoint Analysis techniques). Then use Work Cell Design and Mistake Proofing to optimize the layout of people, machines, materials, and other factors in an office or factory. 

Use a Cause Effect Diagram (Technique 53) to determine the root cause for each potential error. This is a critical step in mistake proofing that is often missed because too many people confuse errors with defects. For example, motion sensor failure is a defect motion sensor zone set incorrectly is an error. You can only truly solve a problem at the error level, so make sure you understand the difference. 

The rejection of outliers is a deeply rooted habit techniques range from the haughty I know the truth attitude, to looks different from what we are used to, somebody must have made a mistake , to attempts at objective proof of having observed an aberration. The first attitude is not only imscientific, but downright fraudulent if unacceptable values are discarded and forgot-... 

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