"Functionality" of Quality EngineeringParameter Design aims to decrease unevenness of products.
There are kinds of unevenness. If there is a complaint from a user, we have to consider all probability of these kinds of unevenness.
1. Unevenness at the time of shipping
2. Unevenness of effects by the environment to use
3. Unevenness of time depended troubles and damages
Often the cause of 2 and 3 includes 1. We need to divide the unevenness into causes.
There two approaches to decrease 1. One is the design of the product itself. The other is the design of the factory, the process and facilities. Parameter Design can be used for both approaches.
Parameter Design is also used to decrease 2.
Quality Engineering does not care about 3.
SPC is the other approach for 1. If we analyze unevenness, we need Division of Errors .
Reliability Engineering is the other approach for 2 and 3.
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