Dimensional variability must be managed. Assembly plant installation processes which require operator adjustment result in random, unpredictable variability. On the other hand, processes which use locators and quality controlled components eliminate operator adjustments. This results in managed variability with repeatable and dimensionally consistent end products.
The 1994½ Windstar mini-van incorporated locators with a detailed component quality control plan and then went one step further. Dimensional variability was managed and verified during the design process to ensure that every vehicle produced would meet customer quality standards.
To verify that the Windstar would achieve the customer quality standards, by design, a full vehicle dimensional variability model was developed. The body structure, interior trim, major instrument panel components, suspension, steering and various subsystems were modeled.
The model was used to:
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Predict high volume production dimensional variability
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Identify the impact of design alternatives
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Identify the variability of dimensional targets
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Analyze supplier variability forecasts
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Resolve dimensional concerns and problems during prototype build and launch.
The purpose of this paper is to overview the modeling process used and discuss the effect on the program.