Quality and Reliability at General Motors Dealing with Statistics in Manufacturing : Correlation of Gauges
White, Heather M.
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The project investigated the correlation of gauges between three cast iron crankshaft manufacturing lines for the 305 cubic inch V8 engine and 360 cubic inch V8 engine. The plant was very interested in this project. They felt that perhaps the largest single burden on the manufacturing process could be attributed to scrap parts. Scrap part refers to a part that is not within a specific tolerance and therefore either it is undersized or oversized. The object was to manufacture a universal part The procedure of off-loading from one crankshaft manufacturing line and loading onto the second manufacturing line with partially finished parts has been perceived to be a major source of scrap for the plant. Parts on one crankshaft manufacturing line are suppose to be within specified tolerance of another part from either of the two other crankshaft manufacturing lines at a specific point within the process. The plant has found that interchanging parts between crankshaft manufacturing lines produces scrap. The interchanging of parts is required due to machinery down time and production rates required. The plant felt that a better understanding of the correlation of gauges between manufacturing lines would help reduce scrap. The hypothesis of this gauge study was then that the gauges are measuring the same specific dimensions at the same specific point within the process as determined by engineering.