Original Date: 02/01/1991
Revision Date: 01/18/2007
Information : Statistical Process Control/Variability Reduction
As part of its Total Quality Management (TQM) philosophy, Litton Guidance and Control Systems Division (GCSD) has implemented a statistical process control (SPC) program to monitor production processes. Through the use of SPC, engineers and operators are able to reduce scrap, testing, and inspection while improving process control and quality.
Litton GCSD began its SPC implementation on assemblies and processes that had the lowest yield. The first step was to establish a baseline by which to gauge each process. This was done by monitoring critical process variables at the lowest possible level, and not just by measuring output yield. The processes were then optimized through the use of designed experiments and variability reduction (Taguchi) methods. Once the preferred process was defined, Litton GCSD utilized a program of process control and continued improvement to maintain and increase yields. Once the process was proven, the number of monitored variables was reduced as long as a high process quality was maintained.
Litton GCSD views the SPC program as an investment in the future, although it has already paid off in the present. To date, SPC has yielded a 50% reduction in solder joint defects, the use of 70% less chlorofluorocarbon solvents, and a 40% increase in process yields. With an investment in SPC, Litton GCSD anticipates even greater improvement in the future.
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