Statistical Process Control in a Commercial Wood Treating Plant

摘要

Statistical Process Control has been used as a tool in several manufacturing industries for almost a century to eliminate variability from products. Universal Forest Products incorporated SPC into all of its affiliated wood treating plants to controlproduct quality and variability. The objective was to eliminate treated wood quality variability while maintaining efficiency and speed. Several key criteria were required to be met in order to sustain SPC in the treating plant including: oversight, training, a good operator, control variables determined, and the program installed at the plant. The treating process was monitored by variability measures, and by keeping a trailing ten assay average above a Lower Control Limit, determined by the variability in the previous data at that particular plant. Taking a before and after snapshot of quality data, variability of the assay data was reduced and quality improved, which improved retention failure rates and thus less retreats. Efficiency and speed werenot significantly affected by installing SPC.