A Proposed Systematic Problem Solving Methodology within Six Sigma Projects Applied for Continuous Improvement of Textile Dyeing Processes

The present paper aimed to develop a systematic, prescriptive and exclusively statistical problem-solving methodology that integrates scientific experimental design methods with the Six Sigma philosophy. This was used for the study and continuous improvement of a direct dyeing process for textile materials. In the first stages of the methodology, the process was systematically analyzed, the color difference was identified, using rank correlation, as the main quality requirement of the customer, and the influence of the electrolyte concentration in the dye bath on this quality characteristic was tested, using analysis of variance. In the subsequent stages, a full factorial experiment was carried out to obtain a mathematical model describing the action of the main selected influence factors on the color difference, and response surfaces and constant level curves were plotted to find the optimal settings of these influence factors. It was concluded that cotton fabric provides a more uniform chromatic reproduction, i.e. a lower color difference, compared to linen, and the electrolyte concentration of 20 g/L yielded the most stable chromatic performance for both fiber types.