Quality constraint approach: A Six Sigma/throughput approach in manufacturing to achieve company success and continuous improvement

This research focuses on developing a methodology for increasing manufacturing throughput by locating and eliminating “Quality Constraints (QC)”. This method is defined in this research as the “Quality Constraint Approach (QCA).” The QCA will be a new method for forecasting or evaluating the impact of bad quality in a production system. This method should be effective for single or multiple product processes. Previous research on TOC has not addressed quality defects and related failure cycle time as part of the constraints applied to TOC methodology. The belief is that increased quality expenditure on operations that do not improve the throughput or profit of the company does not help the company to achieve its ultimate goal, which is to “make money.” QCA methodology should produce positive effects on the flow time of the product through the system. Reduction of waste in the form of failure cycle time (FCT) in the constraints should increase throughput and improve throughput time. When the constraint is improved, variation and quality will be improved as well. Cases of a single process level and double level three-stage process are modeled to conceptualize QCA.; A real world example was used to validate the QCA methodology. The results of the validation indicate that the model developed can assist managers in finding the quality problems that affect the system production output. The new QCA model allows managers to perform a “what-if” analysis on the impact bad quality has on capacity and demand, thus, increasing throughput and profit. Knowing current or historical quality levels (dpu) on operations necessary to build a specific product can help determine the time span necessary to complete specific customer demand, thus, helping improve customer satisfaction by improving delivery time. Historical DPUs can be used for proposal writing or production forecasting for pilot products (products never produced but with similar process steps as actual production). Quality Constraint Approach allows management to use historical quality levels in order to estimate production completion times and production capability including quality as a factor.