Teoria Sic Sigma

PROCEEDINGS OF WORLD ACADEMY OF SCIENCE, ENGINEERING AND TECHNOLOGY VOLUME 37 JANUARY 2009 ISSN 2070-3740

Integrating the Theory of Constraints and Six Sigma in Manufacturing Process Improvement
Kai Jin, Hyder Abdul-Razzak, Yousri Elkassabgi, Hong Zhou, and Aaron Herrera

Abstract—Six Sigma is a well known discipline that reduces
variation using complex statistical tools and the DMAICmodel. By integrating Goldratts’s Theory of Constraints, the Five Focusing Points and System Thinking tools, Six Sigma projects can be selected where it can cause more impact in the company. This research defines an integrated model of six sigma and constraint management that shows a step-by-step guide using the original methodologies from each discipline and is evaluated in a case study from theproduction line of a Automobile engine monoblock V8, resulting in an increase in the line capacity from 18.7 pieces per hour to 22.4 pieces per hour, a reduction of 60% of Work-In-Process and a variation decrease of 0.73%.

Management for companies or businesses that have the need to improve not only the quality of their products and services, but their production lines´ efficiency and productivityas well. An integrated model will demonstrates the path to encounter environments where financial resources are limited, or the line is not profitable enough to program a full Six Sigma project that will solve problems with a large budget on a product that returns very little dividends to the business. II. LITERATURE REVIEW A. Six sigma Six Sigma uses a set of statistical tools as their mainweapon to fight variability inside the company. These statistical tools help measure and analyze the areas with the most variation in the process. Variation is a normal element of any company, so Six Sigma will not eliminate variation, it will reduce it as much as possible. Six Sigma uses a set of statistical tools as their main weapon to fight variability inside the company. These statistical toolshelp measure and analyze the areas with the most variation in the process. Variation is a normal element of any company, so Six Sigma will not eliminate variation, it will reduce it as much as possible. Many project teams have models that aid to approach them; these methodologies are guides or manuals that resolve a problem due to variation. According to Gitlow and Levine [1] the most common modelor strategy followed by teams is the DMAIC (Define, Measure, Analyze, Improve, Control), this method follows a guideline that lets the project team know what and when are the statistical tools used, as well as other tools that are used to understand priorities of the project according to the variation and effect to the company. B. Constraints Management The theory of Constraints converted form amanufacturing scheduling method to a management philosophy that focuses on systems improvement. The best way Dr. Goldratt [2] explained a system is through a chain, he said that the chain is worth the strength of the weakest link found, it does not matter if all the other links are strong enough, the system or chain will break at the moment the weakest link is forced. The system chain extends formmarket demand to suppliers; everything that interacts with the industry can be the weakest link. The Theory of Constraint suggests that the weakest link

Keywords—Constraint Management, Manufacturing Process Improvement, Six Sigma, System Thinking. I. INTRODUCTION HROUGH Six Sigma, companies like Motorola, GE, Kodak or Sony, have created a trust in current and potential customers that any productor service obtain by them will have good quality. A major drawback of Six Sigma, is that for the process to be completed, most quality problems have to be resolved with the purchase of tools, machinery, technology, or just a significant amount of investment, which can be a painful issue for a small company. Other weakness of Six Sigma is the fact that there are so many potential projects to...