Six Sigma and Simulation , so What ’ S the Correlation ?

This paper will explore the fundamental relationships between Six Sigma and simulation. A basic overview of Six Sigma includes: 1. Six Sigma philosophy, 2. Basic tools, 3. Theory of Variation, 4. SPC, 5. Process capability, 6. Six Sigma infrastructure, and 7. DMAIC and DFSS processes. Simulation will be applied to the appropriate areas of the overview. Improvement in the robustness of the Six Sigma methodology will be discussed and the strengths of simulation will be presented as capable and preferable enhancements to the Six Sigma processes. Quotes from Six Sigma and industry leaders will be presented. Simulation will be presented as an innovation tool enhancing the Six Sigma DMAIC and DFSS processes. 1 SIX SIGMA OVERVIEW Six Sigma has received wide acclaim as a methodology, process and vision to accomplish process improvement. Professor Larry S. Aft, PE, Chairman of the Industrial Engineering Department at Southern Polytechnic State University in a course delivered through the Center for Quality Excellence entitled Six Sigma Implementation, Champion and Green Belt Training states, “ Six Sigma is a customer focused, well defined problem solving methodology supported by a handful of powerful statistical tools.” He further states, “Continuous improvement is driven by the execution of carefully selected projects. The goal of the Six Sigma approach is to take small steps forward and no steps backward.” Aft further states that “the objective of Six Sigma is to reduce variation through continuous process improvement. This leads to customer satisfaction.” Motorola was instrumental in the initiation of Six Sigma. In fact, the phrase “Six Sigma” was coined by Motorola. They further stated that a defect is anything that results in customer dissatisfaction. General Electric (GE) has become an avid supporter of Six Sigma over recent years. According to their website, Six Sigma is not a “secret society, a slogan or a cliché. Six Sigma is a highly disciplined process that helps us focus on developing and delivering near-perfect products and services.” They further state that the word “sigma” is a statistical term that measures how far a given process deviates from perfection. The central idea behind Six Sigma is that if you can measure how many “defect’s you have in a process, you can systematically figure out how to eliminate them and get as close to “zero defects” as possible. To achieve Six Sigma quality, a process must produce no more than 3.4 defects per million opportunities. An “opportunity” is defined as a chance for nonconformance, or not meeting the required specifications. This means we (GE) need to be nearly flawless in executing our key processes.” Aft states that three sigma quality is 99.73% defect free. That implies that in a three sigma world, there would be approximately 54,000 incorrect drug prescriptions per year and 40,500 babies dropped in the delivery room each year in the United States. In a six sigma quality world, there would be only one incorrect drug prescription every 25 years and three newborn babies dropped every century. Ferrin, Miller, and Muthler These examples illustrate well the differences in producing defect free work under the traditional three sigma constraints versus the more aggressive, customer oriented six sigma requirements. GE states that “Six Sigma is embedding quality thinking, process thinking across every level and in every operation of our company around the globe. Today, Six Sigma is the way we work. It is a vision we strive toward and a philosophy that is part of our business culture. It has changed the DNA of GE and has set the stage for making our customers feel Six Sigma.” The key concepts of Six Sigma are: 1. Critical to Quality (CTQ) – Attributes most important to the customer 2. Defect – failing to deliver what the customer wants 3. Process Capability – What your process can deliver 4. Variation – What the customer sees and feels 5. Stable Operations – Ensuring consistent, predictable processes to improve what the customer sees and feels Six Sigma is divided into two methodologies, DMAIC and DFSS. DMAIC (which is an acronym for Define, Measure, Analyze, Improve, Control) focuses on improving existing processes and performance. While Design for Six Sigma (DFSS) focuses on generating new processes, products, services, and/or plants to meet customer needs (CTQ) at the Six Sigma level. The Seven Basic Tools of DMAIC are: 1. Flow charts 2. Check sheets 3. Pareto diagrams 4. Cause/Effect diagrams 5. Scatter diagrams 6. Histograms 7. Statistical Process Control (SPC). DFSS uses many of the above tools with the addition of: