Integration of Process Design, Process Improvement, and Process Control
Unfortunately, Six Sigma is often promoted with a great deal of hyperbole, fanfare, and outright hype. Some authors make Six Sigma sound like an organizational "snake oil" that will magically solve any issue or problem. In fact, Snee and Hoerl (2003) is the only book that we are aware of on the subject that discusses unsuccessful Six Sigma efforts. It is important for readers to understand that Six Sigma is a rigorous, disciplined improvement methodology that utilizes scientific tools and formal deployment strategies. As such Six Sigma provides leaders with a set of concepts, methods, and tools that enables them to align organizations to focus on improvement, provide road maps for change and improvement, and empower the right people to make the needed improvements. Therefore, to reap maximum long-term benefits from Six Sigma, organizations must eventually integrate it into an overall process management system utilizing the Six Sigma goals of rapid organizational change and improvement. Typically, this integration is the last phase in Six Sigma deployment (Snee and Hoerl 2003) and occurs years after launching a Six Sigma initiative. As discussed in Chapter 6, Six Sigma is not an organizational cure-all; some issues and projects are best addressed by methods other than Six Sigma.
As you think about using Six Sigma holistically as a key element of your improvement strategy, and eventually as part of your overall process management system, it is important to keep in mind the three major aspects of process management: process design/redesign, process improvement, and process control. Process design/redesign focuses on the design of new processes and the redesign (reengineering) of existing processes. Six Sigma can contribute significantly to design efforts through design for Six Sigma (DFSS), which can utilize the define, measure, analyze, design, verify (DMADV) framework. DMADV is the framework used by GE and other organizations. Other frameworks have been proposed (Creveling et al. 2003). Process improvement focuses on the improvement of existing processes without changing the fundamental design of the process. Process control focuses on keeping the process operating on target and within requirements so that the process produces products and services that satisfy customers profitably.
The key distinction between process improvement and process control is that process improvement determines how to drive the process to new levels of performance. Process control, on the other hand, identifies root causes for why the process performance has deteriorated, so that performance can be brought back to normal levels. For example, most of the routine maintenance done on cars is process controlsuch as doing a tune-up or oil change to maintain performance. By switching to titanium spark plugs and premium gasoline, however, an owner might be able to improve the cars' performance beyond its original capability. This would be an example of process improvement. Further improvement might require redesign of the engine.
Six Sigma uses the define, measure, analyze, improve, control (DMAIC) framework to improve and control existing processes. In general, the DMAI phases focus on improvement, and the C phase focuses on process control and sustaining the gains. It is interesting to note that Six Sigma considers the need for control and implements a formal control plan in each design and improvement project. Chapter 6 further discusses these aspects of Six Sigma and how they should integrate with an overall process management system.