Quality Management for Organizational Excellence Lecture/Presentation Notes By: Dr. David L. Goetsch and Stanley Davis Based on the book Quality Management for Organizational Excellence (Sixth Edition)

Statistical Process Control Defined Rationale for SPC Eighteen: Optimizing and Controlling Processes through Statistical Process Control (SPC) MAJOR TOPICS Statistical Process Control Defined Rationale for SPC Control Chart Development Management’s Role in SPC Role of the Total Quality Tools Authority over Processes and Production Implementation and Deployment of SPC Inhibitors of SPC

Eighteen: Optimizing and Controlling Processes through Statistical Process Control (SPC) (Continued) The origin of SPC was in the work of Dr. Walter Shewhart at Bell Laboratories 1931. Although SPC was ignored in the West after World War II, Japan adopted and subsequently developed it into total quality. SPC is a statistical method of separating special-cause variation from natural variation to eliminate the special causes and establish and maintain consistency in the process, enabling process improvement . SPC is essential in the West today to elevate the quality of products and service while lowering costs, to compete successfully in world markets.

Eighteen: Optimizing and Controlling Processes through Statistical Process Control (SPC) (Continued) A total of 99.73% of the output of a process that is in statistical control will fall within the ±3σ limits of the process. Do not confuse process average and limits with specification average and limits. It is usually desirable to make the process average coincident with the specification average and to make the process spread narrower than the specification limits.

Eighteen: Optimizing and Controlling Processes through Statistical Process Control (SPC) (Continued) Continual improvement of processes requires that special causes be eliminated first. Process improvement narrows the shape of the process’s bell curve, resulting in less variation. Continual improvement is a key element of SPC and total quality. SPC enhances the predictability of processes and whole plants. Elimination of waste is another key element of SPC. SPC can help improve product quality while reducing product cost.

Eighteen: Optimizing and Controlling Processes through Statistical Process Control (SPC) (Continued) SPC makes sampling inspection more reliable. SPC supports process auditing as a substitute for more expensive inspection. SPC requires a capability in statistics, either in-house or through a consultant. Process operators should be key players in any SPC program. Understanding the process is a prerequisite to SPC implementation. All employees involved in SPC must be trained for their involvement. Measurement repeatability and reproducibility is essential for SPC.

SPC requires collaborative team activity. Eighteen: Optimizing and Controlling Processes through Statistical Process Control (SPC) (Continued) Management’s role in SPC is similar to its role in total quality overall: commitment, providing training, and involvement. The seven tools, augmented by flowcharting and DOX/DOE are required for SPC. SPC and the operator must have process-stop authority, SPC implementation must be carried out in an orderly, well thought-out sequence. SPC requires collaborative team activity.