SIX SIGMA-BASED RANGE AND STANDARD DEVIATION CHARTS FOR CONTINUOUS QUALITY IMPROVEMENT
Journal Title: International Journal for Quality Research - Year 2017, Vol 11, Issue 3
Abstract
Control charts for range (R-chart) and standard deviation (S-chart) are commonly used charts along with X-bar control chart for variables. One of the major challenges in these charts is the use of appropriate estimators of the unknown population parameters involved in the control limits. In this paper, first a detailed review on the classical charts for dispersion, R-chart and S-chart, is presented and then by applying the concept of Six Sigma quality characteristics, new set of Six Sigma-based R- and S-charts are developed. The motivation of the proposed approach is due to the fact that “specifications refer to the deviations that are permissible from the target and the units produced from a well-behaved process will match the target and standard deviation associated with its specifications”. Accordingly, unlike the traditional charts, in this new approach, the unknown population standard deviation related to range and standard deviation are derived from specification using the perspective of Six Sigma. Procedures for obtaining control limits of the proposed Six Sigma-based R-and S-chart are given. The average run length values for the proposed new charts are also obtained for different in-control and out-of control shift values. It is discussed that due to various reasons a process may maintain certain sigma quality level at a point of time that may be in terms of number of sigma. Since the goal of Six Sigma is of 3.4 defects per million opportunities, it is recommended to keep monitoring the process in terms of sigma quality level by using the improved control limits for the purpose of continuous quality improvement every time till the goal is achieved. The proposed charts are illustrated with appropriate numerical examples for better understanding.
Authors and Affiliations
Joghee Ravichandran
Keywords
Related Articles
- EP ID EP221084
- DOI 10.18421/IJQR11.03-03
- Views 99
- Downloads 0
THE DEVELOPMENT OF COMPLAINTS HANDLING STANDARDS IN SPA COMPANIES: A CASE STUDY ANALYSIS IN SPAIN
The aim of this paper is to analyze the key features of an effective complaint management process as well as to explore whether these systems are formally constituted in terms of standards or other models for complaints...
IMS in SMES - Reasons, Advantages and Barriers on Implementation
Appearance of a number of management systems with various and sometimes divergent demands, demands for revise of optimal strategy on implementation of these standards in small and medium-sized enterprises (SMEs) and the...
ANALYSIS OF FLEXIBLE BARRIERS USED AS SAFETY PROTECTION IN WOODWORKING
Machine tools use physical barriers, made by flexible thermoplastic materials, to protect the environment and the operators against the projections of wood chips and parts of cutting tools. These barriers constitute a pa...
INFORMATION MODEL OF MAJOR DEPRESSION TREATMENT COST –RELEVANCE OF QUALITY MANAGEMENT OF HEALTH SYSTEM
This paper develops multirelational data base for major depression costs. It lists how data are collected and stored into the fact base and dimension base. Uncertain data is described linguistically and modelled by fuzzy...
QUALITY IN WORLD CLASS MANUFACTURING
The World Class Manufacturing (WCM) is a contemporary concept that is applied by the world leaders in the business. In this concept, one of the nine pillars is directly related to the quality and the other eight are rela...