12

Statistical Quality Control—Phase II Control Charts

*The focus of this chapter is a discussion of phase II control charts.*

# Topics Covered:

- Basic concepts of the CUSUM control chart
- Designing a CUSUM control chart
- Two-sided CUSUM control charts using numerical procedures
- The fast initial response (FIR) CUSUM control chart
- Combined Shewhart–CUSUM control charts
- CUSUM control chart for controlling process variability
- Moving average (MA) control charts
- Exponentially weighted moving average (EWMA) control charts

# Learning Outcomes:

After studying this chapter, the reader will be able to

- Understand the difference between phase I and phase II control charts.
- Set up one-sided and two-sided CUSUM control charts.
- Set up one-sided and two-sided tabular CUSUM control charts.
- Understand the advantages of CUSUM control charts over and R control charts.
- Set up moving average (MA) control charts.
- Set up exponential weighted moving average (EWMA) control charts.

# 12.1 Introduction

In Chapter 11 we studied phase I Shewhart control charts for detecting large shifts in any process. In this chapter we will study the next generation of control charts: cumulative sum (CUSUM), moving average (MA), and exponentially weighted moving average (EWMA) control charts. As noted earlier, large shifts usually occur in phase I of the implementation of SPC, when a process is under strong influence of special ...