Lecture Introduction to operations management - Chapter 9: Quality control and improvement

In this chapter we will discuss: Design of quality control systems, process quality control, attribute control, variables control, using control charts, process capability, continuous improvement, six sigma, lean and six sigma, quality control and improvement in industry.

Operations Management

Contemporary Concepts and Cases

Chapter Nine Outline

Chapter Emphasis

Process definition

Statistical quality control

Continuous improvement

Design of Quality Control Systems

Steps in Designing QC Systems

When the Inspector Finds a Defect…

When the Inspector Finds a Defect

e.g Strap on backpack comes loose

Containment:  pull the bad backpacks from the production line

Process Quality Control

­­Bill James, statistician for the Boston Red Sox

Wall Street Journal, 20 June 2007, p. D7.

Process Quality Control

Process Control Chart (Figure 9.1)

Quality measurement average

Average - 3 standard deviations

Quality Control Chart

Attributes & Variables

Formulas for SPC (3 Sigma)

R A

x 2

Issues in Using Control Charts

Process Capability Index Examples (Figure 9.3)

Seven Tools of Quality Control

(See Figure 9.5)Flowchart

Seven Tools of Quality Control

Battery Manufacturer in NW Ohio in 

6 weeks in 2004, using only the 7 

tools of quality, decreased defectives 

from 7.2 per 100 to 2.6 per 100.

Pareto Analysis

Table 9.4

Defect Items

# of Defectives

Precent Defective

Cumulative Percentage

Pareto Diagram (Figure 9.6)

Cause-and-Effect (fishbone, Ishikawa) Diagram

Six-Sigma Quality

Pioneered by Motorola in 1988 (Juran claimed credit for the idea) 3.4 defects per million

Six Sigma Quality

Six Sigma Quality

Six Sigma uses a project/team approach

A process is selected for improvement

A cross­functional team is formed

A six sigma ‘black belt’ is chosen to head the team

The team uses the DMAIC method for 

Lean and Six Sigma

Quality Control and Improvement

End of Chapter Nine