statistical process control. overview 1.definition of statistical process control 2.common causes...

Statistical Process Control

Overview

1. Definition of Statistical Process Control

2. Common causes and assignable causes of variation

3. Control charts

4. Type I and Type II Errors

5. R, x, p, and c charts

6. Process Distribution

Definition of SPC

Statistical process control (SPC) is the application of statistical techniques to determine whether the output of a process conforms to the product or service design.

Common causes of variation

Process Distribution for the Box-Filling Machine When Only Common Causes of Variation Are Present

Assignable causes of variation

Effects of Assignable Causes

Control Charts - Examples

Type I and Type II Errors

R-chart

A range chart, or R-chart, is used to monitor process variability.

x-ChartsAn x-chart (read " x-bar chart") is used to measure the mean.

p-ChartsThe p-chart is a commonly used control chart for attributes.

c-ChartsWhen management is interested in reducing the number of defects per unit, another type of control chart, the c-chart, is useful.

Process Distribution

Conclusion

1. Definition of Statistical Process Control

2. Common causes and assignable causes of variation

3. Control charts

4. Type I and Type II Errors

5. R, x, p, and c charts

6. Process Distribution

= Quality Control and Lower Costs