文档介绍：Statistical Process Control and Quality Management
Chapter 19
1
GOALS
Discuss the role of quality control in pro the problem.
6
Pareto Chart - Example
The city manager of Grove City, Utah, is concerned with water usage, particularly in single family homes. She would like to develop a plan to reduce the water usage in Grove City. To investigate, she selects a sample of 100 homes and determines the typical daily water usage for various purposes. These sample results are as follows.
7
Pareto Chart - Minitab
8
Fishbone Diagrams
Another diagnostic chart is a cause-and-effect diagram or a fishbone diagram. It is called a cause-and-effect diagram to emphasize the relationship between an effect and a set of possible causes that produce the particular effect.
This diagram is useful to help organize ideas and to identify relationships. It is a tool that encourages open brainstorming for ideas. By identifying these relationships we can determine factors that are the cause of variability in our process.
The name fishbone comes from the manner in which the various causes and effects are organized on the diagram. The effect is usually a particular problem, or perhaps a goal, and it is shown on the right-hand side of the diagram. The major causes are listed on the left-hand side of the diagram.
9
Purpose of Quality Control Charts
The purpose of quality-control charts is to portray graphically when an assignable cause enters the production system so that it can be identified and corrected.
This is accomplished by periodically selecting a random sample from the current production.
10
Mean Chart for Variables
The mean or the x-bar chart is designed to control variables such as weight, length, etc. The upper control limit (UCL) and the lower control limit (LCL) are obtained from the equation:
where is the mean of the sample means and is the mean of the sample ranges
11
Statistical Software, Inc., offers a toll-free number where cust