Chap02-Basic Quality Tools - uoh.edu.sa 51… · (Statistical Process Control), the 7 New Tools for...
Transcript of Chap02-Basic Quality Tools - uoh.edu.sa 51… · (Statistical Process Control), the 7 New Tools for...
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
QEM 511 - Total Quality Management
Mohamed Aichouni
Professor of Quality Engineering, Hail Universityhttp://faculty.uoh.edu.sa/m.aichouni/
Master Program on Quality Engineering and Management
LECTURE 02
METHODS OF TOTAL QUALITY MANAGEMENT –
THE 7 BASIC QUALITY TOOLS
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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Process Variability and Quality
Causes of Variations in Processes
Continuous Process Improvement
SPC Tools (The 7 basic tools) Pareto Diagram
Cause-Effect Diagram
Check Sheets
Process Flow Diagram
Scatter Diagram
Histogram
Control Charts
Outline
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
Quality Definition
Quality is defined by the totality of features and characteristics that satisfy customers needs” (ASQ).
Think about a product (watch e.g) that you would bye; What do you look for?
• .........
• ........
• .........
• ........
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
Quality Characteristics
Variables
Can be measured or expressed with some unit, such as height, length (m), mass (kg), cycle time (s), concrete strength (MPA) etc..
Attributes
Can be counted such as number of defects, errors, accidents etc ..
Process Variations
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
Process Variations and Quality
Quality is inversely proportional to variability (Variability & Quality are enemies).
The more variation in product characteristics, in delivery times, in work practices: the more waste, higher costs and poor quality, is delivered to ourcustomers.
(Out of the Crisis, 1982)
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
Causes of Product Variations
Product characteristics variations are mainly caused by the variations in the components of the process (5 M and E): Man Power Machines Methods Materials Measurements Environment
Raw Material
Process
Product
Man Machine
Measurements Methods
Customer
Environment
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
Process Variations Causes
1. Common causes are ever-present in the process;========= Natural Variations
2. Special causes are intermittent effects that must be investigated immediately.
========= Assignable Causes Variations
Management and quality professionals (YOU) should help manufacturing people to identify and remove special causes and reduce the occurrence of common causes in the process..
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
Process Variation
Process Variability Variations due to:
Natural Causes:• Temperature variation• Material variation• Customer differences• Operator performance
Special Causes:• Machine is breaking• Untrained operative• Machine movement• Process has changed
Must be monitored Early and visible warning required
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
Process Improvement
• Process Improvement is basically about the reduction of variability in processes, products and services.
• Based on the Deming PDCA Cycle
• PI results in waste reduction, quality improvement, Customer Satisfaction and more importantly to Business Excellence.
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
Continuous Process
Improvement:
Reduction of Process
Variability
Standard Deviation () , Cv(%) higher values
Big Variability of Process.
Less variabilityReduce variation by removing special causes from Process
Continually improve the process by reducing variability
() , Cv(%) lower.
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
How to Improve Processes and Quality ?
Study and Understand Process Variation.
Use Appropriate Quality Tools (The 7 Basic tools (Statistical Process Control), the 7 New Tools for Management and Planning etc..
Set Process improvement teams Use Employee suggestions
© Copyright : Dr Mohamed AICHOUNI, PhD, SQC, KAQA
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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A methodology (or set of tools) for:
monitoring a process to identify special causes of variation and,
signal the need to take corrective action on the process when appropriate.
Statistical Process Control
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
Seven Basic Quality ToolsKaoru Ishikawa (1972)
Called the Magnificent Seven
They are simple visual tools based on the use of data to study and understand the things we do (Process) ;
So that we can improve the quality of products in manufacturing plants.
1 2 3 4Dirt
Old
Temp
Fault
xx x
xx
x xx
x
x xxx
xx
x
UCL
LCL
12345
Process
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
SPC Tools : The 7 Basic Quality Tools
The SPC tools (the 7 basic Quality Tools) are Problem Solving Tools which can: Help to identify and prioritize problems quickly and
more effectively. Assist the decision making process. Provide simple but powerful tools for use in continuous
improvement activity. Provide a vehicle for communicating problems and
resolutions throughout the business. Provide a way of extracting information from the data
collected.
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
Flow Chart Check Sheet Pareto Analysis Histogram – Process Capability Cause-and-Effect Diagram Scatter Diagram Control Charts – Process Stability
Seven Basic Quality Control ToolsMagnificent Seven
1 2 3 4Dirt
Old
Temp
Fault
xx x
xx
x xx
x
x xxx
xx
x
UCL
LCL
12345
Process
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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It is a schematic diagram that shows the flow of the product or service as it moves through the various processing stations or operations
Makes it easy to visualize the entire system, identify potential trouble spots, and locate activities
Compares and contrasts actual versus ideal flow of a process
Tool 1 - Process Flow Chart
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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Uses standardized symbols.
Shows unexpected complexity, problem areas, redundancy, unnecessary loops, and where simplification may be possible.
Process Flow Diagram
Process Decision The process flow
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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Allows a team to reach agreement on process steps and identify activities that may impact performance
Improvements to the process can be accomplished by eliminating steps, combining steps, or making frequently occurring steps more efficient
Process Flow Diagram
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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Process Flow Chart
Manufacturing Example
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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The main purpose is to ensure that the data are collected carefully and accurately by operating personnel for process control and problem solving.
Creates easy-to-understand data.
Because it clearly organizes data, a check sheet is the easiest way to track information in manufacturing processes (e.g: problems, defects, etc.)
Tool 2 - Check Sheets
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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Check Sheets
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
Check Sheets
Example 2-1 Check Sheet for paint non-conformities
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
Example 2-2 Check Sheet for product defects during one week
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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Some Sample 80/20 Rule Applications:
80% of process defects arise from 20% of the process issues.
80% of delays in schedule arise from 20% of the possible causes of the delays.
80% of customer complaints arise from 20% of your products or services.
(The above examples are rough estimates.)
Tool 3 - The Pareto Diagram (80/20)
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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A Pareto Chart is a special form of vertical bar graph which helps us to determine which problems to solve in what order.
Doing a Pareto Chart based upon either Check Sheets or other forms of data collection helps us direct our attention and efforts to the truly important problems.
We will generally gain more by working on the tallest bar than tackling the smaller bars..)
The Pareto Diagram
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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Graph that ranks data classifications in descending order from left to right
Pareto diagrams are used to identify the most important problems
Advantage: Provide a visual impact of those vital few characteristics that need attention
Resources are then directed to take the necessary corrective action
The Pareto Diagram
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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Helps a team focus on causes that have the greatest impact
Displays the relative importance of problems in a simple visual format
Helps prevent “shifting the problem” where the solution removes some causes but worsens others
The Pareto Diagram
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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Steps:
1. Determine the method of classifying the data: by problem, cause, type of nonconformity, etc
2. Decide if dollars (best), weighted frequency, or frequency is to be used to rank the characteristics
3. Collect data for an appropriate time interval
4. Summarize the data and rank order categories from largest to smallest
5. Compute the cumulative percentage if it is to be used
6. Construct the diagram and find the vital few
Constructing a Pareto Diagram
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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Pareto Diagram for Defects Found At In-Process Inspection
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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Take the examples 2-1 and 2-2 from check sheet and workout the Pareto diagrams.
Use both hand solution and Minitab solutions
Practice: Pareto Diagram
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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A Histogram takes process data, e.g., temperature, dimensions, and displays its distribution.
A Histogram reveals the amount of variation that any process has within it.
It shows the process capability and, if desired, the relationship to the specifications and the nominal characteristic.
Tool 4 - Histogram
Figure 3-11 Histogram for Hole Location
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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Displays large amounts of data that are difficult to interpret in tabular form
Shows centering, variation, and shape
Illustrates the underlying distribution of the data
Provides useful information for predicting future performance
Helps to answer the question “Is the process capable of meeting requirements?
Histogram
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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The shape of the histogram help us to determine :
a.) Whether the “spread” of the distribution falls within product specifications. If not, how much falls outside of specifications. (VARIABILITY)
b.) Whether the distribution is centered at the right place.Are most items on the “high or low side?”(SKEWNESS)
Histogram
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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A sample of process data were obtained and drawn on the table.
Use this data to construct a histogram for analyzing the process .
Practical Example of Histogram (Ex2-3)
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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Practical Example of Histogram
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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The thickness in mm of a key material in process is given in the table.
Use Minitab to construct the histogram for the process.
Determine the process statistics and compare them with product specifications:
Practical Example of Histogram (Ex 2-4)
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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The data have a central tendency around 9.8 to 9.99.
The process has a normal distribution with a mean (.......mm) and a standard deviation (......... mm).
The specification for the thickness characteristicis 7.5 to 10.5, with a target of 9. Thus, we can see that our Histogram indicates the process is running highand that defective material is being made.
Practical Example of Histogram (Ex 2-4)
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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Developed by Dr. Kaoru Ishikawa in 1943
Picture composed of lines and symbols designed to represent a meaningful relationship between an effect and its causes
Effect (characteristics that need improvement) on the right and causes on the left.
Called also Fishbone diagram or Ishikawa diagram.
Tool 5 - Cause-and-Effect Diagram
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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Enables a team to focus on the content of a problem, not on the history of the problem or differing personal interests of team members.
Creates a snapshot of collective knowledge and consensus of a team; builds support for solutions.
Focuses the team on causes, not symptoms.
Used to investigate either a “bad” effect and to take action to correct the causes or a “good” effect and to learn those causes responsible.
Cause-and-Effect Diagram
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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Steps in the construction of a
Cause-and-Effect Diagram:1. Identify the effect or quality problem2. Determine the major causes 3. Determine all the minor causes. Request a
brainstorming session 4. Once the diagram is complete, evaluate it to
determine the most likely causes5. Develop solutions
Cause-and-Effect Diagram
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
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Advantages:
1. Analyzing actual conditions for the purpose of product or service quality improvement
2. Elimination of conditions causing nonconforming product or service and customer complaints
3. Standardization of existing and proposed operations
4. Education and training in decision-making
Cause-and-Effect Diagram
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
42
Cause-and-Effect Diagram
The 4 M’s: Methods, Machines, Materials, Manpower
The 4 P’s: Place, Procedure, People, Policies
The 4 S’s: Surroundings, Suppliers, Systems, Skills
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
Cause and Effect Analysis
QualityProblem
MachinesMeasurement Man
Methods(Process)Environment Materials
Faulty testing equipment
Incorrect specifications
Improper methods
Poor supervision
Lack of concentration
Inadequate training
Out of adjustment
Tooling problems
Old/worn
Defective from vendor
Not to specifications
Material-handling problems
Deficienciesin product design
Ineffective qualitymanagement
Poor process design
Inaccuratetemperature control
Dust and Dirt
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
Cause and Effect Analysis for Improvement of the Engineering College (UoH)
WhatCan be
ImprovedAt the EngCollege ?
People (Faculty)Policies People (Students)
ProceduresEnvironment Teaching Facilities
…….
…….
……..
……
…..
……..
……….
…………….
…………..
…..
…..
…… ………
……
….…..
…….
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
Tool 6 - Scatter Diagram
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A Scatter Diagram is used to study the possible relationship between two variables.
Used to test for possible cause and effect relationships.
When we need to display what happens to one variable when another variable changes in order to test a theory that the two variables are related.
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
Scatter Diagram – Possible cases
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The following are the various patterns and meaningsthat Scatter Diagrams can have.
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
Scatter Diagram – Example
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Scatter Diagram of Average of manufacturing errors versus Average hours overtime / week in a manufacturing plant.
Average of Manufacturing Errors / Week
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
48
Focuses attention on detecting and monitoring process variation over time.
Distinguishes special from common causes of variation
Provides a common language for discussion process performance.
Tool 7 - Control Chart
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
49
Focuses attention on detecting and monitoring process variation over time.
Distinguishes special from common causes of variation.
Provides a common language for discussion process performance.
Control Charts
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
50
Control charts can be used to monitor processes and make continuous process improvement by reducing process variability (removing special causes variation).
Will be dealt in depth in next chapters.
Tracking Improvement using Control Charts
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Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
SPC Tools : The 7 Basic Quality Tools
The SPC tools (the 7 basic Quality Tools) are Problem Solving Tools which can:Help to identify and prioritize problems quickly and more
effectively. Assist the decision making process. Provide simple but powerful tools for use in continuous
improvement activity. Provide a vehicle for communicating problems and
resolutions throughout the business. Provide a way of extracting information from the data
collected.
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
SPC Tools : The 7 Basic Quality Tools
1. Flow-charts - for describing a process, the current situation
2. Check Sheets - for data collection
3. Pareto Charts - for ordering causes
4. Histograms - for monitoring one variable.
5. Cause and Effect diagrams - for digging to the root causes
6. Scatter Diagrams - for examining the relationship between two variables
7. Control Charts - for monitoring processes
27
Quality Improvement, 9eDale H. Besterfield
© 2013, 2008 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 • All Rights Reserved
Conclusions
"Quality control truly begins and endswith education",
K. Ishikawa (1990).
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