7 Qc Tools 304mf

Quality Tools PROBLEM SOLVING

Quality Improvement: Problem Solving

Quality Improvement: Problem Solving

Quality management activities  Quality assurance 

Establish organisational procedures and standards for quality.

 Quality planning 

Select applicable procedures and standards for a particular project and modify these as required.

 Quality control 

Ensure that procedures and standards are followed by the software development team.

 Quality management should be separate from project

management to ensure independence.

Six Problem Solving Steps  Identify 

recognize the symptoms

 Define 

Agree on the problem and set boundaries

 Investigate 

Collect data

 Analyze 

Use quality tools to aid

 Solve 

Develop the solution and implement

 Confirm 

Follow up to ensure that the solution is effective

Quality Control Tools      



Pareto chart Histogram Process flow diagram Check sheet Scatter diagram Control chart  Run chart Cause and effect diagram

Quality Improvement: Problem Solving

Pareto Principle Vilfredo Pareto (1848-1923) Italian economist 

20% of the population has 80% of the wealth

Juran used the term “vital few, trivial many”. He

noted that 20% of the quality problems caused 80% of the dollar loss.

7 Quality Tools Quality Improvement: Problem Solving

Purpose: Prioritize problems.

How is it done? Create a preliminary list of

problem classifications. Tally the occurrences in each problem classification. Arrange each classification in order from highest to lowest Construct the bar chart

Pareto Charts

Pareto Charts Benefits: 



Pareto analysis helps graphically display results so the significant few problems emerge from the general background It tells you what to work on first

Pareto chart

% Complaints

7 Quality Tools Quality Improvement: Problem Solving

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Quality Improvement: Problem Solving

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Percent from each cause

Pareto (64) Chart

(10)

10 (6) (3)

Causes of poor quality

(2) (2)

Histograms What is it?

LSL

USL

• A Histogram is a bar graph • usually used to present frequency data

How does it Work? • • • • •

Define Categories for Data Collect Data, sort them into the categories Count the Data for each category Draw the Diagram. each category finds its place on the x-Axis. The bars will be as high as the value for the category

What is its use? • Histograms provide an easy way to evaluate the distribution of Data over different categories

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Histograms Example: take the failure rate of a machine over a period of x weeks. Now Assign every week the number of failures that occurred. Draw the Histogram. Let the bar represent the weeks. The height of the Bar on the y-axis is the number of failures that occurred during that week.

LSL

USL

12

Flow Diagrams " Draw a flowchart for whatever you do. Until you do, you do not know what you are doing, you just have a job.” -- Dr. W. Edwards Deming.

Quality Improvement: Problem Solving

Flowcharts Flowcharts  

Graphical description of how work is done. Used to describe processes that are to be improved.

7 Quality Tools Quality Improvement: Problem Solving

Purpose:

Flow Charts

Visual illustration of the sequence of operations required to complete a task    

Schematic drawing of the process to measure or improve. Starting point for process improvement Potential weakness in the process are made visual. Picture of process as it should be.

Benefits:     

Identify process improvements Understand the process Shows duplicated effort and other non-value-added steps Clarify working relationships between people and organizations Target specific steps in the process for improvement.

Benefits

Flow charts Linear

 Show what actually happens

at each step in the process  Show what happens when non-standard events occur  Graphically display processes to identify redundancies and other wasted effort

How is it done?  Write the process step inside

each symbol  Connect the Symbols with arrows showing the direction of flow

Toolbox

Flow Diagrams

Quality Improvement: Problem Solving

Flow Diagrams

Quality Improvement: Problem Solving

Process: Apple Sauce Description of process

Time (min)

Analyst: TLR Operation Transport Inspect Delay Storage

Location: Graves Mountain

Step

Date: 9-30-00

1

Unload apples from truck

2

Move to inspection station

3

Weigh, inspect, sort

4

Move to storage

5

Wait until needed

6

Move to peeler

7

Apples peeled and cored

15

8

Soak in water until needed

20

9

Place in conveyor

5

Move to mixing area

11

Weigh, inspect, sort

Quality Improvement: Problem Solving

20 100 ft 30 50 ft 360 20 ft

10 Page 1 0f 3

Distance (feet)

Process Chart

Total

20 ft 30 480

190 ft

Quality Improvement: Problem Solving

Check Sheet

Defect Type

Shifts











 



  7 Quality Tools

Quality Improvement: Problem Solving

Purpose:  Tool

for collecting and organizing measured or counted data  Data collected can be used as input data for other quality tools

Benefits:  Collect

data in a systematic and organized manner  To determine source of problem  To facilitate classification of data (stratification)

Checksheets

Check Sheet COMPONENTS REPLACED BY LAB TIME PERIOD: 22 Feb to 27 Feb 1998 REPAIR TECHNICIAN: Bob TV SET MODEL 1013

Integrated Circuits Capacitors Resistors Transformers Commands CRT Quality Improvement: Problem Solving

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Cause-and-Effect Diagrams Show the relationships between a problem and its

possible causes. Developed by Kaoru Ishikawa (1953) Also known as …  

Fishbone diagrams Ishikawa diagrams

7 Quality Tools Quality Improvement: Problem Solving

Cause and Effect “Skeleton”

Materials

Procedures

Quality Problem

People

Equipment 7 Quality Tools

Quality Improvement: Problem Solving

Fishbone Diagram Purpose: Graphical representation of the trail leading to the root cause of a problem

How is it done? • Decide which quality characteristic, outcome or effect you want to examine (may use Pareto chart) • Backbone –draw straight line • Ribs – categories • Medium size bones – secondary causes • Small bones – root causes

Cause & Effect Diagrams

Benefits:  Breaks problems down into bite-size pieces to find root

cause  Fosters team work  Common understanding of factors causing the problem  Road map to picture of the process  Follows brainstorming relationship

Fishbone Diagram Measurement Faulty testing equipment Incorrect specifications

Human

Inaccurate temperature control Dust and Dirt

Environment

Out of adjustment

Poor supervision Lack of concentration

Improper methods

Machines

Tooling problems Old / worn

Inadequate training

Quality Problem Defective from vendor Not to specifications Materialhandling problems

Materials

Quality Improvement: Problem Solving

Poor process design Ineffective quality management Deficiencies in product design

Process

Cause & Effect Diagrams Sample Materials

Manpower Typos

Source info incorrect Didn’t follow proc.

Wrong source info

t or Po

Wrong purchase order

i ra

Dyslexic Transposition

ni ng

Incorrect shipping documents

Glare on display

Temp. Environme nt

Corrupt data

No training

No communications

No procedure

Keyboard sticks

Software problem Methods

Machine

Cause and effect diagrams Advantages    

making the diagram is educational in itself diagram demonstrates knowledge of problem solving team diagram results in active searches for causes diagram is a guide for data collection

Quality Improvement: Problem Solving

Cause and effect diagrams To construct the skeleton, : For manufacturing - the 4 M’s 

man, method, machine, material

For service applications 

equipment, policies, procedures, people

Quality Improvement: Problem Solving

Quality Control Tool

Control Charts

Control Charts Purpose: The primary purpose of a control chart is to predict expected product outcome.

Benefits:  Predict process out of control and out of

specification limits  Distinguish between specific, identifiable causes of variation  Can be used for statistical process control

Control Charts  Strategy for eliminating assignable-cause variation:

Get timely data so that you see the effect of the assignable cause soon after it occurs.  As soon as you see something that indicates that an assignable cause of variation has happened, search for the cause.  Change tools to compensate for the assignable cause.  Strategy for reducing common-cause variation:  Do not attempt to explain the difference between any of the values or data points produced by a stable system in control.  Reducing common-cause variation usually requires making fundamental changes in your process 

Control Charts Control Chart Decision Tree 

Determine Sample size (n)



Variable or Attribute Data





Variable is measured on a continuous scale



Attribute is occurrences in n observations

Determine if sample size is constant or changing

Scatter Diagrams What is it? • Statistical tool showing a trend in a series of values.

How does it Work? • Gain values series • Draw graph with value points • Draw trend line: m*x+a » Calculate m value » Calculate a value » Calculate points for trend line.

Y

X

What is its use? • Demonstrating correlations between values and showing trends for value changes.

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Scatter Diagrams Purpose: To identify the correlations that might exist between a quality characteristic and a factor that might be driving it • A scatter diagram shows the correlation between two variables in a process. – These variables could be a Critical To Quality (CTQ) characteristic and a factor affecting it two factors affecting a CTQ or two related quality characteristics. • Dots representing data points are scattered on the diagram. – The extent to which the dots cluster together in a line across the diagram shows the strength with which the two factors are related.

•

If the variables are correlated, when one changes the other probably also changes.

•

Dots that look like they are trying to form a line are strongly correlated.

•

Sometimes the scatter plot may show little correlation when all the data are considered at once.  Stratifying the data, that is, breaking it into two or more groups based on some difference such as the equipment used, the time of day, some variation in materials or differences in the people involved, may show surprising results

Scatter Diagrams

Scatter Diagrams How is it done?: • Decide which paired factors you want to examine. Both factors must be measurable on some incremental linear scale. • Collect 30 to 100 paired data points. • Find the highest and lowest value for both variables. • Draw the vertical (y) and horizontal (x) axes of a graph. • Plot the data • Title the diagram The shape that the cluster of dots takes will tell you something about the relationship between the two variables that you tested.

What is it? • Run Charts are representing change • in measurement over a sequence or time

Measurement

Run Charts Time

How does it Work? • Gather Data • Organize Data » Measurements (y) must be confronted with time or sequence of the events.

• Chart Data • Interpreting Data

What is its use? • Determining Cyclic Events and there average character

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What does it look like? o Adding the element of time will help clarify your understanding of the causes of variation in the processes. o A run chart is a line graph of data points organized in time sequence and centered on the median data value.

Control ChartsRun Charts

Run Charts Example

Measurement

• Oil consumption of a specific machine over a period of time.

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Time

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Control Charts What is it? • •

Y

Statistical tool, showing whether A process is in control or not

How does it Work? • • •

Upper limit

Define Upper limit, lower limit and medium value Draw Chart. Gather values and draw them into chart

Average/Spec Lower limit

X

What is its use? •

Taking samples of a process and detect possibility of process being out of control

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