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Transcript of subjek Quality assurance
Topic 2 Topic 2
Quality SpecificationQuality Specification
LecturesLectures
Mr. Mohd Syafarim B. Md IshakMr. Mohd Syafarim B. Md Ishak
IntroductionIntroduction
1. `Comprehensive details of product attributes’ e.g.: grade, weight, nutritional values, microbe
count, etc 2. Quality specifications is needed in any
condition e.g.: raw materials, process, finished goods,
storage, handling Documented: simple, precise, legible
ObjectiveObjective
1. To ensure wholesome, hygienic, sincerely packed and labeled product.
2. ‘Wholesome’: good in ecstatic value (taste), nutritious and safe to consume
Ishikawa’s Basic Tools of QualityIshikawa’s Basic Tools of Quality
Kaoru Ishikawa developed seven basic visual tools of quality so that the average person could analyze and interpret data.
These tools have been used worldwide by companies, managers of all levels and employees.
Seven Quality ToolsSeven Quality Tools
The Seven Tools~ Histograms, Pareto Charts, Cause and Effect
Diagrams, Run Charts, Scatter Diagrams, Flow Charts, Control Charts
HistogramsHistograms
Histogram DefinedA histogram is a bar graph that shows
frequency data.Histograms provide the easiest way to evaluate
the distribution of data.Provide a quick representation of the “spread”
and “centering” of a process.
Histograms cont…..Histograms cont…..
1. Steps to build a Histogram• Collect data for analysis.
• At least 50 to 100 data points• Use historical data to find patterns or to use as a baseline for past performance
• Determine the range of the data set.• Smallest value subtracted from largest value
• Determine quantity of categories.• Take the square root of total number of data points and round to nearest whole number
Step to a build Histograms Step to a build Histograms cont…..cont…..
• Determine each category’s data point.
• Mid-point of each category
• Plot data on a vertical bar-graph.
• Frequency on Y-axis
• Categories on X-axis
• For each class interval, draw bar with the
height equal to frequency count
Advantage of a HistogramsAdvantage of a Histograms
• Display large amounts of data that are difficult to interpret in a tabular form
• Show the relative frequency of occurrences of the various data values
• Reveal the variation, centering, and distribution shape of the data
• Very useful when calculating capability of a process
• Helps predict future performance of a process
Example of a HistogramExample of a HistogramCategory
Class boundary
Mid-point Frequency
1 10.00 - 10.19 10.1 12 10.20 - 10.39 10.3 63 10.40 - 10.59 10.5 124 10.60 - 10.79 10.7 85 10.80 - 10.99 10.9 66 11.00- 11.19 11.1 3
1
6
12
86
3
0
2
4
6
8
10
12
14
10.00 -10.19
10.20 -10.39
10.40 -10.59
10.60 -10.79
10.80 -10.99
11.00-11.19
Pareto ChartsPareto Charts
Pareto Chart DefinedPareto charts are used to identify and prioritize
problems to be solved.They are actually histograms aided by the
80/20 rule adapted by Joseph Juran.Remember the 80/20 rule states that
approximately 80% of the problems are created by approximately 20% of the causes.
Advantages of a Pareto ChartsAdvantages of a Pareto Charts
• Focuses efforts on problems with greatest
potential for improvement
• Distinguishes the critical causes from the less
significant causes
• Helps prevent “shifting the problem” where the
solution removes some causes but worsens
others
Advantages of a Pareto ChartsAdvantages of a Pareto Charts
• Measure the impact of improvement projects when comparing charts “before” and “after”
• The chart shows the relative importance of problems in a simple, quickly interpreted, visual format.
• Progress is measured in a highly visible format that provides incentive to push on for more improvement.
Step to a build Pareto chartStep to a build Pareto chart
• Identify problem
• Choose categories that will be monitored
• Choose the most meaningful unit of
measurement
• Frequency
• Cost
• Determine time period
• Long enough to represent situation
• Scheduled time to collect data is typical of a
workday
Step to a build Pareto chart cont….Step to a build Pareto chart cont….
• Collect data
• Compare the frequency of each category
• Draw chart:
• List the categories on the horizontal line
• Descending order, from left to right
• Frequencies on the vertical line
Step to a build Pareto chart cont….Step to a build Pareto chart cont….
• Draw the cumulative percentage line showing
categories contribution
• Optional
• Draw vertical line on the right side of the
chart
• Plot cumulative values from left to right
• Interpret results
• Tallest bar represents biggest contributor
• Perform analysis of category that has the
“most
impact”
2418
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Latedelivery
Wrongproduct
Missingparts
Damagedcontainer
Wrongaddress
Not received
Delivery complains
35%
61%
79%
91%
97%100 %
50 %
Frequency
Cum %Example of a Pareto ChartExample of a Pareto Chart
Further Analysis Using Pareto Further Analysis Using Pareto ChartsCharts• Major cause breakdown:
• Tallest bar is broken down into sub-causes
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Late delivery Wrong product Missing parts Damagedcontainer
Wrongaddress
Not received
86 4 4
2
0
2
4
6
8
Missing address Driver mistake Latedocumentation
Transportationproblems
Administrativedelays
Late delivery
•Before and after:• New Pareto bars are drawn side-by-side with the original Pareto showing effect of change
Further Analysis Using Pareto Further Analysis Using Pareto ChartsCharts
24
10
18
8
1210
8
4 43 2 1
0
5
10
15
20
25
Latedelivery
Wrongproduct
Missingparts
Damagedcontainer
Wrongaddress
Notreceived
Before After
Further Analysis Using Pareto Further Analysis Using Pareto ChartsCharts•Change measurement scale:
• Same categories are used but measured differently. Typically cost and frequency.• This exercise defines the category of “most impact”.
24
18
128
4 20
5
10
15
20
25
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Latedelivery
Wrongproduct
Missingparts
Damagedcontainer
Wrongaddress
Not received
Delivery complains
$2,500
$1,850
$1,200$800
$220 $200$0
$500
$1,000
$1,500
$2,000
$2,500
$3,000
Wrong product Not received Missing parts Wrongaddress
Damagedcontainer
Late delivery
Cost/month
1. Flow Charts DefinedA flow chart is a pictorial representation
showing all of the steps of a process.
2. Flow charts are used to identify the actual path
of a product or service.
3. Flow charts show:
• Sequential work activities
• Inputs for each action
• Outputs from each activity
Process Flow ChartProcess Flow Chart
Provide common understanding of how a process works.
Identifies problem areas, unexpected complexity, redundancies, and areas of potential improvement
Serves as a training aid
Provides basis for documentation. Identifies location where additional data can be collected and investigated
Advantages of a Flow ChartAdvantages of a Flow Chart
Shows an activity performed in the process
Shows a point in the process where a Yes/No
question is being asked or a decision is required
Identifies a break in the flow chart and is continued elsewhere on the same
page or another page
Shows the flow of the process
Shows the beginning and end process
Symbols of a Flow ChartSymbols of a Flow Chart
A
List the basic steps of the process.
Determine the logical sequence of the steps.
Identify the inputs of each step.
Determine the outputs of each step.
Draw the chart using the symbols to show the
actions and decisions.
Steps to Build a Flow ChartSteps to Build a Flow Chart
Example of a Flow ChartExample of a Flow Chart
Team is given task to write procedure
Develop outline
Completedraft
Review draft
Revise Draft with changes
CompleteFinal
version
Send toRelease
Dept.
Draftapproved
Releaseprocedure
yes
No
Run Charts DefinedRun charts are used to analyze processes
according to time or order.
Run ChartRun Chart
Creating a Run ChartGathering Data
Some type of process or operation must be available to take measurements for analysis.
Organizing DataData must be divided into two sets of values X
and Y. X values represent time and values of Y represent the measurements taken from the manufacturing process or operation.
Charting DataPlot the Y values versus the X values.
Interpreting DataInterpret the data and draw any conclusions that
will be beneficial to the process or operation.
Creating a Run ChartCreating a Run Chart
An Example of Using a Run ChartAn organization’s desire is to have their
product arrive to their customers on time, but they have noticed that it doesn’t take the same amount of time each day of the week. They decided to monitor the amount of time it takes to deliver their product over the next few weeks.
Example of a Run ChartExample of a Run Chart
Cause and Effect AnalysisCause and Effect Analysis
Cause and Effect Diagram DefinedThe cause and effect diagram is also called the
Ishikawa diagram or the fishbone diagram.It is a tool for discovering all the possible
causes for a particular effect.The major purpose of this diagram is to act as
a first step in problem solving by creating a list of possible causes.
Advantage of a Cause and Effect Advantage of a Cause and Effect DiagramDiagram
Clearly illustrates the various causes affecting a
process:
• Relationship between these causes
• Where are they occurring
Helps in finding the most basic cause of the
problem
Motivates team members participation
Steps to Build a Cause and Effect Steps to Build a Cause and Effect DiagramDiagramPlace problem statement in a box to the right-hand
side of the paper.Select the major cause or categories and place them
to the left of the problem statement.• 4 M’s (Production process):
• Materials• Manpower• Machinery/equipment• Method
• 4 P’s (Service process):• Policies• Procedures• People• Plant / equipment
Steps to Build a Cause and Effect Steps to Build a Cause and Effect Diagram cont……Diagram cont……
Draw a box around each category and connect
to a line pointing out towards the problem statement.
Using the brainstorming technique, generate ideas
of causes, on the major categories.
Record these ideas on a line off the applicable
major category line.
For each cause listed on the diagram, ask “why
does this happen?”.
For each response, ask the same question.
Each successive answer is another possible cause
Look for causes that repeat across major cause
categories.
Ensure all team members agree on the problem
and causes statements.
Steps to Build a Cause and Effect Steps to Build a Cause and Effect Diagram cont……Diagram cont……
Example of a Cause and Effect Example of a Cause and Effect DiagramDiagram
Late deliveries
Method Material
ManpowerMachinery/equipment
Drivers get lost
Drivers don’tShow upUnreliable trucks
Not enough trucks
Poor dispatching
Poor handling of large orders
Run out of products
Not capacity for peak periods
Wrong address on shipper
Database Input error
Poor planning
Lack of trainingLack of
training
Scatter Diagrams DefinedScatter Diagrams are used to study and
identify the possible relationship between the changes observed in two different sets of variables.
Scatter DiagramScatter Diagram
Provides visual and statistical means to test the
strength of a potential relationship
Provides a good follow-up to the cause and effect
diagram to find out if there is a connection between
the cause and the effect
Advantages of the Scatter DiagramAdvantages of the Scatter Diagram
Steps to Build a Scatter DiagramSteps to Build a Scatter Diagram
Constructing a Scatter DiagramFirst, collect two pieces of data and create a
summary table of the data.Draw a diagram labeling the horizontal and
vertical axes. It is common that the “cause” variable be
labeled on the X axis and the “effect” variable be labeled on the Y axis.
Plot the data pairs on the diagram.Interpret the scatter diagram for direction
and strength.
Examples of a Scatter DiagramExamples of a Scatter Diagram
An Example of When a Scatter Diagram Can Be UsedA scatter diagram can be used to identify
the relationship between the production speed of an operation and the number of defective parts made.
Variable 1
Var
iab
le 2
Control ChartsControl Charts
• Control Charts Defined Control charts are used to determine whether a process will produce a product or service with consistent measurable properties. • Line graph of measurements of a process overtime that has statistically based control limits placed on it
• Process control charts monitor and display variations in a process output. • Control limits are based on process variation
• Define expected variation range due to common causes• +/- three standard deviations from centerline
Types of a Control ChartsTypes of a Control Charts•Two primary types are:
• Control charts for variables:• Most used: X –R
• X is average values• R is range
• Others: Run charts, moving range charts (MX –MR charts)
• Control charts for attributes:• p chart: fraction defective• np chart: number of defectives• c chart: number of defects
Steps to Build a Control ChartsSteps to Build a Control ChartsSteps Used in Developing Process
Control ChartsIdentify critical operations in the process
where inspection might be needed.Identify critical product characteristics.Determine whether the critical product
characteristic is a variable or an attribute.Select the appropriate process control
chart.Establish the control limits and use the
chart to monitor and improve.Update the limits.
Advantages of a Control ChartsAdvantages of a Control Charts
• Focuses attention on detecting and monitoring process variation over time
• Distinguishes “special” from “common” causes
• Helps predict performance of a process
• Helps improve a process to perform consistently
• Provides a common language to discuss process behavior
Examples of a Control ChartsExamples of a Control Charts
An Example of When to Use a Control ChartCounting the number of defective products
or services Do you count the number of defects in a given
product or service? Is the number of units checked or tested
constant?
Examples of a Control ChartsExamples of a Control Charts
Upper control limit
Lower control limit
Centerline
3 std.deviations
3 std.deviations
Data plot
Point out-of-control(out of the control limits boundaries)
SummarySummary
•The seven tools of quality discussed in this module
are considered to make up the fundamental
continuous improvement toolkit.
• It is the intent of this course to touch basis on these
tools and not to study them in depth.
• Depth analysis of these theories is considered subject
for another course.