QUALITY MANAGEMENT

K P PATELLME

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The Seven Tools Of Quality Management

1 Flow charts 2 Check sheets3 Scatter diagrams4 Histograms 5 Pareto charts6 Cause and effect diagrams (Fishbone/Ishikawa diagrams)7 Control charts

Note: There are seven new tools, to aid in senior management planning, in addition to the seven tools covered here.

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Flow chartsUses:

• To document flow of a new or current process

• To create common understanding of how a process works.

• To allow checking of sequence of activities

• To indicate problems

• To allow improvement of a process.

• To increase understanding of processes

• To identify linkages between processes.

• To assess compliance between actual and intended processes

• To identify gaps between procedures

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A flowchart is:A diagrammatic tool to show the sequential relationship between activities, or the path or paths a process follows. It can be used as an overview, with broad detail, or as a fine detail tool with precise and small steps in processes.

Read the chart from start to finish following all paths to their end.

Read all notes and labels on the chart. • Question each step in the process as required.

How to use a flowchart:

Flow charts

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Steps in Creating a flowchart1 Determine who should be involved in drawing up the

flowchart.2. Involve all team members. 3 Allow time to create and check the chart.4. Before drawing the chart, decide on the detail required5. Have questions prepared to help draw the chart.6 Identify the start and end-points, each decision point,

each process, then join points together.

You may wish to tape interviews with participants for future reference.

Flow charts

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Symbols used in a flowchart

Start End Decision point. Process Flow, theQuestion must direction ofhave a Yes or movementno answer.

Flow charts

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Check sheetsUses • To gather data• To provide clear record of data gathered• To ensure that everyone will gather comparable data• To provide data in a suitable form for further analysis• To highlight if a problem exists

A check sheet is:A form used to record how many times something has occurred. It is usually used by those involved in collecting raw data.

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How to use a check sheet:• Obtain the correct sheet for the purpose.• Position yourself to clearly see what is going on.• Conduct the observation at the required intervals.• Place lines or strokes of a pen into appropriate box, groups

of five make it easy to count the strokes• Analyse the count of categories.

Check sheets

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Steps in creating a check sheet• 1. Decide what data you need• 2. Design a form to suit the people using

it and the type of data to be collected• 3. Test the check sheet, using someone

not involved with designing the sheet• 4. Revise the sheet as necessary• 5. Design a tally check sheet to

summarise the data from individual forms (if necessary)

Check sheets

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Tenant Times Late

Jones 2

Smith

Malcolm 3

Henare

Hashimoto

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Peterson 3Mene

Gerbic 8

Check sheets

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3530252015105

9.98 9.99 10.00 10.01 10.02

Machine setting (cm)

Check sheetsN

umbe

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00 c

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ars

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DDDDDDDDDDDDD

LLLLLLL

S

SSS

WW

WW

SS

SS

DDDDDDDDDDDDD

Check sheets

Defects in a laminated printed circuit boardKey: L = lamination problem, W = wrong component,

D = defective component, S = soldering problem

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Scatter diagrams

Uses• To show relationships • To show strength of relationship

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Scatter diagrams

Is a graph which shows relationship between two variables. A graph without lines joining the dots.

A graph that shows possible cause and effect relationships (regression)

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How to use scatter diagrams:View the diagram for

• shape• trends (positive upwards, negative downwards)• closeness of points to a line

Scatter diagrams

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Steps in creating a scatter diagram• Identify possible related variables• Collect data• Create scales for axes• Plot the points• Interpret the graph

Scatter diagrams

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Scatter diagrams

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Uses• To display statistical information. • To show frequency of occurrence, • To see concentrations of values• To sort data sets • To see gaps or outliers in the data set.• To see the shape of the data set, symmetry or

skewing etc.• To allow problem identification

Histograms

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Histograms

A member of the Bar graph family. In quality management, histograms are used to plot discrete and continuous data.

These graphs show frequency of occurrence of the group of data by the height or length of a rectangle, which represents a group or category of data. Created by people collecting and analysing data, and read by people who require to understand the relationships between data groups.

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How to use Histogram:• View the diagram for uniformity of shape, asking these

questions:•are there one or more peaks?•is the graph “normal’ in shape?•is the data clumped together?•is there a positive, negative or no skew?•are there any unusual features?

• Calculate the spread, • Note any outliers (values distant from the main group of

values)

Histograms

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Histograms

Steps in creating a Histogram• Collect your data• Determine the range of the data• Determine how many groups you need• Group the data• Construct the axes• Draw the bars• Label the graph

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Histograms

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Uses:•Identifying the one or two situation categories in which most of a problem occurs.•To focus attention on the major contributing factors.•To show progress in quality improvement projects.

Pareto charts

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Pareto charts

A Pareto diagram is:• A method of classifying importance or order of magnitude. It

is a technique used to indicate the relative importance of occurrences. It can be regarded as an ordered or sorted Histogram.

• Managers at any level would read the diagram; people collecting data and performing the data analysis would prepare it.

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How to use a Pareto diagram:• A Pareto diagram is a guide to action. It prioritises tasks or

problems for you.•View the diagram for shape, asking these questions:

•is there one dominant category?•is the diagram the expected shape?

•Check the action to take, •Instigate action on chosen activity.

Pareto charts

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Steps in creating a Pareto Diagram• Create a Histogram• Sort the categories• Read off the categories in order.

Pareto charts

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Pareto charts

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B A D C G OtherDefects Count

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Cause and effect / fish bone / Ishikawa diagrams

Uses:• To solve problems. • To educate. • To guide discussion. • To actively seek causes.• To collect data.• To show relationships.

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Cause and effect diagrams A diagram showing the links between a problem and its possible causes.

Has a problem stated in the box on the right side of the diagram and possible causes (under classification) on the left of the diagram.

Common classifications are:

Workers Materials,

Methods Machines

Environment

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Cause and effect diagrams

How to use a cause and effect diagram

scan the diagram for an overview

Read the diagram, problem, possible causes

Read detail

Seek more causes under the classifications

Rank causes for likelihood of being the cause and degree of difficulty to rectify.

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Cause and effect diagrams Steps in creating a C&E diagram

Gather team to create diagram

Select the scene, ensure all understand the situation

Identify the real problem

Develop possible causes

Classify causes into headings

Agree probable causes

Redraw diagram

Repeat until satisfied

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Cause and effect diagrams Techniques used

Brainstorming for ideas, problem identification and probable causes.

Crawford slip method

codes

N, for not difficult to fix, V very difficult

n, for not expensive, v very expensive

Select items coded Nn to rectify and gain some quick improvement.

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Cause and effect diagrams

Dents in end panel of control box

Dents in end panel of control box

MaterialsMaterials

MachineryMachineryMethodsMethods

WorkersWorkers Lack of training

Poor maintenance

Poor set up

Parts dropped off conveyor

Lack of care

Poor procedures

Faulty roll steel

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Uses:• To indicate changes or differences in patterns over time. • To compare data from the same process at different time-

periods. • To compare different sources of the same process during

the same time-period.

Run chart

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A Run chart is:A record of measurements presented in the order or sequence in which the data was taken.

It can take the form of a scatter graph or a line graph.

It has a time axis (the x-axis ) and a measurement axis (the y-axis).

Run chart

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How to use a Run chart:A Run Chart is a guide to action, an aid to making

decisions. It displays the data in time order and so indicates trends.

View the diagram for shape, asking these questions:• is there a trend up or down?• is the data showing a wide spread?• is the data showing ‘normal’ variation?• Investigate reason for shape, if necessary• Make a choice based on data presented.

Run chart

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Steps in creating a run chartDecide process to be measuredChoose time period, x-axisChoose scale, y-axisRecord dataAnalyse dataMake decision of next action

Run chart

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Run chartrun chart of number of defects in a batch from supplier 1

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Run chartrun chart of number of defects in a batch from supplier 2

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Control charts

Are similar to run charts but have control limits attached to gauge suitability to a process.

See Powerpoint file

control charts.ppt

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Errors associated with Sampling and SPC

DECISION Search for defect Leave process as it is

CONDITION in process and try to correct it

Process is Type I error Correct decisionworking properly

Process is defective Correct decision Type II error