Problem Solving Basic 7 QC Tools

Problem Solving – Basic 7QC Tools

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What are 7 QC Tools ?

QC tools are the means for Colleting data , analyzing data , identifying root causes and measuring the results.

Tools are used to identify , analyze and resolve Problems

Problem Solving Tools

1 Why -Why Analysis ( For Corrective action)2 What If Analysis ( For Potential Problems)

1. Simple Tools for Problem Analysis

2 Simple 7 QC Tools (Statistical Tools)• Check SheetsCheck Sheets• Pareto AnalysisPareto Analysis• Graph / FlowchartsGraph / Flowcharts• Cause & Effect DiagramCause & Effect Diagram• HistogramsHistograms• Scatter PlotsScatter Plots• Control ChartsControl Charts


What is a “Problem “?“Problem is an undesirable event” or ..

Any Gap between what is expected and what is obtained , can be called as a Problem, and any effort to reduce this gap can be called as

“Problem Solving”

Expected

Obtained Obtained

(Gap ?) A Problem! (Gap ?) A Problem!

Ideal situation / Objective

Present Level

What is PROBLEM ?

Example : Objective of machining Throttle body Boring operation

– Bore Dia 40 + 0.025 mm

- Actual – 39.992 mm

Objective – 40+0.025mm

Actual = 39.992 mm

Gap = 0.008 mm


Four types of Problems


Library of Problem Solving Tools Why - Why analysis - An Example

Purpose : It is the simple tool used by the team /observer to find out the cause of the problem/Accident/ Breakdown at the Workplace.Many times, the root cause of the problem can be identified by asking Why 5 times and the repetition of such problems can be prevented by taking countermeasure immediately.

Water Dripping in Substation 1

WHY ?

WHY ?

WHY ?

WHY ?

Water accumulated at the roof

Outlet drain chocked

Atmospheric dust & dirt

Periodic cleaning of drain not done

Action

Proper scheduled procedure for roof cleaning is to be prepared


Library of Problem Solving Tools Why - Why analysis - An Example


Library of Problem Solving Tools What-If Analysis

Purpose : It is the simple Pro active tool used by the team / observer, to identify problems before hand and take appropriate counter measures to prevent such problems .


Library of Problem Solving Tools What-If Analysis - An Example

SL. What If Results Countermeasures

Area : Equipment :CompressorTeam :

1. There is no Water in the Radiator of an Automobile ? And it is not noticed.

The Engine heats up and Piston mayget seized.

• Inspect the Temperature of outlet water . • Provide the temp. Indictor for the driver

What are the Basic Seven QC Tools ?

Check Sheets Pareto AnalysisGraph / FlowchartsCause & Effect DiagramHistogramsScatter PlotsControl Charts

What is Check sheet :

A Check sheet is a paper form on which items to be checked have been printed.

Purpose : To collect the data


• Shown a check sheet of molded ComponentDefective Item check sheet

Part Name: Manifold B Date: 29/01/2011

Part No. E178012 Lot No. Y129

Total No. inspected 780 Inspector Name Ahbay

Sr No. Check Point Standard Defect (Nos.)

1 Flow Mark Not allowed 10

2 Crack Not allowed 4

3 Flashes Not allowed 9

4 Shrinkage Not allowed 17

Total Defects 40

Total Rejects 30


• Shown a check sheet of molded ComponentDefective Item check sheet

Part Name: Manifold B Date: 29/01/2011

Part No. E178012 Lot No. Y129

Total No. inspected 780 Inspector Name Ahbay

Sr No. Check Point Standard Defect (Nos.)

1 Flow Mark Not allowed 10

2 Crack Not allowed 4

3 Flashes Not allowed 9

4 Shrinkage Not allowed 17

Total Defects 40

Total Rejects 30

What is Check sheet :• Another example

Daily Assy . Check SheetPart Name: Throttle Body assy. Date: 29/01/2011

Part No. 13400 M 67LA0 Lot No. C1114

Total No. inspected 240 Checking Freq. 1 / 240

Sr No. Check Point Standard Observation

1 Air leak 6.4 Kpa max 0.2

2 Water leak 68 Pa max 18

3 TPS output 800±15 mV 802

4 ID setting 61.3~72.5 Kpa 66.4

Checked by Yoginder

Purpose of Check Sheet

Variation in the Quality Characteristics of a ProcessApplicable for Histogram , Control Chart.

Difference between Groups / MachinesApplicable for Pareto Diagram.

Relation between two characteristicsApplicable for Scatter Diagram

PARETO DIAGRAM

Pareto is combination of Column & Line graph.

Purpose : To prioritize major contributing problem from others which is less contributing.

PARETO DIAGRAM

Invented by Vilfredo Pareto (1848-1923) Italian economist.

- 20 % of the population has 80 % of wealth

Juran – 20 % of quality problem caused 80 % of the dollar loss.

PRINCIPLE OF PARETO

80-20 Principle

80 % improvement can be achieved by working on 20 % of the causes.

PARETO DIAGRAMMonthly Rejection Data

S. No. Type of DefectNo. of defects

Cumulative of Overall

total

% of overall total

Cumulative %

1 Axial Torque 150 150 50 50

2 Air Leak 90 240 30 80

3 Left side Clearance 30 270 10 90

4 Th. Body tight 20 290 7 97

5 Blow hole 7 297 2 99

6 Dent 3 300 1 100

Total 300 - 100 -

PARETO DIAGRAM

150

90

3020

7 3

50

80

9097

99 100

0

10

20

30

40

50

60

70

80

90

100

0

50

100

150

200

250

300

Axial Torque Air Leak Left side Clearance

Th. Body tight

Blow hole Dent

PARETO DIAGRAM

80 % of rejection can be reduced on taking action on Axial torque & Air Leak.

What is defective : A unit that contains at least one defect.

What is defect :-Output of a process that does not meet a

defined specification.

FLOW CHARTS / GRAPHS

Flow Charts:A Tool that graphically represents the steps of

a process

Purpose :- In which process that Problem occurred

GRAPHS

It is pictorial view of data presentationPurpose : Instance Information

Type of Graph.Line GraphBar GraphPie Chart Radar Chart

LINE GRAPH

It is used to monitor the trend of process.

BAR GRAPH

It is used to compare with other.

PIE CHART

It is used to show share/contribution

RADAR CHARTIt is used to total sharp image as a composite

graph

CAUSE & EFFECT DIAGRAMIt shows the relationship between problem &

its possible cause

Developed by Kaoru Ishikawa (1953)

Also known as …o Fishbone Diagramo Ishikawa Diagram

METHODOLOGY

Step 1: Identify All Possible causes

Step 2: Identify Potentional / Suspect causes

Step 3: Validate the all Potential cause

Step 4: Root Cause

CAUSE & EFFECT

Cause are divided into four major Cause are divided into four major sources:sources:

MANMAN MATERIALMATERIAL METHODMETHOD MACHINEMACHINE

EFFECT- OUTCOME OF CAUSESEFFECT- OUTCOME OF CAUSES

STEP 1: IDENTIFY PROBABLE CAUSES

MAN MATERIAL

METHOD MACHINE

EFFECT

STEP 2: IDETIFY THE POTENETIONAL CAUSE

MAN MATERIAL

METHOD MACHINE

EFFECT

STEP 3 : VADILATE THE CAUSE

Sr. No Potentional Cause Validation Conclusion

STEP 4 : ROOT CAUSE

Why-Why Analysis

Why 1 Why bracket welding brokenBecause it was not welded

properly

Why 2 Why not welded properly Because welding jig was loose

Why 3 Why welding jig was loose Because Welding jig worn

Why 4 Why Welding jig worn Welding Jig life not defined.

Why 5

STEP 4 : ROOT CAUSE

Why-Why analysis of two type:Why-Why analysis of two type:

For Occurrence :For Occurrence : Why defect Why defect generated in processgenerated in process

For Outflow: For Outflow: Why defect pass to Why defect pass to customer.customer.

Histograms

PLOTTING THE SHAPE OF A DISTRIBUTION

COMPARING THE DISTRIBUTION WITH SPECIFICATIONS

USEFUL FOR QUALITY, COST AND DELIVERY IMPROVEMENT

USEFUL FOR PROCESS CONTROL

HistogramsHistogram

LSLUSL

Diameter

Frequency

Constructing a HistogramUse range to estimate beginning and end Calculate the width of each column by

dividing the range by the number of columns

Range

# of Columns

= Width

SCATTER DIAGRAM

A graphical technique to shows the A graphical technique to shows the dependency of two variables / dependency of two variables / factorfactor

For example : what extent surface For example : what extent surface finish of machined part varied by finish of machined part varied by changing the speed of lathe.changing the speed of lathe.

SCATTER DIAGRAM

Speed of lathe (RPM)

Surface finish (Ra)

700 3.3

800 3.0

900 2.7

1000 2.4

1100 2.1

1200 1.8

1300 1.5

1400 1.2

1500 0.9

Data collect for speed & Surface Data collect for speed & Surface finishfinish

Cause Effect

SCATTER DIAGRAM

Output/ Effect

Causes

RULE FOR SCATTER DIAGRAMThere should be minimum 30 There should be minimum 30

readings readings

N=30 to check dependency.N=30 to check dependency.

Positive Scatter Diagram:Positive Scatter Diagram:

Negative Scatter Diagram:Negative Scatter Diagram:

SCATTER DIAGRAM

Speed of car Km/Hr

MileageKm/Ltr

30 15

35 16

40 17

45 18

50 19

55 20

60 21

65 20

70 19

75 18

80 17

85 16

90 15

95 14

SCATTER DIAGRAM

CONTROL CHARTS

Control charts is used to detect the Control charts is used to detect the abnormal trends with the help of abnormal trends with the help of line graphs.line graphs.

Invented by Dr. W.A. ShewhartInvented by Dr. W.A. Shewhart

CONTROL CHARTS

Variable Chart :- Variable Chart :-

a)a)Average & Range ChartAverage & Range Chart

b)b)Median & Range ChartMedian & Range Chart

Attribute Chart :Attribute Chart :

a)a)P & np Chart P & np Chart

b)b)c & u Chart c & u Chart

CONTROL CHARTS

X bar Chart : It shows the centering X bar Chart : It shows the centering of the process.of the process.

R bar Chart : It shows the variation R bar Chart : It shows the variation between the subgroup size.between the subgroup size.

CONTROL CHARTS

Diameter of Shaft :- 23±0.2Diameter of Shaft :- 23±0.2

No. of Subgroup (N)= 10No. of Subgroup (N)= 10

Subgroup size = 5Subgroup size = 5

CONTROL CHARTS

X =(X1+X2+X3+X4+…….+X10)/N X =(X1+X2+X3+X4+…….+X10)/N

R=(R1+R2+R3+R4+……..+R10)/NR=(R1+R2+R3+R4+……..+R10)/N

Control Limit – XbarControl Limit – Xbar

UCLx= X + A2 R = UCLx= X + A2 R =

LCLx= X - A2 RLCLx= X - A2 R

Control Limit – R barControl Limit – R bar

UCLr= D4 RUCLr= D4 R

LCLr= D3 RLCLr= D3 R

Where D4,D3 & A2 are constantWhere D4,D3 & A2 are constant

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Process control ( Standardization )

Evaluation of result

Implementation

Develop Improvement method ( Solution )

Detecting causes of problem

Record of facts

Defining the problem

Identification of problem

Control Chart

Scatter Diagram

Histogram

Cause & Effect Diagram

Pareto Diagram

Check sheet

Graphs / Flow Charts

Application of QC tools in Problem Solving

Relation :-

Strong Normal

Thank You !!!

Documents

Problem Solving Basic 7 QC Tools