7 QC Tools

BASIC PROBLEM SOLVING TOOLS

INTRODUCTION

● Problem Solving Tools - A Systematic, Structured and Organised way to solve a problem.

● Elementary Statistical Methods are used to solve the Problem.

● 80% of all problems within an organisation can be solved by these tools

THE PDCA APPROACH (Deming Cycle)

PLAN

CHECK DO

ACT

1. PlanIdentify problemDevelop plan for

improvement

2. DoImplement plan

on test basis

3. Study / CheckIs the plan working

4. ActInstitutionalize improvement

Continue cycle

THE PDCA APPROACH (Contd…)

TOOL FOR DATA ANALYSIS

● CAUSE AND EFFECT DIAGRAM● PARETO DIAGRAM● GRAPHS● SCATTER DIAGRAM● HISTOGRAM● CONTROL CHARTS● BRAINSTORMING

1.CAUSE AND EFFECT DIAGRAM

Effect

ManMachine

MaterialMethod

Environment

Possible causes: The results or effect.

CAUSE AND EFFECT DIAGRAM (Example)

Why did the Milk Get Sour

Not Fresh Unclean Storage

No hygiene Hands Unclean

Hot weather Process not clear No Training

Sour Milk

Method

Man

Environment

Materials

2. PARETO DIAGRAM

● Helps us prioritize problems● Segregate “Vital Few” and “Trivial Many”

PARETO DIAGRAM (Example)

Factor(Menu)

Freq.(Number Sold)

Cum.Freq. Percent Cum.

Hamburger

Noodles

Fried Fish

Pizza

206

180

70

16

206

386

456

472

44%

81%

97%

100%

Total 472

Effective Space Utilization in Cold Room

PARETO DIAGRAM (Example)

Freq

uenc

y100

80

60

40

20

0

500

400

300

200

100

0 Cum

ulat

ive

perc

enta

ge

Hamberger Noodles Fried Fish Pizza

3. GRAPHS

● The purpose of graph is is to show data in an easy-to-understand manner.

● Use for Analysis and Presentation.● Very good tool for visual display & trend analysis .

Types of Graphs:● Bar Graph● Line Graph● Pie chart

20

15

10

5

0

Num

ber o

f def

ects

First Second ThirdShift

BAR GRAPH (Example)Shift wise Number of Defects.

LINE GRAPH (Example)

8:00 8:30 9:00 9:30 10:00 10:30 11:00 11:30 12:00 12:30

Num

ber o

f pat

ient

s

Time

16141210 8 6 4 2 0

Number of Patients at a clinic at Different Times

PIE CHART (Example)

PROPORTION OF INWARD TELEPHONE CALLS IN A COMPANY

SCATTER DIAGRAM

● Show whether there is a relationship between the main cause and the problem.

● Verify suspected causes identified during Cause & Effect Diagram .

● Identify Problems.● Make predictions

SCATTER DIAGRAM (Example)

Employee A B C D E F G H I J K L M

Years Employed 4 10 8 1 5 2 12 7 9 5 7 9 3

Average monthly Errors 28 12 14 35 20 27 2 23 8 29 13 17 34

RELATIONSHIP BETWEEN THE NUMBER OF ERRORS MADE BY THE TYPIST & EXPERIENCE IN THE COMPANY

SCATTER DIAGRAM (Example) contd…

No. of years employed1 2 3 4 5 6 7 8 9 10 11 12 13

40353025201510 5A

vg. m

onth

ly e

rror

sAVG. MONTHLY ERRORS Vs NUMBER OF YEARS EMPLOYED

HISTOGRAM (Example)

Class Boundary values(wt./bottle) gm

Centre Value(wt./bottle) gm

Frequency

12345678

7.5 – 8.08.1 – 8.58.6 – 9.09.1 – 9.59.6– 10.0

10.1 – 10.510.6 – 11.011.1 – 11.5

7.758.258.759.259.75

10.2510.7511.25

41122312017105

DATA SHEET

HISTOGRAM (Example) Contd…

Content wt./bottle gm 7.75 8.25 8.75 9.25 9.75 10.25 10.75 11.25

30

25

20

15

10

5

0

Freq

uenc

y

STRATIFICATION

● It is a way of sorting out or arranging the data to be collected .

● Purpose of Stratification is to breaking down the causes of the problem into parts to examine each cause better.

STRATIFICATION (example)

Raw Material

Mat

eria

l Str

engt

h

Supplier A

Supplier B