Tugas Wanda

7/30/2019 Tugas Wanda

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CAUSE AND EFFECTDIAGRAMS

Seven Quality Tools


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Definition

Scatter Diagrams are used to study and

identify the possible relationship between

the changes observed in two different sets of

variables.


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Scatter Diagrams

0

5

10

15

20

25

0 20 40 60 80

Time Cooking (minutes)


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How to Construct it?

First, collect two pieces of data and create asummary 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 fordirection andstrength.


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CASE

A scatter diagram can be used to identify the

relationship between the production speed of an

operation and the number ofdefective parts

made.

Displaying the direction of the relationship willdetermine whetherincreasing the assembly

line speed will increase or decrease thenumber of defective parts made. Also, thestrength of the relationship between theassembly line speed and the number of

defective parts produced is determined.


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CAUSE AND EFFECTDIAGRAMS

Seven Quality Tools


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Definition

The cause and effect diagram is also called the

Ishikawa diagram or the fishbone diagram.

It is a tool for discovering all the possible causesfor 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.


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How to Constructing?

First, clearly identify and define the problemor effect for which the causes must beidentified. Place the problem or effect at theright or the head of the diagram.

Identify all the broad areas of the problem.

Write in all the detailed possible causes ineach of the broad areas.

Each cause identified should be looked uponfor furthermore specific causes.

View the diagram and evaluate the maincauses.

Set goals and take action on the main


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When a it Can Be Used?

The Example This diagram can be used to detect the

problem ofincorrect deliveries.

When a production team is about to launch anew product, the factors that will affect thefinal product must be recognized. Thefishbone diagram can depict problems

BEFOREthey have a chance to begin.


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CASE : Incorrect Deliveries

Example:


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The Benefits

Helps determine root causes

Encourages group participation

Uses an orderly, easy-to-read format

Indicates possible causes of variation

Increases process knowledge

Identifies areas for collecting data


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CONTROL CHARTS

Seven Quality Tools


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Definition

Control charts are used to determine whether a

process will produce a product or service with

consistent measurable properties.


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How to Develop it?

Identify critical operations in the process where

inspectionmight be needed. Identify critical product characteristics.

Determine whether the critical productcharacteristic is a variable or an attribute.

Select the appropriate process control chart.

Establish the control limits and use the chart to

monitorand improve.Update the limits.


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Case : Defective Products or Services

An Example

Counting the number of defective products or

services

Do you count the number of defects in a given productor service?

Is the number of units checked or tested constant?


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Control Charts

Upper Limit

Lower Limit

Unacceptable

deviation

X

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