an overview of six sigma

7/24/2019 An Overview of Six Sigma

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An Overview of SixSigma

Delivering tomorrows performance today

By

P Vidya Sagar

09BME040


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What is Six-Sigma ?????

Highly disciplined process that focuses on

developing and delivering near-perfect

products and services consistently.

It is a continuous improvement process

To achieve Six Sigma, a process must notproduce more than 3.4 defects per million

opportunities

Sigma

Process(

)

Defects per

millionopportunities

Yield

1 697,672 30.2328%

2 308,537 69.1463%

3 66,807 93.3193%4 6,210 99.3790%

5 233 99.97670%

6 3.4 99.99966%


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Why Six-Sigma????

Eliminates causes of mistakes and defects in a

process

Reduces variation and waste in a process

Gain competitive advantage and become

world leader in their respective fields

All these to ultimately satisfy customers and

achieve organizational goals


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How Six Sigma Works??

Management Strategy: An environment

where management supports Six Sigma as a

business strategy

DMAIC: Emphasis on the DMAIC (Define-

Measure-Analyze-Improve-Control) method

of problem solving

Focused teams: Teams are assigned well

defined projects that directly impactorganizations bottom line

Use of statistical methods: Six Sigma requires

extensive use of statistical methods

Six sigma quality: Taking a process to SixSigma level ensures that Quality of the

product is maintained


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Structure of Six Sigma Team


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From where does Six Sigma come ??

Assume a machine produces the following number of bottle caps per minute

The following is the number of caps produced for a period of 30 minutes

27,11,13,12,13,12,11,12,9,12,12,13,12,12,13,12,12,12,11,10,12,12,12,11,12,13

,12,12,12,12

Mean () =Sum of all the data points / Total number of data points

=(27+11+13+12+13+12+11+12+9+12+12+13+12+12+13+12+12+12+11+10+12+12+12+11+12+13+12+12+12+12) / 30 = 12.3667

Standard deviation ()

Subtract mean from each data points and square them

(27-12.3667)2 , (11-12.3667)2 , (13-12.3667)2 , (12-12.3667)2 ,

Add them and divide by the total no. of data points = 8.0988

Calculate the square root of the value found in above step = (8.0988) = 2.845

= 2.845

The acceptable limits set by the production manager (the customer for themachine) is between 0 bottle caps per minute (LSL), and 25 bottle caps per

minute (USL)

This means that out of all 30 data points mentioned above, one data point (27)

falls outside customer specification

Calculate ZU (Z-Upper) and ZL (Z-Lower)

ZU = (USL)/ (3) = (25 12.3667) / (3 X 2.845) = 1.4797

ZL = ( - LSL)/ (3) = (12.3667 - 0) / (3 X 2.845 )= 1.4485

Process Capability = Minimum of ZU and ZL = 1.4485

We can say that the machine producing bottle caps is at 1.45 level

Now we implement a Six Sigma project: The output of which is all data points

fall under customer specification

As a result, 27 comes down to 12

Considering all other 29 data points remain the same, calculate Process

capability. The approximate value comes to 4.676 level

The production manager can now say that his machine is working at 4.68 level


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Historyof Six Sigma

1986: Motorola Starts Six Sigma Initiative

2001: Motorola Saves $16 Billion

cumulatively

1995: Jack Welch Initiates Six Sigma at GE

1998: Allied Signal Saves $0.5 Billion

2000: GE Saves $2 Billion Annually

Motorola initiated Six Sigma for process

improvement thereby reducing defects to

negligible levels

It was at GE that Six Sigma was used to

improve the entire Business System


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Process for Six SigmaDMAIC

Define: Define the problem statement and

plan the improvement initiative

Measure: Collect data from the process and

understand current quality level

Analyze: Study the business process and the

data generated to understand the root causes

of the problem

Improve: Identify possible improvementactions, prioritize them, test the

improvements, finalize the improvement

action plan

Control: Full scale implementation ofimprovement action plan, setup controls to

monitor the system so that gains are sustained


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Define Phase

Define Customers and Requirements

(CTQs)

Develop Problem Statement, Goals and

Benefits

Identify Champion, Process Owner and

Team

Define Resources

Evaluate Key Organizational Support

Develop Project Plan and Milestones

Develop High Level Process Map


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Measure Phase

Define Defect, Opportunity, Unit and

Metrics

Detailed Process Map of Appropriate

Areas

Develop Data Collection Plan

Validate the Measurement System

Collect the Data

Begin Developing Y=f(x) Relationship

Determine Process Capability and Sigma

Baseline


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Analyze Phase

Define Performance Objectives

Identify Value/Non-Value Added Process

Steps

Identify Sources of Variation

Determine Root Cause(s)

Determine Vital few x's, Y=f(x)

Relationship


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Improve Phase

Perform Design of Experiments

Develop Potential Solutions

Define Operating Tolerances of Potential

System

Assess Failure Modes of Potential

Solutions

Validate Potential Improvement by Pilot

Studies

Correct/Re-Evaluate Potential Solution


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Control Phase

Define and Validate Monitoring and

Control System

Develop Standards and Procedures

Implement Statistical Process Control

Determine Process Capability

Develop Transfer Plan, Handoff to

Process Owner

Verify Benefits, Cost Savings/Avoidance,

Profit Growth

Close Project, Finalize Documentation

Communicate to Business, Celebrate


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Six Sigma Projects

Foods

Chemicals

Assets

Hospitals

Railway stations


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References

Brady, J.E. & Allen, T.T. (2006). Six sigma

literature: A review and agenda for future

research

Folaron, J. (2003). The Evolution of Six

Sigma. Six Sigma Forum Magazine

Douglas C. Montgomery1 and William

H.Woodall2 :An Overview of Six Sigma

Google


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