leanmanufacturing_module5sixsigma

8/11/2019 leanmanufacturing_module5SIXsigma

1/27

LEANMANUFACTURING

Module-5 SIX SIGMA

1

POM04


2/27

Definitions of quality

2

Traditional Definition

Quality means fitness for use

Modern Definition

Quality is inversely proportional to variability

Quality Improvement is reduction in variability in processes and

products


3/27

What is Six Sigma?

3

Six sigma can be best described as a business processimprovement approach that

seeks to find and eliminate causes of defects and errors,

reduces cycle times and cost of operations,improves productivity,

better meets customer expectations, and

achieves higher asset utilization and returns on investment in

manufacturing and service processes.

Six Sigma was born when Motorola published its Six Sigma

quality programme in 1987.


4/27

What is Six Sigma?

4

Six sigma is based on three key quality principles

Focusing on customers

Critical to quality parameters (CTQs)

Continuous improvement

Employee participation and empowerment

Six sigma is based on the philosophy of integrated systems based

thinking


5/27

Six Sigma

5

Defect

Anything that does not meet customer requirements is called

defect.Metric

A metric is a verifiable measurement of some particular characteristic

,either numerically (e.g. percentage of defects ) or in qualitative terms

(e.g. level of satisfactionpoor or excellent).

In Six sigma a defect or non-conformance is a measure of quality


6/27

Defects per million Opportunities(DPMO)

6

Defects per

unit

Defects per million opportunities(DPMO)

DPMO = (Number of defects discovered/opportunities for

error)*1000000

Defined as number of defects in a given unit of product or process.

Opportunity for error = Number of units produced Opportunities fordefects per unit


7/27

Defects per million Oppurtunities(DPMO)

7

Use of DPMO is used to define quality broadly

For Six Sigma projects ,the value is 3.4 defects per million

opportunities


8/27

Defects per million Oppurtunities(DPMO)

8

If the average no of bags per customer is 1.6 and the airline

recorded 3 lost bags for 8000 customers in one month .

No of defects discovered = 3

No of opportunities = 1.6 8000 = 12800

DPMO = (3/12800 )1000000 = 234.375

Sigma Level

Sigma Level = NORMSINV(1- Number of defects

discovered/opportunities for error) + 1.5


9/27

Sigma Conversion Table

9


10/27

DPMO & Sigma Level

10

HudsonBella company makes designer bags for several of its

client stores in Oklahoma. During

the quality inspection conducted on 500 random bags on each of

its three manufacturing lines on

Sep 5,

2012, following defects were found:

Line 1: 10 defects

Line 2: 15 defects

Line 3: 25 defectsWhat is the overall sigma level at which HudsonBella is operating

?


11/27

DPMO & Sigma Level

11

An electronics firm manufactures 500,000 circuit boards

per month. A random sample of 5,000 boards is inspected

every week for 5 characteristics. During a recent week, 2

defects were found for one characteristic, and one defect,each, was found for the other four characteristics. If these

inspections produced defect counts that were

representative of the population, what is the overall sigma

level for the process? What is the sigma level for

thecharacteristic that showed 2 defects?


12/27

Sigma Problem Solving Methodology

12

The problem solving methodology used in Six Sigma is called

DMAIC (Define , Measure , Analyze , Improve , Control

Define PhaseWhat are the problems and their scope?

Identify the customers and the critical to quality parameters

Address project management issues such as what will need to be

done ,by whom and when.

What are the independent and dependent variables affecting the

project?


13/27

Define Phase

13

The customer perception about quality attributes are updated

from time to time by conducting customer surveys.

Important tools used in this Phase

Brainstorming

Pareto Analysis

Quality Function Deployment (QFD)

Process Mapping


14/27

Project Charter

14

In the Define phase ,the project leaders create a Project

Charter.Necessary Project Charter Areas

Project Title: It is important to the name the project with a properly

descriptive title that will allow people to quickly view and select yourproject based on key words and phrases.

Ex: If you are increasing Call Centre effectiveness, a possible title

may be Call Centre Cycle time or Call Center Variation reduction.


15/27

Project Charter

15

Necessary Project Charter Areas

Black Belt/Green Belt: This is the person leading the process

improvement project . It is important to identify the project leader so

management knows who is leading the effort and others can locatethe leader for gather further knowledge at a later date.

Mentor/Master Black Belt: It is important to identify a resource for

the project leader to lean on if any project questions or issues arise.


16/27

Project Charter

16


Project Start Date:

Anticipated Project End Date


17/27

Project Charter

17


Cost of Poor Quality:

Process Importance


18/27

Project Charter

18


Process Problem

Process Start/Stop Points

Project Goals


19/27

Project Charter

19


Team Members

Project Time Frame

Project Measurements


20/27

20


21/27

Measure Phase

21

Measuring the processes that impact the CTQs and the defects

arising in the product due to the process.

Identify causal relationships between the process performance(X) and

Customer Value (Y), that is

Y =f(x)

Collect data


22/27

Measure Phase

22

Important tools used in this Phase

Process Mapping

QFD

Cause and effect matrix

7 Quality control tools

Calculation of process sigma and process capability studies

Gauge R and R studies

ANOVA


23/27

Analyze Phase

23

Focus on why defects ,errors or excessive variation occurs

Experiments are conducted to verify the hypothesized

relationship

Statistical thinking ,analysis and computer simulation techniques

re used


24/27

Analyse Phase

24

Important tool used in this Phase

Gap analysis and improvement goals

Process map analysis

Regression analysis

ANOVA

Test of hypothesis


25/27

Improve Phase

25

Focuses on removing or resolving the problem and improving the

performance measures of the CTQs

Problem solutions often entail technical and organizational

changes


26/27


27/27

Control Phase

27

Focuses on how to maintain the improvements over time.

Can include establishing the new standards and procedures

,training the workforce and instituting controls like check lists ,periodic status reviews ,statistical process control charts etc.

leanmanufacturing_module5sixsigma

Documents