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8/3/2019 Six Sigma Green Belt Project - By Imran Haq 23-11-2010
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REDUCING REJECTION SCORE OF RFIS DURING
INSPECTION & TESTING PHASE AT PROJECT SITE
A Project of Six Sigma Green Belt
Prepared by:
Muhammad Imran Haq KhanSupervised by:
Iftikhar Ahmad (Black Belt/Green Belt)
Submission date:
November 23, 2010
Organized by:DAS Certification Pakistan
207, Main Street, I-10/3, Main Service Road (East) Industrial Area Islamabad-Pakistan
Ph: + 92 51 5829773, + 92 51 5829773, 4430120 Fax + 92 51 4430121,www.das.com.pk
http://www.das.com.pk/http://www.das.com.pk/http://www.das.com.pk/http://www.das.com.pk/8/3/2019 Six Sigma Green Belt Project - By Imran Haq 23-11-2010
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Table of Contents
Index Description Page
1 Introduction 3
1.1 Brief introduction to six sigma methodology 4
1.2 Introduction to the project 5
2 Define 6
2.1 Six Sigma Project charter 7
2.2 Process Mapping 9
2.2.1 Voice of Customer 10
2.3 Affinity Diagram 11
2.4 SIPOC Diagram 12
3 Measure 13
3.1 Six Sigma Level Calculation 14
3.1.1 Process Capability 15
3.2 Pareto Analysis diagram 16
3.3 RFI Table-Process Data 17
3.3.1 Flaws Identified During Inspection & Testing 18
4 Analyze 19
4.1 Cause & Effect Diagram For Rejection of RFI 20
4.2 RFI Table After Applying Improvement Steps 21
4.3 Fish Bone Diagram 22
4.4 Factors Affecting Rejection Of RFI 23
5 Improve 24
5.1 Co-Relation Of Different Factors 25
5.2 Improved Table Of RFI After Applying Improvement Steps 26
5.2.1 Types Of Defects 27
5.2.2 Process Capability Verification 28
5.3 Fish Bone Diagram For Inspection & Testing Flaws 29
5.4 Inspection & Testing Flaws Affecting Rejection Of RFI 30
6 Control 31
6.1 Rejection Chart (Simple Line Graph) 32
6.2 Process control Plan 33
Summary 34
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1. INTRODUCTION
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1.1 Brief Introduction to six sigma methodology
Six Sigmaseeks to improve the quality of process outputs by identifying and removingthe causes of defects (flaws) and minimizingvariabilityinmanufacturingprocesses. It uses aset of quality management methods, including statistical methods, and creates a specialinfrastructure of people within the organization ("Black Belts", "Green Belts", etc.) who are
experts in these methods. Each Six Sigma project carried out within an organization followsa defined sequence of steps and has quantified financial targets (cost reduction or profitincrease).
The term six sigmaoriginated from terminology associated with manufacturing, specificallyterms associated with statistical modelling of manufacturing processes. The maturity of amanufacturing process can be described by a sigma rating indicating its yield, or thepercentage of defect-free products it creates. A six-sigma process is one in which99.99966% of the products manufactured are statistically expected to be free of defects (3.4defects per million).
DMAIC
The DMAIC project methodology has five phases:
Definethe problem, the voice of the customer, and the project goals, specifically.
Measurekey aspects of the current process and collect relevant data.
Analyzethe data to investigate and verify cause-and-effect relationships. Determinewhat the relationships are, and attempt to ensure that all factors have beenconsidered. Seek out root cause of the defect under investigation.
Improveor optimize the current process based upon data analysis using techniques
such asdesign of experiments,poka yokeor mistake proofing, and standard work tocreate a new, future state process. Set up pilot runs to establishprocess capability.
Controlthe future state process to ensure that any deviations from target arecorrected before they result in defects. Implementcontrol systemssuch asstatisticalprocess control,production boards, andvisual workplaces, and continuously monitorthe process.
http://en.wikipedia.org/wiki/Statistical_dispersionhttp://en.wikipedia.org/wiki/Statistical_dispersionhttp://en.wikipedia.org/wiki/Statistical_dispersionhttp://en.wikipedia.org/wiki/Manufacturinghttp://en.wikipedia.org/wiki/Manufacturinghttp://en.wikipedia.org/wiki/Business_processhttp://en.wikipedia.org/wiki/Business_processhttp://en.wikipedia.org/wiki/Business_processhttp://en.wikipedia.org/wiki/Quality_managementhttp://en.wikipedia.org/wiki/Quality_managementhttp://en.wikipedia.org/wiki/Statisticshttp://en.wikipedia.org/wiki/Statisticshttp://en.wikipedia.org/wiki/Process_capabilityhttp://en.wikipedia.org/wiki/Process_capabilityhttp://en.wikipedia.org/wiki/Design_of_experimentshttp://en.wikipedia.org/wiki/Design_of_experimentshttp://en.wikipedia.org/wiki/Design_of_experimentshttp://en.wikipedia.org/wiki/Poka_yokehttp://en.wikipedia.org/wiki/Poka_yokehttp://en.wikipedia.org/wiki/Poka_yokehttp://en.wikipedia.org/wiki/Process_capabilityhttp://en.wikipedia.org/wiki/Process_capabilityhttp://en.wikipedia.org/wiki/Control_systemshttp://en.wikipedia.org/wiki/Control_systemshttp://en.wikipedia.org/wiki/Control_systemshttp://en.wikipedia.org/wiki/Statistical_process_controlhttp://en.wikipedia.org/wiki/Statistical_process_controlhttp://en.wikipedia.org/wiki/Statistical_process_controlhttp://en.wikipedia.org/wiki/Statistical_process_controlhttp://en.wikipedia.org/w/index.php?title=Production_boards&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Production_boards&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Production_boards&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Visual_workplaces&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Visual_workplaces&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Visual_workplaces&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Visual_workplaces&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Production_boards&action=edit&redlink=1http://en.wikipedia.org/wiki/Statistical_process_controlhttp://en.wikipedia.org/wiki/Statistical_process_controlhttp://en.wikipedia.org/wiki/Control_systemshttp://en.wikipedia.org/wiki/Process_capabilityhttp://en.wikipedia.org/wiki/Poka_yokehttp://en.wikipedia.org/wiki/Design_of_experimentshttp://en.wikipedia.org/wiki/Process_capabilityhttp://en.wikipedia.org/wiki/Statisticshttp://en.wikipedia.org/wiki/Quality_managementhttp://en.wikipedia.org/wiki/Business_processhttp://en.wikipedia.org/wiki/Manufacturinghttp://en.wikipedia.org/wiki/Statistical_dispersion8/3/2019 Six Sigma Green Belt Project - By Imran Haq 23-11-2010
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1.2 Introduction to project
I have chosen a project to find out the possible reasons for the rejection of the RFI and toimprove level of RFI (Request For Inspection) acceptance by reducing inspection flaws andreduction in cost of quality.
I got the data of 5 pressure vessels from the last year, manufactured in two different bays Aand B. All of the testing data disclose the real position of failure rate of RFI in the year 2009.In this green belt project I tried my level best to apply the suitable statistical tools toanalysis and improve product quality by decreasing the rejection rate. Complete studycarried out in the coming phases in order to find out the main causes of the rejection andthe best suitable remedy for the cause by using six sigma DMAIC methodologies.
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2. DEFINE
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2.1 Six Sigma Project Charter
Date: October 10, 2010
Project Name: Reducing rejection score of RFIs during Inspection & testing phase at
project site.
Process owner: QA/QC Manager
Supervisor: Mr. Iftikhar Ahmed, Black Belt / Green Belt
Project Author: M. Imran Haq Khan
Team Members:
Mr. Qazi Muhammad Furqan (QA Engineer) Muhammad Imran Haq Khan
Mr. Ramzan Nadeem (QC Engineer) Mr. Abdul Rauf (QC Engineer)
Purpose (primary reason for this project):To improve level of RFI (Request For Inspection) acceptance by reducing inspection
flaws and reduction in cost of quality.
Problem Statement
In manufacturing works our customer has serious concern about RFIs rejection percentage,
inspection and testing flaws and inspection cycle time. On weekly basis, collective rejection
percentage of RFI activities (inspection and testing) goes beyond 16% which causes delay in
delivery/completion and handover of equipment to our customer. RFI rejections affects oncost of quality of the project which shows poor manufacturing process.
Business Case:
The successful completion of this project will help the company to minimize the cost of
quality. Improvement in process will be helpful to reduce the manufacturing activity cycle
time of our product.
Goal: (expected outcome, deliverables, and or results)
The project goal is to study 100% acceptance of RFI in our manufacturing process to
determine the ability through process improvement. Furthermore to minimize the rejection
percentage up to 3%.
Scope of Project
The scope of the project is to cover the RFI cycle at both locations
Project site fabrication shop
Workshop facility (for the manufacturing of pressure equipments)
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Timeline (Define, Measure, Analyze Improve and Control):
The following gate review dates are recommended for this project.
Define/Measure October 18, 2010
Analyze/Improve October 30, 2010
Control November 13, 2010
Compilation and report submission November 23, 2010
Measurable Metrics
Primary metric: RFI rejection ratesSecondary Metric: (1) Quality cost of project raised
(2) Decrease in Customer satisfaction level
Benefits
Increase in inspection effectiveness, product time, cycle time and reduce in penaltieson the project.Enhance customer satisfaction.Quality cost reduction.Overall improvement of RFI and manufacturing process.
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2.2 Process Mapping:Detailed Process Flowchart
Material Receiving
Inspections
Non Destructive
Examination
In / Out put from
execution team
Acceptanc
e through
RFI
Transportation
NCR
Delay
Verify as
per Dwg.
through RFI
Yes
No
No
3rd party
reports
3rd party
reports
No
Yes
Release for
hydrostatic test
Yes
Yes
Start
End / Finish
Preparation for fit-
ups
Preparation for re-
inspection
Repair of NDE
work
Surface preparation and
painting work
Surface
preparation
& paining
verification
No
Yes
Final visual
inspection
Marking &
identification
No
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Voice of Customer
Customer Satisfaction (Voice of the Customer)
The impact of cost of poor quality on the customer the customer being the externalcustomer who receives product or service that is directly impacted by the process that is thefocus of your Six Sigma project. Description, how the VOC was validated is as follows:
1. Inspection notification (RFI) 12 hour notice prior to inspection.2. Prior internal inspection with sufficient inspection data and quality record.3. Timely attending the RFI by internal QC inspector.4. Availability of resources.5. RFI rejection %age should not increase more than 3%.
Financial Benefits Assessment
The financial benefits realized as a result of your project is the time & schedule of project.The method in which these benefits were calculated, and if finance resources were used tocalculate as we as confirm the financial benefit.
Tools Application
The analytical tools (t-Test) were employed, then the results of the analysis and theconclusions we will be able to make as a result of the test.
Example:
Tool: Sample Variance F-testConclusion/Key Learning: A sample of parts was taken from the Equipment inspection Aand then repeated sampling using other equipment B, while holding all other factorsconstant. The sample size was 500 inspections an alpha of 0.05. The Fcalc based on theactual sample measurements was 553 inspections. Since the Fcalc was greater than Fcrit, Iwas able to reject the null hypothesis that there was no difference due to the type ofEquipment to be inspected. The resulting p-value confirms that the result is outside of myestablished 95% confidence for accepting the null hypothesis. This test result supportedmanagements assumption that the equipment inspections were contributing to changes inthe process variation, and allowed the project team to pursue this part of the investigationfurther.
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2.4 SIPOC DIAGRAM - High LevelRFI Process Integrity Project
Supplier Input Process
Receiving Material
Marking/Layout &
Cutting
Fit-up & Welding
Activity
NED Testing
Final Inspection
Enter Time Sheets &
Job Progress
Output Customer
Pressure Testing
Release For Painting
Enter Vendor Invoices
Final QualityDocumentation
Transportation To
Process Plant
Store / Warehouse /
Vendors
Layout Supervisor /
Contractor officer
Area Supervisor /
Welding foreman
Area Engineer /
Supervisor
Area Engineer /Supervisor
Field Engineer
Area Supervisor
Painting Supervisor
Commercial / Planning
Engineer
QC Engineer /Inspector
Planning / Commercial
Engineer
Generation RFI For
Inspection
Generation RFI &
Identify Dwg.
Generation RFI & verify
Support Docs.
RFI Raised For Testing
RFI Raised For Internal& External Inspection
Supporting Documents
Presentation
Test Packages prep. &
Field Verification
RFI Raised For Painting
Inspection
Work Done As Per
SOW
Shop Dossier Prep &Verification
Preservation, Marking &
Labeling Verification
Accept / Reject Report
Accept / Reject Report
Accept / Reject Report
3rd Part Re ort
PL / Release Note
Productivity / Project
Cost Report
Accept / Reject Report
Accept / Reject Report
Contraction Cost
Report
Shop dossier /CustomerReview/Acceptance
Production Manager &
Team
Production Manager &
Team
QC System Operation
QC Manager/QC System
Operation
Production Manager &
Team
Production Manager &
Team
Production Manager &
Team
Production Manager &
Team
Field Engineer / CustomerQA/QC Manager
Planning Engineer / Process
Plant Supervisor
QC Engineer / ProductionManager
Equipment Release
Note From Customer
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3. MEASURE
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3.1 SIX SIGMA LEVEL CALCULATIONS
Calculate the sigma level and DPMO of 5-nos. pressure vessels, 100 RFI raised for inspectionand testing activities fabricated in ASME workshop. The manufacturer wants to address thefunctionality and sigma level of the pressure vessel manufacturing process in 9-weeks time.
Sigma Measurements TableSigma Defects numbers per million1.5s 500,0002.0s 308,3002.5s 158,6503.0s 67,0003.5s 22,7004.0s 6,2204.5s 1,3505.0s 233
5.5s 326.0s 3.4
Project sigma is 3 because the DPMO level 74,000 which is near the 3 sigma level.
Yield Calculation of the Process 500 RFIs has 53 rejected then,Yield is Yield= (500 53)*100/500= 89.4%
Variable data output is frequency Mean of the data = 110.6Minimum and maximum of the data = 109 112
Data range= 100Variance= 1.92Standard deviation= 3.84
Z-ScoreEvaluation For Z-score measurement specification limit is USL (102) LSL (106)Z-score= (USL-mean)/standard deviationZ-score= (106-110.6)/3.84= -1.19Z-score value is -1.19
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3.1.1 Process Capability
Pressure Vessel RFI Offered RFI Rejected
PV-1 112 10
PV-2 109 12PV-3 110 11
PV-4 112 10
PV-5 110 10
Interpretation of the Process Capability Diagram
Process Capability PPK = z-score/3 PPK=-1.19/3= -0.399(Process is poor capable and improvement is required)
(Note: if PPK value is grater then 1 process is capable if PPK value is less then 1 thenprocess is not capable.)
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3.2 PARETO ANALYSIS DIAGRAM
Defects Counts
Mech. Damages 1Wrong Marking/Cutting 2Fit-up 5
Visual Testing (Welding) 22RT 2Pneumatic Testing 1Hydro Test 0Surface Preparation 7Painting 4Final Inspection 1Lack of supervision 8
Total 53
Basic Steps for Pareto Chart:1. Quantify the Impact of Each Defect2. Rank in DescendingOrder
NOTE:We should have at least three types of defects. If we have too many, then we may want to
group them together.
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4. ANALYZE
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4.3 Fish Bone Diagram
It is also called ISHI KAWA diagram or Cause and Affect diagram which shows thereal situation about the problem and helps us to find out the root cause of theproblem.
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5. IMPROVE
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5.1 CO-RELATION OF DIFFERENT FACTORS
IDENTIFIED IN CAUSE & EFFECT DIAGRAM
During in depth study, after cause and effect diagram definition, improvement pointshave been identified to reduce the rejection of RFI and sustain the improvement.
The following steps have been taken with the serious consideration:
1. Within the fabrication team, control frequency would be increased. If it is 1 to 2times, it should increase to 3 to 4 times to minimize RFI rejections.
2. Re-alignment of resources, from payroll list has been acquired to see the properallocation of skilled man power. During this, it was observed that fabricators,
welders and painters have been not allocated according to t heir skill andexperience. As a result, re-alignment of resource has been managed.
3. Purposely in those areas, where the inspection flaws rate was very high. Skillenhancement, training program has been delivered according to writtenprocedure.
4. Poor quality of food has been identified as a cause of rejection during fabricationprocess. Good quality of food has been provided by replacement with the pre-qualified vendor.
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5.2.2. Process Capability
Pressure Vessel RFI Offered RFI Rejected
PV-1 103 3
PV-2 102 2
PV-3 102 2PV-4 101 1
PV-5 101 1
Interpretation of the Process Capability Diagram
Process Capability PPK = z-score/3 PPK=0.81(Process is still poor capable and more improvement is required, but improved
from the past)
(Note: if PPK value is grater then 1 process is capable if PPK value is less then 1then process is not capable.)
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6. CONTROL
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STATISTICAL PROCESS CONTROL
The points addressed in the improve phase will be monitored through the control charts inthe statistical process control. The abnormalities will be observed through the tendency ofthe data plots for special causes and corrective action will be taken accordingly.
6.1 REJECTION CHART (SIMPLE LINE GRAPH)
Date Sample Size n Rejected RFIWeek 1 23 0
Week 2 45 0
Week 3 72 1
Week 4 78 0
Week 5 97 2
Week 6 90 0
Week 7 60 3
Week 8 30 2
Week 9 14 1
Comments:
To Conclude, Control Plan would be considered and then the rejections are improved and sustain theimprovement like;
1. Re-Alignment of resource - Taking relevant people in relevant place
2. Provided good food by changing pre-qualified sub-contractor
3. In-situ relevant training has been arranged to all group of vessel fabrication yard
4. Flawless Startup Initiative (FSI) system has been launched for in depth identification
of checkpoints for smooth & in time completion of product with maximum customer satisfaction
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Summary
Our fabrication shop situated near project site has not achieved Six Sigma qualitylevels for all five pressure vessels as requested by their customers. Basically it isrequired to apply Six Sigma problem solving methodology to establish an
improvement strategy that minimizes rework costs, yet achieves the desired qualityobjective.
Problem statement
To bring the key process output variables within Six Sigma quality level of < 3.4DPM. Cp 2.0 and Cpk 1.67
Analysis & Control
RFI control frequency should be increased. If it is 1 to 2 times, internal checksshould increase upto 3 to 4 times to minimize RFI rejections.
Re-alignment of resources, to see the proper allocation of skilled man power. Purposely in those areas, where the flaw rate was very high. Skill enhancement, training
program should be delivered. Food quality should be checked frequently and ensure good quality of food for the staff.
Recommended Control
Implement Flawless Startup Initiative (FSI) system for in depth identification ofcheckpoints for smooth & in time completion of product with maximum customersatisfaction.
Establish control plan for ongoing monitoring of every 10 RFI raised.
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