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Application of Quality Improvement Techniques to
the Powder Coat Process
Joan Burtner, Chris Durre & Nikki Smith
Department of Mechanical and Industrial Engineering
Mercer University, Macon, GA
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 2
The Six Sigma Approach in the Business Community
Six Sigma - a comprehensive system for achieving, sustaining and maximizing business success
Drivers a close understanding of customer needs, disciplined use of facts, data, and statistical
analysis diligent attention to managing, improving, and
reinventing the business process
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 3
Benefits of the Six Sigma Approach
cost reduction productivity improvement market-share growth customer retention cycle-time reduction defect reduction culture change product/service development
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 4
The Six Sigma PhilosophyDesigned to foster data-driven
management decisions
The Three C’s common metrics “constant” communication culture change
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 5
Selection Criteria for Six Sigma Improvement Projects
There is a gap between current and desired/needed performance.
The cause of the problem is not clearly understood.
The solution isn’t predetermined, nor is the optimal solution apparent.
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 6
School of Engineering Senior Design Course
Two semester course required for graduation with a bachelor’s degree in engineering or industrial management
Student Teams Two or three students Often interdisciplinary
Management Senior design course instructor Departmental technical advisor
Client – internal or external
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 7
Paint Cell Project
Interdisciplinary team Industrial management Industrial engineering
Technical advisor - Joan Burtner
External client Georgia manufacturer Practices Six Sigma philosophy
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 8
Powder Coat Process Overview
Material - powdered paintTwo basic application methods
Part is lowered into a fluidized bed of the powder, which is electrostatically charged
Powdered paint is electrostatically charged and sprayed onto the part
Curing Part placed in an oven - powder particles melt
and form a continuous film
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 9
Powder Coat EquipmentSpray Gun
Corona charging guns -electric power used to generate the electrostatic charge
Tribot charging guns - electrostatic charge generated by friction between the powder and the gun barrel
“Bell” charging guns -powder charged by being "flung" from the perimeter of the "bell
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 10
Powder Coat Facility
Typical
Spray
Booth
Courtesy: www.thefabricator.com
Accessed March 12, 2004
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 11
Quality IssuesSurface preparationOperators
Training Skill
CoverageColor changeCleanliness/ contamination
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 12
Six Sigma Methodology
DefineMeasureAnalyze ImproveControl
Project Scope D-M-A
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 13
Preliminary Process Map
Load
Wash
Unload
Paint
Cure
Dry
Rework Accept
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 14
Process Step
# Input Measure System
C/U
Type
Output Measure System
Load 4
Wash 4
Dry 2 Drying oven Visual inspection
C Dry panel Visual inspection
Paint 6
Cure 2
Unload 1
Rework 2
Paint Cell Process Matrix
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 15
Key Customer Requirements
Minimal paint thickness
Even coverage
Scratch-free parts
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 16
Preliminary Data Collection
Student teams Observer Recorder
Random sampling75 observations for control chartsCollection sheet variables determined
by client
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 17
Revised Data Collection
Student teams Observer – voltage, temperature, etc Thickness gauge operator Thickness gauge recorder
Revised data collection form Limited variables – panel, color, hook, 5
locations Larger cells for recording data
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 18
# Process Step
Process
Input
Paint
Thickness
Even
Coverage
Damage
FreeTotal
Customer Imp 7
Customer Imp 9
Customer Imp 10
1 Load Hook 3* 3 3 78**
2 Load Conveyor 3 3 3 78
3 Paint Spray Gun 9 9 1 154
4 Cure Temp 3 3 1 58
Cause and Effect Matrix
* Correlation values 0, 1, 3, 9 **Sample calculation 7*3+9*3+10*3=78
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 19
Control Charting Deliverables
Target Factor - paint thickness Data collection plan Documentation of plan as standard
operating procedure Control chart training materials Control charts of baseline data
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 20
Control Charting Locations Factor - paint
thickness 5 locations Repeated
measures 25 samples for
baseline chart
North
West Middle East
South
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 21
Control Charting Sample Preliminary
Range not in control
252015105Subgroup 0
4.54.03.53.02.52.01.51.00.5
0.0
Sam
ple
Mea
n
1
6 5 5 6 5 6
1
Mean=1.818
UCL=3.186
LCL=0.4504
6
5
4
3
2
1
0
Sam
ple
Ran
ge
1
1
R=0.7272
UCL=2.376
LCL=0
Xbar/R Chart f or SB
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 22
Control Charting Sample Results - Revised
Range in control Xbar not in control
2010Subgroup 0
3.5
2.5
1.5
0.5
Sam
ple
Mea
n
51 1
15
12
2
56 6
65
22
2
1
Mean=1.698
UCL=2.511
LCL=0.8855
1.5
1.0
0.5
0.0
Sam
ple
Ran
ge
R=0.4322
UCL=1.412
LCL=0
Xbar/R Chart f or SBrev ised
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 23
Designed Experiments
Dependent variable - paint thicknessFactor 1 - locationFactor 2 - shiftStatistical software package - Minitab
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 24
Failure Modes and Effects Analysis (FMEA) Techniques
48 process steps selected for investigation 4 experts polled
Operators Management
Ratings entered into basic FMEA worksheet RPNs calculated Process steps ranked by RPN (high to low)
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 25
Failure Modes and Effects Analysis - Category Ratings 1
Severity of Effect (10-1) Hazardous without warning Hazardous with warning Loss of primary function Reduced primary function performance Loss of secondary function Reduced secondary function performance Minor defect noticed by most customers Minor defect noticed by some customers Minor defect noticed by discriminating customers No effect
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 26
Failure Modes and Effects Analysis - Category Ratings 2
Likelihood of Occurrence 9 Very High: Almost inevitable 7 High: repeated failures 4 Moderate: Occasional failures 2 Low: Relatively few failures 1 Remote: Failure is unlikely
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 27
Failure Modes and Effects Analysis - Category Ratings 3
Ability to Detect (10-1) Cannot detect Very remote chance of detection Remote chance of detection Very low chance of detection Low chance of detection Moderately high chance of detection High chance of detection Very high chance of detection Almost certain detection
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 28
Risk Priority Number Example Calculations
Paint Material – accident or transport failure Potential Failure Effect
Lack of paint consistency Severity of Effect rating 4
Potential Cause Dropped powder Likelihood of Occurrence rating 3
Current Control Lifting procedures Ability to Detect rating 3
Severity*Likelihood*Detection = 36 = RPN
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 29
Failure Modes and Effects Analysis Results
Ratings ranged from 300s to 20sUncontrolled process steps eliminatedCritical controlled process steps
Powder application - operator Cure process Powder application - spray gun Loading Unloading
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 30
Control Plan Worksheet Critical to Quality (CTQs) factors listed
according to RPN ranking Process step as listed in process map Inputs/outputs Process specifications Measurement system Current control plan
Control method Who Where When Reaction plan
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 31
Control Plan Follow-up
Revision of current standard operating procedures (SOP)
Establishment of standard operating procedures for CTQs that do not already have an SOP
Periodic review
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 32
Future Work Phase 1
Development of plan for constant metrics Implementation of new SOPs
Phase 2 Periodic process review Implementation of new metrics as needed
Phase 3 Project closure Implementation of related Six Sigma projects
IIE Annual Conference May 2004 Presenter: Dr. Joan Burtner, Mercer University 33
Contact Information
[email protected] 105D, School of EngineeringPhone (478) 301- 4127Fax (478) 301- 2331