application of failure mode and effect analysis to the powder coat process joan burtner department...

Application of Failure Mode and Effect Analysis to the Powder Coat

Process

Joan Burtner

Department of Mechanical and Industrial EngineeringMercer University, Macon, GA

Paint Cell Project

• Interdisciplinary team– Industrial management– Industrial engineering

• Technical advisor - Joan Burtner

• External client – Georgia manufacturer – Practices Six Sigma philosophy

Presenter: Dr. Joan Burtner, Mercer University 2

Powder Coat Process Overview• Material - powdered paint• Two 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


Powder Coat Equipment

• Spray 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


Powder Coat Facility

TypicalSprayBooth

Courtesy: www.thefabricator.com

Accessed March 12, 2004


Quality Issues

• Surface preparation• Operators

– Training– Skill

• Coverage• Color change• Cleanliness/ contamination


Preliminary Process Map


Load

Wash

Unload

Paint

Cure

Dry

Rework Accept

Key Customer Requirements

• Minimal paint thickness

• Even coverage

• Scratch-free parts


# 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

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


Control Charting Locations

• Factor - paint thickness

• 5 locations• Repeated measures• 25 samples for

baseline chart


North

West Middle East

South

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


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


Designed Experiments

• Dependent variable - paint thickness• Factor 1 - location• Factor 2 - shift• Statistical software package - Minitab


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)


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



• 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



• Ability to Detect (10-1)– Cannot detect 10– 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 1


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


Failure Modes and Effects Analysis Results

• Ratings ranged from 300s to 20s• Uncontrolled process steps eliminated• Critical controlled process steps

– Powder application - operator – Cure process– Powder application - spray gun– Loading– Unloading


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


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


application of failure mode and effect analysis to the powder coat process joan burtner department...

Documents

mercer university presenter

sigma philosophy presenter

oven powder particles

control xbar

customer imp 101loadhook3

guns electrostatic charge

sample calculation

guns electric power