Introduction to powder coating

1. INTRODUCTION TO POWDER COATING

The Powder Coating Institute
presents
INTRODUCTION TO
POWDER COATING

2. The Contents of the Program

• Introduction & Program Overview
• Pretreatment & Substrates
• Powder Coating Materials & Application
• Curing, Quality Testing, & Packaging
• Materials Handling, Process Control,
Tracking & Recording
• Safety Issues, OSHA, & Environmental
Concerns

3. Performance Goals - Understand These Issues:

• The Powder Process
• The Powder System Components
• Powder Materials
• Application Equipment & Controls
• Performance Testing & Quality Control
• Safety Issues

4. How We Got Started In Powder Coating

• The Beginning
• Our Progress
• Future Plans

5. The History of Powder Coating

• Late 1940s: Flame Spray of Thermoplastic
Powder
• 1953: Fluidized Bed Application
• 1962 - 1964: Electrostatic Spray
Application Introduced
• 1966 - 1973: Introduction of Four Original
Thermoset Powders
• 1970s - today: Rapid Growth of Powder
Industry

6. The Basics of the Powder Coating Process

• Fluidized Bed Application Process
• Electrostatic Spray Application Process

7. Fluidized Bed Application

• Parts are Cleaned
– Washed & Phosphated or Blasted & Primed
• Parts are Preheated to 4000 F or Higher
• Hot Part is Dipped Into the Fluidized
Powder
• Powder Particles Melt & Fuse on the Hot
Metal
• Parts are Post-Cured

8. Slayt 8

9. Electrostatic Spray Application

• Parts are Cleaned & Pretreated
• Powder is Charged & Sprayed onto the
Grounded Part
• Part is Transferred into an Oven to Melt
and Crosslink the Powder

10. Slayt 10

11. PRETREATMENT & SUBSTRATES

PRETREATMENT &
SUBSTRATES

12. Pretreatment

• Cleaning
• Conversion Coating
• Rinsing

13. Why Clean?

• Appearance
• Adhesion
• Corrosion Resistance

14. Cleaning Methods

• Mechanical
– Polishing
– Blasting
• Chemical
– Dip
– Spray

15. Mechanical Cleaning

• Removes
– Mill Scale
– Rust
– Smut
– Die Release Contamination

16. Chemical Cleaning

• Removes
– Oil
– Shop Dust
– Grease
– Rust Inhibitors

17. Slayt 17

18. Cleaner Types

• Acidic - pH of 4.0 to 5.5
• Alkaline - pH of 9 to 10.5

19. Conversion Coating

• Iron Phosphate
• Zinc Phosphate

20. Iron Phosphate

• Most Common for Powder Coating
• 35 to 45 mg/sq. ft.Typ. Coating Weight
• Amorphous Surface Structure
– (no apparent crystalline form)
• Good Adhesion
• Modest Corrosion Resistance
• Moderate Sludge Formation

21. Zinc Phosphate

• Not Commonly Used for Powder Coating
• 60 to 120 mg/sq.ft. Typ. Coating Wght.
• Crystalline Surface Structure
• Very Good Adhesion
• Very Good Corrosion Resistance
• Heavy Sludge Formation

22. Rinsing

• Between Chemical Processes
– To Remove Residual Chemistry
• Final Rinse/Seal
– To Passive the Surface
• Dionized Rinsing
– Pure Water to Remove Residual Salts

23. 3-Stage Spray Washer

• Stage 1- Cleaner/Coater: 90 secs., 1400 F
• Stage 2- Rinse: 30 secs., Ambient
• Stage 3- Rinse/Seal: 30 secs., 1200 F

24. Slayt 24

25. 5-Stage Spray Washer

• Stage 1- Alkaline Clean: 90 secs.,1400 F
• Stage 2- Rinse: 60 secs., Ambient
• Stage 3- Iron Phos.: 60 secs. 1400 F
• Stage 4- Rinse: 30-60 secs. Ambient
• Stage 5- Rinse/Seal: 30 secs. 1200 F

26. Slayt 26

27. Substrates

• Steel
– Cold Rolled Steel
– Hot Rolled Steel
• Aluminum Extrusion
• Galvanized
• Castings
– Aluminum
– Zinc

28. Pretreatment Problems

• Poor Adhesion
• Blisters
• Surface Defects
• Poor Corrosion Resistance

29. Pretreatment Control

• Check Solution Concentration 3 times per
shift
• Keep the Washer Nozzles & Pump Screens
Clean
• Maintain Clean Rinse Water

30. Pretreatment Tests

• Water Break Free
• Adhesion Test
• Coating Weight
• Humidity Test
• Salt Spray Test

31. Slayt 31

32. Slayt 32

33. Slayt 33

34. Slayt 34

35. Slayt 35

36. POWDER COATING MATERIALS

37. Slayt 37

38. Powder Material Components

• Resins
• Pigments
• Cure Agents
• Flow Agents
• Additives

39. Slayt 39

40. Slayt 40

41. Slayt 41

42. Slayt 42

43. Two Types of Powder Materials

• Thermoplastic
– do not chemically react during cure
• Thermoset
– chemically react during cure

44. Thermoplastic Resins

• Nylon
• Polyethylene & Polypropylene
• Polyvinyl Chloride (PVC)
• Polyester
• Poly(Vinylidene Fluoride)(PVFD)

45. Thermoset Powders

• Epoxies
• Urethane Polyesters
• TGIC Polyesters
• Hybrids
• Acrylics

46. POWDER APPLICATION METHODS

• Fluidized Bed Dip
• Electrostatic Spray

47. Fluidized Bed Dip

• Preheated Part is Dipped into Fluidized
Powder; Powder Gels on Hot Surface
• Used for Application of Thermoplastic
Materials

48. Electrostatic Spray

• Charged Powder Material is Sprayed onto
Grounded Part
• Parts are Subjected to High Temperature to
Crosslink
• Used for Application of Thermoset and
Sometimes Thermoplastic Materials

49. Charging Methods for Electrostatic Spray

• Corona Charging
– Uses High Voltage & an Electrode
• Tribo Charging
– Uses Frictional Contact With the Gun Interior
Wall

50. Corona Charging

Negative Free Ions
Powder Spray Gun
Grounded
Part
Voltage
Cable
Charging Electrode
Electrical Lines of Force
Powder Particles
Powder Supply Hose

51. Slayt 51

52. Tribo Charging

Powder Particles
Tribo Spray Gun
Air Flow Pattern
Grounded Part

53. Slayt 53

54. The Powder Delivery System

• Fluid Bed Hopper
• Powder Pump
• Powder Hose
• Spray Gun

55. Compressed Air Supply

• +380F Dew Point or Lower
• Less than 0.1 PPM of Oil
• No Particle Greater than 0.3 Micron

56. The Corona Charging System

• Voltage Supply
• High Voltage Generator
• Voltage Cable
• Electrode

57. Pneumatic Controls

• Fluidizing Air
• Powder Supply Air
• Atomizing Air
• Cleansing or Shaping Air

58. Slayt 58

59. Delivery Pressure & Transfer Efficiency

Delivery Pressure & Transfer
Efficiency
• Powder Charges Better at Lower Pressure
• Transfer Efficiency is Higher at Lower
Pressure

60. Voltage Control

• 80 to 100 KV
– Used for Most Surfaces
• Lower Voltage
– Used for Faraday Cage Areas & Recoats

61. Transfer Efficiency Variables

• Nozzle Type
• Powder Delivery Rate
• Gun Position
• Grounding
• The Powder Material
• System Maintenance & Control

62. BOOTHS & RECOVERY SYSTEMS

BOOTHS & RECOVERY
SYSTEMS
• Booth is Used to Enclose Process &
Contain Overspray
• Recovery System is Used to Capture
Overspray

63. Types of Booths

• Batch Booths
• Conveyorized Systems

64. Slayt 64

65. Slayt 65

66. Two Common Types of Recovery Equipment

• Cyclone System
• Cartridge Module System

67. Booth & Cyclone Recovery System

Booth & Cyclone Recovery
System
Cartridge Collector
Cyclone Separator
Final Filter
Powder Booth
Fan
Recovery Hopper
Scrap Powder Barrel

68. Slayt 68

69. Slayt 69

70. Cartridge Module System

Collector Fan Assembly
Final Filters
Cartridge Filters
Cartridge Collector Module
Powder Booth
Sieve
Feed Hopper

71. Slayt 71

72. Slayt 72

73. Spray to Waste

• Short Runs of Various Colors
– Faster Color Change Time
– Higher Material Cost

74. Reclaiming Powder for Reuse

• Collect Overspray for Reuse
– Long Runs of the Same Color
• Mix Reclaim & Virgin Material
Consistantly

75. CURING, TESTING, QUALITY CONTROL & PACKAGING

CURING, TESTING, QUALITY
CONTROL & PACKAGING

76. Powder Coating Cure Cycle

• Enters the Oven Dry
• Melts & Flows From Heat
• Gels & Chemically Crosslinks
• Exits the Oven as a Hard Film

77. Cure Methods

• Convection
• Infrared

78. Convection Oven

• Hot Air is Used to Heat Substrate
• Heated Substrate Conducts Heat to Coating
• Temperature is Held for Specific Length of
Time to Reach Full Cure

79. Slayt 79

80. Cure Curve for Powder Coating

500
400
Temperature
Degrees F
300
200
100
5
10 15
Time
Minutes
20

81. Infrared Cure

• Energy is Emitted & Directed to Part
• Energy Absorbed into Coating & Part
Surface Causes Quick Crosslinking

82. Slayt 82

83. Convection Cure

• Advantages
– More Flexible for Part Mass & Surface Variety
With Little Required Adjustment
– More Consistent Outcome with a Broader
Range of Process Control Variables
• Limitations
– Requires More Space
– Longer Cycle Time

84. Infrared Cure

• Advantages
– Faster Cure Cycle
• Limitations
– Dependent on Line-of-Sight
– Less Flexible for Part Mass & Surface Variety
With More Adjustment Required

85. Testing & Quality Control

Testing & Quality Control
• Test Oven for Temperature Uniformity
• Test Washer Chemistry
• Test Finished Film Properties

86. Slayt 86

87. Slayt 87

88. Finished Film Tests

• Color & Gloss
• Film Thickness
• Adhesion
• Pencil Hardness
• Impact Resistance
• Chemical Rub Test

89. Packaging

• Protect the Surface After Coating
• Keep Good Records of Packed Product
• Control the Volume per Skid
• Take Account of any Special Costs

90. Packaging Materials

• Boxes
• Paper
• Foam
• Plastic Bags
• Cardboard Dividers
• Shrink Wrap
• Banding

91. Types of Packaging

• Bulk Containers
• Layer Packing
• Layer Packing with Wrap
• Weave Packing
• Cell Packing
• Stacking

92. Slayt 92

OPERATIONS MATERIALS HANDLING,
PROCESS CONTROL,
TRACKING & RECORDING

93. Material Handling

• Purchasing Materials
• Storage of Materials
• Inventory Control
• Material Supply

94. Powder Purchasing Considerations

• Purchase Just Enough to Support
Production
• Avoid Long-Term Storage

95. Powder Storage

• Maintain Temperature as Low as Possible
– Below 800 F Preferred
• Maintain Humidity as Low as Possible
– Below 60%Preferred
• Do Not Stack More Than 3 Boxes High
• First in, First out

96. Powder Supply

• Sieve or Screen all Powder
• Precondition Powder by Fluidizing
• Mix Enough Virgin Material with Reclaim
To Remain Efficient
– 50/50 Typical
• Close Up Containers in Storage

97. Pretreatment Chemicals

• Additions to Washer
– Manual or Automatic
• Handling
– Use Proper Safety Precautions
• Storage
– Indoors, Dry Conditions

98. PROCESS CONTROL

• Application Control
• System Monitoring & Maintenance

99. System Monitoring & Maintenance

System Monitoring &
Maintenance
• Training to Maintain Worker Skills
• Proper Management of Raw Materials
• Housekeeping & Control of the
Environment
• Maintenance of the Equipment

100. Equipment Maintenance

• Spray Washer - titrate solutions, clean
nozzles, clean screens
• Dry-off Oven - keep oven clean
• Application Equipment - keep clean,
replace worn parts
• Cure Oven - keep oven clean

101. Equipment Maintenance (Continued)

• Booth & Recovery System - keep clean,
check filters, clean sieve
• Conveyor - keep clean, lubricate
• Racks & Hangers - keep contacts & frame
clean & in good repair

102. TRACKING & RECORDING COATING JOBS

TRACKING & RECORDING
COATING JOBS
• Control of Inventory From Arrival to
Shipment
• Work in Process Records

103. Receiving

• Enter into Inventory
• Notify Customer of Mistakes
• Store in Consistent Location
• Isolate one Batch from Others

104. Processing

• Verify Proper Count When Loading
• Separate & Count Rejects
• Maintain Counts With Progress
– raw parts
– coated, not inspected
– ready for shipment
– rejects

105. Rework

• Schedule for Quick Turn-around
• Maintain Status Report
• Count Parts that Cannot be Salvaged

106. Status

• Be Able to Inform Customer on Progress
– parts raw
– parts coated
– parts ready for shipment
– parts to be reworked
– parts that have flaws that cannot be fixed

107. SAFETY ISSUES, OSHA, & ENVIRONMENTAL CONCERNS

SAFETY ISSUES, OSHA, &
ENVIRONMENTAL
CONCERNS

108. Handling of Powder Coatings

• Read the MSDS
• Avoid Excess Skin Exposure
• Wear the Proper Respiratory Equipment
• Wear the Proper Clothing & Eyewear

109. Slayt 109

110. Slayt 110

111. Fire Risk

• Maintain Safe Concentration Level of
Powder
• Eliminate Sources of Ignition
• Maintain Good Ground of Everything in the
System
• Maintain Good Ground Through Racks

112. Slayt 112

113. Slayt 113

114. Pretreatment Chemicals

• Read MSDS
• Avoid Skin Contact
• Wear the Recommended Safety Clothing
• Maintain Good Ventilation

115. High Temperature Environments

• Limit Access
• Never Enter Washer or Oven During
Operation
• Disconnect Power Before Entering
• Use Good Lighting When Entering
• Wear a Hard Hat in Areas Where it is
Necessary to Stoop
• Know the Hazards Inside the Equipment

116. Slayt 116

117. For Safe Handling of Materials & Operation of Equipment

For Safe Handling of Materials &
Operation of Equipment
Always Follow the Manufacturers
Written Procedures