Top 10 Fundamentals of a Powder Coating Operation

Transcription

1 Top 10 Fundamentals of a Powder Coating Operation Bill Owens AkzoNobel Jeff Hale Gema

2 Understanding The Expectations of Your Coating

3 Powder Coating what is it? how to use it (correctly)? conclusion!

4 Powder Coating is : Resins Pigments Fillers Additives but no Solvent! thus, no VOCs are released in the atmosphere

5 Powder Coating is : A clean technology A durable coating An economic solution An easy to use process

6 Powder Coating is : A clean technology No VOC released during the process No mud in cabins painting have to be evacuated No solvents needed to clean equipment

7 Powder Coating is : A durable coating Exceptional resistance and durable film (scratch resistance, shocks and abrasion, etc.) Weatherable coating, UV and chemical resistance High level of corrosion protection

8 Powder Coating is : An economic solution Overspray is easily recyclable Spray booth air is recyclable Reduced maintenance and repair costs compared to liquid Reduced waste management costs

9 Powder Coating is : An easy to use process Easy to apply (no runs, self-limitation thickness, easy repair) Setting of powder installations easy and fast Powder is a «ready to use» product, independently of the workshop conditions

10 Understanding the Importance of the Pretreatment Process

11 Why Clean? The bottom line: If the pretreatment isn t good, it doesn t matter how good the powder is!!!!

12 Cleaning Options Mechanical cleaning Surface abrasion Grind, sand, blast Chemical cleaning Alkaline, acidic, neutral aqueous cleaner Immersion or spray

13 Pretreatment Cleaning Conversion Coating Rinsing

14 Mechanical Cleaning Removes Mill Scale Rust Smut Die Release Contamination

15 Chemical Cleaning Removes Oil Shop dust Grease Rust Inhibitors

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18 Pretreatment tests Water Break Free Adhesion Test Coating Weight Humidity Test Salt Spray Test

19 Understanding of Racks, Fixtures, and Hanging

20 Racking Options Carts Hooks Racks

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23 Hanging Methods Wires Rods Fixtures Chains

24 Hanger Considerations Presentation Coat-ability Grounding Hanger length Drainage No angle traps water! INCORRECT Angle allows water to drain. WATER CORRECT

25 Typical Product Profile Hanger Attachment Point 27 Minimum Part 6 Part Clearance 6 Part Clearance

26 Racking Design Issues Stable racks Steady position Good access for spray guns Dense racking Spray more part than air Dedicated tooling Special tooling can save money Improve productivity Pre-rack stations Efficient use of space Rack inventory & maintenance ground

27 Hooks Inexpensive Flexible Easy to maintain

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29 Powder Coating Hooks Designed with good contact points Durable construction Keep them in good repair Try to run full racks Avoid dirty hooks Keep the contact points clean Clean Hooks = better T.E. Routine maintenance Burn Off Stripping

30 Benefits of Hanger Cleaning Ensures good earth ground Improve application performance Uniformity Provides safe application (Less than 1 Megohm resistance to ground)

31 Understanding Application Setup and Performance

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33 Electrostatic Process Components

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35 Pneumatic and Electrostatic

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37 Spray Pattern/Target Distance α α α

38 Powder Injector

39 Total Air = Particle Velocity Too High Too Low Hose Diameter Larger = Slower & Smaller = Faster Hose Material and Design Velocity & Affects on Charging

40 Fluidized Bed Hopper Porous membrane Compressed air aerates the powder Separates the powder particles Makes powder act like a liquid Gentle, rolling motion No evidence of violent bubbling No dust escaping from the hopper Avoid termite hills rat holing Fluidization is like Goldilocks and her Porridge: Excessive Air (Boiling) Too Hot Too Little (Small Chutes of air) Too Cold Consistent Simmer Just Right

41 Excessive Fluidization Excessive boiling is prevalent Dust blowing from top of hopper Large amounts of powder being vented into booth

42 Too Little Fluidization No Lift Small Spouts of powder Partial Movement of Powder Surface

43 Good Fluidization Good Lift No Rat-Holing Consistent movement of powder surface Simmer

44 Powder Level Level influences workload on venturi

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46 When Recoating Any Part Adjust the electrostatic parameters An increase in powder delivery will be required (10-20%) No adjustment to total air, rinsing air, or fluidizing air Increase gun-to-part target distance Use same application technique or gun motion Use same nozzle configuration

47 Color Change Juggling all of the colors Time required for change Cleaning of components Wasted material Proper use of technology Supply & transport of powder materials Risk of cross contamination Risk of operator error Need for more productivity

48 Understanding of Operational Procedures

49 Operational Procedures to Produce Quality Parts Powder Paint Storage Maintain temperature as low as possible Below 80 F is preferred Maintain humidity as low as possible Below 60% is preferred Do not stack more than four boxes high First in, first out

50 Operational Procedures to Produce Quality Parts Paint Room Temperature less than 80 F Humidity between 40 and 60% RH Max 50 fpm air velocities Less than 200 fpm at A/C diffusers 2 micron air filters on A/C Ducts (supply & return air) located away from booth area

51 Compressed Air Is Vital Must be clean Free of oil and water Moisture causes problems Powder absorbs moisture Affects charging efficiency Delivery of powder to the part Pulse clean the filter cartridges Fluidize the powder in the hopper Used for sieving and reclaim equipment

52 Compressed Air Pressure consistency Volume Average 6 cfm per gun Transfer pump 12 cfm Hoppers 3-15 cfm Air supply quality Air dryer Oil content 0.1ppm Dew point - 35 F Particulate matter < 1 micron

53 DOES YOUR SHOP LOOK LIKE THIS?

54 Please Not Like This!

55 SHOP ORGANIZATION Clean and well organized vs. Dirty and disorganized

56 It Pays To Be Clean

57 BLACK AND WHITE DO NOT MAKE GRAY IT MAKES A SALT AND PEPPER LOOK!

58 Understanding of Applied Costs

59 Understanding Applied Cost Vs Price Per Pound Must know the specific gravity of the powder coating Formula is used to calculate square feet of coverage at given film thickness Not all powder coatings are created equal a lower cost/pound coating with higher specific gravity can have a higher applied cost than a higher cost/pound coating with a lower specific gravity Applied Cost is what is important!

60 Specific Gravity An expression of density of a material relative to water. Examples: water ; ammonia -.587; Oil Black Ratio of the weight of a given volume of liquid or solid to the weight of an equal volume of water.

61 Theoretical Coverage The capacity of a given mass of a specific powder to coat, in a cured state, an area of substrate at a determined film thickness. To calculate the theoretical coverage for a powder with an S.G. (specific gravity) of 1.35, just divide the constant by the S.G ft 2 /lb./mil = ft 2 coverage of 1.50 powder at 1 mil

62 Theoretical Coverage Applied Cost Calculator Instructions: Enter the specific gravity, recommended film thickness and price per lb of the chosen powder or powders. Powder comparisons, film thickness consequences and utilization effects can be evaluated using the tables below. Option 1 Option 2 Option 3 Option 4 Product Identification xyz abc xyz abc Specific Gravity Film Thickness Coverage per lb (sq ft) Price per Lb $ 3.50 $ 3.50 $ 3.50 $ 3.50 Material Utilization 100% 100% 50% 50% Cost per Square Ft $ $ $ $ Cost Per 1,000,000 Square Feet $ 92, $ 81, $ 185, $ 163, Applied Cost / 1 Million Sq Ft Cost $200, $150, $100, $50, $ Powder Options Series1

63 Understanding of Curing Methods

64 Ovens Dry & Cure Convection Transmits energy by air circulation Infrared Radiant energy in electromagnetic wave-lengths Ultra violet Uses light energy to react photo-initiators in film Induction Transmits energy by electrical current

65 Curing & Oven Cycle Time (Based on convection heating) Cure depends on time and temperature More time can be used to reduce temperature More temperature can be used to reduce time Standard Cure Schedule Minutes Temperature F F F F

66 Cure & Oven Testing

67 Oven Temperature Testing

68 Understanding of Testing and Measuring for Quality Assurance

69 Testing & Measuring IMPACT TEST BEND TEST COLOR METER GLOSS METER PENCIL HARDNESS Mandrel Bend Test CROSS HATCH FILM GAUGE CURE TEST

70 Testing & Measuring Ground ALL POWDER EQUIPMENT SHOULD BE GROUNDED TO A EARTH GROUND

71 Testing & Measuring Megohm Megger

72 Testing & Measuring Air Supply Moisture Monitoring air flow movement at the application port vestibules. Powder containment Clean-up Booth Containment

73 Understanding Post Coating Handling Methods

74 What Is Your Post Coating Environment? What will your parts be subjected to? Final assembly and/or packaging stages Coating performance specification Place in Bins? Rack on specialized assembly carts? Palletize?

75 Powder Coating Toughness Use of materials for separation between items Paper, foam, cardboard, etc. Shrink wrap Marking from packaging Parts in loose bulk containers Warm parts versus cold parts

76 Understanding of Safety Issues

77 AGENCIES AND CODES

78 EPA Environmental Protection Agency Set and enforce codes relating to environmental hazards such as waste-water, soils and air to name a few. Effect Powder Coating Shops in regards to pretreatment wastes, air quality and other issues.

79 OSHA Occupational Safety & Health Administration Set and enforce codes relating to worker and workplace safety. Effect Powder Coating Shops in regards to worker and workplace safety issues.

80 OSHA OSHA Sets PPE Standards PPE Personal Protection Equipment Safety Glasses Protective Clothing Tyvek Suits Air Assists Gloves Masks Respiration Part Handling Equipment Braces (Back etc)

81 NFPA National Fire Protection Agency Set codes relating to fire safety. Effect Powder Coating Shops in regards to fire suppression and fire detection.

82 FIRE MARSHAL State and Local Level Fire Marshals Set Local Codes and Enforce NFPA codes relating to fire safety. Effect Powder Coating Shops in regards to the enforcement of fire suppression and fire detection and safety violations. Ovens Permitting Wiring Sprinkler Systems Specialized Heating

83 Understanding Finishing Fires Elements of Combustion - Powder System Ignition Source Oxygen Compressed air supply and air flow in spray booth Poor ground Fuel Powder & air mixture

84 Safety Guidelines NFPA 33 NFPA 68 NFPA 69

85 Safety and Grounding General Grounding Equipment continued Use ground clamps and 18 gauge wire. Recommendation is for ground wires be made of #14, bare, stranded wire (minimum). Where possible use larger wire. Never daisy chain ground wires. In order to coat products safely and effectively the following conditions must be maintained.

86 Grounding Check ground resistance value Use MW-meter (500 V) Resistance < 1 MΩ Review hook/rack design Self-masking Contact point Cleaning schedule Burn-off Blasting Stripping

87 Safety and Grounding General Grounding Personnel continued The operator should not wear insulating gloves. Special conductive gloves may be used and is recommended. If insulating gloves are worn, both palms must be cut out to allow bare skin contact with the equipment.

88 Safety and Grounding General Remember 1. The operator 2. The product 3. The electrostatic spray equipment Must be grounded If You Feel a spark See a spark Hear a spark You have a grounding problem

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