Understanding the Basics of Electrocoat
Kelly MooreDevelopment Chemist
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Overview
Why and When to Use ElectrocoatHow Does Electrocoat Work?Selecting the Right Electrocoat TechnologyThe Future of Electrocoat
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Why and When to Use Electrocoat
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Why Use Electrocoat?
Economical & Efficient
EnvironmentallyConscientious
Excellent Performance
SomeDisadvantages
High transfer efficiency
Precise film build control
100% coverage of complex parts
Coats recessed areas
Automated system: low maintenance and
minimal labor
Dense racking of parts
Non-uniform line loading
No or low VOC
HAPs-free products available
Heavy metal-free products
Minimal waste discharge
Reduced fire hazards
Reduced exposure of workers to hazardous
materials
Controlled uniform film thickness
Improved aesthetics
No runs, drips, or sags
100% coverage
One or two coat applications for optimal
performance
Epoxy-based for corrosion, acrylic-
based for durability
Capital expenditure
Color flexibility (multiple colors)
Substrate must be conductive
Bake required (thermoset)
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Performance Requirements &
Specifications
Substrate & Part Configuration
Environmental Factors
Economics –Applied Cost Per
Square Foot
Selecting the Right Coating System
AppearancePhysical properties & durability (adhesion, flexibility, chip resistance, corrosion resistance, UV resistance, etc.)
Heat limitationsPart complexity and size
Air emissions (VOC/HAPs)Waste considerations
Transfer efficiencyLabor/time requirementsNumber of parts to process
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Selecting the Right Coating System
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Liquid Powder E-Coat
Colors / Color Changes Best Better Limited Heat Limitations Best Limited Limited
Environmental Impact High Lowest LowTransfer Efficiency Limited Better Best
Manual LaborAutomated Labor
HighGood
HighGood
N/ABest
# Parts Processed Limited Limited Best
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How Does Electrocoat Work?
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What is Electrocoat?
Method of applying a coating which uses electrical current to deposit aqueous dispersed resins and pigments onto a conductive substrate• Highly efficient and automated process• Precipitation of paint particles at
an electrode• Paint film thickness is regulated
by voltage
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The Deposition Sequence
• Voltage is applied and current flows between electrodes• Water decomposes at the electrodes• Paint particles move to the oppositely charged electrode• Paint particles precipitate• Paint particles become tightly packed (insulated)• Deposition stops automatically
The insulating ability of the deposited wet film is what allows the electrocoat process to coat interior recesses
and cavities – throwpower
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Electrocoat Works Like a Magnet
Cathodic Anodic
PaintParticles
CathodeCoating film
deposits with FE++
AnodeCoating film deposits without FE++
Metal Substrate
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Electrocoat Process: The E-Coat Bath
Pigment1-10%
De-Ionized Water80-90%
Resins10-15%
Solvent / Additives1-5%
Water-Soluble Bath Blend
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Electrocoat Process:Sample Process Layout
Pumps
Oven
Sample Tank Stages• Cleaning• Pretreatment• Rinsing• E-Coat• Permeate Rinsing• DI Rinsing
Racking
Flash (Pre-bake)
Power Supply / Process Control
Particle Filter Ultrafilter
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Electrocoat Process:Pretreatment
• Cleans the metal and prepares it for coating• Common to all application technologies• Can be spray or immersion applied• Major contributor to system performance• Type and number of stages dictated by
performance requirements
Without Pretreatment With PretreatmentPretreatmentRinse
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Electrocoat Process: The Electrocoat Tank
Circulation pumps and eductorsto ensure paint mixing uniformity
Electrocoat tanks may hold up to 100,000 gallonRectifier provides DC
electrical charge; heat exchanger controls bath temperature
Filter removes dirt particles
Ultrafilter produces permeate for rinsing and allow for recovery of paint solids
ElectrocoatPermeate
Rinse
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Electrocoat Process: The Post Rinse & Bake Oven
1 - 3 counter-flowing rinses remove excess paint solidsSmoother finish appearanceHigher operating efficiency
Used to cure and crosslink the paint filmBake varies from 180º F - 375º F
depending on electrocoat typeUsually require at least 10 - 20 minutes
metal temperature for full cure21
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Equipment Design and Operation:Selection Criteria
Capital Expense Floor Space Productivity
Racking of Parts
Maintenance Process Flexibility
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Equipment Design and Operation:Monorail Systems• Highest productivity• Lowest maintenance
• Biggest footprint• Highest capital expense
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Equipment Design and Operation:Programmable Hoist System• Highest flexibility• Medium to low capital expense• Smallest floor space
• Highest maintenance• Lowest productivity
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Equipment Design and Operation:Square Transfer System• Lowest capital expense• Smallest floor space• Medium flexibility
• Medium to low maintenance• Medium to high productivity
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Equipment Design and Operation:Racking vs. Bulk ElectrocoatRacking• Part configuration / design• Size / number / density of parts• Touch points on parts• Maintenance• Contact points
Bulk• Dip-drain / sip-spin• Shift parts to coat touch points• Fasteners, other small parts
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Equipment Design and Operation:Relative Comparison of Systems
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Indexing SystemMonorailProgrammable
Hoist Square Transfer
Productivity Lowest Medium to High Highest
Maintenance Highest Medium to Low Lowest
Capital Expense Medium to Low Lowest Highest
Floor Space Small Smallest Highest
Process Flexibility Highest Medium Lowest
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Selecting the Right Electrocoat Technology
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Paint particles negativeCoated parts positive
Paint particles positiveCoated parts negative
Electrocoat Types
AdvantagesLess iron incorporated
into the filmFormulated for
maximum corrosion resistance and exterior
durability
AdvantagesEconomical systems
for interior or moderate exterior environments
Low cure temperaturesLow VOC
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Electrocoat Technologies
AdvantagesGood U.V. resistance
Gloss retentionGood color control
DisadvantagesLess corrosion protection
AdvantagesCorrosion protectionChemical resistance
"Tough" film
DisadvantagesPoor U.V. resistance (chalks)Poor color stability (cationic)
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Low-bake applicationsHeavy-duty castings,
compressors
Color & gloss control for interior products
Metal office furniture, air diffusers, range hoods,
tool boxes
Electrocoat Technologies
Benchmark for corrosion & chemical resistance
Automotive parts, car bodies, heavy duty trucks,
fasteners
High performance, one-coat applications
UV durability & detergent resistance
Color control
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Electrocoat Technologies
• Agriculture & construction
• Automotive parts• Compressors• Computer parts• Control arms
• Engine cradles• Heavy duty trucks• Marine engines• Spring clips• Suspension
components
• Switchgear• Torsion bars• Transformers• Truck frames
Excellent corrosion resistance, especially on sharp edgesLead-freeHAPs-freeLow VOC
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Electrocoat Technologies
• Agricultural implements• Assemblies fork lifts• Compressors• Concrete
reinforcements
• Construction equipment• Engines & motors• Seat tracks• Heavy duty castings• Military aircraft
• Pipe• Plated plastics• Structural steel• Aluminum substrates• Galvanized substrates
Low cure: 180-225º F cure capabilityFully thermosetHardness/corrosion resistance similar to higher cure coatingsLead and chrome-freeGood throwpowerMore iron in film, which limits performance
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Electrocoat Technologies
• Agricultural implements• Air conditioners• Aluminum extrusions• Appliances• Brass, plated substrates
• Heavy duty equipment• Lawn & garden• Refrigeration• Switchgear• Transformers
• Welding equipment• Wheels
High performance with both high- and low-gloss capabilityColor control and can be formulated as a clearCan be formulated for optimum corrosion or durabilityHAPS compliantTopcoat-able (should be tested)
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Electrocoat Technologies
• Air conditioners• Air diffusers• Furnaces• Hangers• Metal office furniture
• Metal strapping• Range hoods• Toolboxes• Wire screen
Excellent appearance, gloss, and color controlInterior & mild exterior useReduced emissionsNo/low solvent additionsNo heavy metalsMore iron in film, which limits performance
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Electrocoat Applications
Electrocoat + a liquid or powder topcoat produces exceptional performance properties
Two electrocoat layers for high performance
Electrocoat is the final finish
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Electrocoat Applications
• Agricultural implements• Aluminum trim• Condensing coils• Generator housings
• Marine engines• Transformers
Cathodic epoxy basecoat ensures excellent corrosion protectionCathodic acrylic primer-surfacer provides an exterior durable finish and cost-effective topcoatCorrosion protection, chip resistance, UV durabilityNo heavy metals
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Electrocoat Applications
• Automotive• High-end appliances• Sports and recreation
Cathodic epoxy basecoat ensures excellent corrosion protectionLiquid or powder topcoat allows for combination of corrosion resistance and desirable appearance
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Summary
Corrosion ResistanceAuto Parts
Low CureCoat Hangers • Shopping Carts
DecorativeConsumer Electronics • Jewelry
Severe EnvironmentsGenerators • Transformers
UV ResistanceWashers & Dryers • Lawn & Garden • Agricultural Equipment
Performance + AppearanceAutomotive • Appliances • Sports and Recreation
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Questions?
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Thank You
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Kelly MooreDevelopment ChemistPPG Industrial [email protected]
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