understanding the basics of electrocoat - fabtech...

Understanding the Basics of Electrocoat

Kelly MooreDevelopment Chemist

FABTECH Canada 2014 FINISHING Conference

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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FABTECH Canada 2014 FINISHING Conference4


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


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


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


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


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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• 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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• 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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• 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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• 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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• 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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• 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]

understanding the basics of electrocoat - fabtech...

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