Home -> Service -> Sheet Metal Finishing -> E-Coating

Metal E-Coating Services (E-Coat / ED Coating)

SR MFG provides a fully managed e-coat service. We act as your single point of contact—locking down the coating process and acceptance criteria, running incoming and final inspections, and delivering the required reports—so you can close the loop on purchasing and quality through one window. E-coat offers stronger coverage into cavities and internal corners on complex parts and delivers more uniform film build, with a typical thickness of about 12.5–30 μm (a project-specific window can be defined).

We can support film thickness, adhesion, and salt spray verification and documentation per ASTM B117 / ISO 9227. The salt spray method, exposure duration, and acceptance criteria can be defined to your specification or mutually agreed and written into the order and inspection standard.

What Is E-Coating?

E-coating (electrophoretic coating) is a water-based electrodeposition process. A conductive metal part is immersed in an e-coat bath, and under a DC electric field, charged resin and pigment particles migrate and deposit onto the surface. The part is then rinsed (often with ultrafiltration to recover paint solids) and oven-cured to form a continuous, dense coating with excellent corrosion protection.

The key advantages of e-coat are highly uniform film build and strong throwing power—meaning it coats complex geometries, recessed areas, inside corners, and channels more effectively than many spray-applied coatings. It’s well-suited for parts that require tight consistency and robust corrosion resistance.

Note: E-coating is a proven industrial process and has been widely used for decades—especially in automotive corrosion-protection primer systems.

For non-metal substrates, e-coat typically requires a conductive pre-treatment before electrodeposition. Feasibility and validation should be evaluated on a project basis.

E-Coating vs. Powder Coating vs. Wet Painting: How to Choose

E-Coating (E-coat)

E-coating uses a DC electric field to deposit water-based coating particles onto a conductive part, forming a thin, highly uniform primer layer with excellent coverage in recesses and complex geometries. Typical film thickness is 15–30 μm (the allowable range can be defined by the coating system and project requirements).

Advantages

Very uniform film build
Strong corrosion-protection foundation
High transfer efficiency
Well-suited for standardized, high-volume production

Limitations

Colors are typically limited to primer shades such as black/gray (more of a “functional primer” than a decorative finish)
Higher equipment investment and higher changeover cost
Substrate must be electrically conductive

Explore SR MFG’s E-Coating Services

Powder Coating

Powder coating applies dry powder electrostatically to the part surface, then cures it into a durable coating. Typical thickness for most applications is 50–125 μm, balancing corrosion protection and appearance. Thicker builds are possible, but dimensional tolerance and appearance risk should be evaluated.

Advantages

Solvent-free; typically very low VOC emissions
Wide range of colors and textures
Overspray can be reclaimed, enabling high material utilization (depending on the reclaim system)

Limitations

Frequent color changes require more thorough line cleaning
Tight control at very low film builds is more difficult
Cure temperature and energy use must be evaluated against part heat tolerance

Explore SR MFG’s Powder Coating Services

Metal Spray Painting (Wet Painting)

Wet painting atomizes liquid paint (water-based or solvent-based) through a spray gun to form a coating film. It offers flexible color matching and is well-suited for low-volume, high-mix programs.

Advantages

Fast color changes
Compatible with a wider range of substrates (including some non-metals)
Easier for localized touch-ups and repairs

Limitations

Transfer efficiency is often lower (traditional guns ~15–30%; HVLP can improve to 50%+), which typically increases material waste and VOC/compliance burden
More prone to defects such as runs/sags and orange peel—requiring stronger process control

Explore SR MFG’s Metal Spray Painting Services

Practical Guidance

For high corrosion resistance, complex metal structures, standardized high-volume production, and strict environmental requirements, e-coating and powder coating are usually the better fit. For low-volume, high-mix programs, simple geometries, and frequent color changes, wet painting is often the most flexible option.

In fact, many sheet metal programs use a proven hybrid process to balance corrosion protection and appearance: “E-coat primer + powder topcoat.”

E-coat primer: provides strong edge and cavity coverage and a robust corrosion base (salt spray can exceed 1,000 hours, depending on the full system and acceptance criteria).
Powder topcoat: delivers wide color options plus a durable, scratch- and wear-resistant finish.
Combined benefit: integrates the strengths of both processes for demanding applications—commonly used for EV battery enclosures and premium appliance housings, among others.

How Does SR MFG Provide “Outsourced E-Coating” Services?

If you need sheet metal parts with a uniform, high-density, corrosion-resistant e-coat finish—but don’t want to coordinate multiple suppliers and manage handoffs—SR MFG can provide a one-stop solution that combines sheet metal fabrication + outsourced e-coating + program management.

The e-coating itself is performed by qualified partner facilities vetted by SR MFG. We own the engineering review, masking/racking requirements, quality inspection, documentation, and schedule coordination—so you only manage one supplier: SR MFG.

Why Choose “Outsourced E-Coat + SR MFG Control”?

SR MFG brings nearly 19 years of sheet metal manufacturing experience and proven project execution across multiple programs. By integrating e-coat requirements with fabrication needs, we turn a project-based outsourced process into a controlled, repeatable delivery model:

Single accountable owner: SR MFG is responsible for final quality and lead time—so you’re not chasing pretreatment, e-coat, logistics, and rework separately.
Engineering first: We perform e-coat feasibility review and create masking/racking requirements up front to reduce assembly interference and rework.
Traceable quality: Lot records, film thickness at key locations, and test reports when required.
Optional topcoat integration: E-coat is often used as an anti-corrosion primer; we can add powder coating or wet painting on top to meet higher cosmetic or weathering requirements (project-specific).

Our Standard Outsourcing Workflow

DFM & e-coat feasibility review (risk controlled at project kickoff)
Issue three “execution-ready” documents (so partners run to the same standard)
Sampling validation → lock the production window
Production execution: SR MFG in-process sampling + lot traceability

Who Does What? SR MFG vs. the E-Coat Partner

SR MFG (Your Single Point of Contact)

Process review and definition of masking/racking requirements
Sample onboarding and production-window lock-in
Incoming/outgoing inspection, issue containment and corrective-action closure, lot traceability
Lead-time and logistics coordination, documentation package delivery

E-Coat Partner Facility

Execute per SR MFG specifications: pretreatment, electrodeposition, rinsing, curing, and routine bath maintenance
Provide required process records and data (per project requirements)

E-Coatable Parts We Support

Sheet Metal Parts

Stamped Parts

Enclosures and cabinets
housings
brackets
mounting plates
carriers
metal frames
welded assemblies
stiffeners

connector tabs
guards/covers
bases
structural frames
chassis shells
and general equipment components

Pierced parts
blanked parts
deep-drawn parts
reinforcement parts
clip/snap features

support parts
guide parts
and other functional stamped components

Typical Materials (Project-Dependent)

Carbon steel, alloy steel, cast iron, heat-treated parts, die castings, conductive plastics (with conductive pretreatment as required), hot-dip galvanized parts, electro-galvanized parts, Galvalume (aluminum-zinc coated steel), magnesium alloy sheet metal parts, copper parts, and stainless steel sheet metal parts.

Material Compatibility & Pretreatment Strategy

Based on SR MFG’s outsourced e-coat program experience, pretreatment (cleaning + conversion coating/underlayer) is the foundation of e-coat performance. It directly drives adhesion, corrosion-resistance consistency, and production stability. In industrial e-coat lines, pretreatment is treated as the first critical process step because it has a decisive impact on final results.

Carbon Steel, Alloy Steel, Cast Iron

Compatibility: ★★★★★

Key characteristics:
Steel parts conduct well and are the most common substrates for e-coat. Typical pretreatment routes include cleaning and (depending on the system) phosphating, which provides a stable base for adhesion.

Main risks:

Machining oils/rust preventive oils, welding fumes, and mill scale can cause adhesion variation.
Cast iron and porous castings can outgas, increasing the risk of pinholes/blistering.

Pretreatment strategy:

For steel/iron: immersion cleaning + zinc phosphating is a common, robust combination.
Phosphate is best controlled by coating weight (for example, 0.5–1.4 g/m², with the project window defined by your requirements).
For cast iron/porous parts: add blasting/shot blasting to remove oxides and contaminants; when needed, use pre-bake and/or sealing measures to reduce outgassing-related defects.

Aluminum & Aluminum Alloys

Compatibility: ★★★★☆

Key characteristics:
Aluminum can be e-coated, but it is more sensitive to degreasing, oxide removal, and conversion-coating stability. For mixed-material assemblies (aluminum + steel), compatibility of the pretreatment line becomes especially important.

Main risks:
Surface oxides and chemical reactivity can lead to uneven conversion coating, which then drives adhesion and corrosion-performance variation.

Pretreatment strategy:

Prefer aluminum-focused conversion systems, such as chromate-free zirconium/titanium conversion, to improve adhesion and corrosion consistency. Select the specific system based on industry/customer specifications when required.
For mixed-metal projects, clarify whether the line is multi-metal compatible, and define the key control points and inspection method to reduce batch variation.

Zinc and Zinc Alloys (Hot-Dip Galvanized / Electro-Galvanized)

Compatibility: ★★★☆☆

Key characteristics:
Zinc-coated surfaces are highly sensitive to surface condition (passivation layers, white rust, lubricant residue). E-coating galvanized parts is feasible and common in industry—but it requires a matched pretreatment/conversion system and a stable cure window.

Main risks:
Passivation, white rust, and residues can reduce adhesion. Poor pretreatment matching can cause edge lifting or adhesion variability.

Pretreatment strategy:

Use conversion/phosphate systems designed for galvanized surfaces, and manage incoming surface condition (clean/activate when needed for passivation film or white rust).
Lock the e-coat system and process window by project validation. In many practical applications, cathodic epoxy e-coat on galvanized surfaces is commonly run around 18–25 μm, with cure typically in the 160–190°C range (per coating TDS and verified part metal temperature).

Film Thickness & Dimensional Tolerance Control

Typical Thickness Ranges

Cathodic e-coat: typically 18–25 μm (mainstream). Lower-build programs are possible, but final limits should be defined by specification and validation.
Anodic e-coat: commonly around 15–19 μm in certain systems/applications (example range; system-dependent).
Typical by industry (reference):
- Automotive: 18–22 μm, tolerance ±3 μm
- Home appliances: 15–20 μm, tolerance ±5 μm
- General hardware: 12–18 μm, tolerance ±5 μm

Key Tolerance & Control Targets

Single-point tolerance: ±5 μm (single-point variation, range, and batch Cpk can be defined as CTQs by project; critical mating features should be prioritized for Cpk control).
Overall uniformity: within a single part, thickness range ≤ 8 μm.
Batch consistency: Cpk ≥ 1.33 (target 1.67).
Edge effect: edge thickness vs. center ≤ 20% higher. Note: edge readings can be more sensitive to curvature and probe positioning, which may increase measurement variation.
Measurement reliability: thickness measurement should be managed per ASTM D7091 (calibration/verification/adjustment) to keep data traceable and comparable.

Note: Excessive variation can lead to cosmetic non-uniformity, reduced corrosion performance, and even assembly failures.

Film Thickness & Dimensional Tolerance Control

Note: Excessive tolerance can lead to uneven appearance, reduced corrosion protection, and even assembly failures.

Typical DFT Ranges

Cathodic e-coat: 18–25 μm (mainstream), typically 18–25 μm. Low-build programs may run below this range, but the final target must follow your specification and validation results.

Anodic e-coat: commonly 15–19 μm (example range—used in certain systems/applications, such as some anodic systems over iron-phosphated substrates).

Typical by industry (reference):

Automotive parts: 18–22 μm, tolerance ±3 μm
Home appliances: 15–20 μm, tolerance ±5 μm
General hardware: 12–18 μm, tolerance ±5 μm

Key Control Targets

Single-point DFT tolerance: ±5 μm (single-point tolerance, thickness range, and batch Cpk can be defined as CTQs per project; critical dimensions/mating surfaces should be prioritized for Cpk control).

Overall uniformity: within the same part, DFT range ≤ 8 μm.

Batch consistency: Cpk ≥ 1.33 (target 1.67).

Edge effect: edge thickness vs. center ≤ 20% higher. Note that edge readings are more sensitive to curvature and probe positioning, and measurement variation may increase near edges.

Measurement reliability: DFT measurement should be managed per ASTM D7091 calibration/verification/adjustment procedures to keep results traceable and comparable.

E-Coating Process Flow

E-Coating Process Flow (E-Coat / ED Coating)

Part loading → (cleaning / pre-degrease / degrease) → multi-stage rinses (×N) → conversion coating (phosphate / zirconium / silane, depending on the system) → rinse + final DI rinse → drain-off / air knife → e-coat deposition → post-rinse with UF stages (×N) → final DI rinse → drain-off / air knife → oven cure → cooling → (optional: wet topcoat or powder topcoat) → topcoat cure → cooling → part unloading

Are you ready to get started on your metal fabrication project?

Not sure which material is ideal for your project? Feel free to contact us.Our engineering team will recommend suitable material grades and sheet thicknesses based on strength, weight, corrosion resistance and overall cost.

We’ll provide you with a free quote

Who We Serve

SR MFG | Custom E-Coat Solutions for Metal Parts

SR MFG provides custom e-coat (electrophoretic coating) for export programs and high-volume production. We combine a strong manufacturing network with a qualified finishing supply chain to deliver e-coat solutions for metal parts across industries. Our capability covers a wide range of substrates—including steel, aluminum alloys, magnesium alloys, and galvanized sheet—and accommodates parts from 0.1 mm precision micro-components to large structural assemblies over 2 meters. With outsourced e-coating backed by SR MFG’s engineering and quality control, we deliver a high-standard, one-stop service.

View more industries we serveView more industries we serve

Electronics & IT

Medical Devices

Consumer Electronics

Comm Infrastructure

Office & Commercial

IT & Data Centers

Solar & Renewables

Instruments & Precision

Security & Surveillance

View Cart

Details

123 (复制) (复制) (复制)

Uncategorized

View Cart

Details

123 (复制) (复制)

Uncategorized

View Cart

Details

123

Uncategorized

Sheet Metal E-Coating FAQs

What colors are available for e-coat? Are black and gray the most common?

E-coat is available in multiple colors, but black and gray are the dominant choices, accounting for the vast majority of applications (often cited as 90%+ in many industries).

Black: The most common e-coat color, valued for strong corrosion protection and high tolerance to cosmetic variation. Widely used for automotive chassis parts, construction equipment, and consumer electronics components. Available in gloss, semi-gloss, and matte options depending on the system.
Gray: A neutral tone commonly used for industrial components and architectural parts, balancing function and visual compatibility.
Colored e-coat: Custom colors such as white, red, blue, or gold can be developed for differentiated appearance needs (e.g., premium consumer electronics or decorative hardware). These typically require a dedicated colored e-coat system and process tuning.

How do you control thickness or mask critical mating surfaces?

For surfaces that require strict thickness control—or must remain uncoated—we typically use a combination of the following approaches:

Physical masking: High-temperature silicone plugs, ceramic fixtures, or high-temp tape (≥180°C) to mask threaded holes, dowel holes, and precision mating surfaces. For complex contoured surfaces, dedicated masking tooling can be developed to ensure full coverage and prevent lift-off during curing.
Process-based thickness control: Techniques such as staged voltage control (reducing the electric field intensity around critical areas), adjusting rack angles to reduce field exposure, and optimizing deposition time can help keep coating on mating surfaces very low (often targeted around 0–5 μm, when required for fit).
Local insulating pre-treatment: Applying a dedicated insulating primer to critical areas to reduce deposition at the source—useful for standardized parts in long-term production.

Can you provide DFT, adhesion, and salt spray reports?

Yes. Reporting is typically available in two categories:

In-house inspection reports: Film thickness mapping using magnetic induction/eddy-current gauges (typical accuracy around ±1 μm), adhesion tested per cross-hatch (e.g., ISO 2409), and corrosion validation via neutral salt spray (e.g., ASTM B117). Sampling reports can be provided by batch.
Third-party certified reports: Accredited third-party reports (e.g., CNAS/CMA-qualified labs) can be arranged for key metrics such as thickness uniformity (e.g., CV ≤ 10%), adhesion (commonly 0–1 grade targets where specified), and salt spray performance (e.g., 240–1000 hours, as required). Formal reports can be provided after first-article production for project acceptance.

How do you prevent pinholes and blistering on galvanized parts and castings?

For galvanized parts (pinholes):

Use mildly acidic degreasing (pH 5–6) to avoid aggressively attacking the zinc layer and exposing porosity.
Add zirconium conversion after degreasing to seal micro-pores and build a dense conversion layer.
Use pulse-voltage strategies (e.g., a short low-voltage “soft start”) to help release trapped gases at the surface before full deposition.

For castings (blistering):

Shot blast to remove embedded residues, followed by high-pressure washing to remove oils inside pores.
Use phosphate-free ceramic conversion in some cases to reduce bubble risk associated with crystalline porosity.
Add vacuum degassing before e-coat for high-risk castings to pull out trapped gas and reduce expansion-related blistering during bake.

When do you recommend a pre-bake?

A pre-bake is mainly recommended in three scenarios:

Solvent-containing e-coat systems: A low-temperature pre-bake (e.g., 80–100°C for 10–15 minutes) can gently drive off solvents before full cure, reducing bubble/crater risk from rapid evaporation at high temperature.
High-humidity production conditions: In rainy seasons or coastal/high-humidity environments, pre-bake helps remove residual moisture that can interfere with deposition uniformity.
Large, complex structures: For parts over ~2 meters or large castings/sheet metal structures, pre-bake can reduce drag-out (bath carryover), minimize bath loss, and reduce the risk of thickness variation caused by heavy carryover evaporating during cure.

Can you apply powder coating or wet paint over e-coat?

Yes—e-coat can serve as a primer for topcoats, but compatibility must be managed.

Powder coating over e-coat: Improve adhesion with plasma activation or light scuff sanding (e.g., ~200 grit). Keep powder cure temperature compatible with the e-coat substrate (typical reference: 160–180°C for 20–30 minutes, depending on system/PMT). Control total build to avoid fit/tolerance issues (some programs target ≤60 μm total, depending on the part and tolerance stack).
Wet paint over e-coat: Confirm the e-coat is fully cured (e.g., hardness ≥2H, if specified). Use a topcoat compatible with the e-coat chemistry, and remove static dust before spraying to avoid defects such as lifting or fisheyes.

How is quality responsibility defined for outsourced e-coat?

Responsibility is typically defined through a technical agreement that sets clear boundaries:

Incoming part condition: The customer supplies parts that meet agreed cleanliness requirements (e.g., low residual oil, no rust, no deformation). If coating failure is caused by incoming defects, responsibility remains with the customer.
Process execution: The coating partner must follow the confirmed process window. If deviations in voltage, temperature, deposition time, etc. cause out-of-spec thickness, poor adhesion, or failed salt spray results, responsibility rests with the coating partner.
Acceptance criteria: The agreement should define film thickness tolerance, adhesion grade, salt spray duration, and acceptance thresholds. First-article samples serve as the baseline, and third-party reports can be used as the final arbitration method when required.

E-Coating Technical Resources

Stainless Steel Sheet Metal Fabrication Services for Automation and Energy Equipment
Gallery
Stainless Steel Sheet Metal Fabrication Services for Automation and Energy Equipment

Technical Knowledge

Stainless Steel Sheet Metal Fabrication Services for Automation and Energy Equipment

Tan161130.2025-11-05T07:25:22+00:00November 5, 2025|

Understanding Stainless Steel Sheet Metal Fabrication for Automation and Energy Equipment Stainless steel sheet metal fabrication integrates precision [...]