E-Coating

E-coating deposits a uniform paint film by electro-deposition, delivering strong corrosion protection and consistent coverage on complex metal parts at production volumes.

Overview

E-coating (electrophoretic deposition) applies a paint-like coating by immersing conductive parts in a bath and using DC current to deposit a controlled, uniform film. The coating wraps edges and recesses well, making it a go-to for corrosion protection on complex geometries and large batches. Typical e-coats are black, with smooth cosmetic finish options depending on the system.

Choose e-coating when you need repeatable coverage, good chip/impact resistance, and reliable corrosion performance on steel or aluminum assemblies. It’s commonly used as a standalone protective finish or as a primer under a topcoat.

Tradeoffs: parts must be electrically conductive and compatible with pretreatment chemistry. Masking adds cost and risk of edge bleed. Very thick builds and sharp cosmetic “show” finishes are not its strength, and bake schedules can be incompatible with heat-sensitive inserts, adhesives, or some spring-temper conditions.

Common Materials

  • Low carbon steel
  • Galvanized steel
  • Stainless steel 304
  • Aluminum 6061
  • Aluminum 5052
  • Cast iron

Tolerances

±0.0003"–±0.0010" coating thickness (typical 0.0008"–0.0012" / 20–30 µm)

Applications

  • Automotive underbody brackets and mounts
  • Welded chassis and frame components
  • Fasteners and clips
  • Agricultural equipment housings
  • Electrical enclosures and brackets
  • Appliance panels and racks

When to Choose E-Coating

Pick e-coating for conductive metal parts needing consistent corrosion protection across edges, holes, and complex geometries, especially in medium to high volumes. It fits welded assemblies and mixed-feature parts where spray coverage is hard to control. Plan for pretreatment, racking, and bake constraints early in the design.

vs Anodizing

Choose e-coating when you need full-coverage corrosion protection on complex shapes, assemblies, or mixed-surface conditions where anodizing can be limited by electrical contact and alloy-specific cosmetic variation. E-coat also offers better edge coverage and is often more forgiving on weldments.

vs Powder Coating

Choose e-coating when uniform coverage inside recesses, tubes, and sharp edges matters more than thick decorative build. E-coat typically runs thinner and more consistent, reducing fit-up issues on mating features and threaded details.

vs Chromium Electroplating

Choose e-coating when the priority is broad corrosion protection and paint-like toughness rather than a hard, wear-focused metallic surface. E-coat also avoids the dimensional buildup and localized thickness variation common in plating on edges and high-current areas.

vs Zinc Electroplating

Choose e-coating when you want continuous barrier protection on complex assemblies and better edge coverage than a sacrificial thin metal layer can provide. E-coat is also commonly used over zinc-coated substrates when you need improved durability and appearance consistency.

vs Physical Vapor Deposition (PVD)

Choose e-coating when you need cost-effective, high-throughput corrosion protection for larger parts and assemblies rather than a thin decorative/hard coating on smaller, line-of-sight features. E-coat wraps geometry more reliably than line-of-sight deposition.

Design Considerations

  • Define coating class (color, gloss, corrosion hours) and target thickness range on the drawing so the shop can select chemistry and process window
  • Call out masking zones clearly and keep mask lines away from tight-tolerance fits; expect extra cost for plugs, caps, and complex masks
  • Provide robust racking/contact points in non-cosmetic areas; poor electrical contact drives thin spots and rework
  • Avoid blind cavities that trap pretreatment or rinse chemistry; add drain/vent holes and specify orientation if needed
  • Account for bake temperature/time in the design if you have heat-treated parts, adhesives, threadlockers, magnets, or nonmetal inserts
  • Specify which surfaces are functional (threads, bearing seats, grounding points) so they can be protected or post-processed consistently