Electroplating Specifications.
Electroplating specifications define the technical requirements, quality standards, thickness ranges, and performance criteria for plated coatings across industries. These specs guide manufacturers and electroplating suppliers in delivering consistent, reliable metal finishes that meet engineering, durability, and compliance needs.
- SAE AMS 2404
- SAE AMS 2413
- SAE AMS 2422
- SAE AMS 2425
- SAE AMS 2460
- SAE AMS 2465
- SAE AMS 2470
- SAE AMS 2481
- SAE AMS 2485
- SAE AMS 2490
- SAE AMS 2495
- SAE AMS 2500
- SAE AMS 2510
- SAE AMS 2520
- SAE AMS 2530
- SAE AMS 2540
- SAE AMS 2550
- SAE AMS 2560
- SAE AMS 2570
- SAE AMS 2580
- SAE AMS 2590
- SAE AMS 2600
- SAE AMS G 2418
- SAE AMS P 81728
- SAE AMS QQ N 290
- BMW GS90010
- Columbia Chemical GMW 4700 ZNNI Type B
- Cummins 74052
- Ford WSS M1P87 B5
- GM GMW4700
- Honda HES D2003 MFZN NI1 K
- Hyundai Kia MS611 15
- Jaguar Land Rover STJLR 50 5058
- Mazda MES CG310
- Mercedes DBL 8451
- Stellantis PS 50045
- Stellantis PS 50065
- Tesla TM 0009F M 10
- Toyota TSH6530G
- Toyota TSH6532G
- Volkswagen TL 244
- Volkswagen VW 4301
- Volkswagen VW 4320
- Volvo STD 121 0003
Summary
Legacy Military Cadmium: MIL-P-27418 obsolete specification for cadmium electroplating replaced by modern MIL-DTL-5541 and commercial standards eliminating toxic cadmium.
MIL-P-27418 was the military specification for cadmium electroplating on steel components before getting canceled due to environmental toxicity concerns. It provided exceptional corrosion protection for military hardware through sacrificial coating that corroded instead of underlying steel. The spec defined cadmium plating types, thickness classes, and chromate finishes for aircraft, ground vehicles, and naval equipment. Environmental regulations restricting heavy metals killed widespread cadmium use despite superior technical performance. Modern military specs now reference MIL-DTL-5541 chromate conversion or zinc-nickel alloy electroplating as safer alternatives achieving similar corrosion protection without cadmium's toxicity and disposal problems.
Coatings
MIL-P-27418 covered cadmium electroplating for sacrificial corrosion protection on steel military hardware. Legacy toxic coating replaced by zinc-nickel and chromate alternatives.
Requirements Overview
MIL-P-27418 organized cadmium plating by type (steel composition), class (thickness), and finish (chromate treatment). Type I was general steel substrates, Type II high-strength steel requiring hydrogen embrittlement baking. Classes defined thickness from 0.0002 to 0.0005 inch balancing corrosion protection with dimensional tolerance. Finishes specified chromate topcoats: clear, yellow, or olive drab for enhanced corrosion resistance and color coding applications. Standard military cadmium spec before environmental regulations forced industry transition to safer zinc-nickel alternatives.
Type I
General steel substrates. Standard cadmium plating for low and medium carbon steel hardware. No special hydrogen embrittlement controls needed for typical hardness levels below 180,000 psi tensile strength.
Type II
High-strength steel requiring hydrogen embrittlement relief. Mandatory post-plate baking for hardened fasteners, springs, and structural components preventing delayed brittle fracture from hydrogen absorbed during pickling and plating.
Class 1
Minimum 0.0002 inch (5 microns). Light coating for mild indoor or temporary corrosion protection. Adequate for ground vehicles in temperate climates or short-term storage applications needing economical sacrificial protection.
Class 2
Minimum 0.0003 inch (8 microns). Standard military cadmium thickness balancing corrosion life with dimensional control. Most common specification for aircraft structures, weapons systems, and general military hardware requiring reliable outdoor protection.
Class 3
Minimum 0.0005 inch (13 microns). Heavy coating for severe marine or offshore environments. Naval shipboard equipment, carrier deck hardware, and coastal installations needing maximum sacrificial protection against salt spray corrosion.
Clear Chromate
Colorless chromate conversion coating over cadmium. Moderate additional corrosion protection maintaining natural silver-gray metallic appearance. Standard when color coding not required and aesthetic blends with unpainted aluminum aircraft structures.
Yellow Chromate
Bright yellow-gold chromate finish. Maximum corrosion resistance from thick hexavalent chromium seal. Traditional military hardware color providing visual identification and superior salt spray performance for decades of outdoor service.
Olive Drab Chromate
Dark olive-green chromate coating. Tactical non-reflective finish for combat equipment and weapons systems requiring low-visibility corrosion protection. Blends with military camouflage patterns while maintaining excellent corrosion resistance.
Supplementary
Hydrogen embrittlement baking temperature and time, salt spray test duration, adhesion testing, or phosphate post-treatment for paint base. Special testing added for critical flight hardware or life-limited components requiring validated processing controls.
Obsolete Selection Guide: Historical cadmium specification selection before environmental regulations mandated replacement with zinc-nickel and chromate conversion alternatives.
Requirements Selection
Don't specify MIL-P-27418 for new designs—spec's canceled and cadmium banned or heavily restricted across most applications. Historic selections were Class 2 yellow chromate for standard military hardware, Class 3 for marine environments, and olive drab for tactical equipment needing non-reflective finish. Type II with hydrogen embrittlement baking mandatory for high-strength fasteners and hardened components. Modern replacements are MIL-DTL-5541 chromate conversion on aluminum or zinc-nickel alloy electroplating on steel achieving similar corrosion protection without toxicity issues.
Underplate Layer Stacks
Cadmium electroplating applied directly to clean, acid-pickled steel without underplate since cadmium adheres excellently to iron and steel substrates. Simple layer stack was steel surface preparation, cadmium electrodeposition, chromate conversion topcoat for enhanced corrosion resistance and color. No complex underplate systems needed unlike gold or decorative chrome requiring nickel barriers. Direct cadmium application kept processing costs low for mass-produced military fasteners and hardware. Simplicity was advantage for high-volume production before environmental regulations forced industry away from cadmium toward more complex zinc-nickel systems.
Direct Cadmium: Simple sacrificial coating
Cadmium electrodeposited directly on cleaned steel without underplate. Excellent adhesion to iron and steel through direct metal bonding. Universal configuration for billions of military fasteners annually during cadmium era. Simple economical process before environmental regulations forced replacement.
Chromate Topcoat: Enhancing corrosion resistance
Clear, yellow, or olive drab chromate conversion coating over cadmium base. Hexavalent chromium seal closing porosity and providing supplementary corrosion barrier. Standard practice maximizing salt spray resistance for military hardware in harsh outdoor environments.
Phosphate Option: Paint adhesion base
Sometimes cadmium-plated parts received supplementary phosphate treatment before painting improving primer adhesion and additional corrosion resistance. Optional post-treatment when cadmium served as paint base rather than final corrosion barrier for structural assemblies requiring topcoat systems.
Cadmium Specification Errors: Critical mistakes including specifying canceled toxic standard, missing hydrogen embrittlement baking, or creating environmental compliance failures on military contracts.
Common Mistakes
Biggest mistake is specifying MIL-P-27418 on new drawings when spec's canceled and cadmium restricted or banned across most applications. Environmental regulations make cadmium procurement nearly impossible outside narrow military exemptions. Omitting hydrogen embrittlement baking on high-strength steel causes catastrophic delayed fractures killing people when critical fasteners snap. Using cadmium without proper disposal procedures creates expensive hazardous waste violations. Not updating legacy drawings to modern zinc-nickel alternatives perpetuates toxic metal use without performance benefit. Missing that chromate conversion coatings referenced in obsolete cadmium specs are also restricted hexavalent chromium compounds facing elimination.
Specifying Canceled Toxic Standard
MIL-P-27418 is canceled and cadmium electroplating banned or heavily restricted for most applications. Environmental regulations (REACH, RoHS, state laws) prohibit cadmium in commercial products. Military applications have narrow exemptions but procurement difficult and expensive. Replace with MIL-DTL-5541 chromate conversion or zinc-nickel alloy electroplating achieving similar performance without toxicity.
Missing Hydrogen Embrittlement Baking
Type II high-strength steel MUST be baked after cadmium plating within 4 hours preventing hydrogen embrittlement. Hardened fasteners (over 180,000 psi tensile) absorb hydrogen during pickling and plating causing delayed brittle fracture under load. Bolts snap weeks after installation killing people. Never omit baking specification for hardened components.
Environmental Compliance Failures
Cadmium is toxic heavy metal requiring special disposal, wastewater treatment, and worker protection. Using cadmium without proper environmental controls creates expensive EPA or state environmental agency violations. Facility liability and cleanup costs exceed any performance benefits. Modern alternatives avoid hazardous waste issues entirely.
Not Updating Legacy Drawings
Old drawings referencing MIL-P-27418 should be revised to modern alternatives during engineering changes. Simple drawing revision substituting zinc-nickel or chromate conversion eliminates cadmium problems while maintaining equivalent technical performance. Perpetuating obsolete toxic specifications complicates procurement and creates compliance risks.
Hexavalent Chromate Restrictions
Yellow and olive chromates referenced in MIL-P-27418 contain hexavalent chromium also facing environmental elimination. Specifying obsolete cadmium spec perpetuates double toxic metal problem—cadmium base plus hexavalent chromium topcoat. Modern trivalent chromate or chromate-free alternatives required for compliance.
Conclusion
MIL-P-27418 is canceled obsolete specification for cadmium electroplating replaced by environmental regulations banning toxic heavy metals. Modern alternatives include MIL-DTL-5541 chromate conversion or zinc-nickel alloy electroplating achieving similar corrosion without toxicity. Don't specify cadmium on new designs. Update legacy drawings to safer alternatives.
Next Steps
Replace MIL-P-27418 with MIL-DTL-5541 chromate conversion on aluminum or zinc-nickel on steel. Update legacy drawings during engineering changes. Verify environmental compliance for any remaining military exemption cadmium use. Specify hydrogen embrittlement baking for high-strength steel. Work with platers having modern safer alternatives.