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Cadmium Plating

Electroplating & electroless plating · Electrolytic bath

Cadmium is a sacrificial, lubricious coating retained mainly for aerospace, defense, and legacy hardware.

CNC machiningSheet metalHigh cost $$$$Conductive
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Reference page — Cadmium plate is not in the instant-quote configurator. Upload the part, name the finish in the notes, and an engineer quotes it with the part.

Cadmium Plating on a machined part

What is Cadmium plate?

Its toxicity makes it unsuitable for ordinary new designs and subject to strict regulatory exemptions.

How it works

Prepared metal parts are cathodically plated from a controlled cadmium electrolyte, then receive a chromate conversion coating where specified. Cadmium protects steel sacrificially and gives predictable fastener torque behavior. Electrolytic current distribution leaves recesses thinner and edges thicker. Pickling and plating can introduce hydrogen, so high-strength steels require qualified pretreatment and prompt relief baking. Rack tooling, thread allowances, and coating-thickness measurement locations must therefore be defined for critical aerospace hardware.

Why specify it

  • Strong marine and aerospace sacrificial protection
  • Useful lubricity and torque-tension behavior
  • Typical 5–13 µm engineering thickness
  • Galvanically compatible with aluminum assemblies

Where it falls short

  • Cadmium is toxic and heavily restricted
  • Use normally requires aerospace or defense exemption
  • Hydrogen embrittlement risk on high-strength steel
  • Chromate type changes color and compliance

Cadmium plate at a glance

Cadmium plate is strongest on corrosion protection (70 of 100), at a high cost.

Corrosion protectionVery good70 / 100
Surface hardnessLow26 / 100
Cosmetic qualityFair38 / 100
LubricityGood68 / 100
Relative costHigh75 / 100
CorrosionHardnessCosmeticLubricityEconomy

Each score is 0–100 against every finish in this catalog. Corrosion comes from salt-spray life (ASTM B117, log scale) and hardness from the finish layer's Vickers or pencil hardness; cosmetic, lubricity and cost are FabDigit's engineering assessment. Economy on the radar is the inverse of cost.

Cadmium plate key numbers

Typical values from the governing specifications and shop practice; bars are this finish against the highest value among electroplating & electroless plating finishes.

Thickness5–13 µm0.2–0.51 mil
Hardness40–60 HV
Salt spray200–500 h
Max service temp.230 °C446 °F
Thickness
5–8 µm for light service; approximately 13 µm for heavier service classes
Hardness
40–60 HV — Cadmium is soft and selected for sacrificial behavior and lubricity, not hardness.
Corrosion (salt spray)
200–500 h per ASTM B117 to red rust on steel, 8–12 µm chromated cadmium (typical) — AMS-QQ-P-416 Type II requires 96 h without white corrosion; no single value applies across all classes.
Electrical
Conductive
Colours
  • silver
  • yellow iridescent
  • olive drab
Appearance
Soft silver-white with clear, yellow, or olive chromate depending on class.

Where Cadmium plate sits among all finishes

Surface hardness (Vickers, log scale) against corrosion protection (salt-spray hours, log scale) for every coating FabDigit offers, one cloud per finish group. Cadmium plate is highlighted; hover a dot for its name or open the full map.

02550751000255075100Corrosion protection (0–100)Surface hardness (HV, log scale, 0–100)Plating — 19 finishesHard coatings — 17 finishesAnodize & conversion — 8 finishesPaint & powder — 7 finisheshard, low corrosion protectionhard and protectiveprotective, softsoft, little protectionType II anodize — corrosion 71, hardness 54BSA anodize — corrosion 71, hardness 52Type I anodize — corrosion 71, hardness 49Hard anodize — corrosion 71, hardness 61PTFE hard anodize — corrosion 71, hardness 61Nitriding — corrosion 55, hardness 73PEO — corrosion 70, hardness 74Sherardizing — corrosion 83, hardness 56Brass plate — corrosion 35, hardness 44Bronze plate — corrosion 40, hardness 49Copper plate — corrosion 32, hardness 39Decorative chrome — corrosion 64, hardness 71Electroless copper — corrosion 20, hardness 41Electroless nickel — corrosion 70, hardness 68Nickel plate — corrosion 51, hardness 55Gold plate — corrosion 68, hardness 39Hard chrome — corrosion 40, hardness 73Hot-dip zinc — corrosion 90, hardness 42Nickel-PTFE — corrosion 72, hardness 57Silver plate — corrosion 55, hardness 39Solder plate — corrosion 42, hardness 9Tin plate — corrosion 34, hardness 0Zinc plate — corrosion 60, hardness 30Zinc-nickel — corrosion 86, hardness 60Cerakote — corrosion 83, hardness 27E-coat — corrosion 83, hardness 15Epoxy coat — corrosion 83, hardness 15Powder coat — corrosion 83, hardness 14Wet paint — corrosion 59, hardness 10AlCrN PVD — corrosion 58, hardness 93AlTiN PVD — corrosion 52, hardness 94CrN PVD — corrosion 62, hardness 83DLC — corrosion 55, hardness 93MoS2 PVD — corrosion 20, hardness 26TiAlN PVD — corrosion 50, hardness 93TiCN PVD — corrosion 40, hardness 92TiB2 PVD — corrosion 40, hardness 94TiN PVD — corrosion 45, hardness 87WC/C PVD — corrosion 48, hardness 77ZrN PVD — corrosion 52, hardness 90CVD alumina — corrosion 70, hardness 85CVD TiCN — corrosion 38, hardness 92CVD TiN — corrosion 45, hardness 87Multilayer CVD — corrosion 62, hardness 88HVOF coating — corrosion 78, hardness 77Plasma spray — corrosion 60, hardness 68Plastic chrome — corrosion 72, hardness 71Electroless plastic — corrosion 58, hardness 39Clear coat — corrosion 20, hardness 12Soft-touch — corrosion 20, hardness 5PLATINGHARD COATINGSANODIZE & CONVERSIONPAINT & POWDERZinc-nickelType II anodizePowder coatZinc plateHard chromeDLCTiN PVDTin plateE-coatCerakoteWet paintHot-dip zincNitridingHVOF coatingCadmium plate — corrosion 70, hardness 26Cadmium plate
02550751000255075100Corrosion protection (0–100)Surface hardness (HV, log scale, 0–100)Plating — 19 finishesHard coatings — 17 finishesAnodize & conversion — 8 finishesPaint & powder — 7 finishesType II anodize — corrosion 71, hardness 54BSA anodize — corrosion 71, hardness 52Type I anodize — corrosion 71, hardness 49Hard anodize — corrosion 71, hardness 61PTFE hard anodize — corrosion 71, hardness 61Nitriding — corrosion 55, hardness 73PEO — corrosion 70, hardness 74Sherardizing — corrosion 83, hardness 56Brass plate — corrosion 35, hardness 44Bronze plate — corrosion 40, hardness 49Copper plate — corrosion 32, hardness 39Decorative chrome — corrosion 64, hardness 71Electroless copper — corrosion 20, hardness 41Electroless nickel — corrosion 70, hardness 68Nickel plate — corrosion 51, hardness 55Gold plate — corrosion 68, hardness 39Hard chrome — corrosion 40, hardness 73Hot-dip zinc — corrosion 90, hardness 42Nickel-PTFE — corrosion 72, hardness 57Silver plate — corrosion 55, hardness 39Solder plate — corrosion 42, hardness 9Tin plate — corrosion 34, hardness 0Zinc plate — corrosion 60, hardness 30Zinc-nickel — corrosion 86, hardness 60Cerakote — corrosion 83, hardness 27E-coat — corrosion 83, hardness 15Epoxy coat — corrosion 83, hardness 15Powder coat — corrosion 83, hardness 14Wet paint — corrosion 59, hardness 10AlCrN PVD — corrosion 58, hardness 93AlTiN PVD — corrosion 52, hardness 94CrN PVD — corrosion 62, hardness 83DLC — corrosion 55, hardness 93MoS2 PVD — corrosion 20, hardness 26TiAlN PVD — corrosion 50, hardness 93TiCN PVD — corrosion 40, hardness 92TiB2 PVD — corrosion 40, hardness 94TiN PVD — corrosion 45, hardness 87WC/C PVD — corrosion 48, hardness 77ZrN PVD — corrosion 52, hardness 90CVD alumina — corrosion 70, hardness 85CVD TiCN — corrosion 38, hardness 92CVD TiN — corrosion 45, hardness 87Multilayer CVD — corrosion 62, hardness 88HVOF coating — corrosion 78, hardness 77Plasma spray — corrosion 60, hardness 68Plastic chrome — corrosion 72, hardness 71Electroless plastic — corrosion 58, hardness 39Clear coat — corrosion 20, hardness 12Soft-touch — corrosion 20, hardness 5PLATINGHARD COATINGSANODIZE & CONVERSIONPAINT & POWDERPowder coatZinc plateCadmium plate — corrosion 70, hardness 26Cadmium plate
Anodize & conversionPlatingPaint & powderHard coatings

Specifications for Cadmium plate

The documents a drawing cites to define this finish, with the Type / Class rows that apply. Each links to a page explaining the standard.

StandardType / ClassThicknessRequirement / testStatus
AMS-QQ-P-416
Plating, Cadmium (Electrodeposited) · SAE
Type I Class 1≥ 13 µmCadmium as plated, severe-service minimum thickness. · Thickness, adhesion, quality, and hydrogen-embrittlement control as applicable.Active
Type I Class 2≥ 8 µmCadmium as plated, general-purpose minimum thickness. · Thickness, adhesion, quality, and hydrogen-embrittlement control as applicable.
Type I Class 3≥ 5 µmCadmium as plated, thin minimum for dimensional constraint. · Thickness, adhesion, quality, and hydrogen-embrittlement control as applicable.
Type II Classes 1–3≥ 5 µmCadmium with supplementary chromate; use the selected class minimum of 12.7, 7.62, or 5.08 µm. · ASTM B117 salt spray for 96 h after at least 24 h aging; thickness, adhesion, and embrittlement control.
Type III Classes 1–3≥ 5 µmCadmium with supplementary phosphate, generally used as a paint base; use the selected class minimum of 12.7, 7.62, or 5.08 µm. · Thickness, adhesion, supplementary-coating quality, paint-system requirements, and embrittlement control.
SAE AMS 2400
Plating, Cadmium · SAE · alternative
Class 1≥ 13 µmThickest standard cadmium class. · Thickness, adhesion, corrosion, and embrittlement controls.Active
Class 2≥ 8 µmGeneral aerospace cadmium thickness. · Thickness, adhesion, corrosion, and embrittlement controls.
Class 3≥ 5 µmThin cadmium for dimensionally restricted surfaces. · Thickness, adhesion, corrosion, and embrittlement controls.
Type I—As-plated cadmium without supplementary conversion treatment. · Appearance and applicable corrosion test.
Type II—Cadmium with supplementary chromate treatment. · Appearance and applicable salt-spray test.

Test and related methods: ASTM B850 (Standard Guide for Post-Coating Treatments of Steel for Reducing the Risk of Hydrogen Embrittlement).

Drawing call-out

CADMIUM PLATE PER AMS-QQ-P-416, TYPE II, CLASS 2, 0.0003 IN MIN; BAKE FOR HYDROGEN EMBRITTLEMENT RELIEF PER SPECIFICATION; AUTHORIZED AEROSPACE USE ONLY

Pattern: CADMIUM PLATE PER AMS-QQ-P-416 TYPE <I|II|III>, CLASS <1|2|3>, [COLOR], [HYDROGEN-RELIEF REQUIREMENT], [MASKING]

Which materials take Cadmium plate?

Verdict per material family, with the grades that behave differently. Each family links to its datasheets in the material library.

Material familyVerdictNotes
Aluminum
LimitedTechnically possible with specialized activation but restricted to authorized aerospace use.
Brass
LimitedPossible for specialized hardware; regulatory approval still required.
Copper Alloy
LimitedPossible for specialized contacts but regulatory use is restricted.
DMLS / SLM
LimitedOnly authorized steel AM aerospace hardware; hydrogen and powder-residue risks remain.
Stainless Steel
LimitedRequires activation and an authorized specification.
Steel
LimitedTechnically suitable but restricted to authorized applications.
  • High-strength steel requires embrittlement controls.
FDM
NoFused-filament polymers are incompatible with this process.
Magnesium Alloy
NoNot a standard or advisable cadmium substrate.
MJF
NoPolymer powder-bed prints are incompatible with this process.
Polymer
NoOrganic polymers cannot take this inorganic metal-finishing process.
SLA
NoPhotopolymer prints are incompatible with this process.
SLS
NoPolymer powder-bed prints are incompatible with this process.
Titanium
NoCadmium is not a standard titanium finish and creates galvanic and contamination issues.
Zinc Alloy
NoNot specified for zinc die castings in ordinary practice.

How Cadmium plate is applied, and what it does to the part

  1. 1Regulatory authorization
  2. 2Clean
  3. 3Controlled activate
  4. 4Cadmium electroplate
  5. 5Rinse
  6. 6Chromate if specified
  7. 7Embrittlement-relief bake
  8. 8Inspect
DimensionsAllow 5–13 µm per side and verify thread fit and torque after supplementary treatment.
Build-up per side5–13 µm — Electrolytic edge buildup exceeds low-current recess thickness.
MaskingUsually needed. Mask threads or fits where buildup is unacceptable and any surface outside the approved exemption.
ElectricalConductive
Temperature limit230 °C (446 °F) continuous
AppearanceSoft silver-white with clear, yellow, or olive chromate depending on class.
Added lead time7–15 working days on top of the bare part

Design rules for Cadmium plate

What to decide on the drawing before the part goes to the finisher.

  1. Document the regulatory exemption.Cadmium is prohibited for most ordinary products.
  2. Qualify the replacement before substitution.Cadmium lubricity and galvanic behavior are not duplicated by color alone.
  3. Specify embrittlement controls.Aerospace high-strength steel is especially susceptible.
  4. Control disposal and rework.Grinding, stripping, and welding create toxic exposure and waste.

Cadmium plate versus the alternatives

Finishes engineers weigh against Cadmium plate, and when each wins.

FinishCorrosionHardnessCosmeticCostThicknessChoose it when
Cadmium plate
this page
702638$$$$5–13 µm—
Zinc-Nickel Plating
Cadmium plate vs Zinc-Nickel Plating →
866048$$5–15 µmwhen a cadmium-free sacrificial replacement is qualified
Zinc-Flake Dip-Spin Coating
Cadmium plate vs Zinc-Flake Dip-Spin Coating →
85—35$$$6–15 µmwhen avoiding electrolytic hydrogen charging is critical
CorrosionHardnessCosmeticLubricityEconomy
Cadmium plateZinc-Nickel Plating

The radar overlays Cadmium plate with Zinc-Nickel Plating, its most common alternative — chosen when a cadmium-free sacrificial replacement is qualified. Scores in the table are 0–100 across every finish in the catalog.

Cost, lead time and compliance

Relative cost

Cadmium Plating is a high-cost finish ($$$$): more expensive than about 80 % of the finishes FabDigit quotes.

Finishing is priced per part with a lot minimum, from FabDigit's own China-side rates. The exact figure appears on the instant quote once the part is uploaded.

Lead time and compliance

Added lead time7–15 working days
RoHSRestricted
NotesCadmium is a restricted toxic substance; use only under a documented applicable exemption and qualified closed-loop processing.

What Cadmium plate is used for

  • Aerospace fasteners
  • Defense hardware
  • Legacy aircraft components
  • Marine connectors

Cadmium plate — frequently asked

is cadmium plating banned

Cadmium is heavily restricted by RoHS, REACH, and workplace rules, but narrow aerospace, defense, safety, and legacy exemptions can remain. Do not specify it without jurisdiction and program approval.

cadmium plating alternatives

Zinc-nickel at 12–15% Ni is a common cadmium-free candidate, and zinc-flake is useful on high-strength fasteners. Substitution still requires testing for corrosion, galvanic compatibility, lubricity, and torque-tension behavior.

how thick is cadmium plating

Engineering cadmium is commonly about 5–13 µm depending on service class. Specify the exact AMS-QQ-P-416 or AMS 2400 class and supplementary treatment.

does cadmium plating cause hydrogen embrittlement

Yes, preparation and electroplating can introduce hydrogen into high-strength steel. Qualified processing and prompt relief baking are mandatory where the specification requires them.

why is cadmium used on aircraft

It combines sacrificial protection, lubricity, aluminum compatibility, and stable fastener torque behavior in a thin 5–13 µm layer. Those benefits must be weighed against severe toxicity and regulatory limits.