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Hard Anodizing Type III With PTFE

Anodizing & conversion coatings · Electrolytic bath

PTFE hard anodize combines a 25–75 µm Type III oxide with a fluoropolymer impregnation or post-treatment to reduce friction.

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Hard Anodizing Type III With PTFE on a machined part

What is PTFE hard anodize?

It is specified for aluminum pistons, guides, bores, and sliding components that cannot rely on liquid lubricant.

How it works

The aluminum first receives conventional Type III hard anodize in chilled sulfuric acid. Its porous oxide is then impregnated or coated with a PTFE-bearing proprietary treatment and cured according to the processor's system. The hard oxide carries load and resists abrasion; PTFE at and near the surface lowers breakaway friction and reduces sticking. Because MIL-A-8625 controls the anodize but not a universal PTFE formulation, drawings should name the approved process, thickness, sealing condition, and any friction requirement.

Why specify it

  • Combines 350–550 HV oxide with dry lubricity
  • Uses the same common 25–75 µm Type III thickness range
  • Reduces stick-slip on aluminum sliding pairs
  • Can eliminate grease in clean or inaccessible mechanisms

Where it falls short

  • PTFE benefit diminishes as the exposed polymer wears
  • No universal MIL-A-8625 PTFE class exists
  • Not suitable for electrical contacts
  • Dimensions and edge risks match thick Type III anodize

PTFE hard anodize at a glance

PTFE hard anodize is strongest on corrosion protection (71 of 100) and lubricity (82 of 100), at a premium cost.

Corrosion protectionVery good71 / 100
Surface hardnessGood61 / 100
Cosmetic qualityFair45 / 100
LubricityVery good82 / 100
Relative costPremium58 / 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.

PTFE hard anodize key numbers

Typical values from the governing specifications and shop practice; bars are this finish against the highest value among anodizing & conversion coatings finishes.

Thickness25–75 µm0.98–3 mil
Hardness350–550 HV
Salt spray336 h
Max service temp.200 °C392 °F
Thickness
25–75 µm total hard-anodize system; confirm whether the processor reports oxide only or oxide plus topcoat.
Hardness
350–550 HV — Hardness refers to the underlying Type III oxide, not the soft PTFE-rich surface.
Corrosion (salt spray)
336 h per ASTM B117 for sealed Type III per MIL-A-8625 — Confirm that the selected PTFE treatment also serves as the qualified seal.
Electrical
Insulating
Colours
  • natural gray
  • black
Appearance
Matte gray, charcoal, or black with a low-sheen PTFE-rich surface.

Where PTFE hard anodize 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. PTFE hard anodize 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 61Nitriding — corrosion 55, hardness 73PEO — corrosion 70, hardness 74Sherardizing — corrosion 83, hardness 56Brass plate — corrosion 35, hardness 44Bronze plate — corrosion 40, hardness 49Cadmium plate — corrosion 70, hardness 26Copper 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 & POWDERType II anodizePowder coatZinc plateZinc-nickelHard chromeDLCTiN PVDTin plateCadmium plateE-coatCerakoteWet paintHot-dip zincNitridingHVOF coatingPTFE hard anodize — corrosion 71, hardness 61PTFE hard anodize
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 61Nitriding — corrosion 55, hardness 73PEO — corrosion 70, hardness 74Sherardizing — corrosion 83, hardness 56Brass plate — corrosion 35, hardness 44Bronze plate — corrosion 40, hardness 49Cadmium plate — corrosion 70, hardness 26Copper 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 platePTFE hard anodize — corrosion 71, hardness 61PTFE hard anodize
Anodize & conversionPlatingPaint & powderHard coatings

Specifications for PTFE hard anodize

The documents a drawing cites to define this finish, with the Type / Class rows that apply. Each links to a page explaining the standard, and US Government documents are free to download there.

StandardType / ClassThicknessRequirement / testStatus
MIL-A-8625
Anodic Coatings for Aluminum and Aluminum Alloys · DoD
Type I Class 10.5–7.6 µmChromic-acid anodize, non-dyed. · At least 200 mg/ft² unsealed (0.0215 g/dm²). · Coating weight; sealed corrosion test, ASTM B117, 336 h.Supersedednow MIL-PRF-8625
Type I Class 20.5–7.6 µmChromic-acid anodize, dyed. · At least 200 mg/ft² unsealed (0.0215 g/dm²). · Coating weight; sealed corrosion test, ASTM B117, 336 h; light fastness when specified.
Type IB Class 10.5–7.6 µmLow-voltage chromic-acid anodize, non-dyed. · At least 200 mg/ft² unsealed (0.0215 g/dm²). · Coating weight; sealed corrosion test, ASTM B117, 336 h.
Type IB Class 20.5–7.6 µmLow-voltage chromic-acid anodize, dyed. · At least 200 mg/ft² unsealed (0.0215 g/dm²). · Coating weight; sealed corrosion test, ASTM B117, 336 h; light fastness when specified.
Type IC Class 10.5–25.4 µmNon-chromic alternative to Type I or IB, non-dyed. · 200–700 mg/ft² unsealed (0.0215–0.0753 g/dm²); higher weight only when specified. · Coating weight; sealed corrosion test, ASTM B117, 336 h.
Type IC Class 20.5–25.4 µmNon-chromic alternative to Type I or IB, dyed. · 200–700 mg/ft² unsealed (0.0215–0.0753 g/dm²); higher weight only when specified. · Coating weight; sealed corrosion test, ASTM B117, 336 h; light fastness when specified.
Type II Class 12–25 µmConventional sulfuric-acid anodize, non-dyed. · At least 1000 mg/ft² unsealed (0.1076 g/dm²). · Coating weight; sealed corrosion test, ASTM B117, 336 h.
Type II Class 22–25 µmConventional sulfuric-acid anodize, dyed. · At least 1000 mg/ft² unsealed (0.1076 g/dm²). · Coating weight; sealed corrosion test, ASTM B117, 336 h; light fastness when specified.
Type IIB Class 10.5–25.4 µmThin sulfuric-acid anodize used as a non-chromic alternative to Type I or IB, non-dyed. · 200–1000 mg/ft² unsealed (0.0215–0.1076 g/dm²). · Coating weight; sealed corrosion test, ASTM B117, 336 h.
Type IIB Class 20.5–25.4 µmThin sulfuric-acid anodize used as a non-chromic alternative to Type I or IB, dyed. · 200–1000 mg/ft² unsealed (0.0215–0.1076 g/dm²). · Coating weight; sealed corrosion test, ASTM B117, 336 h; light fastness when specified.
Type III Class 113–114 µmHard anodize, non-dyed; thickness must be stated, with 50.8 µm nominal when omitted. · When weight substitutes for thickness: at least 4320 mg/ft² per 0.001 in of unsealed coating (0.465 g/dm² per 25.4 µm). · Thickness or coating weight; abrasion resistance; corrosion test, ASTM B117, 336 h, only when sealed corrosion resistance is specified.
Type III Class 213–114 µmHard anodize, dyed; thickness must be stated, with 50.8 µm nominal when omitted. · When weight substitutes for thickness: at least 4320 mg/ft² per 0.001 in of unsealed coating (0.465 g/dm² per 25.4 µm). · Thickness or coating weight; abrasion resistance; corrosion test, ASTM B117, 336 h, only when sealed corrosion resistance is specified; light fastness when specified.
AMS 2469
Hard Anodic Coating on Aluminum and Aluminum Alloys · SAE · alternative
Standard thickness38–64 µmDefault hard anodic coating thickness unless another thickness is specified. · Thickness, coating weight, and abrasion resistance.Active
Specified thickness—Purchaser-defined thickness replacing the standard nominal value. · Thickness and applicable performance tests.

Test and related methods: ASTM B117 (Standard Practice for Operating Salt Spray (Fog) Apparatus).

Drawing call-out

HARD ANODIZE PER MIL-A-8625 TYPE III, 0.0020 IN TOTAL OXIDE THICKNESS, PTFE IMPREGNATED PER APPROVED PROCESS; MASK THREADS AND DATUM A

Pattern: ANODIZE PER MIL-A-8625 TYPE <I|IB|IC|II|IIB|III>, CLASS <1|2>, [COLOR], [THICKNESS FOR TYPE III], [SEAL], [MASKING]

Which materials take PTFE hard anodize?

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

Material familyVerdictNotes
Aluminum
YesSuitable anodizing-quality aluminum is required.
  • 6061 is commonly processed
  • High-copper and high-silicon alloys need processor review
DMLS / SLM
With careOnly aluminum DMLS/SLM parts can be processed; steel and titanium builds cannot.
Brass
NoBrass is not anodized by this aluminum process.
Copper Alloy
NoCopper alloys are not anodized by this aluminum process.
FDM
NoFused-filament polymers are incompatible with this process.
Magnesium Alloy
NoMagnesium requires a magnesium-specific anodic or conversion process.
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.
Stainless Steel
NoStainless steel is not anodized by MIL-A-8625 processes.
Steel
NoThis is an aluminum anodic process; steel does not form this oxide.
Titanium
NoTitanium uses a different anodizing chemistry.
Zinc Alloy
NoZinc alloys are not anodized by this aluminum process.

How PTFE hard anodize is applied, and what it does to the part

  1. 1Clean / degrease
  2. 2Etch / desmut
  3. 3Rack and mask
  4. 4Type III hard anodize
  5. 5PTFE impregnate or coat
  6. 6Cure
  7. 7Inspect
DimensionsAllow about half the oxide thickness outward plus any separately applied PTFE topcoat.
Build-up per side13–38 µm — Approximate oxide growth; a discrete proprietary topcoat may add further buildup.
MaskingUsually needed. Mask threads, electrical contacts, precision fits, and surfaces that must accept adhesive.
ElectricalInsulating
Temperature limit200 °C (392 °F) continuous
AppearanceMatte gray, charcoal, or black with a low-sheen PTFE-rich surface.
Added lead time5–8 working days on top of the bare part

Design rules for PTFE hard anodize

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

  1. Name an approved PTFE process or performance requirement.PTFE hard anodize is not one standardized chemistry.
  2. Specify whether stated thickness includes the PTFE layer.Processor reporting conventions differ.
  3. Avoid adhesive bonding on impregnated areas.Low surface energy that reduces friction also impairs adhesion.
  4. Mask precision fits unless buildup is designed in.A nominal 50 µm oxide adds about 25 µm per side.

PTFE hard anodize versus the alternatives

Finishes engineers weigh against PTFE hard anodize, and when each wins.

FinishCorrosionHardnessCosmeticCostThicknessChoose it when
PTFE hard anodize
this page
716145$$$25–75 µm—
Hard Anodizing Type III
PTFE hard anodize vs Hard Anodizing Type III →
716150$$$25–75 µmwhen maximum abrasion performance matters more than low friction
CorrosionHardnessCosmeticLubricityEconomy
PTFE hard anodizeHard Anodizing Type III

The radar overlays PTFE hard anodize with Hard Anodizing Type III, its most common alternative — chosen when maximum abrasion performance matters more than low friction. Scores in the table are 0–100 across every finish in the catalog.

Cost, lead time and compliance

Relative cost

Hard Anodizing Type III With PTFE is a premium-cost finish ($$$): more expensive than about 67 % 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 time5–8 working days
RoHSConditional
NotesVerify the proprietary fluoropolymer formulation, cure aids, and current PFAS customer requirements.

What PTFE hard anodize is used for

  • Low-friction wear surfaces
  • Sliding and mating parts
  • Pistons
  • Dry-running aluminum bores

PTFE hard anodize — frequently asked

What is PTFE impregnated hard anodize?

It is Type III aluminum oxide whose pores or surface receive a PTFE-bearing treatment. The oxide supplies roughly 350–550 HV hardness while PTFE lowers dry friction.

Is Teflon hard anodize the same as Type III?

It starts with Type III, but the PTFE step is an additional proprietary treatment. MIL-A-8625 does not define a separate Teflon class.

How thick is PTFE hard anodize?

The hard oxide is commonly 25–75 µm, often 50 µm nominal. Ask whether the quoted thickness includes any discrete PTFE topcoat.

Does PTFE hard anodize need lubrication?

It can run dry in suitable light-to-moderate sliding service. High loads, contamination, and long wear life may still require engineered lubrication and pair testing.

Can PTFE hard anodize be used on threads?

Only if pitch-diameter allowance includes about half the oxide thickness per flank plus any topcoat. Precision threads are usually masked.