Wear & abrasion
Sliding, rubbing or repetitive-contact surfaces where a more wear-resistant aluminum surface is required.
Process intelligence · 001
Hard anodizing
of aluminum.
Hard anodizing is an electrochemical conversion process used when abrasion resistance, wear performance, dielectric behavior or durable engineering surfaces are primary requirements.
What it is
An engineering oxide, not an applied paint or plating layer.
The aluminum component acts as the anode in a controlled electrochemical process. The surface is converted into an anodic oxide layer that grows partly into the substrate and partly outward from the original surface.
Hard anodizing uses process conditions intended to produce a comparatively thick, wear-resistant anodic oxide. The final result depends strongly on alloy, geometry, surface condition, required thickness, sealing and the performance requirement being targeted.
ATLAS does not assume that every alloy, thickness or sealing condition produces equivalent performance. Supplier matching should be driven by the actual drawing and functional requirement.
Simplified route
Where hard anodizing sits in the manufacturing route.
01Machined aluminum partAlloy, temper, tolerances and surface condition defined
→
02Preparation & maskingCleaning, contact strategy, selective masking if required
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03Hard anodizingControlled oxide growth to the specified requirement
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04Optional finishingDye, sealing or impregnation only when technically appropriate
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05InspectionThickness and specified performance / acceptance tests
Use cases & constraints
The process is selected for function.
Hard anodizing is useful when the anodic layer itself is part of the engineering performance of the component.
Electrical behavior
The anodic oxide is electrically insulating relative to the conductive aluminum substrate, which can be useful in dielectric applications.
Corrosion protection
Hard anodic coatings can contribute corrosion resistance, but sealing, alloy and service environment must be specified deliberately.
Alloy dependency
Alloying elements affect oxide growth, achievable thickness, appearance, roughness and performance. Equivalent results should not be assumed across alloys.
Dimensional change
The coating develops both inward and outward. Functional diameters, threads, fits and precision interfaces need an agreed dimensional strategy before processing.
Sealing trade-offs
Sealing can improve some corrosion-related properties but can affect abrasion performance. The final state should follow the application requirement, not habit.
Specification inputs
What the drawing or purchase specification should tell the anodizer.
A useful hard-anodizing specification is more than a coating thickness. ATLAS treats the following fields as matching signals.
01Alloy and temperExample: EN AW-6082 T6, 7075-T6, 5083, casting grade, etc.
02Areas to coat / maskIdentify bores, threads, electrical contacts, sealing faces and forbidden contact marks.
03Coating requirementThickness, tolerance and any local/minimum requirement required by the governing specification.
04Dimensional strategyState finished dimensions, machining allowance or masking strategy for critical fits.
05Final conditionNatural, dyed, sealed, unsealed or impregnated — only where compatible with the required performance.
06Performance / inspectionSpecify the relevant tests or acceptance criteria: thickness, abrasion, corrosion, dielectric or other project-specific requirements.
Reference framework
Standards commonly encountered.
Always use the issue explicitly required by the drawing, contract or customer specification. ATLAS records standards as structured requirements, not as interchangeable labels.
ISO 10074:2021
Hard anodic oxidation coatings
The current ISO specification dedicated to hard anodic oxidation coatings on aluminum and its alloys. It covers requirements and test methods and defines information to be supplied to the anodizer.
ISO reference →
ISO 8251:2018
Abrasion resistance measurement
Defines methods for measuring abrasion resistance of anodic oxidation coatings; ISO notes the use of abrasive-wheel and abrasive-jet methods for hard anodized coatings through ISO 10074.
ISO reference →
MIL-PRF-8625 · Type III
U.S. hard anodic coating reference
A common U.S. aerospace / defense reference in which Type III designates hard anodic coatings. The required coating thickness should be called out by the applicable drawing or purchase documentation. Verify the latest issue in the official ASSIST system when contractually required.
DLA Quick Search →Engineering questions
Hard anodizing: quick answers.
Is hard anodizing always 50 µm?
No. Hard anodizing is defined by the engineering requirement and governing specification. The Aluminum Anodizers Council describes hard anodizing as usually thick by normal anodizing standards, typically greater than 25 µm, but the project thickness must be specified deliberately.
Does hard anodizing have to be black?
No. The natural color depends on alloy, process and thickness. Dyeing can be specified in some cases, but color should not be confused with the underlying functional coating requirement.
Can every aluminum alloy be hard anodized the same way?
No. Alloy composition influences coating behavior, attainable thickness, appearance and performance. Supplier capability should therefore be matched against the actual alloy, not just the word “aluminum.”
Does hard anodizing change dimensions?
Yes. Anodic oxide formation includes both penetration into the substrate and outward build-up. The dimensional effect on precision features must be considered before machining and before the anodizing specification is released.
ATLAS matching model
How this process becomes supplier intelligence.
ATLAS is structuring hard-anodizing capability around fields such as:
AlloysThickness rangePart envelopeSelective maskingSealing optionsColor capabilityStandardsInspection methodsCertificationsGeography
Supplier matching for this process is not yet public. ATLAS will publish coverage only when the underlying Supplier Passport data reaches the required quality level.
Linked standard node
ISO 10074:2021.
The current ISO standard dedicated to hard anodic oxidation coatings on aluminium and its alloys is now represented as a structured ATLAS standard node.
Standard intelligence · 001
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ISO 10074:2021
Official public scope, lifecycle status and evidence-aware supplier links.
Linked material node
Material behavior matters.
The public ATLAS graph currently links this process to EN AW‑6082, a 6000-series alloy used in strength-led engineering applications and compatible with hard anodic coatings.
Material intelligence · 001
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EN AW‑6082 · AlSi1MgMn
Material identity, composition, temper context and anodizing behavior.
Linked Supplier Passport
Documented capability in the ATLAS graph.
ATLAS currently has one public Supplier Passport linked to this process. This is not a ranking or recommendation; it is the first documented supplier node in the public test graph.
Supplier Passport · 001
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Oxycolor Alu SA
Le Locle, Switzerland · Hard anodizing 36 µm / 50 µm · natural part envelope up to 1000 × 800 mm.
Linked manufacturing route
Manufacturing Route · 001.
This node participates in the first public ATLAS manufacturing route connecting EN AW‑6082, hard anodizing, ISO 10074:2021 context and supplier evidence.
Manufacturing Route · 001
→
EN AW‑6082 → Hard Anodizing
Material → process → standard → inspection → supplier evidence gate.
Technical basis
This page is general manufacturing guidance, not a substitute for a drawing, customer specification, controlled standard or process qualification. Primary references used for the current page include ISO 10074:2021, ISO 8251:2018, MIL-PRF-8625 Type III terminology, and technical guidance from the Aluminum Anodizers Council.