✨ From ₹200 / part

Anodizing

Type II and Type III hard-coat anodizing for aluminium parts. Increases surface hardness to 60–70 HRC, improves corrosion resistance, and adds colour.

Get Instant Quote → Type II vs Type III

How It Works

Electrochemical Anodizing

Anodizing is an electrochemical process that grows a controlled oxide layer on the aluminium surface. The part is submerged in a sulphuric acid bath and connected as the anode in an electrical circuit — oxygen ions from the electrolyte react with the aluminium to form aluminium oxide (Al₂O₃) at the surface.

The resulting oxide layer is integral to the metal (not a coating on top), making it extremely durable. Dye molecules can be absorbed into the porous oxide before sealing to produce colours.

Integral oxide layer — doesn't peel, chip, or flake
Surface hardness up to 70 HRC (Type III hard coat)
Electrically non-conductive — ideal for electronics enclosures
Maintains tight dimensional tolerances (layer grows inward ~50%)
RoHS compliant · no heavy metals

Process Types

Type II vs Type III — Which Do You Need?

TYPE II — STANDARD

Decorative Anodizing

The most common anodizing process. Produces a clear or coloured oxide layer ideal for consumer products, electronics housings, and architectural parts.

Layer thickness5–25 µm

Hardness~30 HRC

ColoursClear, Black, Red, Blue, Gold

Dimensional change~5 µm per face

Starting from₹200 / part

TYPE III — HARD COAT

Hard Anodizing

Thicker, denser oxide layer grown at lower temperature. Used in aerospace, defence, and heavy wear applications where surface hardness is critical.

Layer thickness25–100 µm

Hardness60–70 HRC

ColoursClear (grey-black), Black

Dimensional change~25 µm per face

Starting from₹450 / part

Colour Options

5 Standard Colours — Type II

Colours are dyed into the porous oxide before sealing. Type III is available in clear (natural grey-black) and black only.

Clear

Natural Al finish

Black

Aluminium Alloys We Anodize

Anodizing is only suitable for aluminium. Alloy selection affects colour uniformity and hardness achievable.

6061

Best overall · excellent finish

7075

Aerospace · good with Type III

5052

Sheet metal · good Type II

2024

High strength · clear only

Design Guidelines

Preparing Parts for Anodizing

📏 Dimensional Allowance

The oxide layer grows ~50% inward and ~50% outward. Type II adds ~5 µm per face. Type III adds ~25 µm per face. Account for this on mating fits and precision bores — specify tolerances before anodizing.

🔩 Mask Critical Areas

Threads, precision bores, and contact surfaces must be masked. Anodizing inside threads reduces clearance — M4 and smaller threads are often best masked. Specify masked areas in the order notes.

🔲 Alloy Consistency

Mix of alloys in one bath will show colour variation. If colour matching across multiple parts is critical, ensure all parts are the same alloy and temper. Send alloy certification if available.

✨ Surface Prep

Pre-anodizing surface finish is visible after anodizing — machining marks, scratches, and tool paths show through the clear oxide. Specify bead blast or mechanical polish if a uniform appearance is required.

💡 Pro tip: For the best black anodize on 6061-T6, request a 15-minute etch and mid-range sulphuric bath current density. Our team applies this by default for all black Type II orders.