Can anodizing be applied to stainless steel parts?

No, anodizing is a process specifically for aluminum and its alloys. For stainless steel parts, we recommend passivation to enhance corrosion resistance, or electropolishing to improve cleanliness, deburr, and provide a bright, smooth finish.

What finishing process is best for improving wear resistance?

For steel parts, hard chrome plating or nitriding are excellent choices. For aluminum parts, hardcoat anodizing (Type III) is the standard. For extreme wear resistance in any material, tungsten carbide coating or thermal spray can be applied.

What is bead blasting used for?

Bead blasting (or media blasting) is primarily used to create a uniform matte or satin surface finish, remove light tool marks, and prepare a surface for subsequent finishing like anodizing or painting. It provides a clean, non-directional texture.

Surface finishing

Metal Surface Finishing Services for CNC Parts

Sunnyhowe provides professional surface finishing services tailored to CNC machined components. We apply anodizing, powder coating, plating, and chemical conversion coatings to enhance corrosion resistance, wear properties, and aesthetics, ensuring your parts perform perfectly in their end-use environment.

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Name	Applicable Materials	Colors	Can be applied to
As machined	Aluminum, Steel, Stainless Steel	Ra 0.8μm - Ra 3.2μm	All post processes
Anodizing	Aluminum	Clear, black, grey, red, blue,green,orange,gold	Media Blasting, Tumbling, Alodine*
Chrome Plating	Acrylic	n/a	Enhanced Cosmetic Appearance
Electroless Nickel Plating	Aluminum, Steel, Stainless Steel	n/a	Media Blasting, Tumbling
Black Oxide	Aluminum	Black	Bead blasted, Tumbling, Chem film*
Bead Blasted + Anodized type II	Aluminum	Clear, Black, Red, Blue, Orange, Gold	Media Blasting, Tumbling, Type II Anodizing* Type III Anodizing with PTFE*
Zinc Plating	Steel, Stainless Steel	Clear (light blue coating). Black (glossy black coating).	Media Blasting, Tumbling, Passivation
Tumbling	Aluminum, Steel, Stainless Steel, Brass, Bronze, Copper	n/a	All post processes, except Electropolish and Powder Coat
Nano coating	For applicable material processing, please refer to the catalog.	Full Coating or RAL color catalog	Please contact us for detailed instructions
Passivation	Steel, Stainless Steel	n/a	Black Oxide, Electroless Nickel Plating, Zinc Plating, Tumbling, Media Blasting
Brushed	Aluminum, Steel, Stainless Steel, Brass, Bronze, Copper	Small：Draw 6.5-8mm wire to 2.0-4.0mm. Medium：Draw 16-18mm wire to 8.0-12.0mm. Large：Draw 100-120mm wire to 20-30mm.	All post processes, except Electropolish and Powder Coat
Electropolishing	Steel, Stainless Steel	n/a	Passivation, Tumbling

*Additional finishing options include chromic acid anodizing, cadmium plating, copper plating, titanium anodizing (blue anodizing), gold plating, silver plating, and more. For materials not listed here, please contact us directly.

Cosmetic finishes

Surface finishes can serve either a functional or aesthetic purpose. Surface finishes that serve both purposes are deemed cosmetic finishes, and are used for cosmetic parts. Producing cosmetic parts requires additional measures to minimize defects such as hang marks and scratches from tools.

Non-cosmetic

Primary machining marks will still be visible

As machined
Smooth machining
Fine machining
Electroless Nickel Plating
Anodized type III (Hardcoat)
Black oxide

Cosmetic on request

Finishes can be either cosmetic or non-cosmetic as per request

Brushed + Anodizing type II
Bead Blasted + Anodizing type II
Bead Blasted
Brushed
Nano coating

Cosmetic by default

These finishes will always serve a cosmetic function

Brushed + Electropolished
Polishing

Gallery of Surface finishing parts

Below are a small selection of the CNC machined parts and end-use components we produce for our customers.

Aluminum 7075-T6 laser cavity with 0.01mm concentricity

Aluminum 7075-T6 Cavity


Purpose	Laser equipment cavity
Process	CNC machining
Material	Aluminum 7075-T6
Surface finish	Bead Blasted + Anodized type II
Unit price	€1678.58
Industry	Industrial automation

CNC Turned 6061-T6 Aluminum Parts - ISO2768-F Tolerance

Aluminum 6061-T6


Purpose	Automated robot caliper joints
Process	CNC machining
Material	Aluminum 6061-T6
Surface finish	Anodizing clear
Unit price	€136.98
Industry	Robotics

Aluminum 6061 Drone Propeller


Purpose	Drone propeller bracket parts
Process	CNC machining
Material	Aluminum 6061
Surface finish	Anodized red
Unit price	€26.58
Industry	Aerospace

CNC Milled Black Anodized Aluminum 6061 Components

Black Anodized Aluminum 6061 Parts


Purpose	Milling industrial machinery fixtures
Process	CNC machining
Material	Aluminum 6061
Surface finish	Anodized black
Unit price	€56.58
Industry	Industrial machinery

Gray anodized CNC machined aluminum rabbit cage for action cameras

Aluminum 6061-T6 Action Camera


Purpose	Action camera rabbit cage parts
Process	CNC machining
Material	Aluminum 6061-T6
Surface finish	Gray Anodized
Unit price	€48
Industry	Consumer Electronics

What is the difference between anodizing Type II and Type III (Hardcoat)?

Type II (Decorative) Anodizing provides good corrosion resistance and a wide range of color options with a typical coating thickness of 5-25 μm. Type III (Hardcoat) Anodizing creates a much thicker, harder, and more wear-resistant surface (up to 50-100 μm), but with limited color options (often clear, black, or dark gray). It is ideal for aluminum parts in high-abrasion applications like jigs and fixtures.

How does powder coating compare to painting for CNC machined parts?

Powder coating is generally superior for functional parts. It creates a thicker, more durable, and more uniform coating that is highly resistant to chipping, scratching, and chemicals. It is also more environmentally friendly. Painting may be used for specific color matches or very thin film requirements.

How do I specify surface roughness (e.g., Ra, Rz) on my drawing?

Please indicate the Ra (arithmetic average) or Rz (maximum height) value and the sampling length on your 2D drawing. Common callsouts are like "Ra 1.6 μm" or "Rz 10 μm max". For critical surfaces, also specify the measurement direction (e.g., "parallel to lay"). If unsure, we can advise during the DFM stage.

Will finishing affect the dimensional accuracy of my part?

Yes, most finishing processes add a thin layer of material. Anodizing can add 10-50 μm per side, powder coating 50-100 μm, and plating 5-25 μm. For critical features, it is essential to call out these dimensions as post-finish and we will machine the part accordingly to compensate.

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