Surface Treaments

In the Renjiu Machinery manufacturing process, surface treatment technology is an important part of achieving product appearance, improving performance and enhancing durability.

Whether it is a mechanical part that needs strong protection or a high-end decorative part that wants to improve the appearance and texture, you can choose the appropriate surface treatment process according to the characteristics and needs of the material.

Dongguan Renjiu provides professional surface treatment services to help you achieve the perfect balance between product performance and appearance.

Advantages:

Picture	Surface  Treatment	Advantage	Materials	Colors
	Anodizing	Beautiful appearance, scratch resistance, corrosion resistance, insulation, anti-fingerprint	Aluminum, Aluminum alloys	Natural, Black, Gray, Gold, Rose gold, Red, Blue, Champagne, Brown, Purple, Green, Orange, etc.
	Sandblasting	Deburring, beautiful, anti-glare, and conducive to paint adhesion	Metal, Plastic, etc.	N/A
	Electroplating	Improve conductivity, corrosion resistance, and decorativeness	Copper, Zinc, Aluminum Alloy, Steel, Stainless steel, etc.	nickel plating, Chrome plating, Gold plating, Zinc plating, Antique copper, etc.
	Powder Coating	Strong corrosion resistance, high adhesion and durability, good uniformity	Zinc, Aluminum Alloy, Steel, Stainless steel, etc.	Pantone colors
	Brushing	high-end metal texture, strong industrial style	Aluminum, Stainless steel,etc	N/A
	Mirror Finishing	Improve appearance, facilitate electroplating, easy to clean	Metal, Plastic, etc.	N/A
	Painting	Improve appearance, color customization, comfortable feel	Metal, Plastic, etc.	All Pantone colors
	Silk Printing	Bright colors, strong adhesion, multi-color and multi-layer printing	Metal and Plastic surface	All Pantone colors
	Laser Engraving	No mold required, fine pattern, permanent marking	Metal and Plastic surface	All Pantone colors
	Water Transfer	Common patterns: carbon fiber, wood grain, camouflage, custom patterns	Metal, Plastic and Wood surface	All Pantone colors

Surface Treatments We Offer

Surface treatment is chosen for one of three reasons: to protect the part, to change how it looks, or to change how it performs in contact with something else. Most treatments do more than one of these at once.

• Anodising — an aluminium-only electrochemical process that grows a hard, integral oxide layer. Type II gives colour and moderate wear resistance; Type III (hard anodising) gives a much thicker, harder surface for sliding and abrasive duty. It does not flake because it is part of the metal.
• Powder coating — electrostatically applied and oven-cured polymer. Thick, tough, available in almost any colour, and ideal for steel and aluminium where appearance and weather resistance matter.
• Zinc plating and passivation — sacrificial protection for steel fasteners and brackets; passivation restores the corrosion resistance of machined stainless parts.
• Electroless nickel plating — a hard, uniform coating that protects sharp edges and internal bores, with excellent wear and corrosion resistance.
• Bead blasting — a uniform matte texture that hides tool marks and prepares a surface for coating.
• Polishing and brushing — decorative and functional finishes, from a mirror polish to a directional satin grain.
• Laser marking — permanent part numbers, logos and traceability codes without ink or labels.

Choosing the Right Finish

Work backwards from the requirement rather than forwards from the finish list.

Finishes for Aluminium vs Steel

Not every finish applies to every metal, and mixing them up wastes time. Anodising is aluminium-specific — attempting it on steel is not possible. Passivation is a stainless process and does nothing useful for mild steel, which needs zinc plating or paint instead. Powder coating and plating apply to both families, though the preparation differs. When in doubt, name the material and the requirement and let the process follow.

How to Specify a Finish

1. Name the process and the grade — for example "Type II anodising, black, Class 2" rather than just "black anodised".
2. State the cosmetic standard. Which faces are visible? A machined surface that will be seen needs a different preparation from a hidden one.
3. Allow for thickness. Coating and plating build up; anodising and hard anodising grow into the surface. Critical dimensions should be quoted before or after finishing, and the drawing should say which.
4. Say where it must not be applied. Threads, sealing faces and press fits may need masking, and masking is easier to plan than to correct.
5. Match the finish to the assembly. A coated part that must be welded has to be coated after welding, not before.

Frequently Asked Questions

Which finish is most durable outdoors?

For aluminium, anodising or a good powder coat both hold up well; for steel, powder coating or hot-dip galvanising give the longest service life. The right answer depends on salt exposure and abrasion.

Does anodising change the part dimensions?

It grows into the surface by a few microns, so normal tolerances are unaffected. Hard anodising is thicker, and very tight fits should be planned around it.

Can you apply a logo or part number?

Yes — laser marking gives a permanent, ink-free mark, and it can be applied through an anodised layer or on a bare surface.

Do you finish parts made elsewhere?

For most processes we prefer to control the whole chain ourselves, but finishing-only work is possible where the part geometry and material suit it.

Related Reading

• Anodizing vs Powder Coating: Which Finish to Choose?
• CNC Machining Metal Materials
• Sheet Metal Fabrication
• CNC Machining Service

Tell us the material and what the part must survive, and we will recommend the finish that meets the requirement without over-specifying it. Send your enquiry.

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