80 Tons/Month Semi-Automatic Hard Anodizing Line for Black Anodized Aluminum

This semi-automatic hard anodizing production line is engineered for medium-volume surface finishing of aluminum components requiring exceptional surface hardness, wear resistance, and a matte black finish. With a monthly capacity of 80 tons, the integrated wet processing line combines chemical degreasing, acid neutralization, low-temperature Type III hard anodizing, organic black dyeing, and mid-temperature sealing.

Mechanical sandblasting is performed off-line using customer-supplied equipment prior to racking. By eliminating chemical alkaline etching, the system reduces wet tank chemical consumption and sludge generation while leveraging mechanical sandblasting to achieve the targeted surface roughness and matte appearance.

• Controlled Film Thickness: High-voltage DC power rectifiers feature soft-start current ramping and automatic voltage adjustment to control oxide layer growth rates and prevent component burning during high-current-density hard anodizing.
• Automated Process Control: Tanks are configured with digital temperature controllers, automated bath replenishment connections, and countdown timers with audible alarms to assist operators during transfer cycles.
• Batch Color Uniformity: The organic black dye tank includes continuous fluid circulation, electric immersion heaters, and digital temperature control to maintain uniform dye absorption across sandblasted surface textures.
• Temperature & Filtration Control: Industrial screw chillers connected to titanium plate heat exchangers absorb heat generated during hard anodizing, holding bath temperatures within -5°C to 5°C. Continuous cartridge filtration removes suspended particulates from the acid bath.
• Streamlined Pre-Treatment Layout: By replacing chemical alkaline etching with mechanical sandblasting, the wet line footprint is reduced. The subsequent acid neutralization step removes residual blasting dust and native oxides without modifying the mechanically prepared surface texture.

• Electric Bridge Hoist System: Overhead motorized cranes with variable speed controls, dual-hook lifting bars, and manual push-button pendants for tank-to-tank rack movement.
• Hard Anodizing Rectifier Units: High-voltage DC power supplies equipped with current density regulation, ripple control, and automatic voltage ramping programs.
• Low-Temperature Chilling System: Industrial refrigeration units paired with corrosion-resistant titanium heat exchangers and circulation pumps for continuous bath cooling.
• Exhaust & Acid Mist Scrubber System: Lateral slot extraction hoods, UPVC exhaust piping, and packed-bed scrubber towers for acid gas neutralization.
• Black Dyeing Tank Equipment: 316L stainless steel dye tanks equipped with electric heating elements, air agitation, and temperature controllers.
• Bath Filtration & Circulation Modules: Acid-resistant magnetic pumps, UPVC pipe networks, and PP cartridge filter units for continuous electrolyte circulation.
• Reverse Osmosis (RO) Water System: Multi-stage RO purification unit producing deionized water for post-anodizing rinsing steps and bath make-up.
• Wastewater Treatment System: Neutralization tanks, chemical dosing units, and filter presses for acid/alkali wastewater treatment prior to discharge.

The customer utilizes standalone mechanical sandblasting machinery prior to the anodizing stage. Sandblasting provides the required matte surface texture, eliminating the need for chemical etching tanks, reducing chemical usage, and simplifying wastewater treatment.

Yes. The acid neutralization step removes native aluminum oxides, trace alloy smuts, and fine blasting dust left on the surface, ensuring clean metallic contact prior to hard anodizing.

Wrought alloys such as 6061, 7075, and 2024, as well as select cast aluminum alloys, can be processed. Alloys with high copper content may require adjusted current density ramping during processing.

An industrial screw chiller combined with a titanium heat exchanger and heavy-duty recirculation pumps continuously removes heat generated by high current densities during Type III anodizing.

Depending on alloy composition and current density parameters, building a 50 μm oxide layer under Type III hard anodizing conditions typically requires 40 to 60 minutes of bath immersion time.