Automated Powder Coating Line High-Speed

 

Pretreatment for aluminium profiles, particularly for powder coating (e.g., to meet Qualicoat or GSB standards), typically involves a multi-stage process, with 5 to 8 stages being the most common in industrial applications to ensure durability and corrosion resistance.

The goal of these stages is to remove surface contaminants (oils, dirt), remove the natural oxide layer (etching), and apply a conversion coating (chrome or chrome-free).

Standard 5-Stage Process

A common, high-quality 5-stage setup for aluminum includes:

1. Cleaner/Degreaser: Removes dirt, oil, and grease.
2. Rinse: Removes residual cleaner.
3. Etch or Acid Pickling: Removes the natural oxide layer and creates a uniform surface.
4. Rinse: Removes etching byproducts.
5. Conversion Coating: Applies a corrosion-resistant layer (chromium-free/zirconium or chrome).

Note: A final DI (Deionized) water rinse is crucial to prevent contamination before drying.

6 to 8+ Stage Processes (Enhanced)

For higher performance requirements, especially in harsh or coastal environments, more stages are added to ensure thorough rinsing and better chemical deposition:

- 6-Stage: Often includes additional rinses (e.g., Cleaner, Rinse, Etch, Rinse, De-smut, Conversion Coating).
- 7 to 8 Stages: Adds extra rinses (like Reverse Osmosis rinse) and specialized sealers (e.g., chrome-free zirconium seal).

Typical Steps Overview

- Cleaning: Alkaline degreasing.
- Etching/Pickling: Acidic etching to create a matte finish.
- Desmutting: Removing residue from the etching process.
- Conversion Coating: Applying a protective layer (Chromate or Chrome-free).
- Rinsing: Crucial water rinses (tap water followed by DI water) between every chemical step.
- Drying: Hot air oven to ensure no moisture remains before powder application.

Proper pretreatment ensures the powder adheres firmly to the aluminium and meets industry standards like AAMA 2605 or Qualicoat for long-term, corrosion-resistant, and aesthetically pleasing results.