Powder Coating:
Powder coating involves applying powdered paint to the part's surface using specialized electrostatic spray equipment. The electrostatic charge causes the powder to adhere uniformly.
The powder layer is then cured in an oven at high temperature, melting and flowing to form a smooth, durable finish.
- Advantages: Superior to liquid paint in mechanical strength, adhesion, corrosion resistance, and aging resistance. Generally more cost-effective than liquid paint for comparable results.
- Types: Primarily categorized into outdoor-grade and indoor-grade powders.
- Finishes: Can achieve various textures such as smooth gloss, sand texture, and wrinkle (often called "vein" or "shrink").
Baking Paint (Liquid Paint Curing):
Genuine baking paint involves phosphating the aluminum substrate before applying liquid paint, followed by oven curing (baking).
- Result: Provides a coating that is not only corrosion-resistant but also highly glossy, wear-resistant, and durable.
- Critical Pre-treatment: Essential for achieving a good coating. Steps include: Degreasing → Rinse → Derusting (if needed) → Rinse → Surface Conditioning → Rinse → Phosphating → Rinse → Rinse → Drying.
- Purpose of Pre-treatment: Removes oils, oxide scales, rust, dirt, and other contaminants inevitably present on parts from manufacturing, handling, and storage. These contaminants severely impact coating adhesion, appearance, and performance.
Spray Painting (Conventional Liquid Paint):
"Spray oil" refers generally to industrial surface painting/spraying.
- Common Applications: Often used for plastic parts, screen printing, pad printing; color changes for EVA/rubber shoe materials.
- Capabilities(for various substrates,incl.metals):
Electronics: Standard painting, PU paint, rubberized paint (soft-touch paint).
Solves challenging issues in injection-molded parts, like flow marks and weld lines.
Expertise in applying rubberized (soft-touch) paints and rework techniques.
Oxidation:
- Conductive Oxidation (Chemical Conversion Coating): Suitable for aluminum die-castings. Achieved by immersion in a chemical solution (no electricity required). Typical colors include natural (clear/silver) and sky blue. Process time is very short (seconds).
- Anodizing (Electrochemical Oxidation): Primarily suitable for wrought aluminum alloys or extrusions, not generally recommended for standard die-castings (see previous discussion on silicon content). Requires applying a high electrical voltage in an electrolytic bath (electrochemical process). Takes much longer (tens of minutes). Creates a thicker, harder, more decorative, and corrosion-resistant oxide layer than conductive oxidation. Common colors include natural (clear) and various dyed options.
Sandblasting (Abrasive Blasting):
Propels fine abrasive media (e.g., sand, grit) at high velocity onto the aluminum surface.
- Purpose: Creates a uniform matte or textured finish. Enhances the coefficient of friction on contact surfaces, improving grip or mechanical interlock for bonding/adhesion. Can improve paint adhesion.
- Variations: Different media types and grit sizes produce distinct textures and surface roughness profiles.
Electroplating:
A process that uses electrical current (electrolysis) to deposit a thin, uniform, adherent layer of metal (e.g., nickel, chrome, zinc) onto the part's surface from a solution containing metal ions.
- Key Applications: Corrosion protection, decorative enhancement (e.g., chrome plating), and increased wear resistance.
- Note for Die-Castings: Aluminum die-castings are rarely electroplated in production unless specifically required, due to inherent challenges like porosity, complex shapes, and the need for extremely thorough and specialized pre-treatment.
