They are made of aluminium layers on both sides with a polyethylene (PE) or fire-retardant (FR) core.
Excellent final piece to the puzzle. Building on our previous discussions, here is a comprehensive breakdown of what ACP sheets are made of.
Composition of ACP Sheets
An Aluminium Composite Panel is a sandwich panel made of three primary layers, plus key coatings and treatments.
The Two Outer Skins: Rolled Aluminium
- Material: Aluminium alloy (typically 3000, 5000, or 1000 series), chosen for its formability, strength, and corrosion resistance.
- Thickness: Usually between 0.2 mm to 0.5 mm per side. The total thickness of the ACP (e.g., 3mm, 4mm, 6mm) is largely determined by the core, not the aluminium.
- Processing: The aluminium coils are chemically cleaned and pre-treated (with a chromate or chromate-free conversion coating) to ensure excellent paint adhesion and corrosion resistance.
The Core: The Defining Layer
This is the most critical component, dictating the panel’s fire safety, stiffness, and weight. There are three main types:
| Core Type | Composition | Key Property |
|---|---|---|
| Polyethylene (PE) | Low-density polyethylene (LDPE) resin. A thermoplastic polymer. | Standard, cost-effective, but HIGHLY COMBUSTIBLE. |
| Fire-Retardant (FR) | Polyethylene resin filled with mineral compounds (usually Aluminium Trihydrate – ATH, ~70%). | Self-extinguishing. Chars when exposed to flame, slowing fire spread. |
| Non-Combustible (A2) | Mineral-based core (e.g., >90% mineral wool, aluminium hydroxide). Contains little to no plastic. | Will not burn. Highest fire safety rating for building facades. |
The Bonding Agent: The Adhesive
- A specially formulated structural polymer adhesive (often a modified polyethylene) is applied to both sides of the core.
- Under controlled heat and pressure in a continuous laminating process, it permanently bonds the aluminium skins to the core, creating a cohesive, flat panel.
The Protective & Aesthetic Coating
The aluminium skin is coated before lamination. The two most common types are:
- PVDF (Polyvinylidene Fluoride): The premium standard for exteriors. Extremely durable, resistant to UV fading, chalking, and chemical corrosion. Typically has a 20-30 year warranty on color retention.
- PE (Polyester): A more economical coating. Suitable for interiors or short-term exterior applications. Less resistant to UV and weathering than PVDF.
- Other Finishes: Can include anodized coatings, mirror finishes, stone/wood grain laminates, or digital prints.
Summary of the Manufacturing Process:
- Coil Coating: Aluminium coils are cleaned, pre-treated, primed, and painted/coated.
- Core Preparation: The core material (PE, FR, or A2) is produced in large, flat sheets.
- Bonding: Adhesive is applied to the core. The coated aluminium sheets are placed on top and bottom.
- Lamination: The “sandwich” passes through a series of heated rollers (continuous laminator) under pressure, activating the adhesive to create a permanent bond.
- Cooling & Cutting: The continuous panel is cooled and precisely cut into standard or custom sheet sizes.
- Quality Control & Packaging: Panels are inspected for flatness, color, and bond strength before shipping.
