Stage 1: Raw Material Uncoiling & Surface Pretreatment
(Material Preparation Zone)
The process begins with aluminum coils being mounted onto the hydraulic uncoiler. The coil is fed through a pinch roller and an edge guide control system to ensure precise alignment.
The aluminum strip then enters the continuous degreasing and washing tunnel, which consists of multi-stage spray tanks (alkaline degreasing → tap water rinsing → deionized water rinsing). This step thoroughly removes rolling oils, dust, and organic contaminants from the metal surface.
Subsequently, the clean strip passes through the chemical conversion coating section (chrome-free zirconium/titanium treatment), which generates a nano-scale conversion layer on the aluminum surface. This layer is critical for enhancing both corrosion resistance and the final adhesive bond strength.
The treated strip then travels into a hot air drying oven to evaporate all residual moisture, ensuring the surface is perfectly dry and ready for adhesive application. An exit cooling fan unit reduces the sheet temperature before entering the next stage.
Stage 2: Adhesive Application & Core Preparation
(Bonding Preparation Zone)
For the skins (face & back sheets):
The pretreated aluminum sheets are conveyed into a precision reverse-roll coater where a metered amount of structural adhesive (either two-component polyurethane or heat-activated epoxy film) is uniformly applied to the inner surface. The coating thickness is strictly controlled by an automatic gap adjustment system with real-time thickness feedback.
For the honeycomb core:
Simultaneously, the bulk honeycomb core block (expanded aluminum foil) is fed into the core slicing line. First, a multi-blade slitting machine cuts the block into continuous strips of the required width. Then, a high-speed cross-cutting saw precisely slices these strips into core panels of the specified thickness (height). The cut cores are then blown clean by an air knife to remove loose foil fragments.
Stage 3: Automatic Lay-up & Stacking
(Assembly Zone)
The prepared components are transferred to the automatic vacuum lay-up table. Using overhead suction lifters and a CNC-programmable positioning system, the operator or robotic arm stacks the materials in the exact sequence:
Bottom aluminum skin (adhesive side up) → Honeycomb core layer → Top aluminum skin (adhesive side down)
The stacking process includes a peripheral frame positioning jig to ensure the core is perfectly centered with a consistent margin gap from the panel edges. Once stacked, the assembled “sandwich package” is automatically pushed onto the loading carriage of the press system.
Stage 4: Hot Pressing – Curing & Lamination
(Core Bonding Zone – The Heart of the Line)
The loaded sandwich packages are fed into the multi-daylight hot press (or continuous double-belt press). The press applies two critical parameters simultaneously:
- Pressure: Hydraulic cylinders generate a controlled pressure of 2–6 kg/cm² across the entire panel surface to ensure intimate contact between the core cell walls and the adhesive-coated skins.
- Heat: Thermal oil, heated by a closed-loop thermal oil boiler system, circulates through the press platens to maintain a precise curing temperature (typically 180–200°C, depending on the adhesive formulation).
Under heat and pressure, the adhesive undergoes a cross-linking polymerization reaction. After the predetermined curing cycle (usually 3–8 minutes for hot-press systems), the platens open.
The cured, rigid panels are then transferred to a water-cooled cold press for controlled cooling. This step gradually reduces the panel temperature to ambient levels, preventing residual thermal stress that could otherwise cause post-production warping.
Stage 5: Trimming, Cutting & Edge Finishing
(Primary Sizing Zone)
The cooled large-format composite panels are moved to the CNC trimming and sizing line.
First, the longitudinal edge trimmers (equipped with rotary disc shears) cut off the irregular raw edges on both lengthwise sides to achieve a precise, parallel reference edge.
Then, the panel proceeds to the cross-cutting guillotine shear (or flying shear for continuous lines), which cuts the panel to the required customer-specified length. This stage produces flat, rectangular panels with clean, burr-free edges.
Stage 6: Grooving, Bending & Stiffener Installation
(Secondary Fabrication Zone – Optional for Cassette Panels)
If the final product is a cassette (tray-style) panel for curtain wall applications, the flat panel undergoes further processing:
- V-Grooving: The panel is positioned on the CNC V-grooving machine, which mills a precise V-shaped channel on the back side along the bending lines. The machine’s depth control ensures the remaining aluminum skin thickness is exactly 0.3–0.5 mm, allowing for sharp, crack-free folds.
- CNC Bending: The grooved panel is then transferred to the CNC press brake. With the V-groove acting as a hinge, the press brake folds the four edges upward at a 90° angle, forming a rigid box-shaped cassette.
- Stiffener Attachment: Finally, the automatic stud welding machine or riveting station attaches mounting brackets and reinforcement profiles (L-shaped aluminum stiffeners) to the back face of the panel, providing structural support for building installation.
Stage 7: Quality Inspection & Packaging
(Final QC & Dispatch Zone)
All finished panels pass through a final inspection station where:
- Visual inspection checks for surface scratches, color consistency, and adhesive bleed-out.
- Non-destructive testing uses a coating thickness gauge to verify the paint layer on the face side (if pre-coated coils were used).
- Destructive sample testing is performed offline using a peel adhesion tester to measure the core-to-skin peeling strength, ensuring it meets ASTM or EN standards.
After passing inspection, each panel is covered with protective PE film, stacked on wooden pallets, strapped with steel bands, and wrapped with corner protectors. The pallets are then labeled with shipping marks and moved to the finished goods warehouse for dispatch.
Auxiliary Support Systems (Throughout the Line)
- Central Dust Collection System: Explosion-proof type, connected to all cutting, grooving, and trimming stations to safely extract aluminum chips and fines.
- Variable-Frequency Screw Air Compressor: Supplies stable compressed air to all pneumatic cylinders, clamps, and cleaning air knives.
- PLC Central Control Console: Monitors and synchronizes the speed, temperature, and pressure parameters across all stages, allowing for single-operator supervision of the entire production line.