Here's a breakdown of the laminated glass production process
Glass Preparation
Glass Selection: Choose the type of glass based on the desired application (clear, tinted, low-E coated, etc.). The glass can be annealed (standard), heat-strengthened, or tempered/toughened, which adds to the strength and safety characteristics of the final product (tempered creates a much safer product when laminated because it breaks into small pieces rather than large shards).
Cutting: The glass panes are precision-cut to the required dimensions using automated cutting tables.
Washing and Inspection: The glass panes are thoroughly washed to remove any dust, debris and contaminants. The glass should be inspected for defects.
Interlayer Preparation
Interlayer Material: Polyvinyl Butyral (PVB) or Ethyl Vinyl Acetate (EVA) is the most common interlayer material.
Cutting the Interlayer: If the lamination involves unusual shape or designs, the interlayer is cut to match the glass panes' size and shape, typically by automated cutting machines and/or templates.
Assembly
Layup: The cleaned glass panes are placed on the assembly table.
Interlayer Placement: The interlayer (PVB or EVA) is carefully placed between the glass panes, ensuring proper alignment and positioning. For decorative laminates (with fabric, etc.), those are carefully placed as well.
Air Removal: The "sandwich" of glass and interlayer is often processed in a pre-laminating step (e.g., pre-nip, or vacuum ring) to remove air trapped between the glass and the interlayer. This improves bonding efficacy in the later autoclave process. This may be done via a heated roller or a vacuum ring system to remove as much air as possible.
Lamination (The Primary Bonding Process)
Autoclave Process: The assembled "sandwich" is placed in a large, high-pressure and high-temperature oven called an autoclave.
Heat and Pressure: In the autoclave, the glass-interlayer sandwich is subjected to a combination of controlled heat (typically around 130-150°C / 266-302°F ) and pressure (several hundred psi).
Bonding: This process melts the interlayer and fully bonds the glass panes together. The heat and pressure create a strong, permanent bond between the glass and the interlayer.
Air Evacuation: Excess air trapped in the air between the glass and interlayer is eliminated during the process so that a clear bond is formed.
Alternatively - Vacuum Bag or Oven Lamination (for Small to Medium Operations)
Process: Vacuum Bag lamination is used for simpler lamination operations. (and for EVA products) A vacuum sucks the air out, and the pressure is then applied by the autoclave (oven). More affordable.
Oven Bonding: During the oven setting the temperature is set just below or above, the glass transition point.
Inspection and Quality Control
Visual Inspection: After the lamination process, the glass is thoroughly inspected for any defects such as air bubbles, delamination, or imperfections in the interlayer.
Testing: Samples may undergo tests to verify adherence to specifications (impact resistance, optical clarity, etc.).
Trimming and Finishing (If Necessary)
Edge Treatment: If necessary, the edges of the laminated glass may be trimmed or sealed to remove excess interlayer material.
Other treatments, can be implemented, this include drilling holes, etc.
Packaging and Shipping
Safe Handling: Laminated glass is carefully handled to prevent scratches or damage.
Protective Packaging: The finished product is packaged in crates or racks, with spacers (e.g., cork or foam) between the panes to protect the glass during transport.
Shipping: Products are shipped to customers.
Key Considerations for the Process
Cleanliness is Critical: Maintaining a clean manufacturing environment is crucial to prevent defects, as any contamination can compromise the bond between the glass and the interlayer.
Temperature Accuracy: Precise temperature control is essential throughout the process to achieve the desired bonding characteristics.
Pressure Control: Accurate pressure control in the autoclave (or other lamination processes) is vital to ensure uniform bonding.
Quality Control: Regular inspections and testing throughout the manufacturing process are necessary to ensure consistent quality.
Energy Efficiency: Manufacturers are increasingly focused on energy-efficient processes, including energy-efficient autoclaves.
Automation: Modern production facilities incorporate sophisticated automation and robotic systems for efficiency and precision.
This streamlined process, refined over time, achieves the high-performance, safety, and aesthetic qualities that are hallmarks of laminated glass.
