Laminating

 

Laminating

 

The principle

SAP (Southern Auto Products) has one of the only fully automatic Lamination Lines in India. Laminated glass comprises of two or more panes of glass and an interlayer of one or more sheets of clear or colored Interlayer (Poly Vinyl Butyral <PVB> or Sentry Plus), bonded together by heat and pressure.

The standard minimum thickness of a PVB interlayer is 0.38mm. The interlayer possible with PVB is: 0.38, 0.76, 1.14, 1.52, 1.90, 2.28, etc. mm. Sentry Plus comes in standard thickness of 0.90, 1.52, and 2.28mm. Once sealed together, the laminated glass behaves as a single unit. Annealed, heat-strengthened or tempered glass can be used to produce laminated glass.

Laminated Glass provides additional safety to a glass pane. Breaking of one glass, will not cause the pane to shatter/break. The pane will continue to remain in place until it has been replaced. This is one of the primary reasons why Laminated Glass is used in Shop Fronts. By increasing the layers of Glass and PVB, higher security can be achieved. Multilayered Laminated Glass is used for Bullet Proof and grenade resistant applications.

Southern Auto Products is one of only three authorized processors of Sentry Plus Glass, in India. Sentry Plus is a new product of DuPont (one of the pioneers of Glass Inter layers). Sentry Plus Glass has added benefits over ordinary PVB <provide a link to the comparison table between S Plus and PVB>, also have a sub link on the menu to the left pointing to PVB Vs. Sentry Plus. [Laminating-> Process; Laminating-> PVB vs. Sentry Plus]

How do we produce laminated glass?

Step 1:Preparation  
 Laminated glass is generally produced as per customer specifications. The desired Glasses are cut to size from glass sheets. Lamination of Heat-Treated glasses is carried out in the same way as Annealed Glass. However, the Heat-Treatment process is done prior to the lamination process. The output of the tempering/heat-strengthening process will be the input to the Lamination process.
Step 2: Washing  
Each pane is cleaned carefully under controlled conditions to ensure that no impurities are present on the glass surface. Apart from the obvious unwanted visible presence of impurities post lamination, impurities can also result in the delaminating of the glass pane.
Step 3: Layering  
 A clean, controlled environment (low temperature, low humidity and dust free Clean Room) is used to house the Inter-Layer (PVB or Sentry Plus). The glass and inter-layers are assembled in this Clean Room. The number and thickness of each component can be varied to produce an end-product with different characteristics meeting specific safety and/or security requirements, desired by the customer.
Step 4: Pressing  
The assembled unit of glass is then passed through heaters (around 150 °C) and nip-rolls. The glass is passed through two stages of heating and pressing. This technique eliminates any remaining air between the glass panes and facilitates the first stage of bonding. The visual aspect of the PVB/Sentry Plus interlayer changes from translucent to semi-transparent.
Step 5: Loading on the Trolley  
 The Pressed Glass panes are carefully stacked on an A-Frame Trolley, with sufficient space between each pane (facilitate air-flow). The glasses are then tightly fastened onto the trolley. Improper stacking can result in the slipping of the glass panes, thereby leading in a mismatch of holes/edges.
Step 6: Autoclave  
To achieve perfect adhesion between the glass and interlayer, the materials are loaded into an autoclave. Here the glasses are heated to around 130°C and a pressure of 13 bars is applied for a period of 3 hours.  This enables the final bonding of the glass units under these controlled temperature and pressure conditions. 
Step 7: Labeling, Packaging, and Transport  
 Labels outlining full order details are affixed to the finished, laminated glass panes. A protective film can also be used to provide additional protection against scratches during transportation. 
Applications  
  • Floors & Stairs
  • Skylights
  • Wall cladding
  • Conservatories
  • Doors
  • Windows
  • Writing Boards