Over the past 50 years, the Sandwich panel has emerged as a particularly economical construction method. The combined materials always consist of two face sheets (depending on the application, rigid metallic face material or flexible face sheets such as thin aluminum, paper, or membranes) and a core insulating material.
Basically, there are two processes for Manufacturing panels:
- Continuous process:
All used materials are processed together and the finished formed panel is cut to the desired length without stopping the line.
This line has an average speed of about 14 meters per minute in the production of medium thickness panels (40-50 mm) with metal top layers. With an eight-hour shift per day for 220 days per year, production is about 1,180,000 meters per year, assuming an 80 percent efficiency.
- Discontinuous process:
The materials are processed separately, i.e. the face sheets are formed and cut to the desired length and then joined together in a press where the foam is injected.
Besides, this process has lower productivity that cannot be compared to that of the continuous process.
It is used today for products with shapes that do not allow the continuous process, or when the required production rate does not justify the investment in a continuous line.
This line with a 12-meter double press can achieve a production of about 100,000 meters per year under the same conditions with one shift per day.
In the polyurethane panels (PU -PIR) procedure, the foam is created starting from the required chemical components, which are dosed and mixed in the foaming machine. The resulting liquid mixture is evenly distributed over the lower metal sheet.
The metallic facings, the foam, and any side strips or gaskets are pressed in the double belt or continuous press. This machine must hold the metal sheets separated at the desired spacing while the foam expands.
Let’s Dig Into Continuous Panel Production line
A typical continuous line has three sections:
- The external layers processing section:
The first section begins with the sheet decoilers and continues with all the equipment for
forming the two sheets into the desired shape.
This can be a panel for walls or for roofs. In a typical case of a Sandwich panel with the two outer
surfaces made of sheet metal and an insulating core made of rigid polyurethane foam,
Sandwich panels with flexible layers (aluminum, fiberglass sheets, asphalt paper) are
not roll-formed. Then both surfaces of the finished panels are completely flat and their temperature is preheated as required
(usually between 40 and 65 C), and then the insulating material is prepared.
Temperature is again a critical parameter, this time for the reaction
of the adhesive, i.e. for good adhesion of the inner sheet to the outer layers.
- The insulating material processing section:
in case the insulation material was mineral wool or expanded polystyrene,
its inserted and bonded into the sheets in the form of mattresses
which will be cut and shaped to the correct thickness before insertion.
- Panels handling section:
The panel goes throw cutting, cooling, stacking, and wrapping with a plastic film.
Those last operations can be automatic or manual. Depending on the level of automation required by the customer for his production line.
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