What Is Extrusion?
Film extrusion is used to extrude plastic— typically vinyl (PVC) film. In the extrusion of film, raw compound material — PVC resin, additives such as colorants, plasticizers, anti-bacterial agents, mildew inhibitors, UV and heat stabilizers, and flame retardants (in either liquid or pellet form), are gravity fed from a top mounted hopper into the barrel of the extruder.
- The material enters through the feed throat (an opening near the rear of the barrel) and comes into contact with the screw. The rotating screw forces the compound forward into the heated barrel. Extra heat is contributed by the intense pressure and friction taking place inside the barrel. At the front of the barrel, the molten plastic leaves the screw and travels through a screen pack to remove any contaminants in the melt. After passing through the screen pack, molten plastic enters the die. The die is what gives the final product its profile, and must be designed so that the molten plastic flows evenly from a cylindrical profile, to the product’s profile shape – in this case a thin film.
- Cooling is typically achieved by pulling the film through a set of cooling rolls (calender or “chill” rolls). In sheet extrusion, these rolls not only deliver the necessary cooling but also determine sheet thickness and surface texture, or embossing.
- In addition to producing extruded film, Snyder Manufacturing has the capability to produce extrusion laminated fabrics. These fabrics can include nylon or polyester scrims (which we produce ourselves), or we can also use non-woven fabrics. We also have the capability to produce two-ply fabrics, such as vinyl laminated to felt, in addition to our three-ply vinyl laminated fabrics. The advantages of extrusion lamination include wider widths (up to 76” wide) and lower weights since adhesives are not needed to achieve lamination.