· Temperature Control
To ensure that the final materials won`t degrade or become weakened, it`s essential to maintain a consistent temperature inside the extruder`s barrel. Overheating the materials should be avoided to reduce imperfections, so typically the barrel is heated gradually from rear to front. The temperature is also maintained using a series of fan and water cooling systems before your product is extruded into a die mold.
Die Types
A die mold is useful in plastic extruders because they can create one continuous extrusion that can then be cut into parts. Unlike with injection molding, which injects the material into individual molds, die molds will allow your product to be continuously made at whatever size (or sizes) you need. Depending on the type of product being manufactured, there are various types of dies that can be implemented into your process.
· Blown Film Extrusion: In blown film extrusion, typically used to manufacture plastic film or shopping bags, there are three types of dies used-annular, spider, and spiral. As the plastic leaves the die, it creates a semi-solid tube and is slightly cooled as it leaves. Air pressure is then used to rapidly expand the tube and then is drawn upward where the plastic gets stretched over rollers.
· Sheet/Film Extrusion: When plastic sheets need to be thicker, sheet/film extrusion is used employing both a t-shaped and coat hanger die. Both of these dies help to guide the plastic composite into a flat, planar output rather than a rounded tube.
· Tubing Extrusion: Similar to blown film extrusion are the dies used for tubing extrusion. You`ll typically see this type of die for products like PVC pipes.
