Plastic extrusion is a process whereby plastics are melted and joined to form a continuous profile. The extrusion machinery produces pipes, window frames, weather stripping, plastic films and wire insulation among others. In the plastic extrusion process raw thermoplastic material is fed into the extruder’s barrel through the mounted hopper.
This process is in a way similar to the plastic injection molding in terms of extrusion technology. The material that is fed into the barrel moves by gravity and reaches the rotating screw which forces the plastics into the barrel which has been heated to the required temperature. The plastic beads are the melted by the barrel in a gradual manner under controlled temperature. Plastic, which is molten gets out of the plastic extruder screw and goes through a screen pack which eliminates contaminants, and into the plastic extruder die which produces the final results. After these the end product is cooled using a water bath. Plastic extruders are mostly used in preparing recycled plastic wastes and materials after they are cleaned, sorted and chopped into resin beads.
The Blow Film Extrusion
The blow film line is mostly applicable for general plastics and can give various ranges of or forms of film extrusions. The blow film line is designed in an upright or horizontal manner to cater for upward, downward and horizontal extrusion. Blow film extrusion can be used to make single large films, two smaller films or even tubes that can be transformed into bags.
The blow film extrusion process is made of four main stages: the polymer in form of pellets are melted together forming a viscous fluid which is continuous. In the molten state the material is forced through an annular die. Injection of air is done midway the die causing the melted extrusion to form a bubble which is uniform in thickness. This is followed by pulling upwards the bubble from the die and the film cooled from inside to give the bubble uniform diameter. The bubble is then passed through a roller in the blow film line and gets flattened making two flat films. The multilayer blow film line is suitable for food packaging and industrial products, and agricultural and technical applications.
The Future Market for Blown Film Extrusion Machine
There has been a constant growth in the manufacture of high quality plastic extrusion machines with new designs been proposed especially for the flexible packaging industries. Market demand for plastic extrusion machinery is consistently on the increase meaning that in the future it is expected that plastic extrusion machines will be made with more sophisticated features including incorporation of more layers in composite plastics.
The multilayered structures provide more value and growth in the industry. Marketing demands in the recent past has been increasing especially in the food processing and packaging industry. Future markets will embrace more of the possible nine layered blow films which will produce even more properties such as flavor and aroma preservation, sunlight resistance, excellent barrier effect and good sealing properties. Increased extrusion machinery layers are composed an organized and complex blown film plant which must be maintained frequently.