What is Plastic Extrusion?
Have you ever questioned how composite windows, vinyl fencing, or freezer gaskets are made? These products and many others are produced using a high-volume manufacturing process called plastic extrusion.
The Plastic Extrusion Machine
For plastic extrusion to take place an extruder is the core piece of equipment for this manufacturing technique. Extruders involve mainly of these components:
A manual or vacuum hopper: Holds and feeds the raw plastic materials.
A long barrel: Involves a screw-like mechanism that pushes the plastic through the barrel.
External heaters: Maintains the desired temperatures inside the barrel.
A die: Forms the profile of the plastic part being manufactured.
Benefits of Plastic Extrusion
The process of Plastic Extrusion is continuous and can, therefore, establish a high-volume output. This makes it perfect for businesses that find themselves with high demand during particular times or if the output of the company has increased quicker than its internal equipment and procedures have developed. In addition to that, plastic extrusion is perfect for parts that are consistent in wall thickness, alongside with any profiles that are longer and wider than those created by other forms of plastic manufacturing. Plastic films, rods, bags, piping, weather stripping and deck railing are just some of the products that are created successfully and economically by plastic extrusion.
Types of Plastic Extrusion
Below listed are different types of Plastic Extrusions
Sheet (Film) extrusion
This type is utilized for the extrusion of plastic sheets or films that are too thick to be blown. After exiting the die, the sheets are pulled and chilled through a series of cooling rolls, which also adjusts the sheet thickness.
Blow film extrusion:
Blow film extrusion is used to produce plastic films tubes through a continuous sheeting. In this procedure the film tube melt is cooled before leaving the die, creating a semi-solid tube and puffed to expand to a required size and film thickness. Blow film extrusion is used for manufacturing of products such as shopping bags.
Over jacketing extrusion:
This extrusion type is used for wire coating. In this process the wire is pulled through the centre of the die. If adhesion is required between the wire and the coating, pressure tooling is used. In this method the wire is covered in molten plastic whilst in the die and is pressurized when exiting the die. If adhesion is not required, jacketing tooling is used. In this method, the wire is covered by the melt as it exits the die.
This extrusion type is used for the extrusion of tubes and pipes. In this process, air with positive internal pressure may also be applied. The tubes or pipes after exiting the die are pulled into a cooling tank were they are normally water-cooled.
In the co-extrusion procedure two or more materials are pressed through the same die into a single piece. When several plastics are merged, the end result can yield properties distinct from those of a single material which is why manufacturers would use this method. One of the ways co-extrusion is used is in the vinyl fencing industry, where co-extrusion is used to tailor the layers based on whether they are exposed to the weather or not.
In the extrusion coating process, the blown or cast film method is utilized to coat an additional layer onto an existing roll stock of paper, foil or film. One use of this method is to enhance the characteristics of paper by coating it with polyethylene to make it more resistant to water. The extruded layer can also be used as an adhesive to bring two other materials together. A famous product that uses this technology is Tetrapak.
What is Plastic Extrusion Used For?
Plastic extrusion is used to create a wide range of products on the market today, from building materials to consumer products to industrial parts. Pipes, tubing, window frames, electrical covers, fence, edging, and weather stripping are just a few of the common items made by plastic extrusion, along with thousands of custom profiles.
Plastic Extrusion Profiles
Profile extrusion is extrusion of a shaped product that can be a range of configurations but does not consist of sheet or film products. Profile extrusion can include solid forms as well as hollow forms. Products ranging from tubing to window frames to vehicle door seals are manufactured this way and considered profile extrusion.
Plastic profiles are available in a wide range of shapes and sizes including shapes such as thin film, rods, wire sheets, trim, channels, rods, tubing and gaskets.
Plastic profile extrusions can be hot extruded, cold extruded or warm extruded through a die in either indirect or direct extrusion process. Each of these processes has its own benefits and drawbacks.
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