Consider this guide to the extrusion process.
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At Creatingway, we consider plastic extrusion as important as injection molding in today’s plastic industry. The process generally involves melting plastic material, then forcing its molten form through a die continuously. This forms a continuous profile that is then cut depending on the desired length. The process is a great choice for applications that need a constant cross-section. It is also of low cost with high production rates, making it a popular choice with manufacturers. Examples of such products include door profiles, pipes, and tubing.
The Plastic Extrusion Process, Types of Plastics, and Applications.
What’s The Plastic Extrusion Process?
First, you need to know the parts of an extruder to get a clear picture of the process works. An extruder contains several parts that are crucial for its function. It has a hopper where we keep raw material. A feed throat for receiving the plastic pellets from the hopper into the barrel. Then a breaker plate that filters the fed material through screens while also maintaining pressure. A filter pipe that delivers the molten material into the die. Next to it is the die that shapes the molten plastic into the wanted extrusion profile. Lastly is the cooling system that solidifies the extruded plastic evenly.
The plastic extrusion process begins by filling the hopper with raw plastic. It is usually in a solid-state initially. The common form is flakes and pellets. Then the material goes down the feeder throat due to the force of gravity. Once in the barrel, heating begins. We do it in three or more zones with each zone being hotter than the previous. This ensures proper melting of the plastic. While we heat, we simultaneously push the molten plastic towards the die’s end. This is through the help of a motor-driven screw. The pressure generated during this step generates heat lowering the need of heating the hot zones too much. This translates to saving on electricity use.
The molten material then exits the barrel and passes through a screen. This screen filters contaminant present in the material. It, therefore, increases the purity of the raw material to be used. We also reinforce the screen with a breaker plate to avoid spills from occurring due to the high pressures present. The filtered material goes through the feed pipe that connects it to a custom-built die. We would have pre-machined it according to your specifications making an opening of the exact extrusion profile quoted. the material takes shape of the die once it is forced through it, thus completing the process. we finish off the process by cooling the extruded material using a set of cooling rolls for solidification to occur evenly.
What’s The Plastic Materials?
The plastic extrusion process works with several thermoplastics. We heat to high temperatures enough to melt them but not cause thermal decomposition. The temperature may vary from one thermoplastic to the next. Additionally, we use the process to prepare recycled plastic waste. Then we clean, sort, and blend into filaments for blending into resin pellet stocks.
Here are examples of the common plastics used:
Polypropylene melts at 450oC
Polystyrene melts at 450oC
Nylon melts 450oC – 520oC
Polyethylene melts at 400oC
PVC melts at 350oC – 380oC
What’re The Applications of Plastic Extrusion?
Many companies make use of the process to make many parts. as mentioned, it is ideal for final products that need a consistent profile. Here are some we make.
Thermoplastics have excellent thermal stability and electrical insulation. This makes them appropriate for extruding cable and wire insulation and jacketing. Additionally, fluoropolymers can be used for a similar purpose.
Tubing and Pipes
the parts have a simple cylindrical profile. therefore, they are relatively easy to make using the extrusion process. the material used is PVC due to its sturdiness. an exterior gutter is also an example of extruded tubing.
These are products designed to fit near door or window frames. For instance, a draft uses rubber as the source of weather stripping material.
Window blinds consist of multiple identical slats that need repeating. An extruder can do this with ease. Additionally, their profile is short lengths and one-sided round ends. We preferable use polystyrene due to its lightweight to make blinds.
These are the tireless window wipers of a vehicle’s windshield. A synthetic rubber material such as ethylene propylene diene methylene makes them. Another way is by co-extruding synthetic rubber with natural rubber.