What is Extrusion?
Extrusion is placing material in a unique tool and process. Then, it can produce a continuous object with a fixed cross-sectional profile.
What is Plastic Extrusion?
The versatile nature of plastic has made them everywhere. It has longevity and needs simple manufacturing requirements. Injection molding and plastic extrusion aid in producing high-volume products. Extrusion is standard for profiles continuously entailing pipes, doors, and other bulky items.
This process involves melting a plastic material. Then, the molted form is passed continuously through a die. The product is later cut into the desired length. The process needs a cross-section. It has a low cost of production with a high production rate. Hence, plastic extrusion has become popular with manufacturers.
This article will help you learn more about plastic extrusion, its products, and how it has helped manufacturing industries. Stay tuned until the end.
What Does the Plastic Extrusion Process Entail?
What are the extruder parts? Before diving into the process, it’s best to have a basic understanding of the extruder parts. It will aid in having a clear picture of the process.
There are crucial parts in an extruder for its functionality. There is a hopper where raw material is kept, and it connects to a feed throat. It receives plastic pellets from the barrel. A breaker plate filter will feed the raw material through screening as it maintains the pressure inside. A filter pipe is connected to deliver the molten material to a die. Once it receives the products, this die shapes it to the required shape. It is later placed in a cooling system that solidifies the extruded plastic evenly.
The processing starts when the cooling ends since the product needs to be in a solid shape. The raw material is fed in a hopper, which has the usual form of a flake and pellets. Due to the force of gravity, the raw material moves to the feeder’s throat barrel. It can help to heat. During the heating period, the matter is passed through three different zones with higher degrees of heat than the previous.
Heating helps in melting the plastic, with the molten form being pushed to the die at the end. A motor-driven screw aids this process. The pressure produced in each step helps lower the need for heat in the other zones with too much heat. So that can save electricity.
The molten material passes the barrel to the screening filters, where any impurities are filtered out. It increases the purity state of the material to be used. At the screening stage, the pressure is too high. Hence, there is a need for a broken plate that helps avoid any spillage. There is a customized-built die that is piped through the filtered material.
There is a pre-machined opening which is specialized in the extrusion process. The process is completed once the material enters the die, taking the required shape. The material is then placed in a cooling machine to help it solidify evenly. The process might seem straightforward, but it requires concentration to minimize errors. If the errors do not occur, the end product will be high quality. It was, finally, generating better income for the organization.
Different Types of Plastic Extrusion Processes
Plastic extrusion processes depend on the die to be used. The fundamental function of plastic extrusion remains. And the only thing to differentiate is the complexity and shapes with which one deals. Below are four types of plastic extrusion as per the industry today.
Tubing Extrusion
As per the name, the process entails long tubes, pipes, and other related items. The process might seem easy, but the tricky part is producing hollow equipment. Despite these challenges, the extrusion process remains unchanged until you reach the die. After arriving at the die stage, the method uses positive internal pressure. This method aids in overcoming the higher power need that deals with hollow parts. Once the power has been controlled, the final results are surprisingly great to the eye.
Blow Film Extrusion
This process is widely used. Because it helps to create many everyday-to-day items like shopping bags and other packaging materials. The process is just like other extrusion processes. However, the difference is in the final stage of the die. Before leaving the dice, the material must undergo a cooling process.
At that cooling stage, the material does not solidify completely. Hence it must pass through an additional process called expansion through blowing. The only limitation is that the operation can only accommodate thinner plastic films. For thicker sheets, one has to go through other processes.
Sheet Film Extrusion
This process is like blow film extrusion. But it only works on workpieces that are too thick for blowing. Ultimately, the material passes through the pulling and rolling process to provide the shape needed. The rolling process cools down the plastic, allowing it to solidify permanently. This method helps produce ice cream boxes, juice cartons, wine boxes, and other plastic packaging. That can be conducted efficiently.
Jacket Extrusion
This process is carried out to produce insulating wires and other cover jackets that require plastic. The process is simple, and one needs to pull the material that involves coating during the die stage. Adhesive can also be used to give the product a long-lasting span.
What Are the Materials Used For Plastics?
Several thermoplastics are used in the plastic extrusion process. The thermoplastic is heated to higher temperatures. It cannot cause thermal decomposition but can cause them to melt. Temperatures vary from one thermoplastic to the other. This process is additionally used to prepare the recycling of plastic waste. The final product is then cleaned, sorted, and blended into filaments of resin pellet stocks.
Here are some of the materials used in this process:
- Polypropylene which melts at 450 degrees
- Polystyrene, which melts at 450 degrees
- Nylon which melts at the range of 450- 520 degrees
- Polyethylene, which melts at 400 degrees
- PVC, which melts at the range of 350- 380 degrees
These are some of the materials being used in the production of plastic. Most of the materials contain a polymer for faster production of plastic. This shows that the highest percentage of plastic includes a polymer atom.
What Are the Applications For Plastic Extrusion?
This process of plastic extrusion helps in the manufacturing of many parts. The final products are ideal and are used where a consistent profile is needed.
Wire Insulation
Thermoplastics have high stability and insulation to electricity. This property gives them the upper hand for extruding cables, wire insulation, and jacketing. Additionally, some fluoropolymers can be used in a similar case.
Tubing and Piping
The final products can be designed in a cylindrical form used in tubing and piping. Because they are the final product of the extrusion plastic. The material used here is PVC due to its sturdiness. Here is an example of extruded tubing and exterior gutter.
Weather Stripping
Some materials are designed to fit near door or window frames. For example, a draft uses rubber and can be used in weather stripping material.
Blinds
Multiple identical slats can be used as window blinds when they need repeating. This task can be done quickly by an extruder. Additionally, their profiles contain a short length which is the wrong round end.
Windshield Wipers
These are wipers installed in a vehicle to shield the wind. The material is made from ethylene propylene methylene. There is also another way to co-extrude synthetic rubber with natural rubber.
The above uses are just among the many benefits plastic extrusion can give society. Once some arise, one will have to add.
Comparison Between Plastic Extrusion and Aluminum Extrusion
The extrusion process occurs not only in plastic but also in other materials like aluminum. The extrusion process depends on which final product is needed and what the use is.
Aluminum has soft characteristics, which makes it a highly malleable metal. This characteristic makes it easy to extrude it in a continuous profile. Unlike plastic, aluminum has an upper advantage due to its conductivity, lightness, and recyclability nature. The parts that can be extruded for aluminum include tracks, frames, piping, bars, and wires.
The significant difference between aluminum and plastic extrusion is the operating temperatures involved. Temperatures range from 350- 500, and the cold extrusion occurs at room temperature. Other differences are interesting, but that’s a topic to be carried out in the following article.
Conclusion
The plastic extrusion process has its advantages and disadvantages. The benefit includes cost-effectiveness, unparalleled flexibility, and alteration. The extrusion process is the best and can help produce more plastic using the proper procedures. Thanks for staying tuned till the end. See you next time. Thank you.