In the plastics manufacturing process, pellets are used as raw materials in order to create a wide range of finished products. As an additive manufacturing technique, pelletizing is used for converting raw materials into small pellets that can be used directly or further processed into end products. In different plastic manufacturing processes, there are many ways to create pellets from raw material.
Whether you are looking for a manual or automated system, understanding all your options will help you find the best pelletizing machine for your needs and budget. In this article we discuss everything you need to know before investing in a new machine.
What’s a Plastic Pelletizing Machine?
A plastic pelletizing machine is a device that can process raw materials to produce small pellets that can be used as feedstock in further manufacturing processes. The pellets are often spherical in shape, but can also be cylindrical.
Pelletizing is typically done with a range of different materials, including thermoplastics such as polyethylene and polypropylene, thermoset materials such as epoxy resins and phenolic composites, and even materials like ceramics or metals that are processed to create granules. These feedstocks can then be used for injection molding, extrusion, and other manufacturing processes.
Pelletizing machines are often used in the plastics industry to create feedstock for downstream production processes. Pellets are created by a rotating screw that pushes a process material from a hopper and through a rotating screw in the center of the machine. As the material is being pushed through the screw, it is subjected to high pressure and shear forces, which causes it to break down into smaller particles which make it easier to process.
Why Use a Plastic Pelletizer?
Before even considering the different types of equipment, it is important to understand the why behind the need for a pelletizing machine. In short, pellets are easier to process than other forms of plastics, making them ideal for automated manufacturing. They’re also easier to store and transport, which makes them more economical, and they can be used in many different forms of manufacturing processes, including injection molding, extrusion, and pelletizing of granules.
The process of converting plastic into pellets maintains its chemical composition, which means it is easy to recycle and reuse. Pellets also have a higher density than granules or flakes, meaning they take up less space, which is beneficial in terms of storage and transportation. For these reasons, pellets are the most commonly used form of plastic feedstock.
Things to Consider Before Buying a Plastic Pelletizer
- Capability – You need to understand the maximum capacity of your machine, which can vary depending on the type of equipment you are using. Make sure to choose a machine that can handle the volume of material that you will be producing.
- End product -Before choosing a pelletizing machine, you need to understand the end product you are planning to create. While many different types of materials can be fed into a pelletizing machine, they can all be processed into different types of pellets.
- Feedstock – After deciding what type of pellets you need to create, you need to determine what material you will use as feedstock. Typically, different types of plastics, ceramics, or metals are used as feedstock for pelletizing.
- Price – While you should always consider your budget, be aware that not all pelletizing systems can be purchased at the same price. Depending on the type of equipment, you can expect to pay more for different types of pelletizing machines.
Single Screw Pelletizing Machine
A single screw pelletizer is a type of equipment that uses a single screw to process feedstock. The screw rotates, and the material inside the machine is moved by static forces, which makes it a static machine. A single-screw pelletizer has a single rotating screw inside the machine that pushes the material through the machine, which causes it to break down into small pellets. The speed of the screw, the temperature of the screw, and the pressure inside the machine can all be manually adjusted to help ensure the proper degree of break down.
A single-screw pelletizing machine is ideal when there is a small amount of feedstock that needs to be processed. The machine is also commonly used to make other types of granules from scratch. A single-screw machine typically uses a low pressure in the machine, making it a low-cost option.
Double Screw Pelletizer Machine
A double-screw pelletizing machine is a static machine that uses two rotating screws to process the feedstock. Different sections of the feedstock are moved with the rotating screws, making it possible to process multiple materials at the same time. One screw inside the machine pushes the material to create pellets, while the other moves granules. Double-screw machines usually use a higher pressure than single-screw machines, which leads to a higher degree of break down.
Double-screw pelletizing machines are commonly used to process different types of feedstock, including plastics, ceramics, minerals, and even wood. These machines are ideal when you need to process a high volume of feedstock, or when you need to process different types of materials in one batch.
Pros and Cons of a Plastic Pelletizing Machine
Pros
- Pelletizing machines are used to convert raw material into pellets, which are a more easily transportable and processable form of plastic.
Cons
- While pellets are easier to transport and process than granules, they are also more expensive.
- Many pelletizing machines are also static, which means they need a constant flow of material to process.
- Static machines are not designed to be used with intermittent feedstock, such as a batch that is manually added at the beginning of a shift.
- Depending on the type of equipment, it can also be difficult to change the speed of a pelletizing machine.
How does a plastic pelletizing machine work?
A plastic pelletizing machine works by breaking down the raw materials into smaller particles which are then fed into a pelletizing machine. The feedstock is then put under pressure through the use of rotating screws so that the particles are made smaller and more uniform in size. This makes it easier to be used in the manufacturing process because the consistency is more accurate. The material is then pushed out of the machine through a die head where it is given a certain shape and then fed into a hopper. There are different types of plastics pelletizing machines on the market and each one works a little differently.
For example, a single screw machine uses one rotating screw to push the feedstock through the machine, while a double screw machine uses two rotating screws. These machines are commonly used to process a variety of materials, including plastics, ceramics, minerals, and even wood.
Manual or automated equipment?
Some equipment is manually operated, while other types are automated, meaning they are computer controlled. While more expensive, automated machines can be easier to use and have more features, making them ideal for larger facilities. Manual equipment may be easier to operate and offer lower initial costs, but it also requires more effort and attention.
Price point: What you should expect to pay
The type of equipment you choose will have a large impact on the price you pay for your pelletizing machine. Single-screw machines are the least expensive option, while double-screw machines are the most expensive. If you work with a pelletizing equipment supplier, be sure to shop around. Some companies will offer installation, maintenance, and repair services with their equipment, which makes it easier to budget for the long-term cost of your equipment.