The plastic extrusion machine is highly useful when it comes to utilizing plastic materials. Manufacturers use it to create plastic pipes and plastic sheets, among other products such as packaging film and wire insulations. But what exactly is a plastic extrusion machine? Our guide starts with the extruder meaning, a look at the parts that make it, and the cost of buying one.
What is an Extrusion Machine?
A plastic extruder is just one of the many types of extruders out there- and one of the most popular. In order to define it, there’s the need to understand extrusion machines in general. The extrusion process, too, how it happens, and why it’s such an important industrial technology for manufacturers. So, what is an extrusion machine?
An extruder, as the extrusion machine is also called, is a type of device that pushes material through a die to form or create a continuous profile. It has an important role in the industry: it can make almost any shape you desire, and its production process is both low-cost and efficient.
Basically, the extruder function is to heat and compress the material before forcing it through a predetermined orifice to shape it. This happens through the use of a rotating screw (or reciprocating plunger) made from hardened steel, and a shaped opening placed at one end. Common extruders include food, metal, rubber, and plastic extruders.
The plastic extrusion machine is one of the most common extruder types. It pushes plastic through a die, and voilà! You have plastic products. Before we can focus on the plastic extruding machine, let’s have a brief look at what extrusion means and how it happens.
By now, you must be asking what extrusion is all about and why it’s a much-used manufacturing process. Well, extrusion is just a simple manufacturing method that shapes a material (heated or cold) through a die to create a specific product (extrudate).
The extrusion process begins with a single type of material or mixed materials. The material is then metered into and transported down a barrel where it’s forced out of a die with the help of either screw or ram plunger.
The extruded material has many applications in everyday life such as automotive, sports equipment, construction, for food such as pasta, packaging, and more. Now, onto the plastic extrusion machine definition, its function, and construction.
The Plastic Extrusion Machine
A plastic extrusion machine is a type of industrial device that shapes molten plastic into various types of products such as rods, tubes, profiles, and many more other geometric shapes. During the extrusion of plastic materials, the machine softens plastic beads or pellets (sometimes even powder) plasticizing and preparing them for forming into tubes or profiles.
A plastic extruding machine is often used to make these products depending on the shape of the die, the type of plastic, and other factors.
- Feedstock for manufacturing processes such as plastic sheet thermoforming, plastic lamination, and so on.
- Piping or hollow plastic products for different applications such as gas pipes and drain pipes, water pipes, and even the tubes and hoses used in cars.
- Plastic insulation for electric wire cables, communication systems, etc.
- Plastic sheets used for sound barrier installations, light fixtures, and window glazing
- Plastic film and nets used for packaging products
- Filaments for ropes, twines, and for producing brush bristles.
- For making a wide range of profiles to use in the construction industry, automobiles, and more
- To recycle waste plastic into raw materials or finished products
Plastic Extrusion Machine Parts
The plastic extruder machine is composed of several major parts. Depending on the manufacturer and their needs and size, some will incorporate more parts than others. The major components of a plastic extrusion machine include those listed below.
- Extruder drive
- Screw (or plunger in a ram type)
- Barrel heaters
- Cooling system
- Screen and breaker plate
The extruder drive system is responsible for powering the screw that moves material through the barrel. In most extrusion machines, the drive consists of an electric motor to provide the motion, a gearbox/system to reduce the motor speed and increase torque, and the controls or switches. The extruder motor can be an AC or DC type. In some machines, especially the plunger types, hydraulic or pneumatic systems are used.
The extruder hopper is the part that feeds material into the screw channel. The design varies depending on the size and model of the extruder. The material is fed into the hopper from a storage source, usually via a conveyor belt. To enhance the flow of material, the extruder feeder or hopper is sometimes equipped with a vacuum source and vibrating or stirring components. A cooling system is also often incorporated to prevent the material from melting prematurely.
The extruder screw is a long shaft that has ridges or threads on the outside. These threads rotate and push the plastic pellets through the barrel, pushing them into a melting zone on the screw where they will be melted down to liquid form. Twin-screw machines use two screws to push the material forward. In a single screw extruder, the material is moved by a single screw. Extruder screws connected to the motor, which turns the screw at a very specific RPM (revolutions per minute).
The extruder barrel is the section of the extruder that contains both the screw and the die. It is made from a strong, wear-resistant metal alloy, making it strong enough to withstand the high pressure that builds up inside it, which creates friction and heat. In most cases, the extrusion barrel also houses a series of band heaters and thermocouple system to heat the plastic, sometimes also cooling fans to lower extrusion temperatures if too high.
Extruder Barrel Heaters
Extruder barrel heaters are placed around the barrel to provide the temperature that will melt the plastic. The extruder heating system is usually either electrical or fluid-based using water or steam. Most extruders use electrical heaters: they’re more versatile, efficient, and low cost. The heaters can be conductor resistance or induction based. On the other hand, fluid heaters are more expensive and bulky but more effective when it comes to uniformity in the distribution of heat.
Extruder Barrel Cooling System
An extruder barrel is exposed to high heat due to the friction created by the screw running along its inside. If it gets too hot, it can cause problems with some materials or even damage to the machine. To help control the temperature, an extruder barrel cooling system that features water nipples or jackets positioned around the barrel. Cooling fans may also be used. These blow and circulate air to cool the barrel and protect the plastic.
Extruder Screen Pack
Extruder screens are filtering pieces that are arranged just before the die. Their purpose is to help with removing contaminants or solid particles from the plastic melt. The extruder screen pack is also usually reinforced with a breaker plate made of metal. The extruder breaker plate supports the delicate screens while also helping create backpressure in the melt. Its other function is to stop the spiral motion of the liquid plastic, aligning it in a straighter flow in readiness for extrusion.
Also called the extruder nozzle, the die is the section of the extruder that forms, or ‘extrudes’, the final shape into a solid piece. The extruder die design depends on the expected form of the extruded part or its end-use. Some of the most common dies are film or sheet dies, blown film dies, pipe/tubing dies, co-extrusion dies, and profile dies. Extruder dies may also be customized parts, depending on the requirements of the extruded product.
Some plastic extrusion machines also include a vent. These are machines that use more than three extrusion zones. As the material moves along the screw and gets heated plastic volatiles are created. These gases (including moisture) are normally removed by adding an exhaust system (vent) to the extruder. The extruder vent consists of an outlet positioned near the end of the screw channel.
Extruder Control System
The extruder control system consists of physical switches, power buttons and in most extruders today, a touchscreen or control panel. These help the extrusion machine operator to set extrusion parameters as well as monitor the various operations. The controls help manage temperature regulation, die sizing, set auto processes, and many other things.
Plastic Extrusion Machine Price
Plastic extrusion machines vary in price depending on the size and also the brands. A basic machine that is ideal for smaller production runs can be purchased for $1,000, or even less. The machines in this group include small extrusion machines such as a lab plastic extruder, bench top plastic extrude, and a variety of other compact machines.
A large, extrusion machine plant will cost several thousand dollars. For example, if you are looking to buy an industrial extrusion machine line and all its support equipment, you may need to spend up to $15,000 or more. Generally, the plastic extruder price is dependent on these factors:
- Machine size (small or large)
- Capacity (kg/hr) or production output
- Number of screws (single or multi-screw)
- Level of automation (mechanical, electrical, and electronic)
- Number of stations for cooling and other processes such as cutting
The plastic extrusion machine price also depends on the brand. There are several producers on the market. These will set different price tags for the same type of machine and for different reasons such as quality, design, and other differences.
Every manufacturer will have the specifications of their extruders spelt out on their websites. Our advice is to check the cost from different producers so you can get the best deal possible for your quality needs and budget. Better still, we suggest contacting extrusion machine suppliers directly for in-depth information about their machines.
The plastic extrusion machine is a one of the most use machine in the manufacture of plastic products. This first part has covered the extruder meaning and working, in addition, to providing you with an overview of the extrusion process. You also now have an idea of the extruder parts and their function. The estimated extruder cost, too, if you’re looking for one. In our next section, we will provide more information on the different types of the machine.