What is a extruding machine?
The extruding machine is one of the most popular equipments in plastic machinery for melting and extruding of polymer. As we all know, extruder machines can be divided into 2 types: single-screw extruder and twin-screw extruder. Today, we are going to talk about these two kind of extruding machines.
What Is a Single Screw Extruding Machine?
Just as its name implies, single screw extruder is the machine which has only one screw in the barrel. As extruding machine with the most consumption and the most mature technology, single screw extruder machine is widely used in the plastics processing industry. Here are three systems of the single screw extruding machine.
- Extrusion system
This system is mainly composed of feeding system, screw and barrel. It is the most important part the extruding machine. The polymer material will be melted and plasticized to form a uniform melt, and realize the transition from the soild state to the viscous fluid state.
- Transmission System
This system is mainly composed of motor, reducer and bearing. Its work is mainly to drive the screw and supply the torque required by the screw in the process of extrusion.
- Heating and Cooling System
The heating and cooling system of the extruding machine is composed of a heating device and a cooling device, which is a essential condition for the trouble-free operation of the extrusion process.
Advantages of Single Screw Extruding Machine
- Compared toa twin-screw one, a single screw extruding machine is far superior in extruding common materials.
- Single extrduder machines are much cheaper.
- The sheer force of single-screw extruding machinesis smaller.
- It can be used for operations on a variety of different kinds of materials.
- Single screw extruder has satisfactory
Disadvantages of Single Screw Extruding machine
- Due to the transport of plastic material is though friction, there are some limitations in feeding performance.
- It is difficult to mix some materias, such as pastes or powders.
What Is a Twin-Screw Extruding Machine?
Just as its name implies, twin screw extruding machine is the machine which has two screws in the extruder barrel. The twin-screw extruder is made of a transmission system, a feeding system, a barrel, and screw. There are some different criterions to divide the types of twin screw extruders. Then, let’s study it together.
(1.Intermeshing or Non-intermeshing
Intermeshing twin screw extruder means the distance between the two screw axes is shorter than the sum of the outer radius of the two screws. According to the degree of intermeshing, the intermeshing type can be divided in more detail into intermeshing and partially intermeshing types. Intermeshing twin screw extruding machine means there’s no gap between the screw flight and the roots of the other screw. Partially intermeshing type means there’s the clearance.
Then, what about Non-intermeshing type? It means the distance between the two screw axes is equal to or larger than the sum of the outer radius of the two screws, Just like the picture.
(2.Co-rotating and Counter-rotating
Depending on direction of the screw rotation, the twin screw extruding machine can be divided into the co-rotating type and the counter-rotating type. And, according to the distance between the two screw axes, there are two types of counter-rotating twin screw extruder: the intermeshing type and the non-intermeshing type.
(3.Parallel and Conical
Depending on whether the screw axis is conical or not, the twin screw extruding machines can be divided into the conical type and the parallel type, where the parallel twin screws are divided into fully intermeshing type, partly intermeshing type, non-engaged type, etc.
Advantages of Twin Screw Extruding Machine
- Better Pumping efficiency and less dependent on the flow properties of the raw material
- More efficient of mixing
- Faster and more uniform heat exchange rate from barrel surface to the material
- More uniformly distributed residence time
- Thanks to the possibility of flexible modular configuration of the barrel and the screw, the twin-screw extruding machine is a more versatile equipment.
- Twin screw extruding machine can deal with high moisture and sticky materials. I think it’s the most important advantage because it enables processing of materials that could not be handled hitherto by a single-screw extruder, such as food field.
- Self-wiping can reduce the risk of residue buildup.
Disadvantages of Twin Screw Extruding Machine
- The problem of the high discharge rate bearing device has not been handled.
- In the meshing zone, especially in the shrinking section, the barrel and the screw edge are severely worn.
- The screw and barrel of the meshing conical twin-screw extruder have relatively high processing costs.
- Due to heat generated in the barrel is small, the most of the heat is introduced from the heater outside the barrel.
That’s all for today’s article about types of extruding machine. Any questions, welcome to contact us! Thanks for your reading.