Regarding twin screw extruders, Torque is one of the most important factors. Torque refers to the amount of force that is applied to the screws to move them around. In a twin screw extruder, high torque twin screws and low torque twin screws are two different types of machines used for different purposes.
Meanwhile, their difference lies in the torque they provide, and their applications vary depending on what type is used. This article will discuss the differences between high-torque twin screw extruders and low-torque twin screw extruders and how to choose the right one for your application.
What is Torque in a Twin Screw Extruder?
Torque is a critical feature of the twin screw extruder, describing the force required to turn one or both screws. It can also be defined as the rotational force necessary to drive the screws and mix, disperse, convey and compress material continuously.
You can determine torque based on the design of the particular extruder, such as its rotor length and the number of lobes, as well as operating parameters like screw speed, temperature, and feed rate together, torque and pressure developed in an extruder barrel controls production output. High torque is usually preferred because it reduces wear on components while producing a better quality product with greater consistency.
Meanwhile, to get optimum performance from your extruder, it is important to use the correct amount of torque. Under-torquing results in poor performance, while over-torquing can needlessly reduce efficiency and increase wear on critical parts.
Practically, torque must be properly matched with the screw speed, back pressure, and the specific materials being processed to maximize the extruder’s capability and ensure an outstanding end product.
Understanding torque in a twin screw extruder is essential for creating an efficient and versatile manufacturing system.
High Torque Twin Screw Extruders vs Low Torque Twin Screw Extruders
Regarding twin screw extruders, a key distinction is the difference between high torque and low torque varieties.
Design: High torque extruders are typically used for processing difficult materials, such as high-viscosity compounds and plastic alloys. Low torque versions can process lower viscosity resins but are better suited for continuous production runs with a single material.
Screw diameter: High torque versions have larger screw diameters, up to 150 mm, which allows them to handle higher shear rates. They are also equipped with powerful motors that generate greater torque and, as a result, can achieve higher production speeds than low-torque extruders.
Low torque extruders have smaller screw diameters and up to four lobes, two for each screw. They also tend to be compact, making them a cost-effective choice for small and medium-sized operations.
Rotor design: Based on their rotor, high torque twin screw extruders have a longer and stronger rotor. This makes it easier to generate a higher torque output. The longer and stronger rotor also means that the screw can handle more material, thus making it ideal for larger-scale production.
On the other hand, low torque twin screw extruders have a shorter and weaker rotor. Hence, it delivers a lower torque output and handles lesser material, limiting its output to smaller applications and materials.
Heat transfer: High torque twin screw extruders typically operate at high torque and speed. Their higher torque output allows them to mix and process materials faster, leading to a greater amount of heat being generated in the barrel.
In contrast, low torque twin screw extruders generate less heat, making them suitable for longer use without overheating. Since they produce less torque and process materials at a slower rate, does not generate as much heat. Moreover, low torque options work mostly in applications that require lower temperature settings to complete their tasks, thus minimizing the risk of overheating.
How to Choose the Right Torque Twin Screw Extruder?
Several factors should be considered when choosing between high-torque and low-torque twin screw extruders. Check out the below factors to consider when choosing the best torque twin screw extruder:
1. Application
What type of application do you need to use the twin screw extruder for? For instance, if you are looking for a machine that can handle high-volume production, then a high-torque twin screw extruder would be suitable. However, a low torque twin screw extruder would be a better fit if your needs are lightweight tasks and low-temperature settings.
2. Output
What is the output of the material you are working with, and how much torque do you need to process that amount? Since high-torque twin screw extruders can generate more torque than low-torque ones, they should be considered for larger-scale production needs. On the other hand, a low torque twin screw extruder may be the better option when dealing with lighter-duty tasks.
3. Size
If space is limited or weight is an issue, then a low-torque twin screw extruder might be the best choice as they tend to have smaller sizes than high-torque ones.
4. Cost
High-torque twin screw extruders are more expensive than low-torque ones due to their ability to process materials faster and generate more torque. Considering the cost, consider a low-torque model that can still meet your processing needs.
5. Maintenance
High torque twin screw extruders require higher maintenance than low torque ones due to their higher operating speeds and larger size. Where time or resources for regular maintenance is problematic, then a low-torque model might be your best choice.
6. Flexibility and Durability
Whether you are looking for low or high-torque twin screw extruders, consider material make and robust construction that enhances durability. Also, check for additional accessories like screw designs that offer greater flexibility.
Once you have compared the different characteristics of high and low-torque twin screw extruders, you can decide which one best suits your needs. While a high-torque twin screw extruder may be suitable for larger-scale production applications, a low-torque model can still be a great choice for lightweight tasks or small batches. So, research and select the best torque twin screw extruder that fits your specific needs.
Final Thought
In conclusion, both high-torque and low-torque twin screw extruders have their own merits, so it is important to carefully consider all factors before selecting the best one for you.
Furthermore, regular maintenance and monitoring of the machine’s temperature are essential for a successful operation. With careful consideration, you can select the torque twin screw extruder to meet your processing needs.
