How to Increase the Throughput of Your Twin Screw Extruder Machine

How to Increase the Throughput of Your Twin Screw Extruder Machine

Twin screw extruder machines are popular processing machines in the food, chemical and pharmaceutical industries. They are used for mixing, compounding, and shaping different materials to suit the varying needs of different industries. However, increasing throughput without compromising on product quality has remained a challenge to many twin screw extruder operators. In this article, we will show you how to increase the throughput of your twin screw extruder machine.

Understanding the Twin Screw Extruder

A twin screw extruder machine is designed to process materials by forcing them through a barrel using two interlocking screws. Depending on the extruder configuration, the screws can be co-rotating or counter-rotating. The materials are simultaneously mixed, transported, and shaped as they move from the feed zone to the die. The critical parameters that affect the screw efficiency include screw length, diameter, pitch, material feed rate, screw speed, and shear rate.

Increase Material Feed Rate

The first and most natural way to increase the throughput of your twin screw extruder machine is to increase the material feed rate. The higher the feed rate, the more material you can process in a shorter time. However, it is essential to note that increasing the feed rate will also increase the torque and power requirement of the extruder drive. You will need to adjust the screw speed and temperature profile to achieve the desired product quality.

Optimize Screw Speed

The screw speed is the rate at which the intermeshing screws rotate within the barrel. The screw profile, diameter, and pitch determine the screw speed required to achieve an optimal material transport and mixing efficiency. If the screw speed is lower than the recommended level, the material residence time will increase, leading to degradation, product inconsistency, and reduced throughput. If the screw speed is too high, the material flow rate will exceed the extruder capacity, leading to material bridging, a decrease in product quality, and machine damage. Finding the optimal screw speed balance is essential in increasing the throughput while maintaining product quality.

Improve Temperature Profiling

The temperature profiles of the barrel and screw zones determine the material flow properties within the twin screw extruder machine. The temperature profile affects the material viscosity, elastic modulus, and the rate of chemical reactions if any. The optimal temperature profile for a given material depends on its processing and functional requirements. A properly designed extruder should have temperature sensors and heating/cooling controls for each zone, allowing for better temperature profiling. An efficient temperature profile will ensure that the material flows through the extruder uniformly, improving product quality and increasing throughput.

Adjust Shear Rate

The shear rate is the rate at which the material moves relative to the liner wall in the barrel. At low shear rates, the material flow properties become viscous, resulting in increased residence time and lower throughput. On the other hand, high shear rates result in reduced viscosity, reduced residence time, and higher throughput at the cost of product quality. The optimal shear rate for a given material mix should be determined by experimentation based on the desired product quality and the required throughput.

Use Additives

Different additives such as flow enhancers, foaming agents, and plasticizers can be introduced into the material mix to improve their processability and increase throughput. Flow enhancers are designed to reduce viscosity, improve mixing and increase throughput. Foaming agents reduce overall material density, making it easier to process and handle. Plasticizers improve the material elasticity and stretching, leading to a higher quality product.

Conclusion

Increasing the throughput of your twin screw extruder machine requires understanding the interplay between the machine, the material mix, and the process conditions. By increasing the feed rate, optimizing the screw speed, improving temperature profiling, and adjusting the shear rate, you can increase the output rate while maintaining product quality. It is vital to remember that increasing throughput requires additional power, and machine damage can occur if you exceed the machine's capacity.