What is Twin Screw Extruder

Twin-screw extruders are developed based on single-screw extruders and are now widely used in the forming and processing of extruded products due to their good feeding performance, mixing and plasticising performance, exhaust performance and extrusion stability. Our company have numerous types of twin-screw extruders for you to choose from.

  1. The Functions of Twin Screw Extruder

Thanks to the wide range of screw and barrel designs, various screw profiles and process functions can be set according to the process requirements. As a result, twin-screw extruders can guarantee high flexibility in conveying, compression, mixing, cooking, shearing, heating, cooling, pumping and forming.

  1. The Application of Twin Screw Extruder

The twin-screw extruder can process different kinds of waste plastics into plastic pellets, which are now growing in price with a small investment and a large return. It is mainly used to process waste plastic film (industrial packaging film, agricultural film, greenhouse film, beer bags, handbags, etc.), woven bags, agricultural convenience bags, tubs, barrels, beverage bottles, furniture, daily necessities and most other common waste plastics, and is the most widely used and popular plastic recycling processing machine in the waste plastic recycling industry. It has a good development prospect both now and in the future.

  1. The Features of Twin Screw Extruder

(1) Wear and tear

Thanks to the easy opening, the degree of wear of the threaded elements and barrel bushings can be detected at any time, so that they can be repaired or replaced effectively. It is not necessary to detect problems with the extruded product only when they occur, resulting in unnecessary waste.

(2) Reduced production costs

When manufacturing masterbatches, it is often necessary to change colours and if a product change is necessary, to open the open processing area within a few minutes and additionally to analyse the mixing process by looking at the melt profile on the entire screw. The current common twin-screw extruder requires a large amount of clearing material to clear the machine when changing the colour, which is time-consuming, power-consuming and a waste of raw material. The split twin-screw extruder, on the other hand, solves this problem by quickly opening the barrel for manual cleaning in just a few minutes when changing colours, thus saving costs by using no or less cleaning material.

(3) Improved labour efficiency

When servicing equipment, ordinary twin-screw extruders often require the heating and cooling system to be removed before the screw can be withdrawn in its entirety. The split twin screw does not need to be removed, as long as a few bolts are loosened and the upper half of the barrel is lifted by turning the worm gearbox handle device to open the entire barrel for maintenance. This shortens maintenance time and reduces labour intensity.

(4) High-torque, high-speed

The current trend in the world of twin-screw extruders is towards high torque, high rotation speed and low energy consumption, the effect of high rotation speed being high productivity. The split twin-screw extruder falls into this category, with a speed of up to plus 500 rpm. This gives it a unique advantage in the processing of highly viscous, heat-sensitive materials.

In terms of high speed and high torque core technology, asymmetric and symmetric high torque gearboxes are currently only available in Germany and Japan, where the core technology can reach a maximum speed of 1800 rpm or more.

(5) Wide range of applications

Wide range of applications, suitable for processing a wide range of materials

(6)High output, high quality

With the other advantages of a common twin-screw extruder, high output, high quality and high efficiency can be achieved.

  1. The maintenance of Twin Screw Extruder

The twin-screw extruder is maintained in two ways: routine maintenance and periodic maintenance.   

(1) Routine maintenance is a routine that does not take up working hours and is usually completed during the drive. The focus is on cleaning the machine, lubricating the moving parts, tightening the threaded parts that are easy to loosen, checking and adjusting the motor, control instruments, working parts and pipelines in time.   

(2) Regular maintenance is usually done after the extruder has been in continuous operation for 2500-5000h. The machine needs to be dismantled to check, measure and identify the wear and tear of the main parts, replace the parts that have reached the specified wear limit and repair the damaged parts.   

(3) It is not allowed to run empty to avoid rolling the screw and the machine.

(4) If the extruder is running with abnormal sound, it should be stopped immediately for inspection or repair.   

(5) Do not allow metal or other debris to fall into the hopper to avoid damage to the screw and barrel. To prevent ferrous debris from entering the barrel, the material can be installed at the barrel filling mouth with magnetic parts or magnetic frame to prevent debris from falling into the material must be sieved in advance.

(6) Pay attention to the cleanliness of the production environment, do not let the rubbish and impurities mixed into the material block the filter plate, affecting the product yield, quality and increase the resistance of the head.

(7) When the extruder needs to stop using for a long time, it should be coated with anti-rust grease on the working surface of the screw, machine, head and so on. Smaller screws should be suspended in the air or placed in special wooden boxes and padded with wooden blocks to avoid deformation or bruising of the screw.

(8) Regularly calibrate the temperature control instrument to check the correctness of its adjustment and the sensitivity of its control.

(9) The maintenance of the extruder’s gearbox is the same as that of a standard reducer. The main focus is to check for wear and failure of gears, bearings, etc. Reducing box should use the machine manual specified lubricating oil, and according to the specified oil surface height to join the oil, too little oil, lubrication is not anti, reduce the service life of the parts; too much oil, heat, energy consumption, oil is easy to deteriorate, the same make lubrication failure, resulting in damage to the parts of the consequences. Reducing box oil leakage parts should be replaced promptly by the gasket (ring) to ensure the amount of lubricant.

(10) The twin-screw extruder attached to the inner wall of the cooling water pipe is easy to scale external corrosion and rust. Maintenance should be done carefully to check, too much scale will block the pipeline, can not achieve the cooling effect, rust will be serious leakage, so maintenance must be taken to remove scale and anti-corrosion cooling measures.

(11) The DC motor driving the screw rotation should focus on checking the brush wear and contact, the insulation resistance of the motor is above the specified value should also be measured frequently. Also, check whether the connecting wires and other parts are rusty and take protective measures.

(12) Designate a person to be responsible for the maintenance of the equipment. A detailed record of each maintenance and repair should be included in the plant equipment management file.

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