Beginner's Guide To Twin Screw Extruders: Common Problem Solutions And Avoidance Methods
With the increasing awareness of environmental protection and the rising demand for renewable materials, more and more companies are investing in twin screw extruders to try to produce new materials and enter the plastic granulation industry. However, as a beginner, facing complex mechanical systems and process parameters, it is inevitable to encounter various problems.
This article will analyze common problems, provide solutions, and avoidance methods for users who are new to twin screw extruders, helping you reduce learning costs and improve production efficiency.
1, Working principle and market prospects of twin screw extruder
The twin screw extruder melts solid plastic and extrudes it into shape through two screws that alternate in spiral motion with each other. It uses the principle of frictional heat to heat and melt solid plastic, and pushes the melted plastic towards the mold for extrusion through the rotation of the screw.
According to market research data, the global sales of twin screw extruders are expected to reach 10.95 billion yuan in 2031, with a compound annual growth rate of 3.8% (2025-2031). This growth is due to the continuous improvement of various industries' demands for efficient production, customization, and environmental protection and energy conservation.
2, Common problems and solutions for beginners
a. Low lubricating oil pressure
Problem analysis:
The pressure setting value of the lubricating oil system pressure regulating valve is too low; Oil pump malfunction or clogged suction pipe.
Solution:
-Check and adjust the pressure regulating valve of the lubricating oil system
-Check if the oil pump and suction pipe are unobstructed
-Regularly check the lubrication condition inside the rolling bearings of the equipment and inject lubricating oil
Avoidance method: Establish a regular maintenance plan and check the lubrication system status before each start-up to ensure that the oil level and quality meet the requirements.
b. Poor or blocked discharge from the machine head
Problem analysis:
-Some sections of the heater are not working and the material is not well plasticized
-The operating temperature is set too low, or the molecular weight distribution of the material is wide, resulting in unstable performance
-There may be non melting foreign objects (such as smaller metal blocks and sand) entering the extruder and blocking the head
Solution:
-Check the heater and replace it if necessary
-Verify the temperature settings of each section and increase the temperature settings if necessary
-Clean and inspect the extrusion system and head of the extruder
Avoidance method: When the operator fills the material, they must be careful not to add impurities and control the temperature. It is not necessary to use low-quality recycled materials with metal material residues or fine sand, and metal objects that may fall into the feeding port should not be placed around it.
c. Cut off the safety pin or safety key
Problem analysis:
The extrusion system has a distance that is too large.
Solution:
-Check if there are any hard objects such as metal entering the clamping screw in the extrusion system
-If this phenomenon occurs just after driving, it should be checked whether the preheating and heating time is sufficient and whether the set temperature value meets the processing requirements
Avoidance method: The heating and warming time should be sufficient. After reaching the set temperature of the processing technology, the temperature should be controlled for fifteen minutes. Before starting, manually rotate the belt pulley, which should be light and frictionless.
d. Sudden and significant decrease in the amount of extruded products
Problem analysis:
-Feeding system malfunction shutdown or material shortage in hopper
-A hard foreign object enters the extrusion system and gets stuck in a certain part of the screw, preventing the material from passing through
Solution:
-Check the material level in the material system and hopper
-Check and clean the extrusion system
Avoidance method: No residue is allowed in the raw materials, and hard substances such as stones are strictly prohibited from entering the material bin and barrel.
e. Unstable head pressure
Problem analysis:
-Uneven speed of main motor
-The uneven speed of the feeding motor causes fluctuations in the feeding amount
Solution:
-Check the main motor control system and bearings
-Check the feeding system motor and control system
Avoidance method: Regularly inspect and maintain the electrical control system to ensure stable operation of the motor.
3, Precautions for operating plastic granulator
For first-time users of twin screw granulators, the following precautions should be taken:
a. Preheat before startup: Raise the temperature for about 40-50 minutes. Raise the temperature until the triangular belt of the motor is manually driven until it is free. Pull in the normal working direction eight to ten times. Then heat it up again for about ten minutes, and then turn on the device again.
b. Temperature control: Adjust the temperature according to different types of plastics. When the plastic granulator is running normally, the temperature of the plastic granulator should be maintained for a long time and should not be high or low.
c. Feed uniformity: The feed should be uniform and there should be no shortage of raw materials. The cutting speed of the equipment should match the cutting speed.
d. Shutdown procedure: The sequence of stopping the operation is opposite to the sequence of starting the production operation. First, turn off the main engine drive, then turn off the auxiliary power supply in sequence, and then quickly clean the mold head to prevent mold head cooling blockage. Special attention: After the shutdown of each shift, the discharge holes and filter plates of the mold head need to be thoroughly cleaned before reinstalling production, otherwise there is a risk of explosion due to blockage of the mold head.
4, Key points of maintenance and upkeep
Proper maintenance can significantly extend the service life of twin screw extruders:
a. Regular cleaning: Regularly clean the filter screen and mold head to prevent residue accumulation from affecting product quality
b. Maintenance of lubrication system: Check the amount of lubricating oil in each transmission part and add or replace it if necessary
c. Electrical system inspection: Monitor the working status of the electrical control system to ensure its normal operation
d. Record keeping: Keep daily records, including operating time, temperature settings, fault conditions, etc., for future maintenance reference
5, Choose a suitable twin screw extruder
For users who are new to twin screw extruders, choosing a suitable equipment is crucial. Nanjing Kelongweier Chemical Machinery Co., Ltd. is a high-tech enterprise that integrates production, scientific research, design, and sales, focusing on providing high-quality chemical machinery and equipment.
When choosing a twin screw extruder, consider the following factors:
-Select appropriate models and specifications based on production needs
-Consider the energy consumption indicators of the equipment and choose energy-saving devices
-Choose a supplier that provides comprehensive after-sales service and technical support
-Consider the possibility of upgrading and expanding equipment
The operation of a twin screw extruder is a technical activity that requires a combination of theoretical knowledge and practical experience. For beginners, mastering the correct operating methods and maintenance skills is the key to avoiding problems. By following the recommendations provided in this article, you can avoid most common problems, improve production efficiency, and extend equipment lifespan.
In today's increasingly important environment of environmental protection and sustainable development, investing in twin screw extruders to engage in the plastic granulation industry not only has economic benefits, but also significant environmental benefits. By choosing the appropriate equipment and mastering the correct operating methods, you will achieve success in this industry.
Nanjing Kolongweier Chemical Machinery Co., Ltd., as a well-known enterprise in the industry, is committed to providing customers with high-quality products and excellent services. It is a reliable partner for you to enter the plastic granulation industry. Whether you are pursuing environmental protection, high cost-effectiveness, or trying to make new materials, choosing the right equipment and using it correctly will help you succeed in this field.
