Common Problems And Solutions for the Quality of TPE Extruded Pellets
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Common Problems And Solutions for the Quality of TPE Extruded Pellets

Views: 183     Author: Site Editor     Publish Time: 2021-03-15      Origin: Site

The Long Strip Is Larger Than The Normal Pellets

Two times the length is regarded as a long strip. The main reasons for this are as follows: start-up or broken strips, the direction of the strips is not straight, the strips are improperly immersed in water, the cutters of the thermoplastic elastomer pelletizer are worn or chipped, etc. Main solutions:

  1. During normal production, adjust the direction of the strips entering the tpe pelletizer and adjust the length of immersion.

  2. The compounding extrusion process needs to be adjusted if the strip is severely broken during production.

  3. Pay attention to the inspection of the pelletizing rotating knife and replace the damaged rotating knife in time.

  4. Appropriate vibrating screens can be used to screen the long strips that appear.

Pellets Linking of Modified Materials

Two or more tpe pellets connected side by side are called pellets linking. The main reasons for the pellets linking of the modified material are the failure to split or break the strip in time when driving the strip, the length of soaking water is not enough, and the temperature of the die head is too high. Main solutions:

  1. When extruding the strips, choose a nylon wheel with a suitable width for the guiding strip, and separate the sticking strips in time.

  2. Adjust the proper length of cooling water immersion to prevent the material from overheating, which can reduce the pellets linking.

  3. Appropriately reduce the temperature of the die head and adjust the temperature of the strip.

  4. For the emergence of pellets linking, a vibrating screen with appropriate sieve openings can be used for sieving.


The cut surfaces of two or more thermoplastic elastomer pellets are not completely cut, and they are called centipede strips when they are connected. They belong to the category of connecting pellets. The main reasons are the high speed and slow speed when driving the strip melts coming out from the discharge port of the twin screw compounding extruder, insufficient water immersion length, wearing of the pelletizer cutter, or excessive gap between the fixed knife and the rotating knife, etc. Main solutions:

  1. The operator must pull the strip at a constant speed to avoid excessively thick strips.

  2. Adjust the appropriate compounding extrusion process to avoid melts from the feed opening.

  3. Adjust the proper cooling water immersion length to avoid overheating the strip.

  4. Adjust the gap between the fixed knife and the movable knife, and no new tool can be replaced.

There Are Black Speckled Particles on The Surface or Inside of The TPE Particles

The main causes of black spots are unclean screw elements; black spots in the raw materials; screw carbonization; environmental pollution; carry-in due to human mistakes. Main solutions:

  1. In the process of changing the product, if the extruder screw is not cleaned, just re-pull the screw; cleaning the screw elements, the screen behind the filter, and the die head.

  2. Strengthen the inspection of incoming materials, especially the black spots and impurities that are more likely to appear in the filled mineral powder or flame retardant; for example, Z30S or T30S particles containing sawdust in the package; low-level filled mineral powder or flame retardant; these are not used to produce modified plastics with strict requirements for black spots.

  3. Pay attention to the control and adjustment of the extruder barrel temperature and the residence time of the material in the barrel to prevent the processing temperature from being too high; that is, the corresponding extrusion process should be designed according to the formula of each product.

  4. Pay attention to the surrounding environmental sanitation and keep the ground moist. It is necessary to isolate and protect the machines that produce products of different colors.

  5. The auxiliary equipment of the extrusion equipment, such as water tanks, extruder pelletizer, etc., should be cleaned regularly.

  6. Every time the screen is changed, the remaining material on the removable screen and the template must be cleaned to prevent carbonization over a long period.

  7. Note that the floor material strips are strictly prohibited from entering the tpe pelletizer to prevent dust from being introduced.

  8. Anti-plastic static electricity. Static electricity is easy to attract dust.


The discoloration is manifested as a sudden change in the color of the product during the production process, and there is an obvious color difference. The main reasons for the discoloration are uneven or incorrect mixing; the cleaning machine is not clean; the temperature is too high; the shear is too strong; there are impurities in the recycled materials. Main solutions:

  1. Strictly follow the mixing process to ensure the uniformity and correctness of the mixing.

  2. After the cleaning is completed, someone will check to ensure that the cleaning is properly done.

  3. Control the extrusion temperature to prevent the pigments from decomposing when the temperature is too high.

  4. Choose a suitable screw combination to avoid too strong shear.

  5. Make sure that there are no impurities in the recycled materials.

There Are Two or More Vacuum Eyes or Foaming on The Cut Surface of The Poor Vacuum Pellets

The main reasons for poor vacuum are insufficient vacuum, vacuum returned material, bad vacuum system, bad sealing, etc. Main solutions:

  1. Regularly check and maintain the vacuum pump and vacuum pressure gauge.

  2. Clean up the vacuum tank, vacuum chamber, and vacuum pipeline in time.

  3. Properly control the flow of the circulating water of the vacuum pump.

  4. Solve the problem of vacuum returned materials and ensure that the vacuum cover is well sealed.

Iron Filings or Other Metal Particles Have Iron Filings or Other Metal Particles on The Surface or in The Middle of The Plastic Pellets

The main reasons are screw wearing, moving knife broke, iron filings, or other metal particles in the raw material. Main solutions:

  1. Check whether the screw, movable knife, vibrating screen are damaged.

  2. Check whether there are corresponding metal particles in the raw materials.

  3. For bad products, strong magnetic or other metal separators can be used to filter out the metal particles.

  4. Add a filter.

Poor Plasticization Is Seen from The Cut Surface of The Particles

There are insoluble matters, or the surface is black and there is toad skin.The causes of poor plasticization include too low heating temperature, impurities in the raw materials, excessive feeding speed, too weak screw shear, and too much lubricant in the formula. Main solutions:

  1. Control the temperature according to the process regulations and increase the temperature appropriately if there is a bad plasticization.

  2. Check whether there is any impurity and insoluble matter mixed in the raw materials or the process.

  3. Properly control the feeding speed to increase the time for the plastic to be heated and plasticized in the screw.

  4. Choose screw combination with moderate shear capacity.

  5. Adjust the formula appropriately.

Too High Moisture

See shiny water from the surface of the strip, or feel the moisture of the material by hand, or drip under the pelletizer. Excessive water content is caused by excessive immersion of the material strips, failure to split the strips in time when driving, the pelletizer speed is too fast, the air knife wind is weak, and the distance between the pelletizer and the air knife is too close. Main solutions:

  1. Properly adjust the length of the strip soaked in water.

  2. When pulling strips, the strips will be divided into strands immediately after entering the pelletizer.

  3. Properly adjust the speed of the pelletizer and the height of the strip holder.

  4. Ensure that the air knives are strong enough, and use two air knives when necessary.

  5. Properly adjust the distance between the pelletizer and the air knife.

After The Crushed Material Is Cut by The Pelletizer, Many Tiny Crushed Particles Are Produced

Due to the static electricity of the plastics, the main reasons for the crushing caused by their adsorption at the bottom of the vibrating screen are excessive water immersion of the material strips, wearing of the cutters of the pelletizer, too much filler, and too hard material. Main solutions:

  1. Properly adjust the amount of water immersed in the strip.

  2. Replace with a new cutting tool.

  3. Properly adjust the formula and reduce the distance between the thermoplastic elastomer pelletizer and the air knife.

The Leaking Material at The Carbonization Die Is Coked And Turned into A Black Substance, And Granular Scorch Appears on The Surface of The Plastic

The main causes of carbonization are that the heating temperature is too high, causing the melt to burn. The screw is used for a long time without cleaning, and the burnt material accumulates. The downtime is too long, and the head and screw are not cleaned. Main solutions:

  1. Frequently check whether the heating system is normal, and if there is a problem with the heating system, solve it in time.

  2. Regularly pull the screw out or the die head to thoroughly clean.

  3. The screen, filter, and die should be cleaned in time and clean to prevent carbonization. If carbonization is found, the die head and screw should be cleaned immediately.


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