How to solve common problems in the production process of plastic extruder lines?

How to solve common problems in the production process of plastic extruder lines?

With plastic extruder production equipment in good working condition, you can enjoy optimized productivity and reduced operating costs.

However, no matter how perfectly constructed a machine is, it is still prone to occasional breakdowns. Fortunately, knowing the common problems and their exact source comes in handy when troubleshooting or repairing your equipment.
Before we highlight these challenges, it's crucial to work with a reliable plastic extrusion line manufacturer like JKS Extrusion Machinery for top-notch machine quality.

That's why we've summarized a list of errors you may encounter on your line and how to solve them.

1. The finished sheet will have dimensional differences

Size variation is a possible irregularity in the size of the plastic sheet. This problem comes from improperly placed molds, inconsistent production temperatures, and improper design of the screw structure.

How to solve it?

Each component of the extrusion line should be thoroughly inspected to ensure that it is in good working condition, including cooling power, motor load, heating power, line speed and melt pressure must all be consistent to obtain a high quality product.

2. External impurities are generated during the operation of the plastic extruder line

Another reason why an extrusion line may fail may be due to external impurities. This can happen when dead corners of the production equipment are not thoroughly cleaned. When impurities in these corners are mixed with the raw material, the line may fail. In addition to this, impurities can enter the equipment through open surface holes.

How to solve it?

The best way to solve failures related to external impurities is to clean the dead corners perfectly. In addition to this, try to add raw materials to the machine in small pieces or manually screen the crushed raw materials to remove impurities.

3. Aesthetic defects

Aesthetic problems are caused by black spots, drag marks, small holes and dent marks on the surface of the plastic sheet extrusion line. Aesthetic defects can lead to problems related to impurities, as they can allow foreign impurities to enter the machine.

How to solve it?

You must take care of any aesthetic defects that may alter the function of the line. Cover any holes, drag marks, etc. to keep the machine in the best possible condition.

4. Internal impurities can arise

Impurities don't just come from the outside, the line is also susceptible to internal impurities. It occurs in the carbonization process. A great deal of carbonation occurs inside the equipment.

When the carbonized material is transferred to the material strip, the chance of the material strip being broken is super high. The activity associated with traction exacerbates the chances of fracture. Extraction of the material strip is the cause of internal impurities.

How to solve it?

It is vital to check the functional state of the material strip frequently to prevent unprecedented breakage. If the strip seems to be worn out, it should be replaced as soon as possible.

5. Inadequate plasticization of the raw material

Inadequate plasticization occurs when the raw material fails to undergo sufficient plasticization. Inadequate plasticization can also occur when large pieces appear in the material. The same happens if the screw shear force becomes weak or if the extrusion temperature happens to be very low.

When the raw materials are not fully plasticized, their composition becomes too inconsistent to pass through the material strip. Under traction, the material breaks the strip or bar. In turn, the broken bars or strips bring in impurities that affect the quality of the line's output as well as its functionality.

How to solve it?

To curb incomplete plasticization of the material, you need to promote rapid melting of the material by utilizing additives that can lower the melting point. In addition, you need to increase the extrusion temperature by employing an external heating source. Finally, you must correct the screw shear by reducing the gap between the barrel and the screw.

6. Changes in the physical characteristics of the raw material

By feeding raw materials with different physical and chemical characteristics into the extruder, they will have different reaction times or flowability. Due to the incompatibility of the flowability, it brings about a mismatch in the chemical reaction rate and a change in the physical entanglement.
All this happens through the phase separation that occurs during the molding process. If the raw material does not change and react uniformly, this leads to rigidity and hardness.
When the difference between the chemical and physical properties of the material is too great, it can make processing difficult for the extruder. Increased viscosity is the biggest challenge at this point, as it leads to poor plasticization.
As a result, it will adversely affect the screw, causing it to weaken and possibly fracture the strip.

How to solve it?

In order to control the change in viscosity between the blend components, it is prudent to reduce the speed of the material at the main equipment screw. In addition, you can find ways to increase the extrusion temperature to achieve complete plasticization.

7. Inefficient exhaust or cooling systems

As the line continues to work, the temperature becomes quite high. As a result, the screw can overheat, which can cause the flame retardant in the material to break down along with other additives. Gases are also generated during this process. If the vacuum does not get rid of the gas in time, it can get trapped in the strip and affect the traction force as well. When the strip and traction are affected, the material bar will be affected. This can lead to breakage. Similarly, water vapor can be generated if the material becomes wet. If the vacuum and natural exhaust system does not handle the water vapor in a timely manner, it can become trapped in the material strip and cause deterioration of the strip.

How to solve it?

Vacuum and natural venting will be inefficient if the gasket is too high or if there is some seeking air leakage. The same thing can happen in case of a blockage in the exhaust system. You will need to readjust the gasket, seal any air leaks, and clear the blockage.

8. Screw wear

The screw is just as susceptible to wear as any other part of the extruder. A lot of wear on the screw occurs around the feed zone. This is caused by the rigidity of the feedstock before it goes through the melting process. Dry friction between the hard metal structure of the screw components and the chip particles also contributes to the problem.

How to solve it?

To avoid unexpected machine failure due to screw wear, you must pay close attention to the performance of your extruder screw. At the same time, you need to raise the temperature in order to heat the chip pellets or raw material and soften it. When the raw material becomes soft, the dry friction will be reduced.

9. Abnormal noise

When your production equipment constantly produces abnormal noise, it may be a sign of poor lubrication or bearing damage. The noise usually comes from the gearbox, although it may also be generated by other components. Likewise, abnormal noise can be the result of poor equipment installation. Incorrect meshing and poor gear adjustment can also explain abnormal noise.

If the machine produces a sharp scraping sound, it may be due to a faulty barrel. This occurs when the barrel deviates and begins to scrape the drive sleeve or shaft head.

Another noise related problem you may face is a bent barrel screw. When the bent screw keeps touching the hole, an abnormal noise will be generated. Also, if the temperature is set too low, it can cause excessive friction within the solid particles and cause a lot of noise.

How to solve it?

To eliminate the noise, you need to consider replacing the bearings. Likewise, you should increase the amount of lubrication to the machine to make it run smoothly. Changing the gear meshing conditions or replacing the gears is also a good solution to the problem.
On the other hand, you can eliminate the sharp scraping noise by adjusting the barrel. If the noise is coming from a bent screw, you can eliminate it by straightening it.
If the noise comes from solid particles, you must adjust the set temperature to the right level.

10. Abnormal vibration

If you feel any abnormal vibrations coming from the gear box of the extruder, there may be a small problem with the function of the gears and bearings. This error can be triggered when a solid foreign object enters the processed material. However, you will need to check the extruder equipment to confirm this.

How to solve it?

In order to fix the vibration problem, you have to replace the gears or bearings. In addition to this, you need a way to effectively filter out the foreign material that is hurting the bearings or gears. The ultimate remedy is to install a reliable magnetic device inside the hopper of the equipment to filter out ferrous fillers.

11. Unstable host current

Unstable host current is a production setback that is caused by uneven feeding of raw materials. In addition, it occurs when the main motor bearings are poorly lubricated or severely damaged. In a similar manner, your extrusion line is likely to experience this problem when the heater portion of the machine is not working. Likewise, if the adjustment pad on the screw is done wrong, or if the phase is not correct causing inference of the part, the main machine current can become unstable.

How to solve it?

First, you must check and troubleshoot the feeder. At the same time, remove the main motor and put the other set of bearings in place. Next, confirm that the heater is working and replace the heater that may be defective.
Finally, look at the adjustment pads. Remove the screws and verify that there is no interference of any kind within the screw parts. 

12. Main Motor Failure

The main motor of the extrusion line can fail when it fails during the drive process. In addition, the main motor may not work when there is an error within the main motor line, such as a blown fuse. Another cause of main motor failure is a problem with the interlocking parts connected to the main motor.

How to solve it?

To correct the problem with the primary motor, confirm the driver and then utilize the correct drive sequence. If the problem is related to the primary circuit, troubleshoot it and correct the error. After that, look at the lube oil pump and confirm that the interlocking components of the primary motor are in good working condition. If the oil pump does not run, the machine's engine will not run either.
Another way to remedy the fault is to check if the induction current of the inverter is normal.

13. Extreme primary starting current

There are several factors that can bring about an excessive increase in starting current. The first attribute is insufficient torque.
In addition, the primary current can become too high if the heating time is not sufficient. If an area of the heating system is not working, your production equipment will also face this problem.

How to solve it?

All you have to do in order to avoid a recurrence of the fault is to increase the heating time. In addition to that, regularly check that every part of the heater is completely working.

14. Extreme temperature of the main motor bearing

If there is not enough lubrication in the bearings, the main motor bearings will definitely experience extreme temperatures. This is caused by friction. Similarly, if the bearings lose their working condition or wear out, the main motor will become too hot.

How to solve it?

Check the condition of the motor bearing and make sure it is in good working condition. If it is worn out, find a replacement.
If this is not the case, make sure the bearing is adequately lubricated.

15. Unstable head pressure

When the main motor is rotating at an uneven speed, your line equipment may experience unstable head pressure. Another explanation for unstable head pressure is the fluctuating speed of the feed motor. Fluctuations in the speed of the feed motor can cause fluctuations in the amount of material being fed.

How to solve it?

This can be solved by checking the efficiency of the bearings and the central motor of the control system. Also, troubleshoot the control system and make sure the motor of the feeding system is working properly.

16. Low lubricant pressure

If you set the pressure setting of the valve that controls the lube oil pressure system very low, you will experience low pressure in the lube oil. The resulting pressure becomes too low to push the lubricant around the equipment. Again, this error can be related to a clogged suction line or pump failure.

How to solve it?

To fix this error, reset the lube oil pressure to an appropriate value. In addition to this, remove any foreign material that may be blocking the suction line.

17. Clogging at the screw inlet

If an annular blockage affects the screw inlet, the production machine will malfunction. This error leads to insufficient cooling water flow or interruption of cooling water flow.

How to solve it?

Check if there is any material blocking the screw inlet and clean it thoroughly.

18. Blocked vacuum

The vacuum is designed to get rid of any excess moisture or gas generated during the extrusion process. If gas and moisture accumulate or become trapped in the strip due to a blocked vacuum, it may damage the material bar.

How to solve it?

Check that the vacuum is clear or unblock it with a thin wire. Other than that, make sure there are no leaks in the vacuum line.

19. Inaccurate cutting length

When the cutter is not installed correctly or some of its accessories are not working, it will result in inaccurate cutting lengths of SPC flooring sheets. An inaccurate length means you have to redo the process again to get the correct result. This will ultimately result in wasted material.

How to solve it?

You need to install and calibrate the cutter accurately. In addition to this, check that each part of the cutter is working properly. First look at the long wheel bolts and make sure they are tight enough. The wiring system for the travel switch and rotary encoder should also be working properly.

Do you want to buy a plastic extruder? Don't worry anymore; we've got you covered. JKS Extrusion Machinery is engaged in manufacturing and supplying plastic extrusion lines. We not only manufacture, but also ensure that our products are of high quality and meet the needs and standards of our customers. Most importantly, we manufacture custom-designed extruders. Quality and reliability are key factors that are incorporated into our production ethos. Both twin-screw and single-screw extruders are important types of plastic extrusion machinery. Either way, they are part of the extrusion line that is necessary for successful production. JKS makes it possible.

Post your feedback