Hey there! As a supplier of screw barrels, I've seen my fair share of issues that customers run into. In this blog, I'm gonna talk about the common problems with screw barrels and how you can deal with them.
1. Wear and Tear
One of the most frequent problems with screw barrels is wear and tear. The screw rotates inside the barrel at high speeds, and as it moves the plastic material, there's a lot of friction. Over time, this friction can cause the surface of the screw and the inner wall of the barrel to wear down.
The wear usually happens in areas where the pressure and shear stress are the highest. For example, near the feed section where the solid plastic pellets enter the barrel, and at the metering section where the plastic is melted and homogenized. When the screw and barrel wear, the gap between them increases. This can lead to a decrease in plasticizing efficiency. You might notice that the plastic isn't being melted as well as it used to, or that there are variations in the melt temperature.
To reduce wear, it's important to choose the right materials for the screw and barrel. High - alloy steels and materials with special coatings can offer better wear resistance. Also, proper maintenance, like regular cleaning and inspection, can help catch early signs of wear and prevent it from getting worse.
2. Corrosion
Corrosion is another big problem, especially when processing plastics that contain additives or are hygroscopic (absorb moisture). Some plastics release corrosive gases during the melting process. For instance, PVC (polyvinyl chloride) can release hydrochloric acid gas when heated. This gas can react with the metal of the screw and barrel, causing corrosion.
Corrosion can damage the surface of the screw and barrel, creating pits and rough areas. This not only affects the plasticizing performance but can also contaminate the plastic product. You might see discoloration or impurities in the final plastic parts.
To prevent corrosion, we often recommend using corrosion - resistant materials for the screw and barrel. Stainless steel and certain types of alloy steels with good corrosion resistance properties can be great choices. Additionally, using an [Anti - leakage Nozzle](/screw - barrel/anti - leakage - nozzle.html) can help reduce the exposure of the screw and barrel to corrosive gases by minimizing leaks.
3. Overheating
Overheating can occur for several reasons. One common cause is improper heating control. If the heating elements are set to too high a temperature or if there's a malfunction in the temperature control system, the screw barrel can get too hot. Another reason could be excessive friction due to a misaligned screw or a blockage in the barrel.
When the screw barrel overheats, it can cause the plastic to degrade. Degraded plastic can have poor mechanical properties, such as reduced strength and toughness. It might also emit unpleasant odors and form charred particles, which can contaminate the entire batch of plastic.
To avoid overheating, it's crucial to have a reliable temperature control system. Regularly check the heating elements and thermocouples to make sure they're working properly. Also, keep an eye on the motor current and torque. If they suddenly increase, it could be a sign of a problem that might lead to overheating.
4. Blockage
Blockage in the screw barrel is a real headache. It can happen when foreign objects enter the barrel, like small metal pieces or debris from the plastic pellets. Sometimes, if the plastic has a high viscosity or if there's a problem with the feeding system, it can also cause blockages.
When the barrel is blocked, the plastic can't flow smoothly through the screw. This can lead to a build - up of pressure, which might damage the screw, barrel, or other components of the extrusion or injection molding machine. You might notice that the machine's motor is working harder, and there could be a decrease in the output rate.
To prevent blockages, always use high - quality plastic pellets and make sure they're clean. Install filters in the feeding system to catch any foreign objects. If a blockage does occur, it's important to stop the machine immediately and clear the blockage carefully.
5. Misalignment
Misalignment between the screw and the barrel can cause a whole bunch of problems. It can happen during the installation process if the parts aren't properly aligned, or due to mechanical vibrations over time.
When the screw is misaligned, it can cause uneven wear on the barrel. One side of the barrel might wear out faster than the other, leading to an inconsistent plasticizing process. It can also increase the friction between the screw and the barrel, which can result in overheating and reduced energy efficiency.
To avoid misalignment, make sure to follow the installation instructions carefully. Use alignment tools to ensure that the screw and barrel are perfectly aligned. Regularly check the alignment during maintenance to catch any issues early.
6. Screw Breakage
Screw breakage is a serious problem that can bring production to a halt. It can be caused by excessive stress, such as when the machine is overloaded or when there's a sudden blockage. Fatigue can also be a factor, especially if the screw has been in use for a long time.
A broken screw can damage the barrel and other components of the machine. It can also lead to a loss of production time and increased costs for repairs and replacement parts.
To prevent screw breakage, it's important to operate the machine within its recommended load limits. Regularly inspect the screw for signs of fatigue, such as cracks or deformation. If you notice any issues, replace the screw before it breaks.
How We Can Help
As a screw barrel supplier, we understand these common problems inside out. We offer high - quality screw barrels made from top - notch materials that are designed to resist wear, corrosion, and overheating. Our products are precision - engineered to ensure proper alignment and smooth operation.
If you're facing any of these problems with your current screw barrels, or if you're looking to upgrade to a more reliable solution, we'd love to hear from you. We can provide you with detailed technical advice and help you choose the right screw barrel for your specific application.
Whether you're in the extrusion or injection molding industry, we've got the expertise and products to meet your needs. So, don't hesitate to reach out to us for a consultation. Let's work together to solve your screw barrel problems and improve your production efficiency.
References
- "Plastics Extrusion Technology" by Allan A. Griff.
- "Injection Molding Handbook" by O. J. Rudy.
