Common problems and solutions for plastic granules in twin screw extruder granulation

Twin screw extruders are becoming more and more widely used in the plastics industry, whether it is a manufacturer in this industry for many years or someone who has just decided to invest in plastic pellets will first decide to use a twin screw extruder for granulation. However, many particle manufacturers are worried that the manufactured particles will not be beautiful enough, so this article Will lead you to understand some of the problems that will occur in the granulation particles and the problems to be solved. Nanjing Tengda extruder equipment will answer this question for you.

1. Plastic particle adhesion phenomenon

 The phenomenon of plastic pelletization refers to a series of plastic particles connected to each other without completely cutting the particles into a perfect shape.

 So why is this problem? In the plastics production process, there are several processing problems that can cause this phenomenon to occur. When processing, the water is too hot is a cause of continuous granulation, the water temperature is not adjusted to the right temperature or the cooling cycle of soft water does not work well. The low velocity of water flow is also a cause of continuous granulation, which causes the particle pelletization chamber to slow down, and then particle agglomeration occurs.

2. Many black spots

     (1)The quality of the plastic raw material itself is relatively poor, and there are many black spots.

(2)The heating temperature of the screw is too high during the processing, resulting in aggravated carbonization of the material.

(3)When the machine is used for too long, the gap between the screw and the barrel is too large, resulting in too much carbon black stored on the inner wall of the machine.

(4) If the natural exhaust port and vacuum exhaust port are not cleaned for a long time, the accumulated carbon will increase.

(5) Some impurities accidentally enter during processing.

(6) Die cleaning is not clean.

(7) Part of the original screw thread is damaged, resulting in increased carbonization of the material at the dead corner.

3. frequent breaks

(1) Causes of external impurities

When mixing and discharging materials, it is not completely checked whether the equipment is cleaned or whether there are impurities mixed in.

(2) Causes of internal impurities

The main reason is that the carbonization caused by the machining process is too serious, resulting in too long strands.

(3)The exhaust port is not smooth

Ø In the process of processing, the temperature is too high, which leads to the local overheating of the screw, which causes the decomposition of some additives such as flame retardants, and releases the gas. The vacuum exhaust port exhausts the gas slowly.

Ø The raw material is seriously damp, and the water vapor is not removed in time during processing, which leads to the breakage in the final stranding stage.

Ø Natural exhaust or poor vacuum exhaust.

(4)Rigid material

The rigidity of the material is too large, the water temperature is too low, the water is too much, the discharge of the machine head is very soft, and the water immediately becomes very hard, and under the action of the traction force mismatch, it causes a broken strip.

3. Excessive material accumulation

    Too much material is put in, resulting in increased friction between the material and the hopper wall, and this problem can reduce the friction between the material and the hopper wall.

4. Hollow plastic granules

 (1)Poor exhaust

The reason for poor exhaust is because of natural exhaust or poor vacuum exhaust (it may be that the water vapor of the raw material is too heavy, or the vacuum may be blocked or the vacuum is too small, resulting in the presence of gas in the particles, forming hollow plastic particles.

       (2) Too low temperature

The plastic processing temperature is low, and the material is not completely plasticized, which is also a major reason for the hollowing of the particles. Of course, it is also possible that the water temperature is too low, the cooling water temperature is too low, the material will shrink, and excessive contraction will form small holes inside.

Nanjing Tengda extruder equipment always adheres to creating high-end quality machines, and we are always at the forefront of high-tech. Tenda's twin screw extruders can provide customers with honest quality assurance services and technical guidance, and the above problems can be satisfactorily solved.