Recycle Machine Screw Barrel Overview

Plastic recycle granulation machine screw barrel is essential part for the equipment. 

Plastic granulator is a process that changes the physical properties of plastics through high-temperature melting, plasticization, and extrusion, achieving the plasticization and molding of plastics.

Adopting a special screw design and different configurations, it is suitable for the regeneration and color mixing granulation of various plastics such as PP, PE, PS, ABS, PA, PVC, PC, POM, EVA, LCP, PET, PMMA, etc. The gearbox adopts a high torque design, achieving performance such as noise free and smooth operation. The screw and barrel have undergone special hardening treatment, which has the characteristics of wear resistance, good mixing performance, and high output. The design of vacuum exhaust or ordinary exhaust port can discharge water and waste gas during the production process, making the discharge more stable and the rubber particles more solid, ensuring excellent product quality.

Classification of Plastic Granulator Machines

Plastic granulators have the characteristics of uniform, smooth, full particles, high efficiency and energy saving, easy operation, and stable product quality. They mainly include the following categories:

The single screw single stage granulator is mainly used for the recycling and granulation of plastic films and filaments such as PE (polyethylene) and PP (polypropylene), and is particularly suitable for the recycling and granulation of foamed materials. This type of granulator is also suitable for granulating solid materials and materials with a bulk density exceeding 0.3g/l; Processable: PE, PP, PS, PVC, ABS, PA, PC, PET and other plastics.

This plastic granulator is mainly suitable for the recycling and granulation of PE, PP, PS, PA thin and silk films. It can be used for films that are relatively dirty, have high impurities, and have a moisture content greater than 5%.

For plastic granulation with a bulk density of 0.1-0.3g/l solid materials also has good effects; Can process plastics such as PE, PP, PS, PVC, ABS, PA, PC, PET, etc. The characteristic of a single screw double stage granulator is that it is suitable for materials with high impurities, high moisture content, and high output. Simultaneously equipped with a forced feeder.

The parallel twin-screw granulator is widely used in the filling, blending, modification, reinforcement of rubber and engineering resins, as well as the devolatilization treatment of chlorinated polypropylene and high water absorbent resins; Extrusion of biodegradable masterbatch, polyamide condensation polymerization, and polyurethane addition reaction; Multiple fields such as PET bottle chip recycling.

The counter direction twin screw granulator is widely used in PVC cable modification, PVC powder blending, PVC film, etc.

What does Plastic Pelletizing Machine Include

The plastic granulator is composed of extrusion system, transmission system, heating and cooling system.

The extrusion system includes a hopper and a machine head. Plastic is plasticized into a uniform melt through the extrusion system, and under the established pressure in this process, it is continuously extruded by the screw from the machine head.

Screw:

It is the most important component of the extruder, which directly affects the application range and productivity of the extruder. It is made of high-strength and corrosion-resistant alloy steel.

Cylinder:

It is a metal cylinder, generally made of heat-resistant, high compressive strength, sturdy, wear-resistant, and corrosion-resistant alloy steel or composite steel pipes lined with alloy steel. The combination of the barrel and screw enables the crushing, softening, melting, plasticization, exhaust, and compaction of plastics, and continuously and uniformly delivers the rubber material to the molding system. The length of the general machine barrel is 15-30 times its diameter, in order to ensure that the plastic is fully heated and plasticized.

Hopper:

The bottom of the hopper is equipped with a cut-off device to adjust and cut off the material flow, and the side of the hopper is equipped with a sight hole and a calibration measuring device.

Die head:

The machine head is composed of an alloy steel inner sleeve and a carbon steel outer sleeve, and a forming mold is installed inside the machine head. The function of the machine head is to transform the rotating plastic melt into parallel linear motion, evenly and smoothly guide it into the mold sleeve, and give the plastic the necessary molding pressure. Plastic is plasticized and compacted inside the machine barrel, and then flows through a certain flow channel through the neck of the machine head through a porous filter plate into the molding mold. The core and sleeve of the mold are appropriately matched to form a continuously decreasing circular gap, allowing the plastic melt to form a continuous and dense tubular coating layer around the core wire. To ensure the rationality of the plastic flow channel inside the machine head and eliminate dead corners of accumulated plastic, a diversion sleeve is often installed. To eliminate pressure fluctuations during plastic extrusion, a pressure equalizing ring is also installed. There is also a device for mold calibration and adjustment on the machine head, which facilitates the adjustment and correction of the concentricity of the mold core and sleeve.

The function of the transmission system is to drive the screw, supply the torque and speed required by the screw during the extrusion process, usually composed of an electric motor, reducer, and bearings.

Heating and cooling devices are necessary conditions for the plastic extrusion process to proceed.

In 2013, electric heating was commonly used in extrusion machines, which can be divided into resistance heating and induction heating. Heating plates were installed in the body, neck, and nose of the machine. The heating device is composed of plastic inside an external heating cylinder, which is heated to reach the temperature required for the process operation.

The cooling device is set to ensure that the plastic is within the temperature range required by the process. Specifically, it is to eliminate the excess heat generated by the shear friction of screw rotation, in order to avoid the difficulty of plastic decomposition, scorching, or shaping due to high temperature. Machine barrel cooling can be divided into two types: water cooling and air cooling. Generally, air cooling is more suitable for small and medium-sized extrusion machines, while water cooling or a combination of the two forms of cooling are more commonly used for large machines; The screw cooling mainly adopts central water cooling, with the aim of increasing the solid conveying rate of materials, stabilizing the glue output, and improving product quality; But the cooling at the hopper is to strengthen the conveying effect of solid materials, prevent plastic particles from sticking and blocking the material outlet due to temperature rise, and ensure the normal operation of the transmission part.

Recycling Machine Screw Barrel Material

1. Corrosion resistance: During the production process of plastic particles, a large number of chemical reactions occur, so the barrel and screw need to have good corrosion resistance to prevent the material from being corroded and affecting production efficiency. Usually, materials such as stainless steel and alloy steel are used to make the machine barrel and screw, which can meet this requirement.

2. Wear resistance: The barrel and screw will wear under long-term high-speed rotation and compression, so it is necessary to have good wear resistance to extend the service life of the equipment. Usually, high chromium alloy steel, hard alloy and other materials are used to make screws, which can meet this requirement.

3. Strength and hardness: The barrel and screw need to have sufficient strength and hardness to withstand extrusion and tensile forces under high temperature and pressure. Usually, high-strength alloy steel, cast steel and other materials are used to make the machine barrel and screw, which can meet this requirement.

4. Processing performance: The manufacturing of the barrel and screw requires high-precision processing technology and techniques to ensure their dimensional accuracy and surface smoothness. Usually, precision casting, CNC machining and other processes are used to produce machine barrels and screws, which can meet this requirement.

In summary, when selecting the barrel and screw material of a screw granulator, it is necessary to comprehensively consider factors such as material performance, cost, and processing technology to select the most suitable material to ensure production stability and equipment lifespan. At the same time, it is necessary to regularly inspect and maintain the equipment during use to ensure its normal operation.