Plastic Twin Screw Extruder with Side Feeder- Manufacturers Factory Suppliers From China

When the single screw extruder is in the extrusion molding process, its extruder screw is divided into 3 sections: feeding section (feeding section), melting section (compression section), metering section (homogenization section), these three sections Correspondingly, three functional areas are composed of materials: solid conveying area, material plasticizing area, and melt conveying area. Each area has different temperature requirements, and specific problems should be analyzed in detail. The temperature of the single screw extruder will be briefly introduced below.

• What is the general temperature of the solid conveying zone in a single screw extruder?

• What is the general temperature in the plasticizing zone of the material in a single screw extruder?

• What is the general temperature of the melt conveying zone in a single screw extruder?

What is the general temperature of the solid conveying zone in a single screw extruder?

The temperature of the barrel in the solid conveying zone of the single screw extruder is generally controlled at 100~1400C. If the feeding temperature is too low, the solid conveying zone will be extended, reducing the length of the plasticizing zone and the melt conveying zone, which will cause poor plasticization of the single screw extruder product and affect product quality.

What is the general temperature in the plasticizing zone of the material in a single screw extruder?

The temperature of the material plasticizing zone in the single screw extruder is controlled at 170~1900C. Controlling the vacuum degree of this section is an important process index. If the vacuum degree is low, it will affect the exhaust effect, resulting in bubbles in the pipe, and seriously reducing the mechanical properties of the pipe. In order to make the gas inside the material easily escape, the plasticization degree of the material in this section should be controlled not to be too high, and the exhaust pipe of the single screw extruder should be cleaned frequently to avoid blockage. The vacuum degree of the barrel is generally 0.08~0.09MPa.

What is the general temperature of the melt conveying zone in a single screw extruder?

The temperature of the melt conveying zone in the single screw extruder should be slightly lower, generally 160~1800C. Increasing the screw speed in this section, reducing the head resistance and increasing the pressure in the plasticizing zone are all conducive to the improvement of the conveying rate. For heat-sensitive plastics such as PVC, the residence time should not be too long in this section. The screw speed is generally 20 ~30r/min. The head of the single screw extruder is an important part of extruded product molding. Its function is to generate a higher melt pressure and make the melt shape into a desired shape. The process parameters of each part of the single screw extruder are: die connector temperature 1650C, die temperature 1700C, 1700C, 1650C, 1800C, 1900C.

This is some information related to the use of single screw extruders. The use of single screw extruders is also closely related to the quality of its products. If you need more information, please contact Nanjing JlEYA.

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The basic mechanism of the twin screw extrusion process is simply that a screw rotates in the barrel and pushes the plastic forward. The screw structure is a bevel or ramp wrapped around a central layer, the purpose of which is to increase the pressure to overcome the higher resistance. What do I need to pay attention to when using a twin screw extruder? The following is a detailed description.

 

Here is the content list:

l Structural principles

l Temperature principles

l Speed reduction principle

 

Structural principles

For the extruder, there are three kinds of resistance to overcome when working: one is friction, which contains the friction of the solid particles (feed) on the barrel wall and the mutual friction between them during the first few turns of the screw (feed area); the second is the adhesion of the melt on the barrel wall, and the third is the resistance of the internal logistics of the melt when it is pushed forward.

According to Newton's theorem, if an object is at rest in a certain direction, then the object is in a state of equilibrium balance of forces in this direction. For the circumferential movement of the screw, it is no axial motion, that is, the axial force on the screw is in equilibrium. So if the screw exerts a large forward thrust on the plastic melt, it also exerts a backward thrust on another object of the same magnitude but in the same direction. The thrust is exerted on the thrust bearing behind the feed opening. Most single screws have right hand threads, and if viewed from the back, they rotate backward, and they spin backward out of the barrel by rotational motion. In some twin screw extruders, however, the two screws rotate backward and cross each other in both barrels, so one must be right handed and one left handed, and in the case of an occluding twin screw, both screws rotate in the same direction and must therefore have the same orientation. However, in either case, there are thrust bearings that withstand backward forces and still comply with Newton's theorem.

 

Temperature Principle

Plastics extruded by twin screw extruders are thermoplastics, which melt when heated and solidify again when cooled. Thus, heat is needed during the extrusion process to ensure that the plastic can reach the melting temperature. So where does the heat to melt the plastic come from? First of all, the pound feed preheat and barrel/die heaters may play a role and are very important at startup. In addition, the motor feed energy, the frictional heat generated in the barrel as the motor overcomes the resistance of the viscous melt and turns the screw, is the most important heat source for all plastics, except for small systems, low speed screws, high melt temperature plastics, and extrusion coating applications. In operation, it is important to recognize that the barrel heater is not the primary heat source and that it may play a smaller role in extrusion than we might expect. The post barrel temperature is more important because it affects the rate of solids transport in the dentition or feed. In general, except for a specific purpose (such as varnishing, fluid distribution, or pressure control), the die head and die temperature should be at or near the temperature required for the melt.

 

Speed reduction principle

In most twin screw extruders, the screw speed is varied by adjusting the motor speed. The drive motor usually turns at a full speed of about 1750 rpm, which is too fast for an extruder screw. If it turns at such a fast speed, too much frictional heat is generated and a uniform, the well mixed melt cannot be prepared because the retention time of the plastic is too short. A typical speed reduction ratio should be between 10:1 and 20:1, with either a gear or pulley set for the first stage, but with a gear and a screw positioned in the center of the last large gear for the second stage. For some slow running machines (eg. twin screws for UPVC), there may be three reduction stages and the maximum speed may be as low as 30 rpm or less (ratio up to 60:1). On the other hand, some very long twin screws for mixing can run at 600 rpm or faster, thus requiring a very low reduction rate and more deep cooling. If the reduction rate is incorrectly matched to the job, too much energy will be wasted. It may be necessary to add a pulley set between the motor and the first deceleration stage where the maximum speed is changed, which either increases the screw speed even beyond the previous limit or reduces the maximum speed. This increases the available energy, reduces the current value, and avoids motor failure, in both cases, the output may increase due to the material and its cooling needs.

 

If you still have questions, you can consult our company. Nanjing JlEYA is the leading professional manufacturer of twin screw extruders in China.

Plastic extruders can be divided into single-screw extruders, twin-screw extruders, and multi-screw extruders according to their number of screws. The following are the details of the types of plastic extruders.

 

Here is the content list:

• Classification of plastic extruders

• Single-screw extruder

• Twin-screw extruder

 

Classification of plastic extruders

1, According to the number of screws, divided into single-screw extruders, twin-screw extruders, and multi-screw extruders.

2, According to the presence or absence of a screw in the extruder, divided into screw extruders and plunger extruders.

3, According to the running speed of the screw to divide:

Ordinary extruder: speed below 100r/min.

High-speed extruder: speed of 100 to 300r/min.

Super high-speed extruder: the speed is 300~l500r/min.

4, According to the extruder assembly structure classification: there are integral extruders and separate extruders.

5, According to the spatial position of the screw in the extruder, can be divided into the horizontal extruder and vertical extruder.

6, According to whether the extruder is in the process of exhaust and can be divided into exhaust type extruder and non-exhaust type extruder

 

Single-screw extruder

The single-screw extruder occupies an important position both as a plasticizing and pelletizing machine and as a molding machine, and in recent years, the single-screw extruder has developed greatly. Single-screw extruders were the first extruders to gain widespread application in the plastic processing and molding field due to their simple structure and high processing efficiency. Similarly, to meet different processing needs, various equipment manufacturers have explored various screw and barrel structures. The single-screw extruder has evolved from the basic pure screw structure to various structures such as damping screw block, exhaust extrusion, slotted screw barrel, pinned barrel, building block structure, etc., thus enabling the single-screw extruder to have a wider range of molding.

 

Due to the small footprint of single-screw extruders, they are almost the only equipment used in the compounding and blown film fields. Single-screw extruder technology has become an important part of the extrusion process market that cannot be ignored.

 

 

Twin-screw extruder

The twin-screw extruder has less heat generated by friction, more uniform shearing of the material, larger conveying capacity of the screw, more stable extrusion volume, long stay of the material in the barrel, and uniform mixing.

 

The twin-screw extruder has good feeding characteristics, is suitable for powder processing, and has better mixing, exhaust, reaction, and self-cleaning functions than the single-screw extruder, characterized by the processing of plastics with poor thermal stability and co-mingled materials show its superiority. Based on the twin-screw extruder, the multi-screw extruder was developed for easier processing of co-blends with poor thermal stability.

 

If you want to buy an extruder, you can consider our cost-effective products. Nanjing JlEYA is the leading manufacturer extruder manufacturer specializing in a twin-screw extruder, mini twin screw extruder, plastic extruder, and parallel twin-screw extruder in China, which is widely used in compounding, modification, polymerization, after 17 years of development, now we have 20,000 square meters workshop with annual sales over 300+ sets, export over 60 countries.

Twin-screw extruders have barrels with an extension range of 4 and 6D, allowing for precise process design to meet specific customer requirements. All barrels allow for precise temperature control. Cooling is achieved by cooling water injection and high-performance electric heating rods for direct and fast heating. The auxiliary equipment of the twin-screw extruder consists of a straightening device, a preheating device, and a cooling and heating device. The following is a detailed description of the auxiliary equipment.

 

Here is the content list:

l Straightening device

l Preheating device

l Cooling device

 

Straightening device

One of the most common types of plastic extrusion rejects is eccentricity, and bending of the wire core in various patterns is one of the most important causes of insulation eccentricity. In sheath extrusion, scratches on the sheath surface are also often caused by the bending of the cable core. Therefore, a variety of extrusion units in the straightening device is essential. The main types of straightening devices are roller type (divided into horizontal and vertical type); pulley type (divided into single pulley and pulley group); stranded pulley type, which plays a variety of roles such as dragging, straightening, and stabilizing tension; pressure pulley type (divided into horizontal and vertical type), etc.

 

Preheating device

Cable core preheating is necessary for both insulation extrusion and sheath extrusion. For the insulation layer, especially the thin layer of insulation, the existence of pores should not be allowed, the core can be completely removed from the surface of the water, oil, and dirt through high temperature preheating before extrusion. For the sheath extrusion, the main role is to dry the cable core, to prevent the role of moisture (or moisture around the bedding layer) to make the sheath in the possibility of porosity. Preheating can also prevent the plastic from being extruded due to sudden cooling and residual internal pressure. In the process of extruding plastic, preheating can eliminate the cold line into the high-temperature heat, in contact with the plastic at the mouth of the die to form a disparity in temperature, to avoid fluctuations in plastic temperature and lead to fluctuations in extrusion pressure, to stabilize the amount of extrusion and ensure the quality of extrusion. Extrusion unit is used in the electric heating core preheating device, requires sufficient capacity, and ensures rapid temperature rise, so that the core preheating and cable core drying efficiency. The preheating temperature is restricted by the speed of wire release, generally similar to the temperature of the head.

 

Cooling device

The formed plastic extrusion layer after leaving the head should be immediately cooled and shaped, otherwise, deformation will occur under the action of gravity. The way of cooling usually uses water cooling, and according to the water temperature is different, divided into rapid cooling and slow cooling. Rapid cooling is the direct cooling of cold water, rapid cooling of plastic extrusion layer sizing is beneficial, but for crystalline polymers, due to sudden heat cooling, easy to internal residual stress in the extrusion layer organization, resulting in the use of the process of cracking, general PVC plastic layer using rapid cooling. Slow cooling is to reduce the internal stress of the product, in the cooling water tank placed in sections of different temperatures of water, so that the product gradually cool down and set, PE, PP extrusion on the use of slow cooling, that is, after hot water, warm water, cold water three cooling.

 

If you are engaged in a twin-screw extruder-related industry, you can consider our cost-effective products.

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 The main system of the plastic extruder is the extrusion system, which includes screw, barrel, hopper, head, and die. The plastic is plasticized into a uniform melt by the extrusion system and is continuously extruded from the head by the screw under the pressure established in the process. The following are details about the plastic extruder extrusion system introduction.

 

Here is the content list:

• Screw

• Barrel

• Hopper

• Head and mold.

 

Screw

The screw is the most important part of the extruder, which is directly related to the application range and productivity of the extruder and is made of high-strength and corrosion-resistant alloy steel.

 

Barrel

The barrel is a metal cylinder, generally made of heat-resistant, high-pressure strength, strong wear-resistant, corrosion-resistant alloy steel or composite steel tube lined with alloy steel. The barrel and the screw cooperate to realize the crushing, softening, melting, plasticizing, exhausting, and compacting of the plastic, and to continuously and evenly deliver the rubber to the molding system. Generally, the length of the barrel is 15-30 times its diameter, so that the plastic is fully heated and fully plasticized as a principle.

 

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 calibrated measuring device.

 

Head and mold

The head is composed of alloy steel inner sleeve and carbon steel outer sleeve, the head is equipped with a molding mold, the role of the head is to transform the rotational movement of the plastic melt into a parallel linear motion, evenly and smoothly into the mold sleeve, and give the plastic to the necessary molding pressure. The plastic is plasticized and compacted in the barrel and flows through the neck of the head through a certain flow path through the porous filter plate into the forming mold of the head. The mold core and mold sleeve are properly matched to form an annular gap with decreasing cross-section so that the plastic melt forms a continuous dense tubular cladding layer around the core line. To ensure that the plastic flow channel in the head is reasonable and to eliminate the dead angle of the accumulated plastic, there is often a diversion sleeve placed, and to eliminate the pressure fluctuation of plastic extrusion, there is also a pressure equalization ring set. The head is also equipped with a die correction and adjustment device to facilitate the adjustment and correction of the concentricity of the die core and die sleeve.

 

The extruder head is divided into an angled head (120o angle) and a right angle head according to the angle between the head material flow direction and the screw centerline. The shell of the head is fixed to the body with bolts, the die inside the head has a die core sitting and is fixed to the head inlet port with a nut, the front of the die core seat is equipped with a die core, the die core and the center of the die core seat has a hole for passing the core line, the front of the head is equipped with an even pressure ring for equalizing the pressure, the extrusion package forming part is composed of die sleeve seat and die sleeve, the position of the die sleeve can be adjusted by bolts through the support to adjust the die sleeve to the die core The position of the die sleeve can be adjusted by bolts through support to adjust the relative position of the die sleeve to the die core, which is convenient to adjust the uniformity of the thickness of the extruded layer.

 

If you want to buy a plastic extruder or want to know more, you can visit our official website. Our website is https://www.njjyextrusion.com/

 

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