twin screw extruder pelletizing line- China Factory Manufacturers Suppliers

Degradable plastics refer to a class of plastics whose various properties can meet the requirements of use, remain unchanged during the shelf life, and can be degraded into environmentally harmless substances under natural environment conditions after use. Therefore, it is also called environmentally degradable plastic.
There are a variety of new plastics: photodegradable plastics, biodegradable plastics, light/oxidative/biodegradable plastics, carbon dioxide-based biodegradable plastics, thermoplastic starch resin degradable plastics.
There are two main areas for the use of degradable plastics: one is the area where ordinary plastics were originally used. In these areas, the difficulty of collecting used or post-consumer plastic products will cause harm to the environment, such as agricultural mulch and single-use plastic packaging, and the second is areas where plastics are used instead of other materials. The use of degradable plastics in these areas can bring convenience, such as ball tacks for golf courses, and seedling fixing materials for tropical rainforest afforestation.
Specific applications are:
1.Agriculture, forestry and fishery, plastic film, water-retaining materials, seedling pots, seedbeds, rope nets, slow-release materials for pesticides and agricultural fertilizers.
2.Packaging industry, shopping bags, garbage bags, compost bags, disposable lunch boxes, instant noodle bowls, buffer packaging materials.
3.Sporting goods, golf tacks and tees
4.Hygiene products, women's hygiene products, baby diapers, medical mattresses, disposable haircuts.
5.Medical materials, bandages, clips, small sticks for cotton swabs, gloves, drug release materials, and surgical sutures and fracture fixation materials.
Nanjing Jieya also manufactures twin screw compounding extruder for bio-degradable material. We warmly welcome your inquiry.

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.

A twin screw extruder is composed of several parts such as a transmission device, feeding device, barrel, and screw, etc. The role of each part is similar to that of the single screw extruder. So what are the main differences between the twin screw extruder and single screw extruder? The following is the detailed introduction

 

Here is the content list:

l Cross sectional profile

l The way of material transfer

l The material flow velocity field

 

Cross sectional profile

The difference from the single screw extruder is that the twin screw extruder has two parallel screws in an "∞" shaped cross section. Twin screw extruders for profile extrusion are usually closely meshed and heterogeneously rotating, although a few also use co rotating twin screw extruders, which generally operate at relatively low screw speeds of about 10 r/min. High speed meshing co rotating twin screw extruders are used for blending, venting, or as continuous chemical reactors, with maximum screw speeds ranging from 300 600 r/min. Non engaging extruders are used for mixing, venting, and chemical reactions, and their conveyors are very different from those of engaging extruders, and are closer to those of single screw extruders, although they are fundamentally different.

 

The way of material transfer

In the single screw extruder, the solid conveying section is friction dragging and the melt conveying section is viscous dragging. The frictional properties of solid materials and the viscosity of molten materials determine the conveying behavior. If some materials have poor frictional properties, it is more difficult to transfer the material to the single screw extruder if the feeding problem is not solved. In twin screw extruders, especially meshing twin screw extruders, the material transfer is to some extent a positive displacement transfer, the degree of positive displacement depending on the proximity of the screw prongs of one screw to the relative screw grooves of the other screw. The screw geometry of a closely meshed anisotropic rotary extruder yields a high degree of positive displacement transport characteristics.

 

The material flow velocity field

The flow velocity distribution of the material in a single screw extruder has been described fairly well, whereas the flow velocity distribution of the material in a twin screw extruder is quite complex and difficult to describe. Many researchers have analyzed the velocity field of the material without considering the material flow in the engagement zone, but the results of these analyses are very different from the actual situation. This is because the mixing characteristics and overall behavior of a twin screw extruder depend mainly on the leakage flow that occurs in the engagement zone, yet the flow in the engagement zone is quite complex. The complex flow spectrum of the material in a twin screw extruder exhibits macroscopic advantages that cannot be matched by a single screw extruder, such as adequate mixing, good heat transfer, high melting capacity, good venting capacity, and good control of the material temperature.

 

If you want to know more, you can consult our company. 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, devolatilization, reaction, recycling, etc. After 17 years of development, now we have a 20,000 square meters workshop with annual sales of over 300+ sets, export over 60 countries.

 

JIEYA has the most experienced technical core team, with extensive experience in system integration of the development manufacturing, materials processing, application technology, and other fields.

underwater pelletizing machine is similar to airflow granulator and water jet granulator. The equipment part mainly covers: plastic granulator, single and twin screw plastic extruder, plastic film blowing machine, bag making machine, printing machine, coating machine, Adhesive tape machine, tape slitting machine, slitting machine, strapping machine.

• What is the problem of uneven pelletizing by the underwater pelletizing machine?

• What is the workflow of the underwater pelletizing machine?

• What is the technological advantages of the underwater pelletizing machine?

What is the problem of uneven pelletizing by the underwater pelletizing machine?

1. underwater pelletizing machine, the machine head is not evenly heated, and the machine head temperature is stable before starting up;

2. The cooling water of the underwater pelletizing machine is boiled prematurely, and the water should be boiled when the machine head starts to discharge;

3. It is also possible that there is a problem with the hot runner design of the machine head, which is caused by uneven pressure.

What is the workflow of the underwater pelletizing machine?

Before being made into final products, most polymers must be blended and then pelletized to become marketable raw materials. The power required by the underwater pelletizing machine is directly proportional to the extrusion volume and exponentially related to the size of the filter screen. There are many different types of pelletizer designs, but all pelletizers have some common places, and they can be divided into two categories: cold pelletizing system and die face hot pelletizing system. The main difference between the two categories is the time arrangement of the pelletizing process. The cold pelletizing system cuts pellets from the solidified polymer at the end of the process; while in the die-face hot pelletizing system, pellets are cut when the molten polymer emerges from the die, and pellets are processed downstream cool down.

What are the technological advantages of the underwater pelletizing machine?

The underwater pelletizing machine treated by standard process has the following significant advantages:

1. The appearance standard of the products produced by the underwater pelletizing machine is exquisite and bright;

   
   

2. The hardness of the wear layer in contact with the material by the underwater pelletizing machine can reach HV 600-800, and the local hardness can reach HV900-1100. The hardness is increased to 2-4 times the original hardness. Compared with the non-standard machine without heat treatment, it is resistant to The wear performance is increased by 3-5 times;

3. The products of the underwater pelletizing machine are not deformed after long-term use, effectively avoiding the screw breaking due to the excessive wear of the barrel, and the stable service life is 2-3 times that of the traditional machine, which greatly reduces the investor's investment in replacement parts;

4. The wear-resistant layer of the barrel screw produced by the underwater pelletizing machine has high hardness, while the base material still retains good toughness and processing performance;

5. The service life of the screw of the underwater pelletizing machine has increased from the hundred-ton level of the ordinary plastic pelletizing machine to the thousand-ton level.

Nanjing JlEYA has focused on the production and development of underwater pelletizing machines for several years, and they have always put the needs of customers as their top priority. Here, you can choose the underwater pelletizing machine that suits your need.

PVC compounding extruder is made by mixing PVC resin with stabilizers, lubricants, and other additives through granulation and then extrusion, or by using powder in one extrusion. what are the application areas of PVC? The following are the details.

 

Here is the content list:

• General soft products

• PVC film

• PVC foam products

• PVC coated products

• PVC paste resin

• PVC transparent sheet

• PVC rigid sheet

• Other applications of PVC

 

General soft products

General soft products can be extruded into cables, wires, and hoses by the extruder: shoe soles, slippers, various plastic sandals, as well as toys and auto parts by the injection molding machine with various molds.

 

PVC film

PVC film After mixing and plasticizing PVC with additives, transparent or colored film of specified thickness can be made by using a three-roller or four-roller calendar, and calendered film can be processed by this method. It can also be cut and heat laminated to process raincoats, tablecloths, curtains, packaging bags, inflatable toys, etc. The wide transparent film can be used for greenhouse, plastic shed, and ground film; the film stretched in both directions can be used for shrink packaging due to its characteristics of shrinkage by heat.

 

PVC foam products

Soft PVC can be used as sandals, insoles, foam slippers, and shockproof and cushioning packaging materials. In addition, it can also be extruded into low-foaming hard PVC sheets and profiles by extruder, which is a new type of building material and can be used as a substitute for wood.

 

PVC coated products

Artificial leather with backing is made by coating PVC paste on cloth or paper and then plasticizing it at 100 degrees Celsius or above (or PVC and additives can be calendered into film and then pressed together with backing); while artificial leather without backing is directly calendered by calender into soft sheet with a certain thickness and then pressed with the pattern. It can be used to make leather bags, leather boxes, book covers, sofas, and car cushions, etc. It can also be made into flooring leather, which is used as the flooring material for buildings.

 

PVC paste resin

PVC emulsion or micro-suspension resin is dispersed in a liquid plasticizer to make it swell and plasticize into the plasticized sol, and then add stabilizer, filler, coloring agent, etc. After full stirring for de-bubbling, PVC paste is prepared, and then processed into various products such as coat hangers, tool handles, Christmas trees, etc. by casting, impregnating, or laminating processes.

 

PVC transparent sheet

Impact modifier and organotin stabilizer are added to PVC, which is mixed, plasticized, and calendered into transparent sheets. Then it can be made into thin-walled transparent containers by thermoforming and can be used for vacuum blister packaging such as moon cake boxes, etc. It is an excellent packaging material and decoration material.

 

PVC rigid sheet

PVC hard sheet and plate After adding stabilizer, lubricant, and filler to PVC and mixing, it can be extruded into various caliber hard pipes, shaped pipes, corrugated pipes, and other products by using an extruder, and used as a downpipe, drinking water pipe, electric wire casing or staircase handrail, etc.; the calendered sheet can be overlapped and hot-pressed to make various thicknesses of hard sheets, which can be cut into various desired shapes and can be welded into various chemical resistant tanks, ducts and containers by using PVC welding rod with hot air, etc.

 

Other applications of PVC

PVC can be processed into rigid profiles using an extruder and used for window and door assembly. In some countries, the doors and windows assembled by PVC rigid profile have occupied the market of windows and doors together with wooden windows and doors, aluminum windows, etc.

 

If you want to buy PVC compounding extruder, you can consult our company, our company's website is https://www.njjyextrusion.com/

PVC compounding extruder is divided into two types of hard and soft RPVC pipes, RPVC pipes are chemically resistant and insulating, mainly transporting various fluids and used as wire sleeves, etc. SPVC pipes are manufactured by extruding PVC resin with a large amount of plasticizer and a certain amount of stabilizer and other additives after granulation. The following is a detailed description of the equipment functions of the PVC compounding extruder.

 

Here is the content list:

• High Speed Mixer High-Speed Mixing

• Accurate matching of feeding device

• Water tank for pipe forming

• Traction machine frequency conversion speed control

• Automatic cutting

• Unloading the material from the turning frame

 

High Speed Mixer High-Speed Mixing

Raw material intermixture is to feature PVC stabilizer, softener, inhibitor, and different auxiliary materials to the high-speed mixer in proportion and sequence to the method.

Accurate matching of feeding device

The PVC compounding extruder part is equipped with a quantitative feeding device to match the extrusion volume with the feeding volume to ensure stable extrusion of products. Due to the characteristics of the conical screw, the feeding section has a larger diameter, and the heat transfer area and sheer speed of the material are larger, which is contributive to the plasticization of the fabric and also the little diameter of the screw within the metering section reduces the warmth transfer space and also the sheer speed of the soften so that the melt can be extruded at a lower temperature. When the screw rotates in the barrel, the PVC mixture is plasticized and pushed to the head to achieve compaction, melting, mixing, and homogenization and to achieve the purpose of exhaust and dehydration. The feeding device and screw drive device adopt frequency conversion to realize synchronous speed regulation.

PVC compounding extruder dies head part of the compacted, molten, blended, and homogenized PVC has subsequent materials through the screw to the die head extrusion die head is the key component of pipe forming.

Water tank for pipe forming

The vacuum shaping water tank of PVC compounding extruderis used for pipe shaping and cooling, the vacuum shaping water tank is equipped with vacuum system for shaping and cooling and water circulation system stainless steel box body circulating water spray cooling, the vacuum shaping water tank is equipped with front and rear moving device and left and right, high and low adjustment manual device.

Traction machine frequency conversion speed control

The traction machine is used to continuously and automatically lead the cooled and hardened pipe from the head with frequency control.

Automatic cutting

The cutting machine is controlled by the travel switch according to the required length and then automatically cut and delay the turning frame to implement the flow of production, the cutting machine with a fixed-length work switch signal as a command to complete the whole process of cutting in the cutting process and pipe running synchronization cutting process is completed by electric and pneumatic drive, the cutting machine is equipped with a dust suction device to suck out the cutting debris and recycling.

 

Unloading the material from the turning frame

The material turning action is controlled by the cylinder through the air circuit to achieve the material turning frame is equipped with a limit device when the cutting saw cut off the pipe after the pipe continues to transport after a delay, the cylinder into the work of turning action to achieve the purpose of unloading. After unloading, it will be automatically reset after a delay of several seconds to wait for the next cycle.

 

Nanjing JlEYA is the leading manufacturer extruder manufacturer specializing in twin screw extruder, mini twin screw extruder, plastic extruder and parallel twin screw extruder in China, which is widely used in compounding, modification, polymerization, devolatilization, reaction, recycling, etc. After 17 years development, now we have 20,000 square meters workshop with annual sales over 300+ sets, export over 60 countries.

JIEYA has the most experienced technical core team, with extensive experience in system integration of the development manufacturing, materials processing, application technology andother fields.

DRIVE SECTION
The drive section of the twin screw extruder consists of 3 parts: motor, clutch, and gearbox.
The reduction and distribution gear unit reduces the motor speed to the screw shaft speed and distributes the input torque to the two output shafts. Clutch is installed between the drive motor and the gearbox drive shaft.
PROCESSING SECTION
The processing section of the twin screw extruder in SHJ series extruder consists of individual barrel sections which are replaceable. Depending on the process tasks, reserve feed port, liquid injection port or twin screw side feed port is available.
Owing to the modular design of the twin screw extruder screw elements and screw barrels, conveying, plasticizing, homogenizing, pressure build-up and devolatilization zones can be established, depending on the process task.
For product intake and conveying, screw elements are used. The extruder can be fed with powder, pellets, chips, melt, paste, etc.
Plasticizing, mixing and dispersing are done by the twin screw extruder kneading elements. By varying the thickness of the kneading disks and their angle of stagger, their mixing, shearing and dispersing action can be adjusted to the individual requirements.
The screw elements are arranged on screw shafts. The co-rotating and closely intermeshing screw shafts have a sealing profile.  
The screw barrels are supported by barrel supports. Axial displacement of the processing section resulting from thermal dilatation is absorbed by these supports.
EXTRUSION PART
The discharge section of the twin screw extruder consists of die head and screen changer, which is installed at the end of twin screw extruder discharging direction. There are several types of die heads and screen changers to meet the requirements of different polymers and processing technology.

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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