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Extruder Screw Barrel

Jinxing Screw: Your Professional Extruder Screw Barrel Manufacturer!

 

Established in 1989, Zhejiang Jinxing Screw Manufacturing Co., Ltd. is a leading professional screw manufacturer located on Zhoushan Jintang Island. We offer fast and reliable global distribution with customized services following client requirements. We have cooperated with multinational corporations, such as MAPLAN, APPL, WAPO, and SAMSUM.

 

Strong Production Ability
Our company, with 220 employees and a 25 million USD investment, has secured 107 acres for a modern factory complex, including a 2,276.39 square meter electroplating workshop.

 

Advanced Equipment
Our company uses advanced machinery like the Austrian CNC PICK UP 500 for precision machining, an automatic nitriding system for product hardness, and an American plasma screw overlay machine with an automatic grinder for quality and durability.

 

High Quality
Our products feature advanced materials, including high-grade steel, which extends their wear life and ensures stable operation. Each barrel is rigorously tested to exceed industry standards. This commitment to quality guarantees the superior performance and durability of our products.

 

Rich Experience
We have over 30 years experience in manufacturing and designing feed screws and barrels for injection, extrusion, and blow molding applications.

What is Extruder Screw Barrel

 

An extruder screw barrel is a critical component of an extrusion machine that is used to melt and shape plastic materials into a desired form. The extruder screw barrel is made up of two main parts: the screw and the barrel. Extruder screw barrels are available in different configurations and sizes to suit different extrusion applications. They may be made from a variety of materials such as carbon steel, stainless steel, or bimetallic alloys, depending on the specific application and required performance.

Features of Extruder Screw Barrel

 

Increased Output

The design of the screw barrel allows for a higher throughput of material, resulting in increased production efficiency.

Improved Mixing

The screw design allows for more thorough mixing of materials, resulting in more consistent end products.

Greater Flexibility

Different screw designs can be used to process a variety of materials, making extruders more versatile.

Easy Maintenance

Screw barrels are relatively easy to disassemble and reassemble, allowing for quick and easy maintenance.

Better Quality

The screw barrel gives more homogeneous and consistent output, which results in better quality products.

Components of Extruder Screw Barrel

 

Barrel
The barrel is a cylindrical housing through which the material being processed (such as plastic pellets or powder) is fed into the extruder. It provides a controlled environment for the material to be heated, melted, and transported through the extrusion process. Barrels are typically made of durable materials like steel or other alloys that can withstand high temperatures and pressures. They may also have heating elements along their length to melt the material more effectively.

 

Screw
The screw, also known as the extrusion screw or auger, is a rotating shaft housed within the barrel. Its primary function is to convey, compress, melt, and mix the material as it moves along the length of the barrel. The screw is typically designed with a helical flighting (grooves or threads) along its surface, which helps to move the material forward while also applying pressure to melt and homogenize it. The design of the screw can vary depending on the specific requirements of the extrusion process, such as the type of material being processed and the desired end product.

 

Different Sections of Extruder Screw Barrel
 

 

Feeding Section
Its function is to transport the plastic slices added by the hopper quickly. The groove volume in this section is generally unchanged, and the plastic is in a solid-state. Usually, the screw groove is not completely filled with the material. The degree of filling is related to the shape of the material, the degree of dryness and wetness, and the feeding device.

 

Compression Section (Plasticization Section)
The main function is to compact and plasticize the loose material conveyed from the feeding section and discharge the air brought by the clamp. The volume of the spiral groove in this section gradually decreases or suddenly decreases. The plastic gradually changes from a solid-state to a molten state in this section, becoming a continuous short fluid transported to the homogenization section.

 

Homogenization Section (Metering Section)
The main function is to plasticize further the molten material sent from the compression section evenly and evenly extrude the pipe material from the die at a fixed time and pressure.

 

Process of Extruder Screw Barrel
Extrusion Screw Barrel for MILACRON EXtrusion Machine
Extrusion Screws and Barrels for Sheet Extrusion Line
Feed Screw Barrel for HENGLI Weaving Extruder
Barrier Screw Barrel for BATTENFELD-CINCINNATI Extruder

The Injection Molding Process Steps
Clamping
The first step of the injection molding process is clamping. Injection molds are typically made in two, clamshell-style pieces. In the clamping phase, the two metal plates of the mold are pushed up against each other in a machine press.

 

Injection
When the two plates of the mold are clamped together, injection can begin. The plastic, which is typically in the form of granules or pellets, is first melted down into a complete liquid. Then, that liquid is injected into the mold. Manufacturers should take care to ensure the temperature remains constant throughout this step of the process

 

Dwelling
In the dwelling phase, the melted plastic fills the entirety of the mold. Pressure is applied directly to the mold to ensure the liquid fills every cavity and the product comes out identical to the mold.

 

Cooling
The cooling stage is the most straightforward; the mold should be left alone so that the hot plastic inside can cool and solidify into a usable product that can be safely removed from the mold.

 

Mold Opening
Once the part has cooled, a clamping motor will slowly open the two parts of the mold to make for a safe and simple removal of the final product.

 

Ejection
With the mold open, an ejector bar will slowly push the solidified product out of the open mold cavity. The fabricator should then use cutters to eliminate any waste material and perfect the final product for customer use. Waste material can often be recycled and reinjected for the next part, decreasing your material costs.

 

Heating and Cooling of Extruder Screw Barrel
Extruder Barrel Pressure
The pressure inside the extruder barrel during the extrusion process is high. Barrels for most extruders are designed to withstand operating pressures up to 10,000 psi or 700 bar. Normal operating pressures generally range between 1,000 and 5,000 psi. or 70 and 350 bar. Too much pressure could rupture a barrel. To protect the extruder barrel from over-pressurization, several methods have been developed. A shear pin can be installed on a swing gate. Rupture disks can be installed at the die end of the barrel. If melt pressure exceeds the rating of the rupture disc, the disk fails, and the pressure is relieved. As a warning device, a pressure transducer with an alarm is also common.

 

Extruder Barrel Heating
The barrel must be heated for operation. Most barrel heaters are electric. There are several types. Cast heaters are cast aluminum split cylinders with insulated resistance wires embedded inside. The simplest type of heater is the mica band heater. Mica band heaters contain coated resistance wires sandwiched between mica insulation with a steel enclosure for support. Ceramic heaters are used in applications with high heat requirements.

 

Extruder Barrel Cooling Design & Equipment
Barrel cooling is also an important part of the extrusion process. Extruder barrel cooling is necessary if the plastic gets too hot or if the extruder must be shut down quickly. Barrels can be cooled using air or liquid. Barrels that are air-cooled have blower units and a plenum chamber under the barrel at each temperature zone. The blower is turned on by the barrel temperature controller when an upper setpoint is reached.

Using Tips of Extruder Screw Barrel

 

Heating Method Of Extruder Screw Barrel
The machine heater widely uses resistance heating and thermocouples to realize segmented temperature control and detection. The resistance heating uses resistance to generate heat to the barrel, and then transfer the heat to the plastic in it. The method mainly includes strip heaters, cast aluminum heaters, ceramic heaters, etc., which have the advantages of small size, easy manufacturing, and maintenance.

 

Temperature Range Of The Extruder Screw Barrel
According to the different plasticization states of the material along the screw axis, the heating of the screw and the barrel must be carried out in sections to help improve the plasticization capacity in order to make the temperature distribution of the extruder barrel meet the process requirements. Generally, (3–5) Ds, (which is the screw diameter) is used as a heating temperature control section. The temperature control fluctuation range of heating should generally not exceed 5°C meanwhile for heat-sensitive plastics, the temperature should not be over 2°C.

 

Heating Power Of Extruder Screw Barrel
When determining the heating power of the extruder screw barrel, it is also necessary to meet the requirements of productivity to ensure that the barrel has a sufficiently fast heating rate in addition to meeting the heat required for plasticization. The heating time of the machine is not more than 30 min for small machines, but generally about 1h for large and medium machines.

 

Cooling Of Extruder Screw Barrel
The design of the cylinder cooling channel is adopted with a heat exchanger and a large stainless steel water tank. The cooling system shall choose softening water. Then, the cooling effect will be realized by controlling the flow of water in and out of the channel through the solenoid valve.

 

Types of Necessary Wear for Screw and Barrel

 

Extrusion Screws and Barrels for Sheet Extrusion Line

Abrasive Wear

Suppose any fillings can harm any surface damage incited by talc, glass fibers, calcium carbonate, etc. This can be formed under abrasive wear.

Mixing Screw Barrel for Film Blowing Machine

Corrosive Wears

If any barrel or screws are influenced due to a chemical response, it instantly wears away. To protect your equipment from these crises, you need to ensure that you use corrosive wear while equipping the screw barrels.

Extrusion Screw Design for Pelletizing Extrusion Line

Adhesive Wears

Due to overheating, one metal can clasp to each other or force as the screw rotates. If you use adhesive wear, you can have relevant and robust work.

Factors Affecting the Service Life of the Extruder Barrel And Screw

 

Working Conditions Of Extruder Barrel And Screw
When working in a relatively harsh environment, the temperature is generally above 200 °C. The extruder barrel screw must not only accept high pressure, but also accept the abrasive effect of the melt and the frequent load starting during pre-molding, and also accept a lot of pressure and torque during the operation.

 

Failure Mechanism
The main reason for the failure of the extruder barrel and extruder screw due to wear is "abrasive wear". When plastics and fillers are plasticized at high temperatures, corrosive media are often disassembled, which will corrode the surface metal of the barrel and screw, and the corrosion products are easy to It is carried out by the plastic, which then leads to the loss of material. The combined effect of wear and corrosion aggravates the failure of the barrel and screw.

 

Factors Of Production
The design, material selection of the barrel and screw, surface metal plating such as Cr, Ni, nitriding, spraying or spray welding hardened alloy, as well as materials (such as plastic particle size, masterbatch function) and operation (speed, back pressure, etc.) will affect extrusion. The service life of the barrel screw. It can be seen that the service life of the barrel screw is mainly related to the raw material of the screw, especially various surface treatment technologies.

 

Selection Basis
When selecting the barrel and screw, first select or plan the structure of the barrel and screw according to the nature of the plastic to be processed. Such as aspect ratio, compression ratio, pitch, edge width, etc. The second is to select the material of the barrel screw and the corresponding surface treatment method. Only by selecting the extruder barrel screw suitable for the application scenario, it is possible to prolong the service life of the barrel screw.

 

How to Choose the Barrel Screw of the Extruder?
 

Output
The output refers to the output or extrusion volume through a given die under the premise of ensuring the quality of plasticization. As mentioned earlier, the output is generally expressed in kilograms/hour or kilograms/revolution. A good thread screw barrel should have a high plasticizing ability. It should be pointed out that low-temperature extrusion is a current development trend. It can improve the quality of extruded products (such as reducing internal stress, etc.), prevent heat-sensitive materials from overheating and decomposition, reduce energy consumption, reduce the burden on the cooling system of the main and auxiliary machines, and increase productivity.

 

Unit Consumption
Unit consumption refers to the energy consumed per kilogram of plastic (rubber) extruded, generally expressed by N. Where N is power (kw) and Q is output (kg/h). The larger the value is, the more energy is needed to plasticize the same weight of plastic (rubber), which means the more heating power is consumed, and the more mechanical work done by the motor enters the material through shear and frictional heat.

 

Adaptability
The so-called adaptability of the screw refers to the adaptability of the screw to process different plastics, match different heads and different products. Generally speaking, the stronger the adaptability, the lower the plasticizing efficiency.

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FAQ

Q: What is the function of the barrel of an extruder?

A: Extruder barrels are used in large twin screw extruders. The purpose of adopting this type of segmented combined extruder barrel is to facilitate the machining of the extruder barrel and save some more precious alloy steel

Q: What are the different types of extruder barrels?

A: The barrel arrangement of a twin screw extruder can be adapted to the needs of the process to be performed. Barrel types include feed, side-feed, degassing, combi and closed barrels. With a suitable configuration, materials can be added along the processing section or gas or moisture removed.

Q: Why screw is used in injection molding?

A: The screw increases pressure in the metering section, pushing the molten plastic into the injection nozzle and injecting it into the mold to form the product.

Q: Where are extruder screw barrel most utilized?

A: Screws and Barrel are utilized in those enterprises that generate plastic items. But apart from the plastics industries, many other enterprises utilize this product to make their most profitable and efficient such as small Scale Industries, cable wire industries, food processing industries.

Q: What is the working principle of extruder?

A: The working principle of sheet extruder machine is to convert solid plastic into uniform melt by pressure and shear, and then send it to the next process. The production of melt involves additives such as color masterbatch, resin blending, and re-pulverization.

Q: What is the difference between injection screws and extrusion screws?

A: The most obvious difference between injection and extrusion screw designs is the length of the flighted surface, or the L/D ratio. Where a 20:1 ratio is common for injection molding screws, 24:1 is considered a standard L/D ratio for extruder screws- and many have ratios of 30:1 or more.

Q: What is the process of extrusion?

A: The extrusion process involves the application of heat and pressure to force the material, usually in a molten or semi-solid state, through a specifically designed opening—a die shape—with the desired cross-sectional profile.

Q: How do you clean extruder barrels?

A: Use a brass brush to remove the resin residue on the inside and outside of the barrel of the extruder, wrap the waste cotton cloth on the end of the long mallet, and wipe off the residual melt on the inside and outside.

Q: What are the main components of extruder?

A: This component consists of screws, sleeves, barrel heads, and dies. This section makes the extruder either a single screw or twin screw extruder. If we have two shafts parallel, then it will be a twin screw extruder, but if we have only one shaft, then it will be a single screw extruder.

Q: What is the speed of extruder screws?

A: Each size screw has a certain speed range, and the normal speed is 100-150rpm. Too low will not condense the plastic, and too high will scorch the plastic.

Q: How do you measure extruder barrel wear?

A: Set the dial bore gauge to the nominal bore diameter of the barrel using a micrometer. Take a gauge reading throughout the length of the barrel at 2 to 3 inch intervals and record the results on a Barrel Inspection Report.

Q: How does a single screw extruder work?

A: Most extruders are single screw machines. The screw is what forces the material towards, and then through, the die. Shape is imparted by the die, and/or by post-extrusion forming, and the product is then set to shape by cooling while maintaining its shape.

Q: What material is used for screws?

A: Typically, screws and bolts are made from steel due to its strength and relatively inexpensive cost. However, screws and fasteners can also be produced from stainless steel, brass, titanium, and a wide range of other metals depending on the intended application.

Q: What are the benefits of extruder screw and barrel?

A: Simple structure and low price. It is suitable for plasticizing extrusion of polymers and extrusion processing of pellets. There is little shear degradation to the polymer, but the material stays in the extruder for a long time. Easy to operate and simple process control.

Q: What is the difference between stainless steel and carbon steel screw barrels?

A: Compared to low-carbon steel, stainless steel offers a massive upgrade in strength, hardness, and most importantly corrosion resistance. High carbon steel offers strength rivaling and sometimes exceeding stainless steel, but is largely a niche material in the manufacturing world.

Q: How to choose a suitable cleaning method for the screw and barrel of the extruder?

A: If the screw barrel of the extruder is already very dirty, the solution is to pull the screw, because the dirty screw cannot be completely removed no matter what you use. Even if it can be completely removed, it will take too much raw material and time. If you are dealing with a color change, make a judgment first. If changing from white to transparent, just use raw materials to wash. But if toner is added, or red, green, yellow, black, etc. need to be changed to lighter colors, it is recommended to use professional screw cleaning materials to deal with it, especially for hot runners or toners as colorants.

As one of the most professional extruder screw barrel manufacturers and suppliers in China, we're featured by quality products and good service. Please rest assured to buy customized extruder screw barrel at competitive price from our factory.

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