Screw Barrel
Your Leading Screw Barrel Supplier
We are committed to provide system solutions for plastic industry and offers high-end products like Shut off Nozzles, Plasticizing Screw Barrel, Tip Assembly and Tie Bar. After years of technical precipitation, Rootier is currently the only Chinese-based supplier providing full series injection nozzle solutions like shut off nozzle, mixing nozzle and filter nozzles. We have lot ready stock screw barrel for some commonly used IMM like Nissei, Sumitomo, Fanuc, Victor machines, which suitable for high Glass Fiber filled plastics processing with unique solutions to increase lifetime and performance.
Why Choose Us?
High quality
We have 100% quality guarantee to customers. We will be responsible for any quality problem.
Competitive price
Our products are complete in variety, good in quality, reasonable in price.
After-sale service
Good after-sale service, handling the customer complaint and solve problem for customers.
Fast delivery
Huge production capacity to ensure in time delivery and transport to the destination in the first time.
A screw barrel, also known as a screw and barrel assembly, is a crucial component in the extrusion and injection molding processes used in the plastics industry. It consists of a screw and a barrel that work together to melt, mix, and transport plastic material through a molding machine.
Benefits of Screw Barrel
High-maintenance not required
This product is low maintenance; hence you don’t need very high tools or sources to maintain its quality. That is why enterprises can effortlessly regulate it.
Highly durable
It is also understood for its high stability as once you buy this, you don’t need to repair it regularly.
Outstanding strength
Another plus point of this product has its stability. This product comes with outstanding stability, and you will feel it after using it.
Easily availability
One more thing that goes into this product’s popularity is its availability, which is very effortlessly obtainable.
Powerful structure
The Robust Structure of the machinery has improved the efficiency of screw and barrel.
Types of Screw Barrel
Screw barrel for PVC pipe
A screw barrel is playing a vital role in producing PVC pipe. There are two types of screw barrels through which we can produce the PVC Pipe; a Single screw barrel and a twin-screw barrel. Single screw extruders consume more power in comparison to the twin-screw extruder. Twin-screw barrel produces almost double output in the same power consumption.
Screw barrel for injection molding
Injection molding machine molds can be fastened in either a horizontal or vertical position. The majority of machines are horizontally oriented, but vertical machines are used in some niche applications such as insert molding, allowing the machine to take advantage of gravity. The screw barrel is the heart of Injection molding as the quality of the screw barrel decides the quality of the end product. A single screw barrel is used in the Injection Moulding Machine. The important thing in injection molding is mixing and melting the plastic material.
Screw barrel for blown film plant
Blown film plant is used to produce Plastic film which is a thin continuous polymeric material. Thicker plastic material is often called a "sheet". These thin plastic membranes are used to separate areas or volumes, to hold items, to act as barriers, or as printable surfaces. The use of a screw barrel in a blown film plant depends on the layer of the film, mainly 4-5 numbers of extruder and screw barrel get used in blown film plant.
There are some types of screw design which mainly used in Blown Film Plant To maintain output and accomplish the required mixing, screw designers have created a wide variety of mixing devices. No one mixer fits all situations, so it is important to determine exactly what your overall process requirements are before selecting a mixer or even a combination of mixers.
Barrier screw:
Barrier screw is mainly used to Increases Melting efficiency, It increases the plasticizing capacity, Barrel screw also removes solid bed breakup and allows more control and stability.
Screw barrel for tape plant
This process starts by feeding plastic material (pellets, granules, flakes, or powders) from a hopper into the barrel of the extruder. The material is gradually melted by the mechanical energy generated by turning screws and by heaters arranged along the barrel. The molten polymer is then forced into a die, which shapes the polymer into a shape that hardens during cooling
Tape plants require grooved feed for better mixing and melting and to generate better output.
Plastic extruder Machine
Injection Molding Machine
Blow Molding Machine
Components of Screw Barrel
The three basic parts of a screw are the head, threaded shank and point.
Screw drive: This is the slot your screwdriver tip will fit into. It is also known as the screw head. There are many such options; Accordingly, you should have a large number of screwdriver tips in your toolbox.
Screw head: The head is the tip of the screw. It is usually wider than the shank and thread. Heads can be flat or domed. Some are small in diameter in relation to the shank and others are very wide.
Screw thread: Amazingly, the thread has many components and varies between screws. There is the thread angle, which indicates how steeply it angles down. There is also spacing between threads that makes a difference. This is the pitch. Some screws have threads that are small and close together. Other screws have larger threads that are further apart.
Thread length: The thread length is either full length or partial length. Accordingly, there are fully threaded and partially threaded screws.
Screw shank: The shank is the portion of the screw from underneath its head to where the threads begin.
Screw tip: At the very end of the screw is the tip that penetrates the material first when the screw is being driven in. There are many different types of tips.
Material of Screw Barrel
Aluminum
Aluminum boasts the strength equivalent to mild steel but is only one-third of the weight, making it an ideal choice for various applications. It demonstrates remarkable resistance to corrosion in wet environments and is commonly employed for fittings, hardware, and fasteners. Additionally, it possesses nonmagnetic properties.
Brass
Brass, composed of approximately two-thirds copper and one-third zinc, is a relatively softer material. It offers good resistance to rust and atmospheric corrosion, making it suitable for use in gears, bearings, fasteners, and valves. Furthermore, brass exhibits nonmagnetic characteristics.
Copper
Copper, known for its versatility and durability, finds applications in various fields. Its distinctive color is particularly favored by artists and architects for its decorative finish. This electrically conductive material boasts excellent thermal properties, is nonmagnetic, and resists rust in wet environments.
Low carbon steel
Low Carbon steel is employed in numerous general-purpose applications. To resist rust, it requires a finish such as black oxide treatment or zinc plating. Commonly used for binding posts, bushings, washers, inserts, fittings, screws, and nuts, this material exhibits magnetic properties.
How to Maintain Screw Barrel
When assembling, disassembling or replacing nozzles, screw heads, and flanges, apply high-temperature anti-corrosion paste to the threaded surface of the bolts to facilitate future disassembly.
When the molten plastic is found to be abnormal or discolored, or the product is brittle, the temperature should be adjusted to confirm whether the heating coil temperature line is working normally, and the screw and the rubber head assembly should be checked for damage.
Avoid mixing POM and PVC into the barrel at the same time, which will react at the melting temperature and cause serious industrial accidents.
When using new plastic, the remaining material in the barrel should be cleaned. When using POM, PVC, PA+GF and other materials, minimize the degradation of the raw materials, and rinse them with PP materials in time after shutdown.
Avoid idling and slipping of the screw.
When using anti-salvation, make sure that the plastic in the barrel is completely melted, so as not to damage the transmission system parts when the screw retreats.
Avoid foreign matter falling into the barrel and damage the screw and barrel. Prevent metal fragments and debris from falling into the hopper. If processing recycled materials, a magnetic hopper should be added to prevent iron filings from entering the hopper.
If the machine stops for more than half an hour each time, it is best to close the blanking port and shoot clean the material in the barrel, and set the heat preservation.
Do not start the machine when the barrel has not reached the preset temperature. The new electric heating generally requires the temperature to reach the set value for 30 minutes before operating the screw.
Factors Affecting the Performance of Screws and Barrels
Material selection
The material selection of the screw and barrel has an important impact on its performance. Commonly used materials include alloy steel, stainless steel, and high-speed steel. Different materials have different hardness, wear resistance and corrosion resistance. Choosing the right material can improve the life and performance of the screw and barrel.
Accuracy requirements
The machining accuracy of the screw and cylinder has a great influence on its performance. Screws and cylinders with low precision will lead to uneven melting and insufficient mixing of plastics, which will affect molding quality and production efficiency.
Design structure
The design structure of the screw and barrel will also affect its performance. For example, parameters such as pitch, thread shape and depth of the screw will affect its conveying capacity and plasticizing effect. The heating method, cooling method and internal structure of the cylinder will also affect the melting and mixing effect of the plastic.
Use environment
The use environment of the screw and barrel will also affect its performance. For example, high-temperature resistant materials need to be selected in high-temperature environments, and corrosion-resistant materials need to be selected in acid-base environments. At the same time, the cleanliness and lubrication of the operating environment will also affect the operation of the screw and barrel.
Conditions and Methods of Use of Extruder Screw Barrel
Heating method of extruder screw barrel
The machine heater widely uses resistance heating, and uses 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 state 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 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.
Causes of Screw Wear
In the extruder, the relative moving parts are the screw and the barrel and there is also a fluid flowing through the channels that can cause additional wear. There are many factors that can cause the barrel and screw wear:
1.Cold start of the screw
2.Wrong material processing (e.g. corrosive polymers for a screw not suitable for corrosive polymers)
3.Uneven heating of the cylinder
4.Improper screw and cylinder alignment
5.Non-straightness of the screw
6.Abrasive additives in the polymer formula
7.Incorrect screw and/or cylinder material
8.Corrosion due to polymer or additive degradation
All of these factors relate to three main wear phenomena: abrasive, corrosive and adhesive.
Abrasive wear is caused by the hard particles (e.g. glass fiber, calcium carbonate, flame retardants) with which the polymers are added. The sliding of the polymer in the screw channel at high pressures and temperatures causes abrasive phenomena by the hard particles that creep and impact the metal surfaces of the screw and cylinder. The amount of abrasive wear also depends on the hardness of the particles, their shape and size. This type of wear can be reduced by surface hardening of the screw and cylinder (e.g. nitriding, chrome plating).
Corrosive wear is due to corrosive additives and degraded polymer particles chemically attacking extruder components. The largest portion of corrosive wear usually occurs in the metering zone where temperatures are higher and the material remains for longer, increasing the possibility of product degradation. The effects of this wear can be decreased by using the same surface treatments that decrease abrasive wear.
Adhesive wear can be caused by the metal-to-metal contact between the cylinder and the screw, which, while rotating, can cause momentary contact between the thread crest and the surface of the cylinder, from which a sort of small weld is originated, immediately removed by the rotation of the screw. This wear phenomenon can be effectively reduced or even eliminated by the correct alignment of the screw in the cylinder and by making the screw and cylinder as straight as possible.
Screw and Barrel Design Optimization
The design of the screw and barrel plays a critical role in the performance and longevity of plastic processing equipment. A well-designed screw and barrel will efficiently convey plastic material, melt it evenly, and produce high-quality products with minimal wear.
Some elements of the screw and barrel to consider optimizing to prevent premature wear include:
Barrel surface finish — The surface should be smooth and defects-free to minimize friction and wear. A polished surface can also help to prevent material buildup.
Flight clearance — Flight clearance is the distance between the screw flight and the barrel wall. Proper flight clearance is essential for efficient material conveying and to prevent excessive wear. Too little clearance can cause material drag and wear, while too much clearance can lead to material slip and reduced mixing.
Root diameter— The root diameter is the diameter of the screw core. A larger root diameter provides greater stability and wear resistance. However, it also increases the shear stress on the material, which can be detrimental for certain resins.
Helix angle — The helix angle is the angle between the screw flight and the axis of the screw. A steeper helix angle increases the mixing efficiency but also increases the shear stress on the material. A shallower helix angle reduces shear stress but also decreases mixing efficiency.
Our Factory
We have two factories with about 9000 square meters construction area located in Zhoushan. Our engineers are experienced in all kinds of plastic processing design and application. Our production capacities can reach 1500 screw barrel sets monthly that enable us to deliver products to our customers in a short time.
