Extrusion Screw Barrel

$255.00

Detail

Parameters

Characteristics of Extruder Screws

1. Large Length-to-Diameter Ratio

Extruder screws typically feature a substantial length-to-diameter ratio, often ranging from 20 to 40 or even higher. This extended ratio allows the plastic to remain in contact with the screw for a longer duration, providing ample time for thorough plasticization, mixing, and homogenization. For instance, when manufacturing high-quality plastic pipes and films, a screw with a larger length-to-diameter ratio ensures that all components of the plastic are evenly dispersed, resulting in consistent product quality.

2. Stable Thread Structure

The thread structure of an extruder screw is designed to be stable and consistent. Generally, it is divided into three sections based on different plastic materials and product requirements: the feeding section, the compression section, and the metering section. The feeding section has deeper grooves to facilitate the transportation of plastic particles; the compression section features gradually shallower grooves to compress and plasticize the plastic; and the metering section has uniformly shallow grooves to further homogenize the plastic melt. This stable structure ensures that the plastic is processed in a predictable and controlled manner within the screw.

3. Continuous Operation

Extruder screws operate continuously. Plastic particles are fed into the screw from the hopper and are continuously extruded and formed after being plasticized. This requires the screw to have excellent stability and reliability, capable of transporting and plasticizing plastic steadily over extended periods to meet the demands of continuous production.

4. Strong Adaptability

By simply replacing different screw heads and dies and adjusting the process conditions, a wide variety of plastic products with different shapes and specifications can be extruded. These include pipes, sheets, and cable coatings. Moreover, extruder screws can handle a diverse range of plastic materials, from common plastics like polyethylene, polypropylene, and polyvinyl chloride to engineering and specialty plastics.

Differences between Extruder Screws and Injection Molding Screws

1. Length-to-Diameter Ratios

Extruder Screws: These screws have a relatively large length-to-diameter ratio, typically between 20 and 40. This larger ratio is beneficial for the continuous plasticization and uniform mixing of plastics, making it suitable for the continuous extrusion molding process.
Injection Molding Screws: These screws have a smaller length-to-diameter ratio, usually between 18 and 22. This is because the plastic stays in the barrel for a relatively short time during the injection molding process, and an overly long screw is not necessary for plasticization. A smaller ratio can enhance injection efficiency.

2. Compression Ratios

Extruder Screws: The compression ratio is generally between 2 and 5, depending on the type of plastic and product requirements. A higher compression ratio helps to compact and plasticize the plastic more effectively, resulting in a more uniform melt.
Injection Molding Screws: The compression ratio is usually between 1.6 and 2.5. Since injection molding screws need to balance plasticization and injection functions, the compression ratio should not be too high; otherwise, it would increase injection resistance, affecting speed and quality.

3. Functional Focus

Extruder Screws: Their primary functions are to continuously and stably transport, plasticize, and homogenize the plastic, ensuring that the plastic melt is extruded at a uniform temperature and pressure to produce items with stable shapes and consistent quality.
Injection Molding Screws: In addition to plasticizing the plastic, these screws must also perform the injection action, quickly and accurately injecting the plasticized material into the mold cavity. Therefore, injection molding screws place greater emphasis on plasticizing ability and the efficiency of pressure transfer during injection.

4. Head Structures

Extruder Screws: The head structure is relatively simple, typically featuring a smooth transition section that allows the plastic melt to flow smoothly into the die for molding.
Injection Molding Screws: These screws generally have a non-return ring installed at the head to prevent the plastic melt from flowing back during injection, ensuring the precision and stability of the injection volume.

Series

Screw Barrel For Profile Extrusion

Certification

CE, ISO, UL, QS, GMP

Material

Alloy Steel,38CrmoAl,42 CrMo(JIS SCM440),9Cr18MoV

Suitable Plastic Material

PP,PE,ABS,PS etc.

Treatment

Heat and nitriding treatment

Brand

Moiron