All You Need To Know About Screw Barrels & Extruder Screw Barrels

What is Screw Barrel?

A screw barrel, consisting of two parts- a screw and barrel, is of the most important parts manufactured by plastic processing machinery. The production process of the industry remains incomplete without the usage of screws and barrels. The screw barrel ensures that the product smoothens and generates the expected output at the desired rate. 

Manufacturers effectively design the screw barrel so that the product is suitable for the screw by its inner and outer diameter. Usually, the screw barrel manufacturers manufacture the screws from high-quality Musco materials, with diameters ranging between 14mm and 250mm, which increases to the maximum length of 5 meters.

What is Extruder Screw Barrel?

Manufacturers make the extruder barrels through extrusion, which is a manufacturing process that provides shape to the molten plastic. The exploitation of the internal friction and the external heat supply through the heat resistors helps transform base material into a finished or semi-finished, shaping material by forcing it through a die or extrusion crosshead.

For shaping plastics (thermoplastics or thermo-hardening materials), manufacturers use either single or double extruder screw barrels. Single extruder screw barrels consist of the two most fundamental mechanical components- the extruder barrel and the screw. Before using screw barrels in manufacturing applications, the extruder screw barrels undergo a hardening process with a nitriding depth of around 0.5mm that screw hardness of around 800HV and barrel hardness of 1000 HV.

Screw Barrel Composition 

Manufacturers make screw barrels using the following: 

  • Powder metallurgy steels, 
  • Nitriding steels or
  • Bi-metals are composed of two separate parts- a supporter base material and an internal lining. 
  • Extruder screw barrels are made from the following:
  • Nitriding steels
  • Case-hardening 
  • Core-hardening steels 
  • Powder metallurgy steels or
  • Special steels

We classify the extruder screw barrels depending on their external characters or confirmation, which come in two varieties- smooth and machined. Externally smooth barrels are those that are not worked on a machine tool or coated. In these barrels, the manufacturers position the heat resistors in such a way so that they cool via special fans and have a good heating ability with average cooling capacity. The barrels require copper and aluminum-finned thermal cooling systems, which help improve heat dispersion rates during cooling, especially when processing materials that are sensitive to sudden changes in temperature. However, a few degrees in excess can jeopardize process performance. 

Externally machined barrels are usually finned from a solid steel cylinder, thereby enabling these barrels to process a machine tool. Machine tools are better heat dispersers than smooth ones. However. The former comes with several disadvantages, such as: 

  • Presence of localized contact between heat resistors and barrel cooling fins, responsible for reducing the heat supply to the process. 
  • These barrels’ heat resistors have lower life 
  • The cost of barrel production is much higher
  • The internal geometric conformation of the extruder screw barrels is either smooth or grooved (only in the feed zone). 

The smooth barrels usually have a lower capacity than grooved barrels. The melt output of the grooved barrel is between 1.1 and 1.3 times higher than the smooth variety. The presence of grooves with a combination of motor and reduction gear strongly influences the process regularity of the extruder output, without proper processing of the grooves attempting to achieve a particularly low rate that generates excessive driving torque, thereby causing the molten plastic to pulsate while it exists the crosshead. Therefore, there is an increase in the material-barrel friction in this variety of barrels, as do differences in material-screw and material-barrel friction.

Features of Extruder Screw Design 

Extruder screws are the most helpful parts that conveys materials during extrusion that come with the following parameters and design features: 

  • Diameter, length and ratio of its diameter and length
  • Geometric conformation 
  • Pitch and helix angles 
  • Compression ration 
  • Construction material and surface finishing 
  • Axial holes for thermoregulation 

Considering their simplest confirmation, the extruder screws consist of three functional zones- a melt conical compression zone (consisting of a set of compression ratios), a cylindrical metering zone (art the end of the screw), and a cylindrical feed zone. They might also consist of barrier fights or mixing zones. 

The metering zone spans the last three to five diameters of the screw. It helps in serving the molten material forward in the same direction. Therefore, it guarantees the right pumping pressure to convey through the die through the converter inside the crosshead. 

Besides, our extruder screw barrels offer the following features: 

  • Great finishing
  • Durable
  • Robust and rust-resistant 
  • Comes in both standard and customized form 
  • Heat Treatm4ent and wear-resistant 
  • Anticorrosion 
  • Best quality and performance 

Applications of Screw Barrels

Screw barrels has the following scope of applications: 

  • Plastic extruder machine 
  • Injection modeling machine 
  • Blow molding machine 
  • Recycling of PP PE pelleting film extruder
  • Blow molding machine 
  • Monofilament machine 
  • PP film and HDPE film machine 
  • XLPE cable and PVC cable making machine 
  • LLDPE Tubing and HDPE Pile machine 
  • ABS Profile and VC profile machine 

About Us

Mahira Polyglobal LLP, founded in 2020 and headquartered in Ahmedabad, India, is a general manufacturer of various machinery parts and products, including FIBC bags, HFPE t rib liner, screw barrels, IDPE labels, films, and much more. Our manufactured products help us im meeting the needs of several manufacturing industries operating in different sectors. 

As a producer and exporter of a wide range of screw barrels, we include extrusion single and twin parallel screw barrels, vented and injection molding screw barrels, bi-metallic and SS screw barrels. We believe in manufacturing our products with extra perfection. Hence, our team works nonstop on the quality and offers you more output with minimum maintenance. We offer our customers various types of screw barrels, which you can use in plastic extrusion, pellet extruder, blown film extrusion, granulating machine, and food and rubber industries.

Our screw barrels consist of various materials like LDPE, HDPE, PP, and PVC. We also make customized screw barrels according to the request and requirements of our clients. If you are looking for huge designs and specifications, seeking them with Mahira Polyglobal is the best choice, as we believe in manufacturing our products with extra perfection. 

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