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Screw Barrel - EJS | Extruder, Injection Molding, Blow Molding


📌 Product summary
A screw barrel is a core functional assembly in plastic and rubber processing machinery. It directly influences material plasticizing efficiency, output stability, and equipment service life. EJS (established 1992, Zhejiang, China) manufactures and supplies screw barrels for global OEM customers and end-users across plastics, rubber, chemical, and food industries. Products are available in standard and custom configurations with multiple material grades.

What is a screw barrel?

A screw barrel refers to the combined system of a rotating screw housed inside a cylindrical barrel. This assembly performs material conveying, melting, mixing, and pressurization during continuous or cyclic processing. In actual production environments, the performance of a screw barrel depends on three factors: material selection for both screw and barrel, machining precision of flights and inner bore, and surface treatment methods applied. These factors together determine how uniformly material plasticizes, energy consumption, and how long the screw barrel remains in service before replacement.

Why screw barrel quality matters in processing lines

Processing conditions vary widely. Some materials are highly abrasive; others are corrosive or require high temperatures. A screw barrel that works well for general-purpose extrusion may fail prematurely when used with glass-filled composites or halogen-containing formulations. Below are common failure modes observed across extruders and injection molding machines.

Common failure modes of screw barrel assemblies

Failure type

Typical cause

Consequence

Wear

Abrasive fillers (glass fiber, calcium carbonate)

Reduced output, backflow

Corrosion

Halogenated materials or acidic byproducts

Pitting, surface degradation

Fatigue

Cyclic pressure loading

Cracking in flight roots

Thermal deformation

Uneven heating or cooling

Clearance loss, scoring

EJS product line: screw barrel types and configurations

EJS offers multiple screw barrel types to cover different equipment categories and processing methods. The table below summarizes compatibility and typical applications.

Screw barrel product categories by machine type

Product category

Compatible machine types

Typical applications

Extruder screw barrel

Single screw extruders

Pipe, profile, sheet, film, wire/cable

Twin screw barrel

Parallel and conical twin screw extruders

PVC compounding, profile, wood-plastic composites

Injection molding screw barrel

Horizontal injection molding machines

Molded parts, housings, technical components

Blow molding screw barrel

Continuous and reciprocating blow molders

Bottles, containers, automotive ducts

Rubber screw barrel

Cold feed and hot feed rubber extruders

Rubber seals, hoses, tire components

Bimetallic screw barrel

All of the above

High wear or high corrosion environments

Hardfacing screw and barrel

All of the above

Abrasive materials, recycled plastics

Most products are manufactured as OEM custom orders. The same screw barrel design supplied to a machinery brand may also be available directly to end-users.

Material options and specifications for screw barrel

Base material determines mechanical strength, wear resistance, and corrosion resistance of a screw barrel. EJS provides eight material grades, selected according to operating conditions and budget.

Available steel grades for screw and barrel

Steel grade

Hardness (HRC)

Best suited for

38CrMoAlA

28–32 (after nitriding 60–65)

General extrusion and injection

40Cr

30–35

High strength, moderate wear

42CrMo

35–40

High strength, impact loading

1.8550 (34CrAlNi7)

30–34 (after nitriding 62–67)

High wear resistance

1.8519 (31CrMoV9)

32–36 (after nitriding 61–66)

High torque and high load

D2

58–62

Abrasive materials (glass-filled, mineral-filled)

SKD61 / SKD11

50–55

High temperature and combined wear

Hastelloy

35–45 (as cast)

Highly corrosive materials

Surface treatment options for screw barrel

Treatment method

Hardness (HV)

Alloy system

Typical thickness

Gas nitriding

800–1000

Nitrided case

0.3–0.6 mm

Plasma spray coating

550–750

Ni60, Colmonoy 56, Colmonoy 83

0.8–2.0 mm

Bimetallic (centrifugal casting)

600–750

Tungsten carbide content up to 35% / 45%

1.5–3.0 mm

Technical parameters: screw barrel dimensions and tolerances

The following tables provide typical dimensional ranges for extruder and injection molding applications. Custom dimensions are available upon request.

Typical screw barrel specifications (extruder & injection molding)

Parameter

Range / common values

Screw diameter

20 mm – 300 mm

Screw length-to-diameter (L/D) ratio

18:1 – 36:1 (custom up to 48:1)

Barrel inner diameter tolerance

H7 or as specified

Screw flight runout

≤ 0.02 mm per meter

Surface roughness (barrel bore)

Ra ≤ 0.4 μm (nitrided) / Ra ≤ 0.8 μm (bimetallic)

Operating temperature range

100°C – 450°C (depending on material)

Maximum barrel pressure rating

35 MPa – 150 MPa (depending on wall thickness)

Typical twin screw barrel parameters (conical and parallel)

Parameter

Conical twin

Parallel twin

Screw diameter range

35/70 mm – 65/132 mm (small/large end)

35 mm – 150 mm

L/D ratio (effective)

14:1 – 22:1

20:1 – 40:1

Standard material

38CrMoAlA nitrided or bimetallic

38CrMoAlA / 42CrMo / bimetallic

Typical applications

PVC pipe, profile, foam board

Compounding, masterbatch, recycling

Industries using EJS screw barrel solutions

Screw barrel assemblies manufactured by EJS are found in the following fields:

  • PVC building materials and sheets
  • Soft and hard pipes, profiles, tubing
  • Wires and cables (insulation and sheathing)
  • Rubber products (profiles, hoses, tire components)
  • Silicone microporous tubes and medical tubing
  • Plastic modification (single screw and twin screw)
  • Film blowing, injection molding, blow molding
  • Recycled plastics and reclaim systems
  • Chemical, pharmaceutical, food, and agricultural processing

Beyond the Product: Customization & OEM Service Certificate 

Most of the screw barrels we produce never see the EJS name. Instead, they power the production lines of well-known global machinery brands. This is because we master OEM custom manufacturing.



  • Complete OEM Service: Send us an original part, a sample, or even a hand-drawn sketch. We will reverse-engineer, manufacture, and deliver an identical or upgraded screw barrel.
  • No Drawing? No Problem. As mentioned, our field service team can travel to your site for precise measurement. We have successfully performed on-site work in the USA, Germany, Italy, Turkey, and Brazil.
  • 100% Traceability: Every screw barrel we ship comes with a Certificate of Quality that includes material test reports, heat treatment records, and final inspection dimensions.





The EJS Promise: After-Sales Support & Secure Logistics 

We know that shipping a heavy, precision component across the world can be a concern. That’s why our service doesn't end when the product leaves our factory.



12-Month Warranty: We provide a full 12-month warranty against manufacturing defects and premature wear under normal operating conditions.

Professional Packaging: Each screw barrel is individually cleaned, anti-rust treated, vacuum-sealed in VCI film, and packed in a strong wooden case with foam support to prevent any damage in transit.

Fast & Reliable Logistics: We work with major freight forwarders (DHL, Kuehne+Nagel, Sinotrans) to offer sea, air, and rail shipping. We provide real-time tracking and handle all export documentation.

Installation Support: Upon request, we can provide detailed video instructions or send a technician to your factory to supervise the installation and commissioning of your new screw barrel.




Comprehensive Range of Screw Barrels

As a professional Screw Barrel Supplier, EJS offers a complete product line:

Extruder Screw Barrel

Twin Screw Barrel (Parallel / Conical)

Injection Moulding Screw Barrel

Blown Moulding Screw Barrel

Rubber Screw Barrel

Bimetallic Screw Barrel

Hardfacing Screw & Barrel

Customized Extruder Parts (Die, Gearbox, Nozzle, etc.)

Most products are OEM customized, and you may be using them without knowing they come from EJS.


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