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screw barrels
📌 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.
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
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
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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