INDUSTRY COMPONENT

Reciprocating Screw

Reciprocating screw is a key component in injection molding machines that melts, mixes, and injects plastic material into molds.

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Component Specifications

Definition
A reciprocating screw is a precision-engineered rotating and axially moving component within the injection unit of plastic injection molding machines. It performs three primary functions: plasticizing solid polymer pellets through shear heating and barrel conduction, homogenizing the melt through mixing elements, and injecting the molten material into the mold cavity under controlled pressure. The screw rotates to melt material while simultaneously retracting, then moves forward axially (without rotation) to inject the accumulated melt.
Working Principle
The reciprocating screw operates through simultaneous rotation and axial movement. During plasticizing phase, rotation generates shear heat through friction against the barrel wall, melting polymer pellets while retracting to accumulate melt in front. During injection phase, the screw stops rotating and moves forward axially like a plunger, forcing the accumulated molten plastic through the nozzle into the mold cavity under high pressure. This dual-action combines the melting efficiency of a rotating screw with the precise injection control of a plunger.
Materials
Typically manufactured from high-grade alloy steels (AISI 4140, H13 tool steel) with surface hardening treatments (nitriding, chrome plating) for wear resistance. Specialized variants may use bimetallic construction with wear-resistant alloys in high-wear zones.
Technical Parameters
  • Diameter 18-200 mm
  • L/D Ratio 20:1 to 25:1
  • Flight Depth Varies along length
  • Surface Hardness 58-62 HRC
  • Compression Ratio 2:1 to 3:1
  • Injection Pressure 100-250 MPa
Standards
ISO 294, DIN 16773

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Reciprocating Screw.

reciprocating screw injection molding screw plasticizing screw injection unit component screw design plastic injection machine parts screw specifications Reciprocating Screw in Rubber and Plastic Product Manufacturing

Parent Products

This component is used in the following industrial products

Injection Unit

The component of a silicone molding machine responsible for melting and injecting silicone material into the mold cavity.

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Engineering Analysis

Risks & Mitigation
  • Wear and corrosion reducing efficiency
  • Material degradation from overheating
  • Inconsistent melt quality
  • Mechanical failure under high pressure
  • Backflow during injection phase
FMEA Triads
Trigger: Abrasive polymer additives
Failure: Excessive screw and barrel wear
Mitigation: Use hardened surfaces, bimetallic barrels, and proper material selection
Trigger: Overheating due to excessive back pressure
Failure: Polymer degradation and black spec formation
Mitigation: Optimize temperature profiles and back pressure settings
Trigger: Improper screw design for material
Failure: Poor melting and mixing quality
Mitigation: Match screw geometry to material characteristics and processing requirements

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
±0.05 mm diameter tolerance, ±0.1 mm straightness over full length
Test Method
Dimensional inspection with micrometers and dial indicators, hardness testing, material composition verification, pressure testing under simulated conditions

Buyer Feedback

★★★★☆ 4.5 / 5.0 (38 reviews)

"Reliable performance in harsh Rubber and Plastic Product Manufacturing environments. No issues with the Reciprocating Screw so far."

"Testing the Reciprocating Screw now; the technical reliability results are within 1% of the laboratory datasheet."

"Impressive build quality. Especially the technical reliability is very stable during long-term operation."

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Frequently Asked Questions

What is the difference between reciprocating screw and two-stage screw systems?

Reciprocating screws combine plasticizing and injection in one unit, while two-stage systems separate these functions with a plasticizing screw feeding a separate injection plunger, allowing independent optimization of each function.

How does screw L/D ratio affect injection molding performance?

Higher L/D ratios (typically 20:1 to 25:1) provide longer residence time for better melting and mixing, improved temperature homogeneity, and reduced pressure drop, but require more torque and longer barrels.

What maintenance is required for reciprocating screws?

Regular inspection for wear, cleaning to prevent material degradation, checking for corrosion, monitoring torque requirements, and periodic measurement of critical dimensions to ensure proper clearance with barrel.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

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