Conveying Screw Elements: Diameter 20-300 mm, Pitch 0.5D to 2D

Component Specifications

Definition

Conveying screw elements are precision-engineered components used in twin-screw assemblies (extruders, compounders) to mechanically transport raw materials, intermediates, or products along the barrel length. They feature helical flight geometry that creates positive displacement movement through rotation, handling powders, pellets, pastes, or melts with controlled throughput. These elements are mounted on screw shafts and work in intermeshing or non-intermeshing configurations to move material from feed zones to mixing/kneading zones without significant pressure generation.

Working Principle

Conveying screw elements operate on the Archimedes' screw principle: as the twin screws rotate (typically co-rotating or counter-rotating), the helical flights create a continuous channel that pushes material forward axially. The geometry (pitch, flight depth, helix angle) determines conveying efficiency, fill factor, and residence time. Material moves by drag flow in the screw channel and pressure flow between flights, with minimal shear or mixing action compared to kneading elements.

Materials

Typically manufactured from nitrided steel (e.g., 34CrAlNi7), tool steel (e.g., H13), or stainless steel (e.g., 1.4404/316L) for corrosion resistance. Surface treatments include nitriding, hard chrome plating, or tungsten carbide coatings for wear resistance. Operating temperatures range from -50°C to 400°C depending on application.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Pitch	0.5D to 2D
Length	0.5D to 4D (D=diameter)
Max RPM	100-1200
Diameter	20-300 mm
Clearance	0.1-0.5 mm (between screws and barrel)
Helix Angle	10° to 30°
Channel Depth	0.1D to 0.2D
Pressure Rating	Up to 300 bar

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 14104, DIN 32711, DIN 32712

Parent Products

This component is used in the following industrial products

Twin Screw Assembly

The core rotating element in a twin-screw extruder that conveys, mixes, and processes polymer materials.

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Engineering Analysis

Risks & Mitigation

Wear from abrasive materials
Material degradation from excessive shear
Insufficient conveying causing feed starvation
Overheating from friction
Corrosion from chemical exposure

FMEA Triads

Trigger: Abrasive fillers (glass fibers, minerals)
Failure: Flight wear reducing conveying efficiency
Mitigation: Use hardened surfaces (nitriding, coatings), monitor wear patterns, implement preventive maintenance

Trigger: Improper material feeding
Failure: Uneven filling causing surging and output variation
Mitigation: Optimize feed rate control, use starve-fed systems, ensure consistent feedstock properties

Trigger: Thermal expansion mismatch
Failure: Jamming between screws and barrel
Mitigation: Maintain proper clearances, control temperature gradients, use compatible materials

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

Diameter tolerance: ±0.05 mm, Straightness: 0.02 mm/m, Surface roughness: Ra 0.4-1.6 μm

Test Method

Dimensional verification with CMM, hardness testing (HRC 50-60), material certification per EN 10204 3.1, pressure testing at 1.5x operating pressure

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

Check the legal entity, factory address, ownership, certifications, and direct contacts.

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Manufacturers of Conveying Screw Elements

Manufacturer profiles associated with Conveying Screw Elements.

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Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review

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Frequently Asked Questions

What is the difference between conveying and kneading screw elements?

Conveying elements primarily transport material with minimal mixing, featuring continuous helical flights. Kneading elements have interrupted flights that create high shear and dispersive mixing for homogenization.

How do I select the right pitch for conveying elements?

Larger pitches (1.5D-2D) provide faster conveying with lower fill degree, suitable for free-flowing materials. Smaller pitches (0.5D-1D) offer higher fill degrees and better pressure build-up for viscous materials.

Can conveying elements be used in food applications?

Yes, with food-grade materials like stainless steel 316L and appropriate surface finishes (Ra < 0.8 μm) to meet FDA/EU compliance for direct food contact.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Conveying Screw Elements