Screw Conveyors — Enclosed Transport and Dosing of Bulk Solids
The screw conveyor moves powders and granules inside a closed trough or tube by a rotating helical flight — dust-tight, compact and inherently suited to dosing. Pro Makina manufactures U-trough and tubular screws with project-calculated diameter, pitch and speed for your material.
Working Principle and Design
A helical flight welded on a central pipe rotates inside the casing and pushes the material forward. Capacity depends on screw diameter, pitch, rotation speed and filling degree — and filling degree must respect the material: free-flowing granules allow higher filling than sticky or aerating powders.
Screws also meter: with an inverter-driven motor the conveying rate becomes controllable, which is why dosing screws feed dryers, mixers and granulators across our plants. For sticky materials we use adapted flight geometry (ribbon or paddle sections) and generous inspection covers for cleaning access.
Typical Applications
- Powder raw material transfer in fertilizer plants
- Dosing screws feeding dryers, granulators and mixers
- Dewatered sludge transport with adapted flight design
- Dust discharge under cyclones and filters
- Inclined transfer where space excludes belt conveyors
Technical Features
U-trough or tubular
Trough design for access and cleaning; tube design for dust-tightness and inclines.
Flight variants
Full, ribbon and paddle flights matched to material behaviour.
Material options
Carbon steel, wear-protected or stainless execution for corrosive duties.
Dosing capability
Inverter drive and load cells turn the screw into a metering device.
Sealing
Shaft seals and gasketed covers for dust-tight operation.
Modular lengths
Intermediate hanger bearings and flanged sections for longer routes.
Data Required for Screw Conveyor Design
| Design input | Role in the calculation |
|---|---|
| Material, bulk density, flowability | Filling degree and flight type |
| Capacity (t/h or m³/h) | Diameter, pitch and speed |
| Route length and incline | Drive power and bearing concept |
| Temperature and corrosivity | Material selection and sealing |
| Dosing accuracy requirement | Drive control and weighing integration |
Screw diameter and speed are calculated per material; incline reduces capacity and is always checked in the design.
Why Pro Makina
Manufactured in Turkey
Design and fabrication are carried out in our own facility in Eskişehir, Turkey, with full in-house engineering control.
Project-based engineering
Every machine is sized around your raw material, moisture content and capacity target — not sold from a fixed catalogue.
Export experience
We prepare international technical proposals, shipping documentation and commissioning support for overseas projects.
Single point of responsibility
Process design, fabrication, automation and commissioning are managed by one engineering team.
Frequently Asked Questions
Can screw conveyors handle wet sludge?
Yes, with shaftless or adapted flight designs, suitable liners and drive reserves. Sludge screws are a standard part of our sludge drying lines.
How accurate is screw dosing?
With inverter control and gravimetric feedback (load cells), screw feeders achieve recipe-grade accuracy for most fertilizer and chemical applications; the achievable tolerance depends on material flowability.
What limits the length of a screw conveyor?
Torque on the central pipe and hanger bearing wear. Long routes are split into modular sections or handled by chain or belt conveyors — we advise the economic boundary per case.
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Share Your Project Details
Send us your raw material, capacity and process data. Our engineering team will review your requirements and prepare a project-specific technical proposal.
Screw Conveyors — Enclosed Transport and Dosing of Bulk Solids
Final dimensions, capacity and drive power are determined per project, based on your raw material analysis, moisture content and process calculations.