Screw Conveyor Manufacturer
The screw conveyor that moves dry cement powder and the one that transfers dewatered ETP sludge are not the same machine. Different materials, different moisture levels, different bulk densities, and different process integration requirements demand different flight geometry, shaft configuration, trough design, and material of construction. Buying a standard-catalog screw conveyor for the wrong application leads to flight wear, shaft deflection, trough corrosion, and frequent unplanned stops.
AS Engineers designs and fabricates custom screw conveyors for chemical, pharmaceutical, food processing, water treatment, and general industrial applications. Every conveyor is sized to the specific material, throughput, and plant layout. ISO 9001:2015 certified, with 25+ years of process equipment manufacturing experience from Ahmedabad, Gujarat.
Get a Custom Quote
Need a reliable screw conveyor solution for your plant? AS Engineers is ready to help. Contact us for a free consultation and custom quote tailored to your material handling needs.
What a Screw Conveyor Is – and Where the Design Decisions Actually Matter
A screw conveyor moves bulk material by rotating a helical flight fixed to a central shaft inside a trough or enclosed tube. The rotating flight pushes material forward from the inlet to the discharge. Simple in principle. Complex in practice.
The decisions that determine whether a screw conveyor works reliably in your process are:
- Flight type and pitch: Standard helical flight for free-flowing powders and granules. Ribbon flight for sticky or wet materials that would otherwise pack around a central shaft. Variable pitch for controlled feed at the inlet, where material tends to flood. Cut-and-folded flight for materials that need mixing and aeration during transport.
- Shaft or shaftless: A central shaft supports the flights and is appropriate for most dry, free-flowing materials. For stringy, viscous, or high-moisture materials like ETP sludge, biosolids, or thick chemical pastes, a shaftless configuration eliminates the shaft entirely. Sticky material has no central pipe to bind against, and the conveyor keeps flowing.
- Trough vs. enclosed tube: An open U-trough allows easy access for cleaning and inspection. An enclosed tube prevents fugitive dust and is required for food-grade, pharmaceutical, or hazardous material applications.
- Material of construction: Sets the difference between a screw conveyor that corrodes in 18 months and one that runs for 10 years.
Types of Screw Conveyors Manufactured by AS Engineers
Horizontal Screw Conveyor
The most common configuration. Moves bulk material along a flat or near-flat path between two fixed points. Suitable for dry powders, granules, and coarse bulk solids. Used widely in chemical, cement, food, and fertilizer plants for inter-process material transfer. Standard flights work well for free-flowing materials. Ribbon or shaftless construction available where material is wet or cohesive.
Inclined Screw Conveyor
Moves material upward at an angle, typically between 15° and 45°. As inclination increases, volumetric efficiency drops because material tends to slide back on the trailing face of the flight. Inclined conveyors for high angles use reduced pitch flights and a fully enclosed tube to hold material in the conveying zone. Used for transferring material between process levels in chemical plants, dryer feed systems, and boiler ash removal.
Shaftless Screw Conveyor
The preferred solution for wet, sticky, and fibrous materials that would clog or jam around a conventional central shaft. A shaftless spiral rotates inside a lined trough with no central pipe obstruction. Dewatered ETP sludge, municipal biosolids, thick chemical pastes, wet wood chips, and food processing by-products are all handled reliably in shaftless designs. Maintenance is lower because there are no intermediate hanger bearings to service inside the material path.
Enclosed Tube Screw Conveyor
A fully enclosed screw inside a round tube rather than an open trough. Required where dust containment is a regulatory requirement (CPCB ambient air quality compliance), where the material cannot be exposed to ambient moisture or contamination, or where the process involves hazardous or pharmaceutical-grade materials. Also used in inclined and vertical conveying where an open trough would cause spillback.
Vertical Screw Conveyor
Moves material straight up within a compact footprint. Requires a controlled, steady feed rate at the inlet. Used for elevating powders, grains, and granules between floor levels where space does not allow a belt elevator or inclined conveyor. Feed rate control at the inlet is critical – starved or flooded feeding causes erratic discharge.
Screw Conveyor Application Matrix
Use this table to identify the right configuration for your material and operating condition.
| Material Type | Moisture / Condition | Recommended Configuration |
|---|---|---|
| Dry powder (cement, flour, chemical) | Low moisture, free-flowing | Horizontal, standard helical flight, U-trough or tube |
| Granules and pellets | Free-flowing, moderate bulk density | Horizontal or inclined, standard flight, U-trough |
| Dewatered ETP/STP sludge | 60–75% moisture, sticky, pasty | Shaftless, ribbon flight, enclosed trough |
| Chemical slurry or paste | High moisture, cohesive | Shaftless or ribbon flight, enclosed tube |
| Food-grade powder or grain | Hygiene-critical, low contamination | SS 304/316 enclosed tube, standard or ribbon flight |
| Pharmaceutical powder or API | GMP-required, no contamination | SS 316 enclosed tube, clean-in-place (CIP) design |
| Boiler ash or fly ash | Hot, abrasive, dry | Hardened flights, CS or MS construction with wear lining |
| Wet agricultural by-product | Fibrous, sticky | Shaftless, polymer-lined trough |
Where Screw Conveyors Fit in Your Process
ETP and STP Sludge Handling
Under NGT directions and CPCB consent conditions, ETPs and STPs must achieve compliant sludge disposal. Filter press or centrifuge dewatering reduces sludge moisture to 60–70%, but the resulting cake needs to be transferred reliably from the dewatering equipment to the next stage – whether that is a storage silo, a sludge dryer, or a truck loading point.
A shaftless screw conveyor handles dewatered sludge cake without the bridging, shaft-wrapping, or bearing failures that standard screws develop when handling wet, sticky material. AS Engineers designs screw conveyors as the feed system for its sludge dryer and paddle dryer systems. When the screw conveyor and the dryer come from the same engineering team, the feed rate, inlet moisture, and thermal load are all designed to the same operating point. There is no interface problem between two suppliers quoting separately.
Chemical and Pharma Plants
Enclosed tube screw conveyors in SS 316 construction provide dust-free, contamination-free transfer of chemical intermediates, APIs, and excipients. For corrosive or reactive materials, duplex stainless steel or polymer-lined trough options are available.
Food Processing
Hygienic screw conveyors in SS 304 or SS 316 with polished internal surfaces, no internal crevices, and quick-disassembly features for cleaning are used for flour, sugar, spice, grain, and by-product transfer. Design complies with food-grade material handling requirements under FSSAI guidelines.
Cement, Power, and Ash Handling
Fly ash, bottom ash, and raw meal are abrasive and hot. CS construction with hardened flights and wear-resistant trough liners extends service life significantly over standard mild steel conveyors.
Material of Construction Options
| MOC | When to Specify |
|---|---|
| Mild Steel (MS) | General industrial duty, dry non-corrosive material |
| Carbon Steel (CS) | Moderate temperatures, abrasive duty, boiler ash |
| SS 304 / SS 304L | Food-grade, mildly corrosive environments |
| SS 316 / SS 316L | Pharmaceutical, chemical, and high-corrosion applications |
| Duplex SS 2205 | Highly corrosive chemical service |
| Hard-faced or lined trough | Abrasive bulk solids — fly ash, clinker, limestone |
Shaft, flight, and trough material are selected independently. In some applications, the trough is MS while the flights are SS 316 because the flight surface contacts the material and the trough does not.
Technical Specifications
- Drive: Gearbox-coupled electric motor, variable speed drive available for controlled feed rate
- Intermediate bearings: Hanger bearings for long conveyors; shaftless designs eliminate internal bearings
- Trough options: U-trough (open), enclosed tube, split trough for easy access
- Drive location: Drive at discharge end (standard); drive at feed end available for specific layouts
Why Choose AS Engineers
Most conveyor suppliers quote the screw conveyor in isolation. You then coordinate separately with the dryer supplier, the filter press supplier, and the blower supplier. Each supplier’s equipment is designed to its own parameters, and when the system underperforms, no one owns the interface.
AS Engineers manufactures paddle dryers, centrifugal blowers, bag filters, and screw conveyors from a single facility in Ahmedabad. For ETP sludge drying systems, the screw feeder and the paddle dryer are designed together. Feed rate, inlet moisture, and shaft torque are all matched at the design stage – not reconciled after installation.
- ISO 9001:2015 certified design and manufacturing
- 25+ years of process equipment fabrication
- Custom-engineered to material properties, throughput, and plant layout
- Single-source supply: screw conveyor + dryer + blower + pollution control
- Full documentation: GA drawings, fabrication drawings, test records
- Commissioning support and spare parts supply
Frequently Asked Questions
What is the difference between a shaftless and a standard screw conveyor?
A standard screw conveyor has a helical flight welded to a central rotating shaft. This works reliably for free-flowing dry materials. For wet, sticky, or fibrous materials like ETP sludge or thick chemical pastes, the material wraps around the central shaft, builds up at hanger bearings, and eventually stalls the conveyor. A shaftless screw conveyor uses a thick spiral rotating inside a lined trough with no central shaft. There is no surface for wet material to bind to, and there are no internal hanger bearings to clog. For sludge applications specifically, shaftless is the correct choice.
Can a screw conveyor handle dewatered ETP sludge at 65–70% moisture?
Yes, with the correct configuration. A shaftless design with a ribbon-form spiral and a fully enclosed trough handles dewatered sludge cake reliably. AS Engineers supplies screw conveyors specifically as the feed system for its paddle dryer installations, where the inlet material is dewatered sludge at 60–75% moisture. The feed rate is controlled by variable-speed drive to match the dryer’s thermal load.
What information is needed to size a screw conveyor?
Material name and description, bulk density (kg/m³), inlet moisture content (%), particle size distribution, throughput required (kg/hr), horizontal distance and any elevation change, operating temperature, and any special requirements (food-grade, explosion-proof, enclosed design for dust control). The more complete the data, the more accurate the engineering proposal.
What material of construction is right for a chemical plant screw conveyor?
It depends on the material being conveyed and whether it is corrosive, abrasive, or temperature-sensitive. SS 316 is standard for corrosive chemical service. Duplex SS 2205 is used for highly corrosive environments. For abrasive dry materials at elevated temperature (boiler ash, clinker), CS with hardened or wear-faced flights is the correct choice. Our engineering team specifies MOC based on a full review of the material data sheet and operating conditions — not a generic recommendation.
Does AS Engineers supply screw conveyors as part of a complete sludge drying system?
Yes. For ETP and STP applications, AS Engineers supplies the complete material handling and drying system: screw conveyor from the dewatering point, paddle dryer, off-gas handling system (cyclone, scrubber, or bag filter), and dried product discharge conveyor. All equipment is engineered to the same process parameters. Contact our team to discuss your sludge drying requirement.
Discuss Your Screw Conveyor Requirement
Share the material data and throughput requirement with our engineering team. We will recommend the right configuration, specify the correct material of construction, and provide a detailed technical proposal.
Contact AS Engineers – +91 99090 33851 – info@theasengineers.com