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MetalKeen manufactures custom stainless steel transfer screws and spiral conveyor shafts for bulk material handling, mixing, and extrusion applications. Produced from 304, 316L, 310S, 2205, 410, 420, and 430 stainless steel, our helical screws support shaft ODs from 50 mm to 3000 mm and lengths up to 12 meters. Mounting options include shaft ends, flanges, or splines—individually or in combination. All products are made to customer drawings.
A transfer screw (also called a spiral conveyor shaft, screw flight, or auger screw) is a rotating helical blade mounted on a central shaft or pipe. It is the core component of screw conveyors, screw feeders, and screw extruders, used to:
Transport granular, powder, or slurry materials along a trough or tube
Meter precise quantities of material for batch or continuous processes
Mix multiple ingredients through controlled shear and folding
Extrude or crush viscous or semi-solid materials under pressure
MetalKeen produces continuous and sectional screw flights, paddle screws, ribbon screws, and tapered screws to match your conveying requirements.
Table
Material | Grade | Key Properties | Best For |
|---|---|---|---|
304 SS | S30400 | General corrosion resistance, cost-effective, food-safe | Food processing, general chemical, ambient temperature |
316L SS | S31603 | Superior chloride and acid resistance, low carbon for welding | Marine, pharmaceutical, acidic foods, salt environments |
310S SS | S31008 | Excellent high-temperature oxidation resistance up to 1150°C | Furnace feed, hot ash, high-temperature calcining |
2205 Duplex | S32205 | High strength, excellent pitting and stress corrosion resistance | Mining slurry, seawater, aggressive chemicals |
410 SS | S41000 | Martensitic, heat-treatable hardness, wear-resistant | Abrasive materials, mining, sand, cement |
420 SS | S42000 | Higher carbon than 410, greater hardness and wear resistance | Heavy abrasion, crusher feed screws, mineral processing |
430 SS | S43000 | Ferritic, magnetic, good oxidation resistance, lower cost | Non-critical conveying, magnetic separation applications |
Selection Tip: For food and pharmaceutical applications, 316L is the standard. For high-temperature processes above 800°C, choose 310S. For abrasive mining applications, 410 or 420 martensitic stainless steel offers superior wear life. For chloride-rich or seawater environments, 2205 duplex provides the best corrosion resistance.
Table
Specification | Range / Options |
|---|---|
Shaft Outer Diameter | 50 mm – 3000 mm |
Shaft Length | 0.2 m – 12 m (longer on request) |
Flight Inner Diameter | 20 mm – 2800 mm |
Flight Outer Diameter | 50 mm – 3000 mm |
Flight Thickness | 1 mm – 40 mm |
Pitch | 20 mm – 6000 mm (standard, variable, or tapered pitch) |
Flight Type | Continuous helical, sectional, paddle, ribbon, or cut-and-folded |
Mounting Style | Shaft-end fixed, flange fixed, spline fixed, or any combination |
Surface Finish | Mill finish, polished (Ra ≤ 0.8 μm for hygienic), sandblasted |
Welding | TIG (GTAW) or plasma welding; full penetration flight-to-shaft joints |
MetalKeen offers flexible mounting solutions to integrate with your drive system and bearing arrangement:
Table
Mounting Type | Description | Best For |
|---|---|---|
Shaft-End Fixed | Precision-machined shaft ends with keyway, journal, or thread | Direct coupling to gearbox or motor |
Flange Fixed | Welded or bolted flange at one or both ends | Overhung load support, easy assembly/disassembly |
Spline Fixed | Internal or external splines for torque transmission | High-torque applications, positive drive engagement |
Combination Mounting | Shaft + flange, shaft + spline, or all three | Complex drive trains, heavy-duty conveyors |
End Bearing Options: We can machine or weld end plates for pillow block bearings, flange bearings, or thrust bearing housings.
Table
Step | Process | Quality Control |
|---|---|---|
Material Sourcing | Prime stainless steel plate, bar, or pipe | PMI spectrometer verification |
Shaft Preparation | CNC turning, grinding, or pipe selection | Straightness and runout check |
Flight Forming | Cold rolling, press forming, or CNC plasma cutting | Pitch accuracy, OD/ID tolerance |
Flight Welding | Continuous TIG welding flight to shaft/pipe | 100% visual + PT inspection |
End Fitting Machining | CNC machining of shaft ends, flanges, or splines | Dimensional CMM report |
Heat Treatment | Solution annealing (austenitic) or quench/temper (martensitic) | Hardness verification |
Surface Finishing | Pickling, passivation, polishing, or sandblasting | Surface roughness check |
Final Inspection | Assembly check, balance test (if required) | Dimensional and functional report |
Table
Application | Material Type | Recommended Material |
|---|---|---|
Quantitative feeding — Precise volumetric or gravimetric dosing | Granular, powder | 304, 316L |
Micro-dosing — Small-batch additive feeding | Fine powder | 316L (polished) |
Non-sticky granular conveying — Grain, plastic pellets, sand | Free-flowing solids | 304, 430 |
Slightly viscous material conveying — Wet powders, pastes | Cohesive solids | 316L, 2205 |
Viscous material extrusion — Sludge, dough, polymer melts | High-viscosity paste | 316L, 310S (heated) |
Table
Application | Function | Design Feature |
|---|---|---|
Mixing screw — Blend multiple solids or solid-liquid slurries | Paddle or ribbon flights with reverse pitch sections | Cut-and-folded or ribbon flights for axial mixing |
Crushing screw — Break agglomerates while conveying | Interrupted flights with hardened wear strips | 410/420 flights with replaceable hardfacing |
Dewatering screw — Extract liquid from slurry | Tapered shaft with reducing pitch | Compression zone with screen basket |
Heated screw — Maintain material temperature during conveying | Hollow shaft with steam or thermal oil passage | 310S or 316L with internal heating circuit |
Our stainless steel transfer screws serve critical roles across industries:
Food & Beverage — Grain conveying, flour dosing, sugar transport, meat extrusion (316L, polished)
Pharmaceutical — API powder feeding, tablet granule conveying (316L, FDA-compliant finish)
Chemical Processing — Catalyst transfer, polymer pellet conveying, acid slurry handling (316L, 2205)
Wastewater Treatment — Sludge dewatering and conveying (2205, 316L)
Mining & Minerals — Ore concentrate, sand, cement, fly ash transport (410, 420, 2205)
Power Generation — Bottom ash, fly ash, limestone powder feeding (310S, 304)
Recycling — Plastic flake, rubber crumb, biomass pellet conveying (304, 430)
✅ Extreme Size Range — Shaft OD 50–3000 mm, length up to 12 m
✅ Full Material Portfolio — 304, 316L, 310S, 2205, 410, 420, 430
✅ Custom Flight Geometry — Standard pitch, variable pitch, tapered, paddle, ribbon, or cut-and-folded
✅ Flexible Mounting — Shaft end, flange, spline, or combination to fit your drive
✅ Hygienic Finishes — Electropolished and passivated surfaces for food and pharma
✅ Wear Solutions — Hardened 410/420 flights with hardfacing for abrasive service
✅ Drawing-to-Product — Manufactured strictly to your CAD drawings and specifications
Q1: What is a stainless steel transfer screw used for? A stainless steel transfer screw is a helical conveying component used to transport, meter, mix, or extrude bulk materials in screw conveyors and feeders. It handles powders, granules, slurries, and viscous materials across industries including food, chemical, mining, and wastewater treatment.
Q2: What stainless steel grade should I choose for my screw conveyor? For food and pharmaceutical applications, 316L is standard due to its corrosion resistance and hygienic properties. For high-temperature service above 800°C, use 310S. For abrasive materials like sand or ore, 410 or 420 martensitic stainless steel offers superior wear resistance. For chloride-rich or seawater environments, 2205 duplex stainless steel is recommended.
Q3: What is the maximum size you can manufacture? We can produce transfer screws with shaft outer diameters from 50 mm to 3000 mm and lengths up to 12 meters. Flight outer diameters range from 50 mm to 3000 mm with thicknesses from 1 mm to 40 mm. Larger or longer custom designs can be reviewed by our engineering team.
Q4: What mounting options are available for the screw shaft? We offer shaft-end mounting (keyway, journal, or threaded), flange mounting (welded or bolted), and spline mounting (internal or external). These can be used individually or in combination to suit your bearing arrangement and drive configuration.
Q5: Can you manufacture mixing or crushing screws? Yes. Beyond standard helical flights, we produce paddle screws for mixing, ribbon screws for blending, and interrupted-flight screws with hardened wear strips for crushing agglomerates. Please specify your mixing or crushing requirements when submitting your inquiry.
Q6: Do you provide food-grade or pharmaceutical-grade surface finishes? Yes. For food and pharmaceutical applications, we offer electropolished surfaces with Ra ≤ 0.8 μm, full pickling and passivation, and documentation to support hygienic compliance. 316L is the recommended material for these industries.
Q7: Can you manufacture from my drawings or samples? Yes. All our transfer screws are custom made to customer drawings (PDF, DWG, STEP, IGES) or reverse-engineered from physical samples. We manufacture to your exact material, dimension, pitch, and mounting specifications.
