142 industrial manufacturers list 241 distinct screw conveyor models on DirectIndustry's 2026 catalog, with trough/chain-drive (SCUTTI CNU series) and shaftless auger geometries dominating new builds [S1][S2].
Screw conveyors — commonly called augers — handle 0.5-500 TPH of free-flowing bulk solids in horizontal, inclined, and vertical layouts at rotor speeds of 30-200 RPM, making them the lowest-cost-per-ton conveyor in their envelope but the most sensitive to overfeed and tramp metal [S3]. Buyers in 2026 select on six gates: bulk density, particle size, abrasiveness (CEMA class I-V), moisture content, incline angle, and the make-or-break question of shafted versus shaftless design.
Throughput Math: CEMA 350 TPH vs. Real-World Friction Factors
The CEMA 350 formula Q = (A × N × ρ × 60) / 1728 gives theoretical capacity, where A is the cross-section area (ft²), N is RPM, and ρ is bulk density (lb/ft³).
Buyers should expect de-rating multipliers of 1.0 at 0°, 0.85 at 15°, 0.60 at 25°, and 0.30 at 45°; vertical screw conveyors rarely exceed 60% of horizontal capacity for the same screw diameter because gravity loading replaces flight push [S3]. KWS Manufacturing's 2026 product line specifies a 98.6% on-time ship rate on standard trough units up to 24-inch diameter, with 30° and 45° incline variants built to the same heavy-duty Class II standard [S4].
Shafted vs. Shaftless: The 2026 Material-Fit Decision
Shafted (helicoid or sectional flight) conveyors handle 90% of general-purpose applications up to 12-inch flight pitch, but shaftless augers — single continuous helix with no center pipe — win on three material classes: dewatered cake, fibrous sludge, and sticky sludges above 65% moisture [S2][S3].
DirectIndustry's 2026 manufacturer index shows shaftless units concentrated in the wastewater-municipal segment, with 9 AGRITECH models and 1 Akkerman unit accounting for most of the listed shaftless inventory alongside the conventional SCUTTI trough-and-chain-drive CNU family [S1][S2]. Shaftless designs run 30-45% premium over equivalent-diameter shafted units but eliminate the centre-shaft fouling that kills availability on biosolids and grit slurries; for an alternative geometry comparison, see belt vs. overhead conveyor trade-offs.
Five Selection Criteria, Ranked by Failure Cost
Bulk density is the primary gate: at 30 lb/ft³ (grains, plastics) a 9-inch screw moves 80 TPH, while at 100 lb/ft³ (sand, mill scale) the same screw drops to 35 TPH because higher mass overloads flight face and stalls the drive [S3][S4].
Five criteria ranked by failure cost: 1) particle size relative to flight clearance (max lump ≤ 1/3 flight pitch); 2) abrasiveness mapped to CEMA wear liner class; 3) corrosion exposure, with 304SS / 316SS / AR400 liners as the three common material choices; 4) flight pitch ratio (standard 1:1, short-pitch 2:3, variable-pitch for incline); and 5) drive package (direct-coupled gearmotor vs. shaft-mount reducer with V-belt), where shaft-mount dominates 60-80 HP range and direct-coupled takes over above 100 HP [S2][S4]. Made-in-China's June 2026 chips-conveyor wholesale range of US$ 960-1,000 per set represents the entry-tier band for small-diameter chip and swarf handling, with the SCUTTI CNU family sitting in the mid-tier trough-and-chain segment [S1][S5].
Drive, Bearing and Sealing: Where Engineers Get Burned
End-bearing and intermediate-hanger failures account for 70% of screw-conveyor downtime on inclined and abrasive-service units, because hangers interrupt the trough cross-section and let material pack at the shaft [S3][S4].
Specify removable, greaseable, outboard-mounted end bearings with packing-box or air-purge seals for dusty service; intermediate hangers should be limited to 10-foot spacing maximum, with 8-foot centers on inclined or sticky applications. The SCUTTI CNU chain-drive geometry shown on DirectIndustry eliminates the centre shaft and most hanger problems, trading higher chain tension (typically 4,000-12,000 lbs on 12-24 inch units) for a clean trough profile [S1]. Inherently related, the roller conveyor six-gate spec logic applies to the same downstream-packaging line — bulk feed from the screw, distribution onto roller, gravity accumulation — so the two decisions are coupled.
Comparison: Trough, Tubular and Vertical Screw Conveyors
Cross-check the spec against duty: on abrasive iron-ore or mill-tailings service, trough designs with AR400 bolt-in liners last 3-5x longer than unlined carbon-steel flights; on corrosive chemical or fertilizer duty, 316SS troughs with UHMW flight faces are now standard for new units at 50-100% cost premium over carbon-steel equivalents [S1][S3][S4]. The SCUTTI CNU trough/transport/chain-drive family [S1] is the typical mid-duty geometry for granules, chips, and pellets, while AGRITECH's shaftless range [S2] is the recurring pick for sludge and dewatered cake. For broader cross-equipment selection logic on material handling, see single girder crane span, duty, and headroom trade-offs where the same CEMA class and duty-cycle vocabulary governs.
Use Cases, Limits and Sourcing Signals
Working envelope: screw conveyors handle free-flowing to mildly cohesive bulk from 10-200 lb/ft³ bulk density, particle sizes up to 6 inches on heavy-duty flights, and ambient temperatures from -20 °C to 200 °C on standard units (high-temp 400 °C available with exotic alloys and special bearings) [S3][S4].
Limits: sticky wet materials above 25% moisture pack on shafted flights; fibrous or stringy materials wrap on intermediate hangers; highly aerated cement and fly-ash fluidize inside enclosed tubular screws and need a deaeration vent. KWS Manufacturing's 2026 catalog shows 98.6% on-time shipping as a trackable vendor signal, and the 142-vendor DirectIndustry index is the broadest sourcing reference available for unit-by-unit comparison [S2][S4]. Two signals worth tracking into Q3-Q4 2026: rising specification of 316SS and AR400 liners for food/chemical duty in mid-tier brands, and continued penetration of shaftless augers in the municipal-wastewater segment where the direct competitive alternative is the belt or overhead geometry.
For component-level specifications, see linear guide, crossed roller guide, and screw conveyor.