# Shaftless Screw Conveyor Selection Guide for Seafood and Food Processing Plants ## Why Food Processing Lines Need Sha

Waste from seafood and food processing has distinct characteristics: high moisture, strong adhesion, rapid spoilage, and frequent presence of flakes and fragments such as fish scales, shrimp shells, and fruit peel. If fish residue or vegetable waste remains inside equipment, it ferments, produces odor, and becomes a breeding ground for bacteria. In conventional shafted screw conveyors, the center shaft and internal supports create cleaning dead zones. When flushing is incomplete, hygiene risks accumulate over time.

A shaftless screw conveyor eliminates the center shaft and internal supports. Material is pushed by a continuous ribbon flight along a smooth U-shaped trough. With no dead zones and full wash-down capability, this design reduces material retention and odor residue at the structural level. For food factories subject to hygiene audits, this configuration is easier to clean and inspect.

Key Selection Parameters

Screw Diameter and Conveying Capacity

The WLS series offers six standard sizes with screw diameters ranging from 150mm to 500mm, covering a maximum conveying capacity of 0.5–28 m³/h. Small fish processing or fruit and vegetable lines typically match their offal discharge rate with WLS200 or WLS250. Large seafood plants and canning lines usually select WLS300 or above.

Conveying Distance and Inclination

A single unit can convey up to 30 meters (WLS400/WLS500 sizes) at an allowable working inclination of 0°–30° (WLS250: 0°–25°). Typical layouts include horizontal transfer of production line offal to a waste collection area, and inclined feeding to elevated receiving points such as refrigerated containers or composting bins. Actual capacity decreases as inclination increases, so a design margin should be reserved.

Material and Hygienic Design

For food contact, stainless steel (commonly 304) is recommended for both trough and screw, with welded and ground surfaces that support water washing and disinfection. The U-shaped trough uses flanged sections joined by bolts, allowing length extension and disassembly for cleaning. The equipment presents no paint flaking risk, making it suitable for high-humidity and wash-down environments.

Typical Applications in Food Plants

• Seafood offal discharge: continuous transfer of fish heads, viscera, and shrimp shells to waste bins or refrigerated collection areas
• Fruit and vegetable waste transfer: transport of peel and pits from peeling and pitting stages to composting or feed processing points
• Canning line waste connection: inter-stage waste transfer between equipment at different elevations, reducing manual handling

Selection Considerations

1. Calculate the design capacity from the plant's per-shift waste output, leaving a margin for peak periods.
2. Prioritize stainless steel construction in high-humidity environments with frequent washing.
3. For inclinations above 20°, derate the capacity or select the next larger size.
4. Seal flange joints properly to prevent juice leakage onto the plant floor.
5. Add overload protection at the drive end, and schedule periodic flushing during line stops to prevent residue from drying and hardening.