Screw Conveyors

A screw conveyor is an enclosed conveyor in which a rotating spiral helix (an endless screw) inside a cylindrical or semi-cylindrical housing pushes material from the feed point to the discharge point. The direction of rotation and the pitch of the helix are determined by the material's characteristics.

The TMD GRUP manufacturing programme uses two basic housing geometries: U-trough (semi-cylindrical, open on top or lidded) and tubular (fully enclosed pipe). U-trough is used on horizontal or mildly inclined runs; tubular can operate horizontally or at steep angles.

U-trough screw conveyors are designed for horizontal runs or mildly inclined ones (10°–20°). The top is closed with a sealed cover, though multiple feed/discharge openings are possible. Dust emissions are at a reasonable level.

Tubular screw conveyors, thanks to their fully enclosed structure, can operate at any angle from 0° to 90°. They are preferred when dust release must be absolutely prevented and when steep-angle conveying is required. The tubular type is particularly common for inclined runs in the food, chemical and cement sectors.

Which type to select is determined at the TMD GRUP engineering office based on the material's dust-release risk, the route's incline profile and the required capacity.

In screw conveyors, the housing and helix material is selected according to the abrasion, corrosion and hygiene requirements of the conveyed material:

Screw conveyors can be designed in two main drive configurations:

• Motor + gearbox (conventional): an electric motor and gearbox drives the helix. Suitable for high-capacity, high-torque applications. Speed control can be done via frequency inverter.

• Vibro motor: a vibro motor drives the helix through vibration. Common in low-capacity applications requiring precise dosing, and in the food sector.

TMD GRUP recommends the appropriate drive based on the project's capacity, control needs and energy profile.

The TMD GRUP catalogue lists the following main service sectors for screw conveyors: cement, glass, gypsum, lime, concrete, grain and food. In each of these sectors, screw conveyors are used for different purposes:

• Cement and lime: silo-outlet dosing, kiln feed, transfer from clinker crusher to raw-meal preparation.

• Glass and gypsum: raw material transfer, dosing lines.

• Concrete batching plants: cement and additive dosing, mixer feed.

• Grain and food: hygienic conveying of materials such as flour, animal feed, sugar and spices (manufactured in stainless steel).

For every sector, material data (density, particle size, moisture, flow behaviour) is evaluated per project.

TMD GRUP's bespoke engineering approach is clearly visible in screw conveyors. Beyond a standard conveyor, we offer the following customisation options:

A screw conveyor project at TMD GRUP proceeds in the following order: sharing material data with the customer (density, particle size, moisture, temperature, chemical properties) → type selection (U/tubular, incline, material) → engineering design and 3D model → manufacturing (CNC cutting, welding, NDT, powder coating at our Başkent OSB facility) → in-house testing → site installation and commissioning → operator training and documentation handover.