Helical Screw (Auger)

The helical screw, commonly known as an auger, is a critical component of screw conveyors consisting of a central shaft with a continuous helical flighting (blade) wrapped around it. It operates by rotating within a stationary housing (trough or tube), creating a positive displacement action that pushes granular, powdered, or semi-solid materials along the conveyor's length. The design parameters—such as pitch, diameter, flight thickness, and helix angle—determine the conveying capacity, efficiency, and material handling characteristics. It is engineered to handle various bulk densities and flow properties while minimizing degradation and segregation of materials.

The helical screw operates on the principle of Archimedes' screw, where rotation of the helical blade generates axial thrust. As the screw rotates, material is trapped between the flights and the housing wall, causing it to slide along the helical path. The inclined surface of the flighting converts rotational motion into linear material displacement, with the pitch defining the advance per revolution. This creates a continuous, controlled flow of material from the inlet to the discharge point, with performance influenced by screw speed, fill level, and material properties like cohesion and abrasiveness.