Screw Conveyors

Screw conveyor systems, also called auger conveyors, helix conveyors, worm conveyors and flexible screw conveyors, handle all kinds of different substances, including powder, sludge, dust, flakes, granules and other loose products like seeds, food waste, wood chips, cereal, grain, boiler ash, fuels, feed and cement. In addition to transporting materials down a linear plane, industrial screw conveyors also aide in the mixing, agitation or breakdown of some substances due to their rotating motion with the screw's paddles. While most are made out of metals like aluminum and steel, some plastic screw conveyors are used in high heat, sanitary and high impact applications. The screw and bulk materials that are being conveyed are held in a trough or wholly incased. Tubular screw conveyors completely cover the screw, ensuring that no material will be lost in transit. Whether they are stationary and permanent or portable screw conveyors, these bulk handling systems are positioned at a number of orientations. Standard conveyors are horizontal, while some vertical screw conveyors lift material straight up and down. Inclined screw conveyors are positioned at an angle and are considered flexible conveyors if they can alter or bend in some way.

While industrial screw conveyors are used mostly in bulk handling applications, they are popular in agriculture as components of farm machinery like threshers or balers. They also transport animal feed, grains and seeds to different locations. The food processing industry also uses industrial screw conveyors to transport dry ingredients like salt, flour, nuts and any other raw material used to produce food products. These conveyors are always made from food grade stainless steel, which exhibits a smooth surface and is non-contaminating. They are also popular within the construction industry when mixing dry and wet materials to form cement or plaster. In some situations, screw conveyors will even outperform more standard types of conveyor systems. Because the screw will cut through materials during operation, sticky substances like gels, materials that do not breakdown easily or those materials not intended to be broken down are not ideal for screw conveyor systems to process. Rather, they are used mostly to transport dry to semi-dry bulk materials, both free-flowing and non-free-flowing.

Screw conveyors have three different orientations: horizontal, vertical and inclined. Horizontal screw conveyors transport the material in a linear direction and require only a trough. Vertical conveyors carry material straight up and down and require a tubular casing to hold all the material inside. They are needed when material must be transported from a receptacle low to the ground to one that is very tall. Compared to bucket elevators, vertical screw conveyors are lower maintenance and provide continuous conveying. Finally, many applications require the use of inclined conveyors, which are set at an angle. They require ample space and an increased amount of power to lift the material, but their slant economically transports bulk material between facility floors. Some are portable and mounted on stands, carts or vehicles and may be moved around a facility. Flexible screw conveyors are able to adjust their angle and may bend in different directions, creating a wider range of uses within a single facility. Most conveyors, however, are manufactured out of steel and are therefore unable to move.

These conveyors transport loose, dry materials to and from vats, hoppers, silos, rail cars, barrels, trucks and pits. They can be powered by an electric motor, although some harness the energy from nearby machinery like a trailer's power take-off shaft. Standard industrial screw conveyors are usually constructed with metal. However, some that are used in the food industry are made out of thermoplastic resin that has been injection molded and can withstand high impact and temperature without contaminating the products they carry. The selection of screw conveyors depends upon the industrial application, material and material consistency as well as additional operations required of the screw conveyors system. Screw conveyors fabricated by screw conveyor manufacturers are found in numerous industrial applications in the agricultural, food and beverage processing, plastic, pharmaceutical, chemical, mining, oil and gas and construction industries. Because of their gentle handling and blending, screw conveyors can be used to transport a wide variety of materials in many different industries. Some examples of these products include carbon black, caffeine powder, gypsum, ferric sulfate, cocoa beans, flour, garlic powder, Epsom salts, vitamins, fiberglass, whey, lead oxide and many other materials.

Image Provided by Flexicon Corporation

Image Provided by Aerocon

Screw Conveyors Types

• Auger conveyors are a kind of screw conveyor that uses a spinning helix.
• Conveyors are used to efficiently transport products and materials from one place to another.
• Flexible conveyors are pliant screw conveyors that can bend in order to better fit a space.
  
• Flexible screw conveyors move solids and powders in all directions and contain a flexible screw capable of centering itself within the conveyor tube, which prevents scraping of the screw against the tube wall. Because the conveyor motor powers the screw directly, the need for extra components is eliminated, reducing upkeep and maintenance and increasing cost-effectiveness.
• Helix conveyors, also known as auger and screw conveyors, are enclosed materials handling systems that move products through conveyance channel with a rotating screw. 
• Inclined screw conveyors are materials handling systems that move products through an inclined conveyance channel with a rotating screw.
• Industrial screw conveyors are materials handling equipment that move industrial ingredients through a conveyance channel with a rotating screw.
• Jacketed screw conveyors use substances such as water, oil and steam to provide heating or cooling to transported materials. These conveyors consist of an enclosure surrounding the conveyor trough.
• Plastic screw conveyors are materials handling equipment that move materials through a conveyance channel with a rotating plastic screw.
• Portable screw conveyors can be transported from one location to another, which increases convenience and efficiency of the industrial application.
• Screw conveyor systems use large, rotating screws to move product from one place to another.
  
• Trough screw conveyors are common in the food processing industry and contain an open channel duct through which materials are conveyed. Trough configurations allow for easy cleaning, which reduces product contamination.
  
• Tubular screw conveyors protect against material contamination during conveyance, which remains advantageous in industrial applications involving sensitive materials. Tubular screw conveyors consist of an enclosed tube-shaped duct through which the materials are conveyed; unfortunately, tubular screw conveyor configurations can be difficult to clean.
• Vertical screw conveyors are materials handling equipment that move products through vertically-oriented conveyance channel with a rotating screw. 
• Worm conveyors, also known as auger conveyors and helix conveyors, are materials handling equipment that move products through a conveyance channel with a rotating screw.

Screw Conveyors Terms

Conveyor Screw - The driving force of a screw conveyor, consisting of a spiral flight fused to a metal pipe that rotates within the conveyor trough.
 
Discharge End - The point of exit for conveyed materials.
 
Double Pitch Screw - Conveyor screw containing two flights.
 
Flight - The metal spiral ridges or threads on a screw.
 
Flow - A product's direction of travel on a conveyor.
 
Frame - The structure that supports the various components of the conveyor.
 
Hanger - Screw conveyor mechanism that aids in the correct alignment of the conveyor screws.
 
Helicoid Flighting - Screw conveyor flight that consists of a continuous metal strip configured in a spiral shape.
 
Horsepower - A measure of the time rate of doing work.
 
Inlet Opening - The point of entry for conveyed materials.
 
Liner - A barrier placed between a conveyor screw and a screw conveyor component, such as a trough, to reduce friction between the screw and trough.
 
Long Pitch Screw - Conveyor screw in which the pitch is greater than the diameter of the screw.
 
Motor - The machine on the conveyor that converts electrical energy into mechanical energy.
 
Multiple Ribbon Screw - Conveyor screw containing more than one ribbon flight along the length of the screw.
 
Paddle Screw - Conveyor screw containing blades attached at different angles, depending on the industrial application, used for mixing, blending or similar applications.
 
Pitch - Distance between conveyor screw flights.
 
Ribbon Screws - Conveyor screws that contain sectional flighting and are used to prevent sticky conveyor materials from accumulating inside screw conveyor pipes.
 
Sectional Flighting - A screw conveyor flight consisting of individual bends or sections, fused together into spiral form. Sectional flighting is created by inserting a ring in a hydraulic press. It is a durable yet sometimes expensive type of flighting that is useful in tough applications, such as those in the construction and mining industries.
 
Shaft - The portion of the screw that provides support onto the flight to which it is fused.
 
Short Pitch Screw - Conveyor screw in which the diameter is greater than the pitch. Short pitches are used on inclined screw conveyors with slopes measuring 20° or greater.
 
Total Load - The total amount of material being conveyed at any particular moment in time.
 
Trough - A duct inside of which the screw is inserted and through which the materials are conveyed.
 
Variable Pitch Screws - Conveyor screws in which the pitch increases along the length of the screw.