A feed screw can look like an auger.
A feed screw is a component of certain types of industrial machinery designed to move or feed materials through a tube. Typically, a feed screw is a metal cylinder with an inclined plane wrapped around its outside, similar to a long screw or auger. The feed screw is then placed in a tube into which various materials flow from a hopper or chute. As the material from the hopper flows into the tube, the feed screw rotates and pushes the material along the tube where it will be used. Feed Screws are commonly used in the food and plastics production industries to move, mix, and extrude products.
In the plastics industry, screw feeders are at the heart of extruders used in blow molding, injection molding, sheet extrusion, and profile extrusion. In these cases, the tube surrounding the screw is heated to the point of melting the plastic resin. As the screw moves the material through the tube, called a barrel, the material melts and mixes. At some point along the screw, the pitch of the threads changes, leaving less room for the material to flow and causing the material to build up pressure. Once the material reaches the end of the screw, it is either extruded through a die, forming the molten plastic resin into the desired shape or profile, or into a mold where it cools into the desired shape.
In the food industry, feed screws are used in basically the same way as in the plastics industry. The main difference is that instead of melting the material, the food is cooked as it passes through the feed screw and is ultimately shaped into the desired shape. Instead of applying direct heat, some types of food processing equipment use the feed screw to increase pressure, which generates the heat needed to cook the food product.
Feed screws are not only useful for extruding products. They are also frequently used in many industries to blend various raw materials into a final product. In this type of application, a series of feed screws will be collected into a die where each screw feeds a separate ingredient into a hopper, box, or other container. Since each screw feeds the material into the container at a specific rate, very precise and different amounts of material can be dispensed as desired. For example, if three screws of the same size are arranged and one screw rotates at 5 revolutions per minute (rpm), the next at 20 rpm, and the final screw at 25 rpm, the final compound will consist of 10% of the first material. , 40% of the second and 50% of the third.