The feed system in an extrusion equipment is utilized for holding the solid material and delivering it to the extruder. It comprises of two main components they are the hopper and feed throat. A material handling system transports the raw material to the hopper.

• Hopper
  A hopper's function is to hold the solids before they enters the barrel. A dryer can sometimes be integrated with the hopper. The hopper must be maintained at a near-full level as in case of single screw extruders they are mostly flood fed. Flood feeding takes place when the throat area is kept full, thus allowing the screw channels to fill completely with each of the screw rotation. Some times, single screw extruders may be starve fed. This becomes necessary in case of materials like powder which are difficult to feed.
• Feed throat
  The feed throat is a sort of pre-barrel component whose location is just under the hopper. It is typically cored with cooling channels. The throat is cooled for keeping the solids moving through the feed throat so that there is more flow of the solids and there is no occurrence of premature sticking of the solids. In some instances the feed throat comprises shallow grooves that is machined into internal surfaces. The aim of these grooves is to boost a higher feed rate down the barrel.

Design of the Feed System
A perfectly designed feed system should consider the following points.

• The design of the hopper should be done in a manner to prevent hang-up of material during its flow down into the feed throat.
  
  
• The design should also take into account the form of the feed material. For example in case of pellets may be fed perfectly in a hopper that has a relatively large cone angle. But in case of powder there may be a requirement of a much smaller cone angle.
  
  
• By and large, the hopper shape should be circular and designed to minimize friction with the feed material.