An extruder barrel is a long cylindrical metal tube used in plastic extrusion processes. It houses a screw or screws that rotate and push the plastic material through the barrel, creating pressure and heat that melts the plastic and forces it through a die. The extruder barrel is typically made of steel and may be heated to maintain a consistent temperature during the extrusion process.

The bush of the extruder is a component that fits snugly around the screw(s) inside the extruder barrel. It helps to create a seal and prevent plastic from leaking out of the extruder. The bush is typically made of a wear-resistant material like ceramic or carbide, which can withstand the high temperatures and pressures of plastic extrusion. The bush may also be designed with a tapered shape to help compress and melt the plastic material as it moves through the extruder barrel.

Overall, the extruder barrel and bush are critical components of plastic extrusion machinery. They work together to create the necessary heat, pressure, and friction to melt and shape plastic materials into a desired form.