Basics of Extrusion02/17/2017Extrusion is a process of forming raw materials into shaped and usable products. The process of plastic extrusion is done by starting with a raw materials such as pellets, powder, flakes, etc. The material is fed from a hopper into the barrel of the extruder. The barrel will contain heaters to melt the pellets and a screw to push the viscous molten material into a die to form the plastic. Due to the high viscosity of many materials high torque is often necessary to accomplish the movement into a feeder for the die. Because a constant high torque is necessary, an extruder will typically use a DC drive to run the motor that turns the screw. One such drive is the Eurotherm 590+ DC drive. It is imperative that the speed and torque remain constant to ensure that even flow is maintained. Most extruder screws will have three typical zones. The first being the feeder zone or solid conveyor zone. This zone feeds the material into the extruder from the hopper and will have a larger channel depth to accommodate the solid particles. The melting zone is also referred to as the compression zone. This zone is where most of the material is melted and may have a progressively smaller screw channel depth. The third area is the metering or melt conveying zone. It is this zone in which the last of the particles is melted and mixed into a uniform texture, viscosity, and temperature. The screw channel depth is usually constant throughout this zone as it is in the feed zone. Because of the changing properties of the material as it’s melted, the degree of control the motor must maintain is very high. It for this reason the Eurotherm 590+ drive is an excellent DC drive to use for this application. There are vast array of die types used in extrusion manufacturing including blown film extrusion, sheet film extrusion, tubing extrusion, over jacketing extrusion, coextrusion, coating extrusion, and compounding extrusion to name a few. Once the product passes through the die, it may be cooled naturally by ambient temperature, or rapidly through water or refrigeration. Back To Blog
Basics of Extrusion02/17/2017Extrusion is a process of forming raw materials into shaped and usable products. The process of plastic extrusion is done by starting with a raw materials such as pellets, powder, flakes, etc. The material is fed from a hopper into the barrel of the extruder. The barrel will contain heaters to melt the pellets and a screw to push the viscous molten material into a die to form the plastic. Due to the high viscosity of many materials high torque is often necessary to accomplish the movement into a feeder for the die. Because a constant high torque is necessary, an extruder will typically use a DC drive to run the motor that turns the screw. One such drive is the Eurotherm 590+ DC drive. It is imperative that the speed and torque remain constant to ensure that even flow is maintained. Most extruder screws will have three typical zones. The first being the feeder zone or solid conveyor zone. This zone feeds the material into the extruder from the hopper and will have a larger channel depth to accommodate the solid particles. The melting zone is also referred to as the compression zone. This zone is where most of the material is melted and may have a progressively smaller screw channel depth. The third area is the metering or melt conveying zone. It is this zone in which the last of the particles is melted and mixed into a uniform texture, viscosity, and temperature. The screw channel depth is usually constant throughout this zone as it is in the feed zone. Because of the changing properties of the material as it’s melted, the degree of control the motor must maintain is very high. It for this reason the Eurotherm 590+ drive is an excellent DC drive to use for this application. There are vast array of die types used in extrusion manufacturing including blown film extrusion, sheet film extrusion, tubing extrusion, over jacketing extrusion, coextrusion, coating extrusion, and compounding extrusion to name a few. Once the product passes through the die, it may be cooled naturally by ambient temperature, or rapidly through water or refrigeration.