Profile Extrusion Equipment
Profiles may consist of a single material or multiple materials. Single material profiles utilize one extruder while multiple material profiles require more than one extruder to feed material into a central die. These processes can utilize single screw or twin-screw extruders. Single screw machines are focused on pelletized materials or applications requiring less true mixing. Twin-screw extruders are usually focused on powdered materials or where more intensive mixing is required. These extruders can be of a variety of sizes from a few pounds per hour of output up to thousands of pounds per hour output depending on the application.
Secondary extruders are called “co-extruders” and can also be a variety of sizes but normally fall toward the smaller end of the spectrum and are normally smaller than the main processing extruders. The number of co-extruders used is limited only by the space in the processing line. Some processes can cheat by utilizing the same co-extruder for multiple application requirements (as long as the material required is identical the co-extruder can be utilized for more than one location. (An example of this is stripes on the outside of drinking straws. If the strips are the same color, one machine can be used for all the strips). Co-extruders can be mounted on the floor or suspended over the die head as required.
Die tooling is application specific and can be a simple metal plate with a hole in it for the material to flow through, or a sophisticated multiple components affair designed for advanced flow characteristics and precision sizing. Dies are mounted either to the main extruder directly with the co-extruders connecting into it, or the die is on a floor stand with extruders piped to it. The Die tooling is oriented in one of two directions is relation to the main extruder. The directions are “inline” and “crosshead”. The inline process utilizes a flow that follows the extruder direction and the die is connected with flow in the process direction. The crosshead process utilizes a flow that is at an angle to the flow of the extruder. For profile extrusion this would be at a ninety degree angle to the flow. (Crosshead processes are required for any product requiring a component to be inserted into the extrudate for coating. Such as wire, pul-truded products, etc.
Downstream equipment is separated into three areas of the process: 1) cooling/sizing, 2) pulling, 3) cut/coil/takeoff. Below are the main styles of equipment to achieve these process requirements.
The part must be cooled to maintain the desired shape. This equipment falls into a few sub categories. Some processes require minimal impact to work. Others require extensive interaction at this stage to achieve the desired product. Cooling/sizing equipment falls into a few types:
- Air Cooling
- Water Cooling
- Water Cooling and Vacuum Sizing