Extrusion (ejection) - the technology of obtaining products or semi-finished products by forcing a melt of material through a forming hole. Extrusion is a continuous process consisting in extruding a melt of a polymer having a high viscosity in a liquid state through a die forming die of a extruder in order to obtain a cross-sectional shape of the desired shape. Extrusion, along with the injection molding of plastics, is one of the most popular methods of manufacturing plastic products. Almost all basic types of polymer materials are extruded, such as thermoplastics, thermosets, and elastomers. In the extrusion industry, various molded products are manufactured: pipes, sheets, films, cable sheaths, elements of optical systems of luminaires-diffusers, etc. The main technological equipment for processing polymers into products by extrusion is single-screw, multi-screw, piston and disk extruders.
An extruder for molding plastic materials, by shaping them, by extrusion through a profiling tool (extrusion head).
Schematic diagram of the extruder:
The extrusion line is a series of equipment for obtaining the final product by extrusion, it can consist of an extruder, a cooling device, a calibration table, a pulling and cutting device, etc.
Coextrusion (joint extrusion) -process of obtaining multilayer materials, which are a combination of several polymer layers, in one cycle.
When co-extruded, the melts of two or more polymers from individual extruders are forced into a common head of a special design. The coextrusion can be divided into flat-slit and co-extrusion with blowing. The main difference between these methods is the different geometric shape of the forming tool: a flat straight or closed ring head.
