Under the action of three-dimensional uneven compressive stress, the blank is extruded from the orifice or gap of the die, which reduces its cross-sectional area and increases its length. The processing method of becoming the required product is called extrusion, and the processing of blank is called extrusion molding.
Extrusion, especially cold extrusion, has the advantages of high material utilization rate, improving material structure and mechanical properties, simple operation and high productivity. It can be used to manufacture parts with long rods, deep holes, thin walls and special sections, and is an important machining process with less cutting. Extrusion is mainly used for the forming of metals, and can also be used for the forming of nonmetals such as plastics, rubber, graphite and clay blanks.
In the process of extrusion, the blank produces three-dimensional compressive stress, and even the blank with low plasticity can be extruded.
Extrusion molding is not only used for mechanical processing, but also for food processing. Dough is extruded into various shapes of macaroni by screw conveying and pushing.