Extrusion
Extrusion is a continuous manufacturing process, in which the plastic granulate (compound) is continuously melted by external heating elements and in some cases friction heat by the screw. The melt is then pressed through a forming nozzle (tip and die) by which an endless stream of product is created. The model and the dimensions of the tip and die influence both the outside and inside shape and diameter. With a cutter, the specified length is determined. It is also possible to produce on a roll! We are able to extrude products with tolerances till 0.01mm!
Extruder
An extruder is a construction of a pipe, heated from the outside, and a motor-driven screw. The heat transfer is made through contact with the heated barrel and friction heat generated by the rotation of the screw.
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Methodes
Wire mandrel extrusion
Mandrel wire extrusion is a forced shaping process. The internal diameter of the product is determined by the wire dimensions and the external diameter by the parameters of the die. This application is often used in combination with braiding, to produce catheters. First, an inner layer (base coat) is extruded, then a knitting pattern is applied for extra strength and finally, the top layer is extruded in order to achieve a nice smooth surface.
Airmandrel extrusion
A more suitable name for air mandrel extrusion would be air tubing extrusion, which means free extrusion using a tip, without applying a solid wire. The imaginary wire consists of air. The dimensions of the product are not solely determined by the tip and die, but also influenced by the airflow through the tip. Enlarging the natural air flow by applying forced air feed, influences the yield and product dimensions. Another important process parameter, especially to obtain the specified wall thickness, is the plastic flow generated by the extruder. The volume flow is regulated by the mold temperature and the rotation speed of the screw.
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