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It is often acceptable to have a different range of thicknesses however, a profile with uniform metal thickness is easy to extrude. In many cases, uniform metal thickness reduces the die stresses and improves productivity. [2] Common Commercially Available extrusion profiles
Abrasive flow machining (AFM), also known as abrasive flow deburring [1] or extrude honing, [2] is an interior surface finishing process characterized by flowing an abrasive-laden fluid through a workpiece. [1] [3] [2] This fluid is typically very viscous, having the consistency of putty, [2] [3] or dough. [1]
The solution, however, for a difficult ratio shape is to make the part on a press with a smaller container. Another option is to use a multihole die that lets a number of profiles extrude simultaneously. They also come in handy for small shapes that are too long to handle practically, with even the shortest billets a press can extrude. [5]
Aluminium is the most commonly extruded material. Aluminium can be hot or cold extruded. If it is hot extruded it is heated to 575 to 1100 °F (300 to 600 °C). Examples of products include profiles for tracks, frames, rails, mullions, and heat sinks. Brass is used to extrude corrosion free rods, automobile parts, pipe fittings, engineering parts.
Extruded tubing, such as PVC pipes, is manufactured using very similar dies as used in blown film extrusion. Positive pressure can be applied to the internal cavities through the pin, or negative pressure can be applied to the outside diameter using a vacuum sizer to ensure correct final dimensions.
The wall thickness of the work piece is directly correlated with the clearance between the punch and die. The thinner the wall of the work piece the tighter its tolerances are.
The ratio of the blown diameter to the extruded diameter is known as the blow-up ratio, and affects the resulting physical properties of the film, such as stiffness and strength. Film thickness and blow-up ratio can be varied by altering the take-up rate of the rollers, the internal pressure in the blown tube, and the melt extrusion rate.
The initial workpiece is usually wire or rod, but some machines can accept bars up to 25 cm (9.8 in) in diameter. The standard upsetting machine employs split dies that contain multiple cavities. The dies open enough to allow the workpiece to move from one cavity to the next; the dies then close and the heading tool, or ram, then moves ...