Q. What do you mean by extrusion?
• Extrusion is a process used to create objects of a fixed cross-sectional profile. A material is pushed or drawn through a die of the desired cross-section.
• The two main advantages of this process over other manufacturing processes are its ability to create very complex cross-sections and work materials that are brittle, because the material only encounters compressive and shear stresses.
• It also forms finished parts with an excellent surface finish.
• Hollow cavities within extruded material cannot be produced using a simple flat extrusion die, because there would be no way to support the center barrier of the die. Instead, the die assumes the shape of a block with depth, beginning first with a shape profile that supports the center section.
• The process begins by heating the stock material. It is then loaded into the container in the press. A dummy block is placed behind it where the ram then presses on the material to push it out of the die. Afterward the extrusion is stretched in order to straighten it.
• The extrusion ratio is defined as the starting cross-sectional area divided by the cross-sectional area of the final extrusion.
• One of the main advantages of the extrusion process is that this ratio can be very large while still producing quality parts.