MAS 2.0 - Guides - F.A.Q. - Tutorials - Home

More Information

Forward extrusion

Forward extrusion is sometimes known as the Hooker process. In this process the confined metal is forced to flow downward in the direction of the punch travel.

The process is generally used to produce thin-walled tubular parts with heavy flanges, straight tubular shapes, and extrusion of stepped; multiple diameters.

Forward extrusion is best applied to parts having an outer diameter of 25.4 mm (1 in) or more. The production of rods and other solids shapes is also possible with forwards extrusion.

In forward extrusion the work piece is placed in a close-fitting die. The punch is forced downward, displacing the metal through a restricted opening in the bottom of the die. The metal is forced to flow considerable distance beyond the end of the punch. Cupped or tubular parts of the punch extension serve as a mandrel. This controls the wall thickness and inner contour of the extruded parts.

Backward extrusion

Backward extrusion is a process that forces the metal confined in the cavity to flow in a direction opposite to that of the punch travel.

The slug (workpiece) is contained in a closed die. The descending punch enters the slug. The pressure displaces the metal upward through the opening between the punch and die. This is generally used for extruding symmetrically shaped parts having a closed end.

Combined extrusion

Combined extrusion uses a combination of forward extrusion and backward extrusion. The metal is confined inside a matrix between the lower and upper punches. This forces the metal to flow both up and down. The extruded part is lifted from the die on the upward stroke of the slide by a lift out on the bed of the press. Some aspects of combined extrusion are:

• it is fast
• it can complete parts in few steps
• it can produce large quantities with low unit costs
• it wastes little material
• it can make parts with small radii
• it requires mirror tooling