An experimental procedure for studying the flow in plane strain extrusion

An experimental procedure is described for observing the flow of aluminium through near frictionless wedge-shaped plane strain extrusion dies. The selection of the billet size and shape, type of lubrication, die design and photographic grid printing technique are described. It is shown that the use of a square chequerboard pattern of 0.1 mm side enables the flow to be observed in considerable detail and flow fields are given for the extrusion of annealed aluminium alloy 5086 through 15° and 60° half angle dies with 50% reduction in thickness.