Characterization of Metal Flow in Metals Processing by a Combined Approach using Advanced Experimental Grid Pattern Techniques Coupled with FE-analysis

On material flow and aspects of structural modification during direct and indirect extrusion of aluminium alloy

“…From this point the graph representing columns approaches the surface at a greater rate with increasing ram travel. However, this does not apply to column 5 in which sensor (9,5)'s position is further from the extrudate surface than sensor (7,5), rather than being closer if it were to follow a similar path to the other sensor loci described above. It seems abnormal if we further compare it with other sensors [sensor (9,6), sensor (9,7), sensor (9,8) and sensor(9,9)] with which sensor (9,5) is in the same row in the initial setup.…”

“…Reviewing both Figs. 7 and 8a leads to the conclusion that extrudate-surface-forming material comes from near the line connecting sensors (1,9), (1,8), (1,7) and (2?6) and between columns 6 and 1. The DMZ exists behind this line in the corner of the container.…”

“…It also is approximately close to sensors located on row 7 and the closer-to-billet-surfacethe-closer-to-extrudate-surface observation applies as in direct extrusion except that in column 5 sensor (2,5)'s final position is further from the extrudate surface than those that are in the same row and is caused by that section which will become the back-end effect. It also shows that the surface of the extrudate will be formed mainly from the material located in the designation of row 10 (initial positions are marked in the inset figure), which are sensors (10,9), (10,8), (10,7), (10,6), (10,5) and (10,4). The figure indicates that in the early stage this material does not reach the surface of the billet which suggests that a DMZ may be very temporarily formed in the centre region of the die face as previously reported by Sheppard and Patterson but will certainly not be a permanent feature as in the direct case.…”

“…It is obvious that as the ram/or die progresses then, with the process of extrusion for both modes, more and more sensors will flow into the extrudate and by recording their position in the extrudate, we can get a better understanding of metal flow and the extrudate surface formation. which would appear to occur at points around sensors on row 7 [sensor (7,4), sensor (7,5), sensor (7,6), sensor (7,7), sensor (7,8) and sensor (7,9)]. From this point the graph representing columns approaches the surface at a greater rate with increasing ram travel.…”

Investigation of metal flow in bridge die extrusion of Alloy 6063 and subsequent effect on surface quality and weld seam integrity

“…Studies of the material flow during extrusion are well documented in the literature. The techniques employed range from commonly used physical techniques such as gridded billets (introducing pins of an aluminium alloy into the as cast billet and then grinding and etching the surface after the end of the extrusion [2][3][4] to more recently numerical methods. [5][6][7][8] These techniques did achieve practical results describing metal flow, but none of them disclose the comprehensive insight to understand the basic formulation of a bridge die extrusion.…”