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FEM study of extrusion complexity and dead metal zone

Qamar S. Z.

Archives of Materials Science and Engineering

2009

Vol. 36, nr 2

110-117

Purpose: Quality of the extruded product and efficiency of the manufacturing process can be seriously affected by inconsistent metal flow through the extrusion die. Metal flow problems can also significantly reduce die life. Various researchers have investigated the effect of profile complexity on extrusion pressure, product quality, die life, etc. However, the relationship between shape complexity and metal flow through the extrusion die has not been studied in detail. Cold extrusion experiments on some solid profiles and simulations using the finite element method (FEM) have been used in this work to investigate the effect of profile complexity on dead metal zone and metal flow. Design/methodology/approach: Cold extrusion experiments were performed using flat-face dies of different complexities. 3D finite element simulation was carried out using the commercial finite element packages ANSYS and ANSYS-LSDYNA. Findings: Findings of this FEM study are that there appears to be no definite correlation between dead metal zone (DMZ) size and the currently existing definitions of extrusion shape complexity. Factors such as die profile symmetry and extrusion ratio may also play significant role in the formation of DMZ and distortion of metal flow through an extrusion die. Practical implications: The study can be of direct utility in extrusion die design improvement, and reduction of extrusion defects related to metal flow. Originality/value: The paper provides basis for a deeper understanding of the factors involved in the formation and development of dead metal zone (and related metal flow problems) in metal extrusion.

Effect of process parameters on metal flow and dead metal zone in extrusion

Qamar S. Z., Pervez T., Arif A. F. M., Sheikh A. K.

Archives of Materials Science

2007

Vol. 28, nr 1-4

118-123

Extrusion finds increasingly more frequent and important applications in automobile, aircraft, construction and other industries. Optimization of metal flow is crucially important in both design and manufacture as it directly affects extrusion speed (essential for higher productivity) on the one hand, and mechanical properties and surface finish of the extruded product on the other. It is reasonable to assume that material flow properties, die-workpiece and container-workpiece heat transfer and friction conditions, die profile, and die design all affect metal flow. However, the mechanism of dead zone formation and how it affects metal flow is not understood well enough to forecast with an acceptable degree of accuracy what is actually happening. Predictive numerical models are limited because of this lack of perception of the physics of the process. The current paper presents some results from a study about the behavior of metal flow and dead metal zone in cold extrusion. Experiments have been performed on flat-face dies fabricated from H13 tool steel and heat treated and surface hardened to approximately the same specifications as commercial extrusion dies. Three workpiece materials have been experimented with: Al-6063 as it is the most common aluminum alloy in the construction sector, and pure aluminum and lead for their better extrudability. Extrusions have been carried out at four different speeds. Commercial finite element packages ANSYS and ANSYS-LSDYNA have been used for numerical investigation of the effect of variations in important extrusion parameters.