Aluminium Based Material Extrusion Through Mathematical Contoured Die: Numerical & Experimental Investigation

Abstract

The metal forming process is preferable for manufacturing the parts of moderate complexity and greatly diversified profiles for the larger volume of productions to reduce the tooling cost. Energy saving, less scrap generation and near net shape production with better mechanical properties along with high production rate have enhanced the specific forming process, extrusion, for the production of long straight metal products. The huge demand of aluminium alloy in the extrusion industry for fulfilling the market requirements in the sector of building and architecture, construction, automobile and transport system, electrical and electronics, aerospace, and heat exchangers tends to optimize the process for improved process efficiency as well as product quality. Prediction of the influence of process parameters is very difficult owing to the concealed material deformation during extrusion. Due to this reason, an illustrious finite element analysis tool (DEFORM TM) was adopted to investigate the process. The simulations were performed to ascertain extrusion load, effective stress, effective strain and temperature distribution for square to square extrusion process. To decipher the effect of die length, ram velocity and extrusion ratio in the process, simulations were carried out by varying the variables in a wide range with different types of dies. The process was also employed for the investigation of the round to square extrusion considering the same parameters along with punch shape for Al-6063 alloy. Influence of die profile plays a predominant role in predicting the ultimate load requirements and flow characteristics. Considering the die profile an important component, the profile for round to square shape has been developed by following cosine, linear converging, elliptic, hyperbolic and 3rd order polynomial laws. Considering the above die profiles the simulations were conducted with optimised process parameters to find out a suiatable die profile. The simulations were validated with high-temperature experimentations. To improve the product properties, aluminium metal matrix composites (AMMC) prepared by powder metallurgy (PM) route has been extruded. Four different reinforcing elements of 2 wt. % (Zn, Ti, Soda lime silica glass and ZrO2) were added to Al / 5 wt. % of Mg / 1 wt. % of Gr matrix. To avoid the product defects, mathematically contoured cosine profiled die was used for the thermo-mechanical treatment. The improvement of the product properties has been studied. The optimum parameters before experimentation can be set by utilising the finite element tool successfully. Computerised finite element techniques are the best suitable
technique to understand the concealed operations like extrusion.
The optimum ranges for the extrusion of simple square bar section from the same shape billet and round to square extrusion has been established. The cosine profiled die for both kinds of extrusion as well as PM composite was found suitable as it generates lesser velocity relative difference at die exit. A significant amount of property improvement was observed in the AMMC after thermo-mechanical treatment.