Prediction of liquid nitrogen die cooling effect on the extrusion process parameters by means of FE simulations and experimental validation

The temperature monitoring during aluminum extrusion is a crucial task performed in order to avoid profile defects, to increase the die life and to optimize the process productivity. Among the different available systems used to control the process temperatures, in the last decade, the die cooling through liquid nitrogen has been installed on several extrusion plants. In order to provide extruders and die makers with a modelling tool able to gain a better understanding of the extrusion and die thermal field, a numerical model of the extrusion that accounts for liquid nitrogen cooling has been developed in the present work. A simplified 1D modelling of the cooling channel was used and validated against an experimental investigation previously specifically carried out to evaluate the cooling efficiency in a multi-hollow industrial profile. Results showed a significant impact of the design aspects of channel on the thermal efficiency of the cooling and an important heat removal when the liquid nitrogen cooling is used. A good experimental-numerical agreement was achieved in terms of temperature map and extrusion load both in cooled and uncooled conditions, thus suggesting the reliability of the developed simulation tool and its potential integration in a flexible procedure to be used for die/cooling system design and process optimization.