Three-dimensional fluid-thermal-structure multiphysics interaction simulation model of aluminium extrusion process

Three dimensional fluid-thermal-structure multiphysics interaction simulation model of aluminium extrusion process has been simulated and presented in this paper. This multiphysics complex geometrical engineering process is simulated effectively using computational fluid dynamics (CFD) simulation with very high accuracy, where the aluminium material is treated as a fluid that has a very high viscosity which depends on temperature and velocity. When aluminium moving, the inner friction will work as a heat source, therefore the model of the heat transfer is completely coupled together with those governing model of the fluid dynamics. Material properties come into a viscosity function that can be related to the flow stress locally depending on forming velocity and temperature. In addition, the stresses distribution in the die that introduces due to the fluid pressure and the thermal loads has been modelled by fully coupled the simulation model with the structural mechanic's analysis. Fully three-dimensional results during the process of the temperature distribution, velocity profile, von Mises stress distribution, total displacement and deflection distribution, equivalent volumetric strain distribution, and pressure distribution are presented and analysed with a focus on the fundamental understanding. The model is shown to be able to provide a computer-aided design tool for optimize this complex engineering process by improving productivity and reducing scrap.

Liquid Nitrogen in The Industrial Practice of Hot Aluminum Extrusion: Experimental and Numerical Investigation

Nowadays, the liquid nitrogen cooling in aluminium extrusion is a widely adopted industrial practice to increase the process productivity as well as to improve the extruded profile surface quality by reducing the profile exit temperatures. The cooling channels are commonly designed on the basis of die maker experience only, usually obtaining modest performances in terms of cooling efficiency. Trial-and-error approach is time and cost consuming, thus providing a relevant industrial interest in the development of reliable numerical simulations able to foresee and optimize the nitrogen cooling effect during the die design stage. In this work, an extensive experimental campaign was performed during the extrusion process of an AA6060 industrial hollow profile, in different conditions of nitrogen flow rate and ram speed. The monitored data (die and profile temperatures and extrusion load) were compared with the outputs of a fast and efficient numerical model proposed by the authors, and developed in the COMSOL Multiphysics code, able to compute not only the effect of nitrogen liquid flow but also the gaseous condition. The results of the simulations showed a good agreement with experimental data and evidenced how far was the experimental cooling channel design from an optimized condition.

Comparison of Metal Flow Characteristics in Aluminium Extrusion Die using Numerical Simulations for AA6063 and AA7075

Aluminium extruded profiles are used for light weight structures used in architecture, transportation, aerospace, industrial sectors etc. Increasing use of profiles for applications has been driving extruiders to focus on reliable techniques to produce profile that meet consistent quality. In aluminium extrusion, profitability can be achieved by pushing maximum number of billets i.e maximum speed during production. However, in the shopfloor different aluminium alloys and geometries are limited by manufacturibility limitations which based on alloy properties and metal flow charcateritics. Hence, product quality is largely dependant on the closer control of metal flow charcateritics that can be compensated by right quality aluminium billet and die design paramaters. In this regard, numerical simulation studies have been adopted prior to production to ensure the consistent and reliable quality of profiles. In this technical communication, metal flow characteristics such as velocity, temperature and strain rate in an extrusion die were compared using numerical simulation studies for two alloys namely AA6063 and AA7075.

Stabilisation of a Plastic Soil with Alkali Activated Cements Developed from Industrial Wastes

The development of alternative materials for the construction industry, based on different types of waste, is gaining significant importance in recent years. This is mostly due to the need to increase sustainability of this heavily polluting activity, thus mitigating the dependence on, for instance, Portland cement. The present paper is related to the development of an alkaline activated cement (AAC) exclusively fabricated from industrial by-products (both precursor and activator). Coal combustion fly ash, a common residue from thermoelectric powerplants, and glass waste, from the manufacture of ophthalmic lenses, were used as precursors. These precursors were activated with a recycled alkaline solution, resulting from the cleaning of aluminium extrusion dies, instead of the more common commercial reagents usually applied for this type of binder. Several pastes were studied, combining the precursor and alkaline solution in different proportions. When the most-performing cements were defined, they were used to stabilise a cohesive soil. The experimental procedure and subsequent analysis were designed based on a Response Surface Methodology model, considering the Activator/Solids and Soil/Precursor ratios as the most relevant variables of the stabilisation process. It was observed that, depending on the type of alkaline cement used, there was an optimum precursor and activator contents to optimise the mechanical properties of the stabilised soil. The reliability of this prediction was especially dependent on the type of precursors and, also, on their respective dissolution process right before the homogenization with the soil, under the working conditions available.