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Title: Thermal and structural modelling of gravity die cast aluminium-silicon alloy automotive parts
Author: Wishart, H.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 1998
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The automotive industry has shown an increasing interest in the use of aluminium castings to produce, light, high performance, complex shaped parts. In gravity die-castings, the die and its design are central features. The project is designed to enhance the understanding of the influence of the die on the solidification behaviour of commercial Aluminium-Silicon Alloy (LM25) casts and addresses the question of how closely a numerical model can simulate an industrial casting process. The simulation work was based on the MAVIS FD-casting package. Experimental measurement methods were developed and were applied to monitor and analyse the temperature profiles of some production and test dies during industrial batch trials. The results were correlated with trends in parameters obtained from the numerical model. Extensive numerical heat transfer and solidification modelling was applied in order to predict the effects of specific changes to the die construction. Attempts were made to manage die thermal-gradients using targeted water-cooling. Measurements of the 'as-cast' microstructures were correlated with monitored thermal-profiles of the dies and with the predictions of numerical models. Both the simulation studies and measurements confirmed that die shapes tended to have very little influence on the macro-freezing pattern of the castings. The water-cooling had the effect that the die temperature dropped and the dendrite arm spacings were reduced but the principle-freezing pattern remained the same. However, the freezing pattern was found to be sensitive to the presence or absence of the mould coating. Measured die temperatures and the principle-freezing patterns were predicted well by the numerical model. The precision of spot parameter values however depended very much on the tuning of the model. Values of simulation variables evaluated for a test-piece casting were not necessarily transferable to simulation of commercially cast automotive brackets.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available