A common problem that can plague metal castings is microporosity. This is defined as miniature, sub surface pores that can become exposed and magnified during machining and paint applications. A previously developed virtual casting process design (VCPD) strategy has been implemented to understand and improve scrap levels of visible microporosity in machine face wheels. Computational fluid dynamics and heat transfer modelling was embedded with numerical optimisation techniques to enable accurate visualisation of the casting and solidification process. The calibrated model was then optimised to improve solidification performance and the results were implemented into a LPPM production die at Ford Alloy Wheel Plant. Extensive casting trials were performed with over 50000 wheels cast under standard process and virtually designed process settings. The results produced a reduction in first time microporosity from 30 percent (standard process) to only 12 percent (implemented VCPD improvements). Also, the typical design lead time for process enhancements (due to traditional casting trial and error strategies) was reduced by 47 percent. Cost benefits have also been immediately evident in terms of less rework for defective wheels and greater productivity in the paint line process. This paper describes the application of VCPD to microporosity in wheels and quantifies some important sensitivities of this defect to process variables such as solidification and metal quality. The success of this investigation exemplifies the significant potential for improvement in casting and plant performance, using a systematic virtual casting process design strategy.
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