The study of flow pattern and phase-change problem in die casting process

Wang, T. S.; Wei, Heng; Chen, Y. S.; Shang, H. M.

doi:10.2514/6.1996-1806

Cited by 2 publications

(1 citation statement)

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“…Elsewhere, researchers have focused on aluminum and magnesium alloys, which are more commonly used for automotive structural parts. The simulation results are primarily concerned with the fill pattern [22], air entrapment in the shot sleeve [23,24], shrinkage defects in the hot spots [25,26], and microstructural defects affecting the tensile properties [27,28]. With the exception of a single attempt to optimize the process parameters and avoid long fill times [29], few simulation studies have a direct relation to the cold flow defects.…”

Section: Background and Literaturementioning

confidence: 99%

Cold flow defects in zinc die casting: prevention criteria using simulation and experimental investigations

Armillotta

Fasoli²,

Guarinoni

2015

Int J Adv Manuf Technol

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High-pressure die casting of zinc alloys is increasingly used in the manufacturing of parts with high aesthetic value. These parts must comply with strict requirements on surface quality, which are generally overlooked in traditional mechanical applications. Cold flow defects, which are a primary concern for surface quality, originate from several different causes that have not yet been fully understood. This report investigates the factors that influence cold flow defects and the choices that can lead to an improvement in surface quality. The research method is based on a case study performed at a die casting company. First, an existing process has been analyzed using simulation to explain the causes of cold flow defects observed in production samples. The temperature at the end of the cavity fill has emerged as a key index for the occurrence of defects, which can be controlled by three primary process parameters: injection velocity, temperature of the cooling medium, and lubricant spraying time. These same factors are then assessed using experimental tests on an existing die, where the number of defects in the selected regions of the casting has been evaluated by image processing. The results suggest that the surface quality can be particularly improved by increasing the flow rate of the molten metal through the gates and avoiding excessive flow turbulence in the wide cavity sections. Consequently, the increase in the gate area has been identified as a specific criterion for the die design. These findings have been validated in the redesign of the die and the selection of the process parameters, which have resulted in a significant reduction in the surface defects.

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