In foundry practice the occurrence of solidification defects limits the production and the performance of cast components. In high-pressure die casting (HPDC) the most common defects are shrinkage or gas porosities and bifilms. Thin sections, typical of HPDC components, are the most susceptible to casting defects, and these microstructural imperfections can be detrimental to both the mechanical and aesthetic properties. Even though laminations are not as harmful as internal defects, die cast components with this kind of superficial defects are always rejected by customers, thus requiring further machining operations. The aim of this study is to analyse the lamination defects that occur on the surface of some Al-Si-Cu cast covers produced by means of HPDC. In order to evaluate the influence of the different injection parameters on the final quality of the die casting products, melt temperature, plunger speed and upset pressure have been varied within a range of suitable values. The obtained castings have been studied by performing visual inspections and metallographic analyses by means of optical microscopy (OM), revealing the presence of many bifilms spread over the entire cross section of some cast parts. The presence of laminations, bifilms and cold shuts has been correlated to the considered processing conditions, proposing a new criterion parameter for the quantification of surface quality, called Lamination Ratio (LR).
Influence of injection parameters on the final surface quality of Al-Si-Cu die cast components
CASARI, Daniele;MERLIN, Mattia;GARAGNANI, Gian Luca
2012
Abstract
In foundry practice the occurrence of solidification defects limits the production and the performance of cast components. In high-pressure die casting (HPDC) the most common defects are shrinkage or gas porosities and bifilms. Thin sections, typical of HPDC components, are the most susceptible to casting defects, and these microstructural imperfections can be detrimental to both the mechanical and aesthetic properties. Even though laminations are not as harmful as internal defects, die cast components with this kind of superficial defects are always rejected by customers, thus requiring further machining operations. The aim of this study is to analyse the lamination defects that occur on the surface of some Al-Si-Cu cast covers produced by means of HPDC. In order to evaluate the influence of the different injection parameters on the final quality of the die casting products, melt temperature, plunger speed and upset pressure have been varied within a range of suitable values. The obtained castings have been studied by performing visual inspections and metallographic analyses by means of optical microscopy (OM), revealing the presence of many bifilms spread over the entire cross section of some cast parts. The presence of laminations, bifilms and cold shuts has been correlated to the considered processing conditions, proposing a new criterion parameter for the quantification of surface quality, called Lamination Ratio (LR).I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.