Computer-aided engineering (CAE) simulation for the robust gating system design: Improved process for investment casting defects of 316L stainless steel valve housing

Defects in investment casting will inevitably reduce the lifetime and degrade the casting quality and increase manufacturing costs, accordingly. In particular, shrinkage porosity was numerically conducted, and a retained melt modulus model was implemented to analyze highly probable regions. The proposed casting schemes of gating designs are compared by quality of casting (shrinkage porosity) and practical feasibility in terms of small hole drilling machinability. The purpose of this study was to determine the feasible plan with the lowest PES (percentage of elements with shrinkage porosity) while promoting the near net shape casting with minimum machining cost and increase material usage. Virtual thermo-dynamical sensors were adopted in the simulations to indicate the impacts of different gating system of pattern assembly on the cooling gradient and direction of solidification. The best-case scenario of investment casting conditions was chosen to fabricate valve housing in an investment casting foundry. Experimental results of X-ray image differentiated nearly none of the pernicious defects that typically occurred with proposed casting, authenticating the proposed scheme's efficacy accordingly.

Compute-Aided Design of Low Pressure Die-Casting Process of A356 Aluminum Wheels

The lightweight design of aluminum automobile wheel can easily bring about all kinds of defects during die-casting, which often causes wheel frame deformation and creep damages in the future use and in turn affects traffic safety. To understand the evolution of mold flow, temperature field, and solidification, the low pressure die-casting processes of A356 aluminum wheel were simulated by Anycasting software package. Various casting parameters combined with the designs of flow channel and overflows were adopted to reduce the defects occurred in wheel products. In addition, we adopted the retained melt modulus (RMM) to predict the position of defects to be formed as well as their distribution so as to eliminate the shrinkage voids and porosity defects during die-casting. The research findings showed that the setting up of overflow tank could effectively prevent the formation of shrinkage void and porosity of die-castings and significantly promote the quality and productivity of die-casting wheel products.

Numerical Simulations of Low Pressure Die-Casting for A356 Aluminum Rims

This study conducted mold flow analyses on low pressure die-casting A356 aluminum rims to improve the shrinkage and porosity defects which usually occurs in die-castings so as to enhance the quality of die-casting wheels. We adopted different lift tube designs with cylindrical, taper opening and back taper opening structures while discussing the filling, exhaust, and solidification of molten flows and predicting the shrinkage and porosity formed based on the retained melt modulus. The study found that the configuration of lift tube as well as the optimization of process parameters such as the processing pressure and progressive time could effectively reduce the formations of shrinkage and porosity defects and improve the quality of die-castings.