This paper takes an aluminum alloy automotive engine mount as research object, combining numerical simulation and orthogonal experimental methods to conduct research on design and optimization of die-casting process. Aim is to solve internal defect problem of complex thin-walled die-cast parts, improve casting quality, provide theoretical and engineering references for production of aluminum alloy die-cast parts under background of automotive lightweighting. Core research content and conclusions can be summarized as follows:
Research Background and Significance
Automotive lightweighting has become a core design indicator, and aluminum alloy is preferred material for lightweighting. High-pressure die casting is an important technology for its mass production. As a key load-bearing component of automotive powertrain, engine mount has a complex structure and uneven wall thickness. Die-casting process is prone to defects such as air entrapment, shrinkage cavities, and porosity, making its process optimization of significant engineering value.
Casting Process Analysis and Gating/Overflow System Design
Research object is an ADC12 aluminum alloy engine bracket, a typical complex thin-walled part with dimensions of 480 mm * 400 mm * 135 mm and an average wall thickness of 3.5 mm. Thick-walled sections are prone to hot spots, so a DCC1650 cold chamber die-casting machine was selected for production. A suitable gating and overflow system was designed, employing a fan-shaped gate with three main runners. Main gate is located in the center of casting. Overflow channel volume is 15%–20% of casting volume, venting channel is 0.15 mm thick and 15 mm wide to ensure cavity venting and collection of cold molten metal and oxides.

 

Positive Side

 

Negative Side
Numerical Simulation and Initial Process Defect Analysis of Die Casting Process
A 3D model was built using UG and imported into AnyCasting software for die casting process preprocessing. Heat transfer coefficients and initial process parameters were set for molten metal and mold, mold and cooling channels. Transient simulations of filling and solidification processes revealed abrupt changes in flow path of molten metal through complex ribs under initial process conditions. Thick-walled mounting seats formed "isolated hot spots," due to an unreasonable combination of mold and pouring temperatures and insufficient targeted cooling, directional feeding could not be achieved, resulting in defects such as air entrapment, shrinkage cavities, and porosity. Cooling system was optimized to address these defects by arranging cooling water channels at defect locations, setting inlet and outlet water temperatures of pipes, and improving solidification sequence of casting.

 

Analysis of Defects at Different Locations in Castings
Orthogonal Experimental Design and Process Parameter Optimization
Pouring temperature, mold preheating temperature, and injection speed were selected as key influencing factors. An L9 (3*3) orthogonal experiment was designed, using shrinkage cavity volume and maximum internal stress as evaluation indicators. Range and variance analyses of experimental results showed that injection speed had a highly significant impact on both evaluation indicators, pouring temperature significantly affected shrinkage cavity volume, and mold preheating temperature significantly affected maximum internal stress. Considering dual-objective optimization requirements, optimal process parameters were determined as follows: pouring temperature 660 ℃, mold preheating temperature 180 ℃, and injection speed 4.8 m/s.
Production Verification and Research Conclusions
Using optimized process parameters, trial castings were produced using a DCC1650 die-casting machine. Finished products showed no surface defects, and X-ray flaw detection revealed no obvious shrinkage cavities or porosity defects, meeting production requirements. This study ultimately verified effectiveness of combining numerical simulation and orthogonal experiments in optimizing die-casting process. Optimized process reduced internal defects in castings, improved forming quality and yield, provides a practical reference for process design and quality control of complex thin-walled aluminum alloy die-castings.

 

Film Castings