Prediction bias caused by input parameter errors in CAE simulation of low-pressure casting molds for wheel hubs | Simulation specification for low-pressure casting tooling molds
Deviation in material parameter input for CAE simulation of low-pressure casting molds for wheel hubs can result in a mismatch between 49% of simulation results and actual defective positions in on-site trial molds.
The input value of thermal conductivity of aluminum liquid deviates from the true value by more than 8%, the simulation error of solidification timing is amplified, and the predicted position of shrinkage and looseness in thick and large areas is offset.
The initial mold temperature setting and the actual temperature difference on site are greater than 20 ℃, and the cooling simulation results are distorted. The deviation of the predicted yield rate in the simulation can reach 27%.
The heat transfer coefficient is uniformly taken, without distinguishing between water-cooled, air-cooled, and natural heat dissipation areas, and the simulation judgment of thin-walled position filled coil air is invalid.
The pressure rise curve of the charging type is simplified as a linear curve, ignoring the actual pressure lag of the equipment, and the simulation cannot capture the instantaneous process of turbulent entrainment.
The heat transfer coefficient of the casting interface is set higher than the actual working condition by 0.005W/(mm ² · K), and the simulation predicts that the cooling rate is faster than on site, with no risk of shrinkage or looseness.
Low pressure casting molds for wheel hubs, low-pressure die-casting molds (LPDC), reverse pressure casting molds (CPC), gravity casting molds, motorcycle wheel hub casting molds, and differential pressure casting molds are increasingly being requested by high-end overseas customers to deliver CAE filling and solidification reports before placing orders. Structural casting molds, aluminum alloy wheel hub molds, aluminum casting forming molds, low-pressure casting tooling molds, and simulation have become entry requirements for automotive parts customers in Mexico and Europe. Zhejiang Xinfeng Machinery compared the simulation and trial data of over a hundred sets of molds, and many service providers directly called the parameters of the general material library without adjusting the alloy grades on site. The simulation is only a formal document with limited reference value. The thermal properties of commonly used aluminum alloys such as A356, A357, and AlSi7Mg vary significantly, and mixing a set of parameters for simulation inevitably leads to errors. The simulation grid size is also crucial. If the grid size in the thin-walled area of the hub and spoke exceeds 2.5mm, small air holes and cold insulation defects cannot be identified by simulation. Simulation can only serve as a predictive tool and cannot directly replace trial mold verification. If the simulation is qualified, adverse effects may still occur on site due to equipment, release agents, and aluminum liquid quality. Many customers mistakenly believe that simulation can eliminate all defects and reduce the number of trial runs at once, which leads to communication differences. The simulation output file includes filling animation, temperature field, and shrinkage criteria. Overseas technical procurement personnel should focus on checking the shrinkage risk cloud map and the marking of the rolled air area. Google search for "low pressure die casting CAE simulation parameter" belongs to high-value technology long tail keywords, and inquiry customers are mostly medium-sized casting enterprises with research and development capabilities.
FAQ
1. Question: What is the upper limit of allowable deviation for the thermal conductivity input of aluminum liquid?
Answer: The deviation of thermal conductivity parameters should be controlled within 8% as much as possible.
2. Question: What is the allowable difference between the simulated mold temperature and the on-site mold temperature?
Answer: The initial simulation temperature and on-site temperature difference should not exceed 20 ℃.
3. Question: What is the upper limit of the simulation grid for the thin-walled area of the wheel hub?
Answer: It is recommended that the grid size for thin-walled positions should not exceed 2.5mm.
4. Question: Can CAE simulation completely replace on-site testing?
Answer: Simulation is used for prediction and cannot completely replace trial and error verification.
5. Question: Which parameter is most prone to errors in simulation?
Answer: The unified value of interface heat transfer coefficient is a high-frequency error point.
6. Question: What are the key focuses of simulation delivery for overseas high-end customers?
Answer: The focus is on checking the shrinkage risk cloud map and predicting the location of air entrainment.
