Effects of Process Parameters on Shrinkage Porosity in 357 Semi-Solid Die Casting Parts

2020 ◽  
Vol 993 ◽  
pp. 166-171
Author(s):  
Zi Kang Liu ◽  
Min Luo ◽  
Da Quan Li ◽  
Long Fei Li ◽  
Jian Feng

The shrinkage porosity that was caused by the insufficient feeding during solidification, was a common defect in the semi-solid die casting process. This defect decreased significantly the mechanical properties of the casting. In order to avoid the shrinkage porosity in casting, the die design, slug preparation and die casting process were carefully considered. In this study, a designed mold was used to make the sequential solidification of the slug. The process parameters, including intensification pressure, die temperature and biscuit thickness of the casting, were studied to show their influence on shrinkage porosity defects. The experimental results show that the high intensification pressure, high die temperature and long biscuit can be beneficial to obtain castings with no shrinkage porosity.

2016 ◽  
Vol 256 ◽  
pp. 334-339 ◽  
Author(s):  
Song Chen ◽  
Fan Zhang ◽  
You Feng He ◽  
Da Quan Li ◽  
Qiang Zhu

Semi-solid slurry has significantly higher viscosity than liquid metal. This character of fluidity makes product design and die design, such as gating system, overflow and venting system, be different between these two die casting processes. In the present paper, taking a clamp product as an example, analyses the product optimization and die design by comparing the experimental and computational numerical simulation results. For the clamp, product structure is designed to be suitable for characters of SSM die casting process. The gating system is designed to be uniform variation of thickness, making the cross-sectional area uniformly reduce from the biscuit to the gate. This design ensures semi-solid metal slurry to fill die cavity from thick wall to thin wall. Gate position is designed at the thickest location, the gate shape of semi-solid die casting is set to be much bigger than traditional liquid casting. A good filling behaviour can be achieved by aforementioned all these design principles and it will be helpful to the intensification of pressure feeding after filling.


2013 ◽  
Vol 312 ◽  
pp. 475-479
Author(s):  
Wei Gang Zheng ◽  
Cun Hong Yin ◽  
Yu Hong Yuan ◽  
Zhen Min Pan ◽  
Chao Tang

This paper analyzes traditional die casting process to find out the reasons that cause shrinkage cavity and porosity defects in casting. An optimized process of die casting by using local extrusion is proposed. A device used in local extrusion which realizes forcing compensating contraction on key parts of crankcase is designed and the parameters of local extrusion process are discussed. Compared the mechanical properties and microstructure of local extrusion used in die casting production with traditional. It shows that local extrusion used in die casting production can not only achieve the aim eliminating shrinkage porosity and cavity of a casting but also can refine grain to improve the mechanical properties.


2011 ◽  
Vol 474-476 ◽  
pp. 255-259 ◽  
Author(s):  
Ya Ping Hu ◽  
Yong Hu

Numerical simulation can be used to predict die filling, and hence to optimize the die design. In the study, the flow characteristics of liquid filling comparing with those of semi-solid filling were analyzed. The results indicated that the liquid filling turned out to be turbulent, while the semi-sold filling had laminar flow characteristics which could reduce the foundry defects such as gas cavity and oxidation mixture. The distribution of pressure reduced gradually in the filling direction during semi-solid filling process which would generate back pressure that was favorable for filling process.


2016 ◽  
Vol 850 ◽  
pp. 642-648 ◽  
Author(s):  
Song Chen ◽  
Da Quan Li ◽  
Fan Zhang ◽  
You Feng He ◽  
Qiang Zhu ◽  
...  

Compared with traditional liquid and solid processing methods, semi-solid die casting process can apparently overcome shrinkage cavity and porosity defects in castings and high deformation resistance and high residual stress shortcomings in forging parts. Semi-solid die casting process with advantages such as high efficiency and low cost, will become the optimal process for high quality automobile parts. In this study, using the clamp as an example, the author introduced product structure optimization and die design for semi-solid die-casting process of aluminum alloy in a new product development.The Computer Aided Engineering technology was applied to the product structure optimization according to the stress analysis. The optimal mold structure, including cavity layout, gating system, overflow and vent systems, were confirmed based on the die design criteria for traditional die casting, combining with the characteristics of semi-solid forming and the simulation results. The semi-solid aluminum alloy clamp parts with excellent performances were finally developed successfully by means of product structure optimization, die design, parameters optimization of die casting process, and the mechanical properties test of products.The existing parts were optimized to make them more suitable for semi-solid die casting processing. In addition, a reasonable die design specially for semi solid processing was an important guarantee for a successful semi solid product applied in industry. Computer numerical simulation was applied in product structure design for semi-solid die casting, die design, die-casting process optimization and other aspects, to shorten the development cycle of new product, reduce cost and improve efficiency.


2019 ◽  
Vol 285 ◽  
pp. 429-435 ◽  
Author(s):  
Song Chen ◽  
Da Quan Li ◽  
Fan Zhang ◽  
Min Luo ◽  
Xiao Kang Liang ◽  
...  

There are two new processes to development automobile structural components which have certain thickness. In the present paper, taking a main bearing cap product as an example, analyses die design by comparing the experimental and computational numerical simulation results. For the main bearing cap, product structure and mold design were designed to be suitable for characters of SSM die casting and squeeze process. Semi-solid slurry has significantly higher viscosity than liquid metal. This character of fluidity and solid fraction phase make the flow condition more laminar than liquid squeeze casting with the partial fill experiment. And compared with squeeze casting process, the globular shape grain size is smaller than dendritic structure. And mechanical property result shows that the elongation of SSM die casting can achieve more than twice than squeeze casting.


Author(s):  
M. Imad Khan ◽  
Saeid Nahavandi ◽  
Yakov Frayman

This chapter presents the application of a neural network to the industrial process modeling of high-pressure die casting (HPDC). The large number of inter- and intradependent process parameters makes it difficult to obtain an accurate physical model of the HPDC process that is paramount to understanding the effects of process parameters on casting defects such as porosity. The first stage of the work was to obtain an accurate model of the die-casting process using a feed-forward multilayer perceptron (MLP) from the process condition monitoring data. The second stage of the work was to find out the effect of different process parameters on the level of porosity in castings by performing sensitivity analysis. The results obtained are in agreement with the current knowledge of the effects of different process parameters on porosity defects, demonstrating the ability of the MLP to model the die-casting process accurately.


2012 ◽  
Vol 192-193 ◽  
pp. 293-298 ◽  
Author(s):  
Fan Zhang ◽  
Nan Nan Song ◽  
Jun Zhang ◽  
Yong Lin Kang ◽  
Qiang Zhu

According to semi-solid slurry rheological behavior, an apparent viscosity model of A356 alloy developed based on the Carreau model was established to simulate filling process of rheo-diecasting about automobile shock absorber parts and to compare with conventional liquid filling process. Numerical simulation results showed that the filling process of rheo-diecasting was smooth but difficult to splash, which reduced the tendency of the alloy oxidation and inclusion. Meanwhile, a certain percentage of the primary solid particles precipitated before filling and solidification shrinkage of semi-solid slurry were small. This benefited to reduce or eliminate shrinkage defects of the castings. Compared with conventional liquid die casting process, rheo-diecasting process had unique advantages in reducing the internal defects and improving mechanical properties of castings.


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