**3.1 Design of gating system based on CFD analysis**

In this study, a capstan drum (**Figure 2**) is used as the product shape. Also, a casting runner with a diameter of 30 mm is used for the solution. The capstan drum was analyzed for metal flow using the two gating systems shown in **Figure 2(a)** and **(b)**.

Gating system A has a gate directly on the arm, which is considered to be prone to many residue defects. Since an enormous amount of time would be required to analyze everything from the pouring to the filling of the product part, a simple

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**Figure 3.**

*Results of flow analysis for capstan drum.*

*CFD Optimization Method to Design Foam Residue Traps for Full Mold Casting*

gate was used. The inflow pressure was set at 1.425 × 105

pouring temperature was increased by 20 K to 1643 K.

flows may actually reduce the number of residue defects.

model in which metal flows into the product part at a constant pressure from the

and the temperature of the pouring molten metal was set at 1623 K. The pouring

since the shape was symmetrical, we were able to cut the analysis area in half to

The results of the CFD analysis are shown in **Figure 3(a)**. As shown by the dashed ellipses, the metal flows by gravity from top to bottom. Due to the difference between the density of the metal and the density of the gas and residue generated by the pyrolysis, the metal would entrain the gas and residue, which would affect

Then, gating system B is modified to install gates at the rim and hub to improve the flow of gating system A. To prevent the formation of defects in the residue, the

A molten metal flow analysis was performed on the drum using this gating system B. The results of the analysis are shown in **Figure 3(b)**. The flow in the rim proceeds gradually from the bottom to the top, which makes it difficult for the metal to entrain gas and residue. In addition to the increase in temperature, these

In other words, if a gate is installed on the arm as in gating system A, a drop-in flow occurs, leading to the generation of residue defects, so the gate must be installed on the bottom of the hub and rim as in gating system B. If the

Pa in absolute pressure,

Pa in absolute pressure. In addition,

*DOI: http://dx.doi.org/10.5772/intechopen.95505*

temperature of the metal was set at 1.425 × 105

reduce the analysis time.

the occurrence of residue defects.

**Figure 2.** *Shape of capstan drum and gating systems.*
