Case Study 1302 : Flow Simulation

This is a general case of a Flow simulation and its applica­tion and uses in a day to day design of the HPDC design in terms of the following approaches:

  • Flow
  • Solidification
  • Thermal Die Cycling
  • Thermal and Mechanical

The part, an Oil Filter Adaptor is used in an automobile application in which hot oil will be continuously flowing through when the engine is running. This casting was taken as a sample case with the following challenges:

  • Multi-cavity (2 in this case) balancing of flow is needed
  • Leak-proof and free from exposed porosity
  • Minimum warping

After multiple iterations and analyses the following shot design (Figure 2.1 ) was arrived at and used.

Figure 2.1 - Two Cavity Shot Design of a Part.

Figure 2.2 depicts the results at half way through the filling cycle and indicates the flow is optimized and bal­anced. It also indicates the first and last fill areas and ensures the over flow pads are filled only after the local area is filled completely.

The premature filling of the bottom portion of the parts is also evident but was not significant as the results (Figure 2.3) were within the required norms and proved at the time of actual production.

Figure 2.2 - Flow Simulation Result - Half way through the Filling Cycle.

Figure 2.2 - Flow Simulation Result - Half way through the Filling Cycle.

Figure 2.3 shows the results at the end of the filling cycle and indicates a minimum surface defects.

Figure 2.3 - Flow Simulation Result - at the end of the Filling Cycle.

Figure 2.4 shows the solidification results, 3.7 seconds into the cooling cycle, and indicates the last solidification areas are away from machining areas and holes. This confirms that there will be only minimum chances of the exposed porosity.

Figure 2.4 - Solidification Result - 3.7 seconds into the Cooling Cycle.

Figure 2.5 illustrates the thermal die cycling results after 25 cycles without water cooling and after 35 cycles with water cooling switched on from 25th cycle. The difference between the two demonstrates the apparent effect of the water cooling.

Thermal die cycling considers the following parameters and their effects

  • H eat transfers due to water cooling or hot oil circulation, die lubricant spraying, thermal conductivity of the die, etc.
  • Timings such as spray time, cooling time, overall cycle time, die open and close times, etc.

Figure 2.5 - Thermal Die Cycling Results - Temperature Distribution of the Die.

Thermal die cycling could be used to design the size and location of the water cooling as well as the hot oil systems very accurately. Also the effect of the rate of flow and the inlet temperature of the fluids viz., water or oil can be pre­dicted very precisely. Hence, the applications of only the thump rules by the designers are only an excuse.

Figure 2.6 indicates the mean iso stress distributions of the part while still in the die after solidification cycle is over. This will help the designers to predict the warping effect in the part at the time of ejection and after a few seconds in the air. Also the residual stress on the die can be predicted in a similar way.

Figure 2.6 - Mean iso stress Distributions -After Solidifica­tion in the Die.

Since this is an evolving concept, there are a lot of opportunities for the designer to use this tool for newly emerging applications.

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