Series 1: HPDC of Bell Housing- Gating options

This is a simulation of an automotive flywheel or bell housing, showing velocity contours of an aluminum alloy during a fast shot of a high pressure die casting process. It is part of a design phase to evaluate different gating options. Shown here is a comparison of five gates simulating filling from a runner below the parting line to accomplish an 80-millisecond casting fill. The left-hand simulation (Case 1) in the video shows gates pointed upward below the parting line, while the right-hand simulation (Case 2) shows gates at the same location, angled at 45 degrees. The comparison helps visualize the highly turbulent fill, showing how metal enters the casting cavity from different gate locations and orientations. The idea is to quickly understand different gating options with a casting part at hand before addressing runner designs.

Shown below are the air entrainment results from both gating configurations at end of fill:

Case 1-

Case 2-

While neither gating design may appear ideal, it is important to understand the correlation to design and outcome of results for further design work. The different gating designs result in different air entrainment within the cast part. This can be attributed to momentum carried by metal from gates, resulting in turbulence or simply entrapment by metal fronts. It is important to note that whether an area of high entrained air is near a parting line or not significantly changes the available options to remove that volume of entrained air in future designs. Interestingly, the result on the left in the image above is better than the result on the right.

Below are complete videos of filling in both scenarios with output frequency controlled to provide clear representation of first and last regions to fill. Among other things, it helps in understanding the moving metal front, die erosion from cavitation, spraying within casting, and potential cold shots that may result from this gating configuration.

Case 1-

Case 2-

Following best modeling practice, this preliminary analysis omits runners, vacuum in cavity, shot sleeve or overflows, features that are normally later incorporated into a more complete model.

Considering the air entrainment result shown earlier, a good next step is to run another simulation with a gate angle of, say, 20 degrees. Watch for this in the next post!

Later in this series of articles, we’ll move on to include the design of a runner system ending at the gate locations, including a shot sleeve. Analysis of the shot sleeve and runner system will help us evaluate slow shot options and runner design. From there, we’ll continue to add elements of the full casting process in a step-wise, evaluative way, demonstrating the best method for applying casting simulation to ensure a successful process design.

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