One of the most common challenges in creating a parametric model of a die casting
design is creating features in an order that allows for changes without creating errors in the
feature tree. In addition, creating as-cast and machined versions of the model may be difficult or
time consuming. Presented here is a method for ordering CAD features in a way that eliminates or greatly
reduces feature tree errors and eases the development of a die casting design model.
CAD Feature Order Methodology
1. Base Geometry Features: Features such as extrusions, bosses, cuts, shells, revolves, lofts,
and sweeps that make up the base geometry of the model should appear at first at the top of the
feature tree.
2. Cast Cored Holes: Next as-cast cored holes should appear. These are holes that will be cast
during the die casting process and may or may not be machined or tapped later.
3. Parting Lines: Parting lines, if needed, should be next. Some castings will have a natural
parting line that will appear after draft has been applied to the part in the next step.
4. Draft: Draft application should be next.
5. Fillets: Next fillets should be added to all geometry. In some cases, fillets will not be
added to the parting lines.
6. Machining: Finally, all machined features should be added. By having the machined features
at the end of the feature tree, they can be suppressed and un-suppressed creating an as-cast and
machined part model very quickly. Adding machined features last also makes it much easier to determine
the amount of as-cast geometry required to provide the correct amount of machining stock.
The feature order method presented here also allows for machined features to be suppressed and
un-suppressed easily to create as-cast and machined part model configurations. Creating as-cast and
machined part model configurations is an excellent way to clearly convey what features should be as-cast
and what features should be machined. In addition, creating
separate drawings for as-cast and machined
parts will be simplified by using this feature order method.
Note: Occasionally very large fillets and highly tapered or drafted features may also be used as core
geometry features and placed in the top sections of the feature tree.
