Pro Engineer/Design Intent
Why Learn Design Intent?
Pro/Engineer [also: Solidworks & Autodesk:Inventor] is a parametric modeler. That means that features can be related to one another in a number of different ways. These relationships govern how the model will behave when changed. Design intent is the careful control of these relationships so that they correctly govern the intended behavior of the model. With good design intent, models can be updated almost effortlessly. Changes made to one aspect of a model propagate appropriately through the model, assembly, and drawing. With poor design intent, features may update inappropriately, or fail.
Design intent builds intelligence into the model.
Ways to control design intent
Part model references
The first way to control design intent in a Pro/Engineer model is simply to select references appropriately when modeling a part. Except for the default datum plane, every feature must reference something else. You create a reference when you choose a sketching plane or any sketcher reference.
Reference stable features for stability
- Use datum planes as a baseline. Solid features may change. For instance, a hole referencing an edge may fail when a round or chamfer is created on that edge. A hole referencing a face may fail when a draft is created on that face.
- When using solid features as references, choose more stable features. That is, reference faces before edges and edges, when necessary, before vertices.
- Create a base feature with the basic shape of a part. Use its features
- Use the model tree and Insert Here functionality to control feature order.
- Features can only reference other features that occur earlier in the model tree. Features cannot reference subsequent features.
Model for design intent
- When choosing references, ask how the model might change. Should a hole stay centered on the part? Should it remain a fixed distance from some face or edge? Should it move with an associated feature, such as a boss?
- Consider the full range of possible changes. Will a drastic change in a dimension make a sketch impossible to resolve, for instance by turning it inside-out?