CORE & CAVITY MODELING IN PRO-ENGINEER

• Approaches part modeling from a tooling perspective.
• Uses 3 basic parts to create a final product
• Core – the male part of a mold
• Cavity – the female part of a mold
• Part Body – the solid that the core and cavity act upon
• This approach simplifies modeling irregular and complex geometries

• This is necessary when using the “Design in Place” approach.
• All major components have the same Zero
• Assembly placement is within parts by the relationship between the geometry and the Zero
• Global Zero is not used for:
• Assemblies that rely on constraints
• Components shared between multiple assemblies, for instance screws

• Create a Local Zero Coordinate System
• Defined by the Global Zero
• Defines the position of geometry to Global Zero
• May be offset or rotated
• Define axis directions based on project conventions
• Create Local Datum Planes
• Based on Local Zero Coordinate System
• Base of all part geometry
• Name them after the axis that define them
• Alternate Approach
• Use skeleton geometry to define and control the part coordinate system and planes from the parent assembly

• Points, Datum Planes, and Axis in Addition to the Local Zero features
• Define major features of the part
• Parting lines
• Screw boss levels and locations
• Interfaces to other parts
• Screen center
• Alternate Approach
• Use skeleton geometry to define and control the part coordinate system and planes from the parent assembly

• Extrude a block from the parting line
• Make the block bigger than the final part will be
• Add the basic internal shape of the part to the block on the parting line side

• Add draft and rounds to features as you go
• The earlier they are added, the better the chance of them working properly

Designing as a separate part has many advantages:

• Drafts and rounds are performed on a simpler part and are more likely to work
• Common features like bosses and snaps are easier to reuse in different parts
• It is easier to swap out or remove a feature from the part model
• Interactions between the feature and complex surfaces on the part are not part of the modeling process
• The resulting part model tree is much cleaner and easier to understand

• Cut the secondary features from the core part
• Add rounds and drafts to surfaces created by this operation

• Cut features like ribs past the outside of the core
• This will ensure that they conform with the contours of the housing without relying on complex surface operations or rib commands
• When the core is complete, create a publish geometry feature of the solid surfaces

• The part is a separate model
• It starts out with a base block, just like the core did
• Make the block slightly larger than the desired part in all directions
• Use the cutout from other model feature
• Select the publish geometry feature from the core as the cutter
• Add any features that rely on surfaces resulting from the cutting operation

• Create the Cavity Part with the same techniques as the core part
• The cavity base block extrudes to the opposite side of the parting line from the core
• Separate features between the core and cavity based on their draft direction
• Add any finishing features