Core & Cavity Modeling in Pro-Engineer
USEFUL FOR COMPLEX MOLDED PARTS
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Approaches part modeling from a tooling perspective.
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Uses 3 basic parts to create a final product
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Core – the male part of a mold
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Cavity – the female part of a mold
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Part Body – the solid that the core and cavity act upon
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This approach simplifies modeling irregular and complex geometries

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

PART COORDINATE SYSTEM DEFINES THE LOCAL ZERO
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Create a Local Zero Coordinate System
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Defined by the Global Zero
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Defines the position of geometry to Global Zero
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May be offset or rotated
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Define axis directions based on project conventions
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Create Local Datum Planes
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Based on Local Zero Coordinate System
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Base of all part geometry
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Name them after the axis that define them
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Alternate Approach
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Use skeleton geometry to define and control the part coordinate system and planes from the parent assembly
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USE ONLY THE LOCAL DATUM PLANES
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HIDE THE GLOBAL DATUMS, FRONT, TOP, & RIGHT AND THE COORDINATE SYSTEM IN THE LAYERS AND SAVE THAT STATUS.
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DO NOT CREATE ANY LINKS TO GLOBAL DATUMS OR COORDINATE SYSTEMS!
DEFINE REFERENCE GEOMETRY FOR THE PART
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Points, Datum Planes, and Axis in Addition to the Local Zero features
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Define major features of the part
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Parting lines
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Screw boss levels and locations
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Interfaces to other parts
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Screen center
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Alternate Approach
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Use skeleton geometry to define and control the part coordinate system and planes from the parent assembly
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CORE PART START
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Extrude a block from the parting line
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Make the block bigger than the final part will be
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Add the basic internal shape of the part to the block on the parting line side

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

CREATE COMPLEX FEATURES AS SEPARATE PARTS
Designing as a separate part has many advantages:
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Drafts and rounds are performed on a simpler part and are more likely to work
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Common features like bosses and snaps are easier to reuse in different parts
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It is easier to swap out or remove a feature from the part model
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Interactions between the feature and complex surfaces on the part are not part of the modeling process
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The resulting part model tree is much cleaner and easier to understand

ADD SECONDARY FEATURES TO CORE PART
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Cut the secondary features from the core part
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Add rounds and drafts to surfaces created by this operation

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

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

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

WORKING WITH MULTI-PART MODELS
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In order to modify a subpart it must be in either the working directory or the path
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To change a subpart such as the core, right click on it in the model tree and select open base
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The main part must be regenerated before the changes to a subpart will appear
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In order to create a copy of a part in another location, open the part and all subparts and use the backup command