An undercut is identified against an intended release direction. A groove, hook or recess becomes a release problem when the mold surface forming it cannot withdraw along that direction without interfering with the molded part.
That makes the mold arrangement part of the definition. The same contour can be trapped in one orientation and accessible in another. A circular feature or a wall perpendicular to the opening axis is not automatically an undercut.
Packaging sample showroom.
Start with the release path
A cosmetic cap may have a recess that is open to one side. Whether tooling can leave that recess depends on its opening, surrounding walls and the motion assigned to the tool that forms it.
Changing the parting line or orientation may expose the feature to a straight withdrawal. It may also move a witness line onto a different surface, so release and appearance have to be considered together.
The relevant question is where the steel must move after the polymer has formed around it. Looking only at the finished part's outside silhouette can miss an internal obstruction.
What draft contributes
Draft is taper relative to a release direction. An appropriate taper can create clearance as the tool and part separate, reducing prolonged surface contact during withdrawal.
Its effect depends on the direction of taper. A surface that narrows the wrong way can create interference rather than improve release. Texture, depth and material behavior also affect the draft assessment.
Simply adding taper to a neighboring wall does not remove a hook that remains trapped across the tool's path. However, changing the obstructing geometry itself may eliminate that undercut.
This is why draft and undercut checks are related. They address different aspects of release, but a geometric redesign can change the answer to both.
Choose a release approach for the actual feature
A slide or lifter can withdraw a forming surface before the part is ejected. Unscrewing or collapsible tooling may suit other geometries. Each approach needs space and a workable sequence.
Some shallow features can be stripped through elastic deformation when the polymer, feature geometry and allowable strain permit it. That is a designed release method, not proof that any undercut can be forced out.
The mold review should distinguish intended elastic stripping from accidental interference. The part must recover acceptably and retain the dimensions and appearance needed for its function.
For a packaging project with SamBound New Material Technology Company Ltd., product information at sambound.com can establish the component being discussed. The release decision still belongs to the actual geometry and tooling review.
A useful drawing therefore identifies the proposed pull directions and the surfaces forming the recess. That provides a specific basis for deciding whether draft, a geometry change or additional mold motion is appropriate.
sambound.com
SamBound New Material Technology Company Ltd.
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