injection mold part with undercut

Help Guide

Undercuts Design Guide

An undercut is any indentation or protrusion that prohibits part ejection from a straight-pull mold. It is a feature that cannot be captured with the cavity and core alone. Though they add complexity to a mold and can increase production costs, parts sometimes require undercuts and side actions to achieve the expected fit, form, and function.


Complete the form to download our two-page Undercuts Guide which covers:

  • Design modifications that can help to minimize the need for undercuts/side actions
  • Design Tips to design complex features to optimize the molding process when using undercuts/side actions
  • Little known facts to improve effectiveness of molding undercuts

Rely on Quickparts sales engineers for consultation on your project. We can support you with design tips, material selection, or advice about the appropriate finish choices. 

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