What it is
An undercut is a feature that prevents a part from pulling straight out of a mould — snap hooks, side holes, internal threads. Tools handle them with side actions, lifters, or collapsible cores, all of which add cost.
Design conversation
Some undercuts earn their cost (functional clips); others can be redesigned away. If a moulder flags undercuts in DFM feedback, ask what the tooling saving would be for each alternative.
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