Design Guidelines
Simple, straight-pull parts
Protomold can make many complex features, however, a mold costs less if it is a straight pull, i.e. it doesn’t have undercuts.
A part that can be made with a straight pull mold has all its features designed so that when the two halves of the mold pull straight away from each other, there is no mold metal that wants to pass through part plastic. Undercuts on the part require mold pieces to pull out sideways, perpendicular to the direction of pull.
Consider using telescoping shutoffs to create through-holes
As noted earlier, telescoping shutoffs benefit from drafted sliding surfaces whenever possible.
But they are also useful in the implementation of part features that might otherwise not be possible with straight-pull molds.
This example shows how the redesign of a part with an undercut (e.g. the through-hole) can be changed into a part with no undercuts through the use of a telescoping shutoff approach, without losing its functionality.
Note: we request at least 3 degrees draft on shutoffs.
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Through-hole in part cannot be molded with straight-pull mold |
An equally functional redesigned part without undercuts can be molded using telescoping shutoffs |
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