Injection Molding DFM Advisor
(Used under permission of Dixon and Poli,
Engineering Design and Design for Manufacturing)
Fill in the following form to determine the relative tooling cost and cycle time for the injection molded part. See the definitions below for information on certain form fields.
- External undercuts are holes or depressions on the external surface of a part which are not parallel to the direction of mold closure. Projections which are on the external surface of a part and are such that a single dividing surface cannot pass through all of them are also considered external undercuts. The number of external undercuts is equal to the number of surfaces bearing unidirectional holes and/or depressions not in the direction of mold closure and/or projections that prevent a single dividing surface from passing through all of the projections.
- Internal undercuts are recesses or projections on the inner surface of a part which prevents solid plugs, conforming to the exact shape of the inner surface of the part, from being inserted.
Shown in the figure below are examples of parts with external and internal undercuts: