Feman Tooling Co.,Limited
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Hole Design in Injection Molding

Common holes in injection molding include through hole, blind hole, profile hole ( holes with complex shapes) and threader hole. All of these holes should be placed at where are difficult to weaken the plastic tensity. There shall remain enough distance between holes and holes, holes and walls. The relation of holes and holes as well as holes and walls of injection molded parts can refer to relevant industry forms.

Universal cores generally have the following installations:

1. It's simple to fix one side of the mold core but there will be transverse flash not easy to trim and easy to bend in the case of deeper holes or with smaller diameter.

Two cores with one fixed side are molded and one is 0.5 to 1 mm bigger than the other one, which makes a little difference though, there will not be any trouble in installation and use. The feature is that with core length cut in a half, it becomes more stable. This molding method is suitable for that with deeper holes and undemanding diameters.

2. The core is guiding support with one side fixed. This way is more commonly used, ensuring both good tensity and stiffness and concentricity. But the guiding part will have wear due to the guiding error and cause fillet parallel overflow.

Blind holes can only be shaped with a fixed core at one end, so their depth should be shallower than through holes. As a rule of thumb, during the operation of plastic injection mold and molding, the depth of the hole should not exceed 4 times the diameter of the hole during injection or injection molding. 


Holes in injection molded parts are roughly divided into the above. Holes design should be taken into consideration in advance of designing plastic products so that the tensity and stiffness will not be affected, making products unqualified and reducing production efficiency.