Some Common Gate Types
Direct (Sprue Gate)
Used for single-cavity molds. Part is gated directly from the sprue.
The molten polymer is injected directly into the center to the cavity.
Suited for symmetrical, cylindrical, and disc-shaped parts
Tab Gate
The tab gate is the simplest type of gate.
Tab gates are most often used for flat and thin parts.
The tab gate reduces stress in the cavity. Stress around the gate is channeled into the auxiliary tab, which is trimmed off after the part is molded.
Requires a separate degating process
Fan Gate
Similar to the fan gate: attached to the part at the parting line. Requires a separate degating process.
The fan gate expands outward in the shape of a fan, with the widest end open to the cavity.
Suitable for large parts, molds with fragile areas
Disc Gate
Used on cylindrical parts that are open at either end (such as a tube).
Do not leave weld lines
Also called a diaphragm gate
Pin Gate
A pin gate is used in three-plate cold runner molds.
A pin gate must be small enough to be detached from the part wall without damaging the part. Pin gates are usually less than 50% of part wall thickness.
The pin gate is also called a pinpoint gate.
