Glossary

Gate (injection moulding)

What a gate is in injection moulding, why gate position matters, and what brands should know about gate marks on parts.

What it is

The gate is the opening where molten plastic enters the mould cavity. Its type and position affect filling, strength, warpage, and where a small witness mark appears on the part.

Sourcing tip

If a face is cosmetic, say so before tooling — the moulder will position the gate away from it. Gate marks discovered at first-off sample stage are a tooling change, not a polish.

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