If a cold runner is used and an automated separation between part and runner is wanted, a tunnel gate can be used.
In this case the gate will be on the side of the part or a rib.
The tappered shape leads to a small gate size on the part surface and allows a good removal of the cold runner during mold open.
A baffle wall at the end of the tunnel is used to collect cold melt at the start of injection.
The separation between runner and part is possible by using a standard two plate mold.
Often there is a positive impact to the parts appearance due to the less visible gate on the side of the part.

Tunnel gate in Injection Molding

Injection mold: Using a tunnel to fill the part

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This glossary of plastic industry is provided by PLEXPERT Canada Inc.