Injection Mold Melt Delivery System Runners and Gates

5 Injection Mold Melt Delivery System (Runners and Gates) 

2 Cold Runners Cold runners are machined into the mold plates therefore, the temperature corresponds with the overall mold temperature. The material in the mnner freezes after injection, and needs to be demolded with the part after each injection molding cycle [8]. The optimum runner cross-sectional shape for SPS is the full-round mnner profile shown in Rgure 14.11. The trapezoidal and modified trapezoidal profiles are common alternatives. 

3 Hot Runners The hot-runner system of an injection mold is characterized by a heated manifold, inside the framework of the mold, which carries melted plastic from the machine nozzle to the gates of the cavity without heat loss. Hot runners are also viewed to save material volume, as 

Ejector boss minimum depth same as gate 

Recommend largest possible gate diameter to reduce pressure drop 

---