Sprue (manufacturing)

The gate is in the sand-casting and injection molding of metal and plastic of the part of the molding, which is not part of the molding. It is formed by solidified in the supply ducts for mold melt and should have the least possible weight to avoid waste.

In the simultaneous manufacture of several molded parts, the channel or runner system must be designed so that the mold parts to be filled simultaneously and evenly with a melt of the same pressure and the same temperature.

The gates are usually removed by hand by knocking or scissors and cause a not insignificant part of the cost, since the rest of the casting process can be automated. Gates of thermoplastic injection molded parts of the hobby model building are often left on the parts and must be removed by the user.

Serves the material in the sprue also to balance the shrinkage, so it is also called a feeder.