The terms "gates" and "sprues" are used interchangeably in the jewelry industry. How this came about is of little importance; however in normal foundry practice the following definitions are used as set forth in Webster’s New Collegiate Dictionary:

Gate: a channel in a mold through which molten metal flows into a cavity made by the pattern.

Sprue: a hole through which metal is poured into the gate and thence into the mold.

It will be assumed in this paper that the gate is that part of the casting which feeds metal to the cavity and which is subsequently removed from the completed casting. The sprue is the main feed for one or more gates. In jewelry casting this sprue is usually the central core or tree from which many gates are fed.

In describing methods and practices of gating it might have been preferable to use separate headings, viz., purpose, function, size, position, shape, etc. In the real world these terms tend to overlap, and thus it seemed better simply to give a general description.

Author: Al Schaler