input: [Foundry Process] Permanent Mold [Process] Permanent molds consist of mold cavities machined into metal die blocks and designed for repetitive use. Currently, molds are usually made of cast iron or steel, although graphite, copper and aluminum have been used. Permanent mold castings can be produced from all of the metals including iron and copper alloys, but are usually light metals such as zinc-base, magnesium and aluminum. Gravity Permanent Mold-The flow of metal into a permanent mold using gravity only is referred to as a gravity permanent mold. There are two techniques in use: static pouring, where metal is introduced into the top of the mold through downsprues similar to sand casting; and tilt pouring, where metal is poured into a basin while the mold is in a horizontal position and flows into the cavity as the mold is gradually tilted to a vertical position. Normally, gravity molding is used because it is more accurate than shell molding. It is preferred almost exclusively to shell molding for light alloy components. Low-Pressure Permanent Mold -Low-pressure permanent mold is a method of producing a casting by using a minimal amount of pressure (usually 5-15 lb/sq in.) to fill the die. It is a casting process that helps to further bridge the gap between sand and pressure diecasting. [Pros / Cons] 
output: Advantages Superior mechanical properties. Produces dense, uniform castings with high dimensional accuracy. Excellent surface finish and grain structure. The process lends itself very well to the use of expendable cores and makes possible the production of parts that are not suitable for the pressure diecasting process. Repeated use of molds. Rapid production rate with low scrap loss. Disadvantages Higher cost of tooling requires a higher volume of castings. The process is generally limited to the production of somewhat small castings of simple exterior design, although complex castings such as aluminum engine blocks and heads are now commonplace.