It is hot and dirty out on the casting floor. However that is where die casting happens. Many engineers hired to accomplish flow modeling avoid visitng the casting floor like the plague. Once a high pressure die cast die is complete, a short shot is a more accurate indicator of the actual fill pattern. I perform a short shot by hand ladling a calculated amount of metal out of the autoladle cup as it passes by. The short shot example pictured above is a typical example of a common die casting fill problem. The molten metal blocked the vents before all of the gas within the cavity was released. This short shot confirmed the customer quality complaint. This casting had unaccptable porosity. The trapped gas was compressed into porosity bubbles as the metal was pressurized. This problem was eventually solved by retrofitting new gating. However supporting full volume production, including building a bank, had to be accomplished first. Subsequent short shots were used to tune in a fast shot take off point. These short shots proved that prefilling some of the part at slow speed reduced the amount of trapped gas. Somewhere in the future we will have flow simulation software that accurately models the effect of varying the fast shot takeoff point.