Bennett Stephen, Tschopp Mark, Vrieze Allison, Zelkovich Evan, Ramsay, Christopher W, Askeland Donald R Transactions of American Foundry Society, Volume 109, Paper No 01-056, Pages 1--15, 2001

Abstract: Several sets of aluminum flange castings with various gating arrangements were produced. Variables included the type of sprue (foam versus untapered hollow ceramic), filters, overflows, number and location of gates, and pattern orientation. Metal velocities, maximum metal temperatures during fill, and the number and location of pyrolysis defects were determined. Except when the pattern was oriented vertically rather than horizontally, the gating system had little or no effect on metal velocities observed during fill. Maximum observed metal temperatures at various locations in the pattern during fill were not significantly affected by filters, although excess glue and foam sprues did tend to reduce temperatures. Use of a foam sprue rather than an untapered hollow ceramic sprue increased pyrolysis defects, as did excessive amounts of glue. In these tests, filters and overflows had little effect. Multiple gates also had little effect on reducing defects. When the pattern was oriented vertically, top gating increased defects and bottom gating nearly completely eliminated defects. The type of pyrolysis defects observed varied with position along the pattern, which correlated with the maximum observed temperature of the liquid metal.

Keywords: Aluminum,Casting, Defect formation,Effect, Gating design, Gating system, Lost foam casting, Metal flow, Observations