Casting Pour Weight, Gating Yield, and Melt Energy

Yield is the casting weight over the poured weight, and 60 to 70 percent is normal for sand casting -- which means a third or more of everything melted is gating and risers. The metal in them is not lost, because they are cut off and remelted, so the yield is not a materials loss. It is an ENERGY loss, and that is the part that is paid again on every cycle: a 62 percent yield turns 500 BTU per pound of melting into about 800 BTU per pound of saleable casting, and that penalty is permanent for the life of the pattern. THE TENSION THIS SITS IN IS REAL AND IT DOES NOT RESOLVE BY PUSHING THE YIELD UP. The risers that lower the yield are the risers that feed solidification shrinkage, and cutting them to hit a yield target puts shrinkage porosity in the casting. One scrap casting costs more than the energy saved on many sound ones, and porosity is often found late -- after machining, sometimes after assembly. So riser sizing is a feeding calculation done on the casting's own geometry, and yield is the OUTCOME of that calculation rather than an input to it. Reading it the other way round is the error this makes visible. The lever that genuinely moves both at once is an insulating or exothermic sleeve. It raises the riser's effective modulus so the same feeding is achieved from a smaller riser, which raises the yield without giving up soundness -- and that is the move that resolves the tension rather than trading one side against the other. Improving the gating design and pouring more castings per mould do the same thing from different directions. This is a weight and energy ratio on entered figures. It does not size risers or gating, evaluate whether a casting will be sound, model solidification, account for melting loss, slag, or dross (which are real material losses on top of the yield), include the energy in remelting the returns as a separate line, or address sand, moulding, or finishing costs -- which on many castings exceed the melt energy. The foundry's own melt records, a solidification analysis, and the methods engineer govern.

yield = casting weight / poured weight; melt energy per saleable pound = poured weight x melt energy per pound / casting weight, and the poured weight for a target yield inverts it.

Foundry casting yield and its melt energy consequence. The theoretical melt energy is ENTERED because it varies by alloy. The metal in gating and risers is remelted and is not a materials loss; the loss is the ENERGY, spent again on every heat.

One ratio and one multiplication.

Estimate. AHJ and licensed professional govern.

Field names used by the API: casting_weight_lb, gating_weight_lb, castings_per_mould, melt_energy_btu_lb, target_yield_pct, annual_castings, poured_weight_lb, yield_pct, btu_per_saleable_lb, target_poured_lb, target_btu_per_lb

• Melt energy is entered varies by alloythe foundry's own melt records
• Yield is an outcome riser sizing is a feeding calculation, not a yield targeta solidification analysis
• No melting loss slag, dross and oxidation are real losses on top of the yieldthe foundry's melt records