A low pressure aluminum casting apparatus includes a pair of steel dies each presenting a molding surface and a heat transfer surface. Copper heat sink blocks are disposed on the heat transfer surfaces to remove heat from the steel dies. Steel contact plates and steel spacer plates can be disposed between the heat sink blocks and the steel dies to optimize cooling. In addition, a portion of each contact plate can be spaced from the steel die to reduce cooling. The steel dies include conventional cooling passages for conveying cooling fluid, and the heat sink blocks, contact plates, and spacer plates also include cooling channels for conveying cooling fluid.