Air-cooling represents one of the simplest methods of permanent mold cooling. However, this method has limited cooling capabilities because the heat transfer from the mold to the air often isn’t fast enough for the production levels required by most foundries.

To enhance air’s cooling capabilities, cooling fins and compressed air can be used as well as designing contours into the mold to allow the air more access to the internal segments of the mold.

the typical design of an air-cooled permanent mold in which the back of the mold shell is contoured to maintain uniform mold thickness around the mold cavity. The contour of the mold back may be thickened or thinned out as needed to increase or decrease the cooling rate in localized areas. Cooling fins are placed across the back of the mold to aid in mold cooling.

The back of the mold also can be designed flat rather than contoured with the addition of a large quantity of cooling fins with either a circular or rectangular cross-section. Rectangular fins have an advantage due to the increased surface area.
The main advantages to air-cooled permanent molds are: a longer service life because the mold cools gradually without high stress in comparison to the immediate cooling effects of water-cooled molds;
in isolated casting designs and materials, reduced cooling rates may aid casting solidification and casting quality.