[sanddrag]

My experience with the CIMs in both robots and controlled test conditions has indicated that blowing air over them, even at significant volume, has little effect. Under approximately 25 Amps steady continuous load, I could not run a CIM for more than about 4 minutes without it becoming so hot you couldn't hold a finger on it for more than a second or two. This was with a large custom-machined finned aluminum heat sink affixed with thermal compound, and a fan blowing over it. The problem is the heat is all generated in the armature windings, and its only conductive path out is through the bushings in the endbell and the face of the motor. It's a pretty slow heat transfer. It would appear that due to the lack of an internal fan, the convection internally is not really enough to make the CIM motor suitable for extended use.