Staggered cooling holes for enhanced heat transfer in air-cooled motors

A stack of motor laminations, comprising:

• a plurality of substantially identical motor laminations having cooling holes on a plurality of hole axes, at least one of the hole axes separating the motor laminations into two asymmetrical portions, the stack of motor laminations including some motor laminations which are stacked in an original orientation and some other motor laminations which are flipped over on the at least one of the hole axes separating the motor laminations into two asymmetrical portions so that at least some of the cooling holes of the some other motor laminations are partially coincident but not located in identical positions as compared with the cooling holes of the some motor laminations which are stacked in the original orientation with adjacent ones of the cooling holes thus forming staggered cooling passages with some of the cooling holes extending further into the cooling passages than others of the cooling holes to provide turbulence for mixing air at boundary layers of the cooling passages when bulk air flows through the cooling passages;
• wherein the motor laminations have a plurality of evenly spaced winding slots with adjacent ones of the evenly spaced winding slots forming substantially smooth winding slot passages.