The volume of 1 iron bar is 12 cm x 8 cm x 6 cm = <<12*8*6=576>>576 cubic cm.
The volume of 10 iron bars is 10 x 576 cubic cm = <<10*576=5760>>5760 cubic cm.
Therefore, there are 5760/8 = <<5760/8=720>>720 iron balls that have been molded.
#### 720