The thermal cleaning equipment my school uses was purchased in 1998. So it's 24 years old and has cleaned several thousand blocks, heads, sheet metal and crankshafts. Minimal maintenance, reliable equipment. Our system has a slow rotating drum that the parts are fastened into. Iron and steel like crankshafts are baked in the oven at 600-625 degrees F for an hour. Aluminum blocks, 275-300 degrees F. Overhead cam aluminum heads can't be baked. Ruins the cam bearing journals and tiny shot gets caught in all the teeny, tiny passages. Ultrasonic cleaner is the best we can do with that stuff. From oven, directly into the blaster/tumbler. Ours uses .030" chopped stainless steel wire. It works great but you MUST get all the tiny wire shot out of the castings and all the passages. Looks like new metal when it comes out. The crud and sludge acts as fuel in the oven. The dirtier they go in, the cleaner they come out. All machined surfaces need to be restored when the castings come out of the oven. So every block cleaned this way MUST be line honed, surfaced and cylinders honed. Crankshafts also must be ground undersize if cleaned in our system.
|