Abrasive Flow Machining

This finishing method uses putty with abrasive filler, forced through passageways at pressure, so you can deburr and polish surfaces you could never reach with a tool. I’d never seen it in action before seeing some videos today. It makes so much sense.

This video is showing the refinishing of a Mustang intake manifold, but this is a common finishing technique for new production of parts that need high-flow passageways (turbines, large bearing races, valves).