Multi-layer valve guides

摘要

A method of making valve guides by thermal spraying a wear-resistant layer onto a rotating mandrel that is subsequently built up by thermal spraying steel on the wear-resistant layer. A flame spray polymer lubricant may be applied to the wear-resistant layer to improve self-lubricating properties of the engine valve guide. The mandrel and applied layers are then cut off and the remaining segment is further processed in a machining operation to remove the mandrel from the inside of the engine valve guide. The mandrel is preferably cooled as the thermal spray is applied preferably by routing a cooling fluid such as air through the mandrel.