Multi-layer valve guides

摘要

A method of making valve guides by thermal spraying a wear-resistant layer 52 onto a rotating mandrel 10 that is subsequently built up by thermal spraying steel on the wear-resistant layer 52. A flame spray polymer lubricant is applied to the wear-resistant layer 52 to improve self-lubricating properties of the engine valve guide. The mandrel 10 and applied layers 52,54 are then cut off and the remaining segment is further processed in a machining operation to remove the mandrel 10 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 10. Application of the polymer material through spray gun 22 may be simultaneous with or subsequent to beginning application of the wear resistant material.