Effect of Embedded Abrasive from Grinding and Honing on Wear in the Orbital Engine

Scoring of important sealing and bearing surfaces in the orbital engine after very short running times has been found to be caused by embedded abrasive. These surfaces have been prepared by grinding or honing and it was found that during these operations abrasive grit was detached from the grinding wheel or hone and embedded into the surface. Abrasive particles were identified in these surfaces using electron probe microanalysis and scanning electron microscopy techniques. Grinding studies have shown that embedding of abrasive is most prevalent if the wheel is freshly dressed prior to taking the finishing passes. It has been found that embedded abrasive can be virtually eliminated by not freshly dressing the wheel prior to taking the finishing passes, packing the wheel with soap or wax, and taking light finishing cuts. Engine production trials of surfaces prepared in this way showed that there was a marked improvement in wear behaviour. Preliminary experiments designed to eliminate embedded abrasive due to honing are also described.