When {HEAD ~ the burnisher} 54 engages {TAIL ~ the hole} first to upset the material and to leave a beneficial residual stress, the slightly larger reamer 52, while removing some material around the hole, stills leaves the cold worked material in the hole 
engages
When { HEAD ~ the burnisher } 54 engages { TAIL ~ the hole } first to upset the material and to leave a beneficial residual stress , the slightly larger reamer 52 , while removing some material around the hole , stills leaves the cold worked material in the hole
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH