The burr is re solidified material inside the hole which can affect {HEAD ~ air flow} through {TAIL ~ the hole} 
The burr is re solidified material inside the hole which can affect { HEAD ~ air flow } through { TAIL ~ the hole }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL