Machinability Parameters on New and Selective Aerospace Materials

Four groups of alloys of current interest to the aerospace industry were selected for the machinability studies. The four groups of alloys consisted of (1) ultra high strength steels; (2) titanium alloys; (3) high temperature alloys; and (4) hot work die steels. Tables of recommendations were compiled from the machining tests conducted for various machining operations on all of the alloys. Drilling tests were conducted on boron epoxy composites with high speed steel, carbide, and diamond core drills. The results indicated that, in general, high speed steel and carbide drills are not satisfactory for drilling this material. A study was also conducted on the surface integrity of drilled and tapered holes in a titanium alloy. The results indicated that even under careful machining conditions, serious defects regarding the surface integrity of the hole can occur. Drilling tests with ultrasonic assist were conducted on a titanium alloy. It was found that the ultrasonic assist was beneficial when the holes were drilled dry. (Author)