An Experimental Comparison of Dimensional and Geometrical Tolerances in Milled Holes on AISI D2 Steel

In order to make accurate holes with traditional hole-making methods, it is necessary to use secondary operations such as reaming. Furthermore, by using this method, the tolerance of the hole has a limited range, therefore, it is not useful for shaft based systems. But it is feasible to make a hole with the desired accuracy by using new hole-making methods such as helical and profile milling only by one operation. This study investigated the nominal size, roundness and cylindricity tolerances of helical and profile milled holes in AISI D2 hardened steel. The full factorial design of experiments was used In order to study the effects of the cutting parameters on the dimensional and geometrical tolerances of the holes. The results demonstrated that the range of the dimensional tolerance of the helical milled holes was between 0.001 mm and 0.034 mm which is tighter than the profile milled holes. However, due to the fewer interpolation errors in the profile milling strategy, the geometrical tolerances of the profile milled holes were tighter. The best cylindricity tolerance was obtained by profile milling strategy with the 110 m/min of cutting speed, 0.03 mm/tooth of feed rate and 0.3 mm of depth of cut.