The surface roughness of drilled hole in aluminum alloys

Abstract

The surface roughness of drilled hole is affected by many factors. In the present studies, the effects of drill shapes and drilling conditions on the surface roughness of various aluminum alloys were pursued by experiments. The results obtained were as follows.(1) The materials to be drilled were arranged in ascending order of the degree of surface roughness as follows: 24ST3 <17ST3 <56SH <61ST3. The above order just corresponded with the descending order of strengths of the materials.(2) The effect of helix angle with a constant point angle (118°) was as follows: the surface roughness was more improved with the increase of helix angle and reached the best state at 35° of helix angle. The effect of point angle with a constant helix angle (27°) on the surface roughness was not very great, but the roughness was slightly improved outside the range of 90 130° of point angle.(3) The surface roughness was greater with the increase in cutting speed or feed.(4) The surface roughness was improved when the chips continously flowed in coiled form. There would be a close connection between the chip flow angle at drill edge and the surface roughness finished.