Abstract
The normal drill grinder with a stepped ground point drill having a chisel edge angle of 90° can drill smaller dimensions of oversize of holes than with the conventional chisel point drill.
However, the optimum condition of drilling aluminum and its alloys by using the drill of the former type is still unknown. This paper discusses the effects of drilling conditions and the shapes of drill points on the dimensions of oversize of holes for materials of 5 kinds of F-metals; 1S, 2S, 17S, 52S, and 61S.
The principal results obtained were as follows.
(1) In dry drilling (with no cutting fluids), the dimensions of the oversize were arranged in ascending order of 17S<52S<61S<aluminum.
(2) In drilling of aluminum, the point angle was obliged to be smaller for decreasing the dimensions of oversize. In drilling of aluminum and its alloys, the pointed chisel drill was effective in decreasing the dimensions of oversize.
(3) In dry drilling of aluminum, the dimensions of oversize were decreased with the increase of feed, but were little affected by cutting speed except for the case of 1S.
(4) The effects of cutting fluids on dimensions of oversize were sometimes different between drilling of aluminum and its alloys. However, emulsions were effective in drilling of the both materials.
