ADVANCES IN THE PRECISION MACHINING OF SMALL DEEP HOLES

Based on the analysis of the forces acting on a deep-hole drilling hea d and the understanding of the burnishing action of the carbide guide pads, an investigation of the precision drilling method of small deep holes in difficult-to-cut materials was carried out. The influence of tool geometry and cutting parameters (cutting speeds and feed rates) o n the surface quality of the drilled holes was studied, the results of which indicating that empty set 10 - empty set 20 small deep holes of high tolerance grades (IT7 to IT9) and lower surface roughness values (R-a) in the range of 0.2-1.6 mu m can be achieved and the problem of axial deviation of holes drilled minimised under optimised cutting pa rameters by means of the new/improved BTA drill. (C) 1997 Elsevier Sci ence S.A.