How to choose the drilling tool

There are many drilling tools, mainly ordinary twist drills, indexable shallow hole drills and flat drills. Drilling holes with machining centers usually use ordinary twist drills, ordinary twist drills are mainly composed of the working part and the shank. The shank part of the tool is both straight and tapered. Straight shank tool shank is mainly spring collet shank, which has the advantages of automatic centering, automatic elimination of the advantages of the pendulum, so the best choice for small-size tools of this type. The working part includes cutting part and guiding part, as shown, the cutting part of twist drill has 2 main cutting edges, 2 sub-cutting edges and 1 cross edge. The guiding part of twist drill plays the role of guiding, trimming chip removal and conveying cutting fluid. Twist drill is generally used for lower precision hole roughing, due to the machining center fixture used without drill sleeve centering guide, the drill bit in the high-speed rotary cutting is prone to pendulum movement, and the cross edge of the drill bit is long, so in the drilling of holes, with a center drill to play the center of the hole, in order to lead to the correct drill bit.