Holes are machined by the following three methods.

For the best cost economy it offers, a) is the most general hole machining method.

Some notes on the points are introduced below to consider for the shape designs when drill machining.

Examples to be noted when drill machining.

• For drilling, the metal is cut by a rotating bit with push forces and rotational speeds.
• When drilling, the tip of the drill (Name: chisel edge) is rotating at zero speed since the center of the point has no radius.
• The function of this chisel edge is to dig into the metal to be cut and create a priming point.
• When the drill is pushed against the metal to be cut, the chisel edge can cut into the metal perpendicularly.
• However when the drill is not perpendicular, the chisel edge does not bite the metal correctly and the hole machining will not be straight.
• Therefore, the drilling surface should be designed to be perpendicular to the drill axis.

[Example-1] Machining a tapped hole on a slope

[Example-2] A case of hole machining on a circumference of a circle