Hitachi Tools Introduces D/D for Deep Hole Machining to 100
April 05, 2023
On December 5, 2007, Hitachi Tools introduced the "Epoch Micro Step Borer" drill bit for micro-hole machining (Fig. 1). It can be used to machine micro-holes with L/D (depth/machining diameter) up to 100. Mainly used for nozzles in automotive engines, air holes in molds, and electronic components.
A major feature of the drill is that the length of the blade (groove length) is only about 5 times the tool diameter. This is based on the premise of step-by-step machining. Another feature is the increased rigidity by growing the non-blade (neck).
However, if the length of the groove is shortened, the chips will flow to the neck and be welded to the neck. Like most drills, the neck of the product is also thinner than the tool diameter. Therefore, a structure called "chip stopper" is used between the groove portion and the neck portion (Fig. 2). The diameter of the stopper is almost the same as the tool diameter. That is to say, the outer diameter of the blade is tapered from the tip to the neck, and returns to the original thickness in front of the neck.
