Geometric Characteristics of Tungsten Carbide Drill Bit Ⅲ

In last part we know that the twist rate of a tungsten carbide drill bit affects removal speed of chips, and the correct point angle varies with working material hardness. This part will go on discussing the geometric characteristics of tungsten carbide drill bits.

3. The lip angle: it determines the amount of support provided to the cutting edge. A greater lip angle will cause the tungsten carbide drill bit to cut more aggressively under the same amount of point pressure as a bit with a smaller lip angle. Both conditions can cause binding, wear, and eventual catastrophic failure of the tool. The proper amount of lip clearance is determined by the point angle. A very acute point angle has more web surface area presented to the work at any one time, requiring an aggressive lip angle, where a flat bit is extremely sensitive to small changes in lip angle due to the small surface area supporting the cutting edges.

4. The length of a bit: it determines how long a hole can be drilled, and also determines the stiffness of the tungsten carbide drill bit and accuracy of the resultant hole. Twist drill bits are available in standard lengths, referred to as stub-length or screw-machine-length (short), the extremely common jobber-length (medium), and taper-length or long-series (long).

 (To be continued. This article is divided into several parts. Here is part 3. For part 2, please refer to http://news.chinatungsten.com/en/tungsten-information/80547-ti-10417; for part 4, please refer to http://news.chinatungsten.com/en/tungsten-information/80549-ti-10419)

• < Prev
• Next >