Regular HSS drills couldn’t work on the materials with higher HRc, and have bad efficiency and tool’s life. 
In order to increase the performance and lower the cost of end mills for customers, 
DHF R&D team had considered about designing a kind of carbide drill with widely uses from HRc 18 to HRc 52. 
Cutter with wide uses is quite different than “purpose-only” end mills, its design has to combined the feature and hardness of working materials. 
To be cautious, R&D team developed several designs and had strict drilling tests on common materials.
 
Introduction of DHF drills carbide drills:


  ＜flg.1＞ Drills with internal coolant hole
 
1、 What’s the difference between drills with internal coolant hole and without it ?
a. Drill with internal coolant hole doesn’t need to discharge chip. Have good cooling performance, working efficiency, and fine chip-removal ability.＜see figure 1＞。

2、 Have 3 kinds of international description: 3D, 5D, 8D:
D represents diameter of cutters, 3D means 3 times of diameter for safety drilling depth, following comes the explanation:
Safety drilling depth: ＜3D＞=3*6mm=18mm

The Effective length is 28mm (surplus flute length, saves the room for chip removal). If excessing the safety depth, must consider the risk of broken cutter due to bad chip removal of drill.
Demo of DHF drill:

1、Item number: DAK060＜see figure 2＞ 
Working material:＜S45C // 1.1206＞ 
Cutting parameter: Vc reaches 125 m/min，Feed=1100~1400mm/min


＜flg.2＞

2、Item number: DAK060＜see figure 2＞ 
Working material: Aluminum Alloy ＜AL5052＞ 
Cutting parameter: Vc reaches 150-180 m/min，Feed=4000~4500 mm/min


＜flg.3＞



Written by DHF Technology Center