In the field of modern metal cutting tools, people concentrated on basic topics indexable carbide-coated tools, CBN tools, ceramic cutting tools and so on. However, one can not ignore the reality is: China high-speed steel twist drill production, a sharp increase in sales volume, China machining industry is the largest amount of high-speed steel twist, twist around the world there is a huge civilian market (for the hand drill, Bench etc.). So has been used for hundreds of years, has recently been neglected high-speed steel twist drill should still belong to the category of modern metal cutting tools.

"Multi tip of the bit," originated in the fifties invention Ni Zhifu drill, later renamed drilling group. The principle is the standard twist drill tip were grinding to form a "three-point seven blade" type drill, to improve its drilling performance and extend the life of the drill. After years of research and development, the group has been more diamond drill type systems development and improvement, setting 1967 as the representative of the drilling group, compared to the standard twist drill, has three significant advantages:

1, drilling axial resistance decreases about 40%, so high drilling efficiency, long life drill cutting, compared with standard twist drill, and can improve the cutting life of 3 to 5 times;

2, excellent centering, sub chips, chip performance, so finish drilling accuracy are better than standard twist drill;

3, a variety of diamond type, roughly divided into a dozen categories, broken dozens of sheets were used to drill, drilling steel, cast iron, aluminum, stainless steel, brass, copper ...... numerous, its use performance is far superior to standard twist drill;

However, "drilling group," the third advantage also contains its shortcomings, namely diamond drill type narrow range for each type of scope, or the universal good. Plus tip drill sharpening group set up in skilled workers on the basis of the skill, hand sharpening numerous, complex angle drilling group. Above have seriously hampered the large-scale promotion and application of group drills.

Another major contribution drilling group is its principle is high-speed steel twist innovation provides a theoretical basis and practical experience. Based on the principle of group drill, conducted research standard multi-blade sharp twist drill type. Our ideal standard drill type should have the following characteristics:

1, to further reduce cutting resistance than the group drilling;

2, a variety of materials commonly used for drilling, such as: carbon steel, stainless steel, cast iron, aluminum ......;

3, both for drilling sheet metal, but also for deep hole drilling;

4, particularly suitable for use in hand drills;

5, suitable for large-scale industrial production.