Twist drills are widely used in the field of mechanical processing. They are used primarily for drilling various materials. Although their design is simple, they contain profound engineering principles and precision manufacturing technology. The following content will explore the basic structure and working principle of twist drills in-depth and explain why this tool is efficient and durable.

1. Basic structure of twist drills

The structure of twist drills can be roughly divided into the following parts:

1. Drill tip

As the core component of twist drills, the drill tip has the primary function of directly contacting the material and performing cutting tasks. Its sharp angle design is usually 118 degrees or 135 degrees. This geometric structure enables the drill to quickly penetrate the material layer when it starts working, effectively reducing the resistance during the drilling process, and thereby improving the overall cutting efficiency.

2. Spiral grooves

The spiral grooves are the core part of the twist drill. These two spiral grooves extend from the drill tip to the drill shank. The primary function of the spiral groove is to take the chips generated during the cutting process out of the hole and， at the same time help the coolant flow into the cutting area, reduce the temperature, and extend the service life of the drill.

3. Main cutting edge

The primary cutting edge of the drill bit is located at the intersection of its tip and the spiral groove and is responsible for directly processing the material. The sharpness and angle design of this part are the key factors that determine the efficiency and accuracy of the drilling operation.

4. Flank

The flank is located behind the primary cutting edge. Its function is to reduce friction with the material during the drilling process, prevent the drill bit from overheating, and maintain the stability of the drilling process.

5. Drill shank

The drill shank, as a pivotal component of the twist drill bit, is exquisitely designed to ensure a stable connection on various drilling machines or electric drills. This design is not only simple and efficient but also greatly improves safety during use through the choice of two common shapes, cylindrical and hexagonal, effectively avoiding the problem of the drill bit slipping, so that every drill can be accurate and correct.

2. Working principle of twist drill bit

The working principle of twist drill bit can be summarized into two main processes: cutting and chip removal.

1. Cutting process

When a twist drill starts drilling, its tip first contacts the workpiece. Because the tip has a sharp angle design, the drill can effectively cut into the material during rotation and start to form the initial hole. As the drill continues to move forward, its primary cutting edge will cut material along the spiral groove path, gradually deepening the depth of the hole until a complete hole is formed.

2. Chip removal process

When cutting something, those small pieces will be taken out by the spiral groove. This design is excellent because it not only takes away those chips, but also allows coolant to come in, which can reduce the temperature, protect our drill bit, and make the cutting quality better. If those chips cannot be removed, the temperature will rise, and the drill bit may break or break due to excessive heat.

3. Cooling and lubrication

In metal-cutting operations, significant heat is generated due to friction. If cooling measures are not effectively implemented, not only the drill bit may be damaged, but the workpiece will also be affected. When drilling hard materials, it is necessary to use coolant to cool down effectively. The coolant is delivered directly to the processing part through the tool's spiral groove. Its function is to absorb the generated heat and lubricate the cutting edge. This process not only helps to extend the service life of the drill but also improves the overall processing accuracy and quality.

3. Types and applications of twist drill bits

Depending on different application requirements, the design of twist drill bits can be different. For example:

1. High-speed steel twist drill bits

This drill bit is widely used for drilling holes in general metals, wood, and plastics. High-speed steel has good wear resistance and toughness and is suitable for high-temperature and high-speed drilling.

2. Cobalt alloy twist drill bits

Cobalt-containing drill bits are tougher than high-speed steel drill bits and are suitable for higher-strength materials such as stainless steel and titanium alloys. They can still maintain good cutting performance at high temperatures.

3. Carbide twist drill bits

Carbide drill bits are often used to process difficult-to-cut materials such as ceramics and composites. Due to their extremely high hardness, they are suitable for working under extreme conditions, but they are relatively brittle and easy to break.

4. Care and maintenance of twist drills

Although twist drills are durable, proper care and maintenance are essential to extend their life. After use, the residual substances and oil stains on the drill should be thoroughly removed to ensure that it is dry to prevent rust. The sharpness of the drill should be evaluated regularly, and it should be sharpened in time when wear is found. In addition, the reasonable selection of working speed and feed rate is also critical to extending the service life of the drill.

Conclusion

Twist drills, a necessary tool widely used in daily processing, although their design and operation mechanism seem simple and intuitive on the surface, actually contain profound scientific principles and engineering technology. A deep understanding of this underlying knowledge can not only improve our proficiency in operating tools but also significantly enhance work efficiency, thereby achieving better processing results. Therefore, in future application practices, keeping in mind and applying these basic theories will greatly promote the efficient use of twist drills.