Why Are The Drill Bits Black, White, And Gold What’s The Difference And Which One Is Better?

Drilling with a drill bit is a very extensive processing method in the manufacturing industry. When purchasing drill bits, it has different materials and colors, so what is the difference between drill bits of different colors? Does the color have anything to do with the quality of the drill bits? Which color drill bit is better to buy?

Does the color of the drill bit have anything to do with the quality?

First of all: it is impossible to distinguish the quality of the drill from the color alone. There is no direct and inevitable relationship between color and quality. Different colors of drills mainly have different processing techniques. Of course, a rough judgment can be made from the color, but the current poor quality bit will also color itself to achieve the appearance of a high quality bit.

What is the difference between different colored drill bits?

High-quality fully ground HSS drills often appear in white, of course, rolled drills can also achieve white by fine grinding the outer circle. The reason why it is said to be high quality is that in addition to the material itself, the quality control during the grinding process is also quite strict, and there will be no burns on the surface of the tool. Black is a nitrided drill bit. It is a chemical method to improve the durability of the tool after placing the finished tool in a mixture of ammonia and water vapor, and after thermal insulation treatment at 540-560C°. At present, most of the black drill bits on the market are only black in color (in order to cover up the burn or black skin on the surface of the tool), but the actual use effect has not been effectively improved.

There are 3 processes for producing drill bits, black is rolling, the worst. The white ones are edged and grinding. Unlike rolling, high temperature oxidation does not occur, so the grain structure of steel is not damaged, and it is used to drill workpieces with slightly higher hardness. Yellow-brown drill bits, known in the industry as cobalt-bearing drills. Cobalt-containing diamonds are originally white, and are produced by grinding. When atomized later, they are made into yellowish brown (generally called amber), which is currently the best in circulation. M35 (Co 5%) also has a golden color. This drill is called titanium-plated drill, which is divided into decorative plating and industrial plating. Decorative plating has no effect at all, it is beautiful and golden. Industrial plating is very good, the hardness can reach HRC78, which is higher than the hardness of cobalt-containing diamonds (HRC54°).

Since color is not a criterion for judging the quality of a drill, how to select a drill?

Judging from experience, the white ones are generally all ground high-speed steel bits, and the quality should be the best. The gold ones are titanium nitride plated and are generally either the best or the worst. The quality of black is also uneven, and some are made of poor carbon tool steel, which is easy to anneal and easy to rust, so it needs to be blackened.

Generally, when buying a drill, you can see the trademark on the drill shank and the logo of the diameter tolerance. The logo of laser or electro-corrosion is clear. Generally, the quality of this kind of drill is not too bad. If it is a molded word, and the edge of the word is bulged, the quality of the drill is poor, because the bulging outline of the word will cause the clamping accuracy of the drill to fail to meet the requirements. In addition, it depends on the cutting edge of the drill tip. The edge of the fully ground drill is well opened, and the helical surface meets the requirements.