Is there any relationship between drill color and quality

First of all: it is impossible to distinguish the quality of the drill bit simply from the color. There is no direct and inevitable relationship between the color and the quality. The different color drill bits are mainly different in processing technology. Of course, you can make a rough judgment from the color, but the current poor quality drill bits Will process their own colors to achieve the appearance of high-quality drills.

What is the difference between different color drills

High-quality full-grinded high-speed steel drill bits often appear in white. Of course, rolled drill bits can also be whitened by fine grinding of the outer circle. The reason for high quality is that in addition to the material itself, the quality control during the grinding process is also Quite strict, no burns on the tool surface. Black is a nitrided drill bit. It is a chemical method to improve the durability of the tool by placing the finished tool in a mixture of ammonia and water vapor and subjecting it to a temperature of 540-560C °.

At present, most of the black drills on the market are only black (in order to cover the burn or black skin on the surface of the tool), but the actual use effect has not been effectively improved.

There are three processes for producing drill bits. Black is rolled, the worst. The white ones are trimmed and polished. Unlike rolling, which does not produce high temperature oxidation, the grain structure of the steel is not damaged, and it is used to drill slightly higher hardness workpieces. The tan drill bit is called cobalt-containing drill in the industry. This is the hidden rule of this drill industry.

Cobalt-containing diamonds were originally white and produced by grinding. When they were later atomized, they were made into yellow-brown (commonly called amber), which is the best in circulation at present. M35 (Co 5%) is also gold-colored. This type of drill is called titanium-plated drill, which is divided into decorative plating and industrial plating. The decoration 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 that of cobalt-containing diamonds (HRC54 °).

Since color is not a criterion for judging the quality of a drill, how do you buy a drill?

Judging from experience, in general, white is generally made of high-speed steel drill bit, the quality should be the best. The golden ones are titanium nitride plated and are generally either the best or poorly fooled. The quality of black is also uneven. 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 you buy a drill, you can see the trademark on the drill shank and the diameter tolerance mark. The logo is clear, and the quality of laser or electric corrosion is not too bad. If it is a embossed character, if the edge of the character is bulging, the quality of the drill is poor, because the contour of the bulged character will cause the precision of the drill to be less than required, and the edge of the character is clear, very good and the cylindrical surface of the drill shank Junctions are of good quality. In addition, it depends on the cutting edge of the drill tip. The edge of the full-grind drill is very good, the spiral surface meets the requirements, and the poor quality is poor at the rear corner surface.