Black, White, Gold Drill Bits: Which to Choose?

Black, White, Gold Drill Bits: Which to Choose?

Drilling with a drill bit is one of the most common ways that things are made. When you buy drill bits, they come in different colors and made of different materials. What’s the difference between the different colors? Does the color of the drill bits have anything to do with how well they work? What color drill bit should you get?

Does the color of the drill bit affect how well it works?

First of all, the color alone can’t tell you anything about the quality of the drill. There is no direct link between color and quality that can’t be broken. Drills of different colors are mostly made in different ways. You can make a rough guess about the quality based on the color, but a low-quality bit will also change color to look like a high-quality bit.

What’s the difference between drill bits of different colors?

High-quality, fully ground HSS drills are often white. Rolled drills can also be white if the outer circle is finely ground. It is said to be of high quality because, in addition to the material, the quality control during the grinding process is very strict, and the surface of the tool will not be burned. A nitrided drill bit is black. It is a chemical way to make the tool last longer. The finished tool is put in a mixture of ammonia and water vapor, and then it is heated to between 540 and 560C. At the moment, most black drill bits on the market are just black, which is done to hide burns or black skin on the tool’s surface. However, the actual use effect has not been improved.

There are three ways to make drill bits, with rolling being the worst. The white ones are rough and have sharp edges. High-temperature oxidation doesn’t happen like it does when rolling, so the grain structure of steel isn’t damaged and it can be used to drill pieces that are a little bit harder. Yellow-brown drill bits, which are called cobalt-bearing drills in the business world. Diamonds with cobalt in them start out white and are made by grinding. When they are atomized later, they turn into a yellowish brown color called amber, which is the best right now. The color of M35 (Co 5%) is also golden. This drill is called a titanium-plated drill. There are two types of titanium plating: decorative and industrial. Decorative plating has no effect at all, but it is beautiful and gold. The hardness of industrial plating can reach HRC78, which is higher than the hardness of diamonds with cobalt (HRC54°).

Since the color of a drill has nothing to do with how well it works, how do you choose one?

From what I’ve seen, the white ones are almost always high-speed steel bits that have been ground, so the quality should be the best. The titanium nitride coating on the gold ones makes them either the best or the worst. Black is also of different quality, and some are made of low-quality carbon tool steel that is easy to soften and rust, so they need to be blackened.

When you buy a drill, you can usually see the brand name and the logo for the diameter tolerance on the shank. The symbol for laser or electro corrosion is easy to see. Most of the time, this type of drill isn’t too bad. If it is a molded word and the outline of the word is bulging, the quality of the drill is bad because the clamping accuracy of the drill will not meet the requirements because of the bulging outline of the word. Also, it depends on how sharp the drill tip’s cutting edge is. The fully ground drill has a well-opened edge and a helical surface that meets the requirements.

As a professional CNC machining company, junying makes parts not only out of metal but also out of plastic and wood.


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