Drill tools—What are the difference of drills with different colors?

High-quality, fully ground high-speed steel drill bits often appear in white. Of course, rolled drill bits can also be white by fine grinding of the outer circle. The reason why it is high quality is that in addition to the material itself, the quality control during the grinding process is also quite strict, there will be no burns on the surface of the tool.Black is a drill bit that has been nitrided.


It is a chemical method that puts the finished tool in a mixture of ammonia and water vapor and heats it at 540~560°C to improve the durability of the tool.At present, most of the black drill bits on the market are only black in color (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 rolling, the worst. The white ones are trimmed and polished. Because it does not produce high-temperature oxidation, unlike rolling, the grain structure of the steel is not damaged. It is used to drill workpieces with slightly higher hardness. The yellow-brown drill is called the cobalt-containing drill in the industry.This is the unspoken rule of this drill industry. Cobalt-containing diamonds are originally white and are produced by grinding. When they are atomized in the later period, they become yellowish brown (generally called amber), which is currently the best in circulation. M35 (Co 5%) also has a golden color.

This type of drill is called a titanium-plated drill, which is divided into decorative plating and industrial plating. The 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).


Post time: Dec-17-2021