Why are there black, white and gold drill bits, and what is the difference

Drilling is a very wide range of processing in the manufacturing industry, I believe that often in the drilling line of partners for the understanding of the drill bit will not be very strange, the purchase of the drill bit, the drill bit will have different materials and different colors, then the different colors of the drill bit in the end what to help to distinguish, the color and the quality of the drill bit has no relationship, buy which color of the drill bit is better?

Is there any relationship between drill color and quality?

First of all: it is impossible to distinguish the quality of drill bits simply from the color, there is no direct and inevitable relationship between color and quality, different color drill bits are mainly processed differently, of course, you can make an approximate judgment from the color, but at present the poor quality drill bits will also process their own color to achieve the appearance style of high quality drill bits.

What is the difference between different colors of drill bits

High quality fully ground HSS drill bits often appear in white color, of course, rolled drill bits can also be white by fine grinding the outer circle, the reason why it is said to be high quality, in addition to the material itself, the quality control of the grinding process is also quite strict, the tool surface will not appear burned. Black is a nitride treated drill bit, a chemical method to improve the durability of the tool by placing the finished tool in a mixture of ammonia and water vapor, after 540-560C° insulation treatment. Most of the black drill bits currently on the market are only made to be black in color (in order to hide the burn or black skin on the tool surface), but the actual use has not been effectively improved.

There are 3 processes to produce drill bits, black is rolled, the worst. The white is edge clearing and grinding. Because, unlike rolling, it does not produce high temperature oxidation, so the steel grain organization is not destroyed and is used to drill slightly harder workpieces. The yellowish-brown drill bit is called cobalt drill in the industry, which is the unspoken rule of the drill industry. M35 (Co 5%) is another kind of gold, this kind of drill is called titanium plated drill, which is divided into decorative plating and industrial plating. Decorative plating is not useful at all, it's just nice and golden. Industrial plating is very good, the hardness can reach HRC78, higher than the hardness of cobalt-containing drill (HRC54 °).

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

Judging from experience, generally speaking the white ones are usually fully ground HSS drill bits and should be of the best quality. The gold ones are titanium nitride plated, which are generally either the best or very poorly muddled. The black ones also vary in quality, some are made of very poor carbon tool steel and are easy to anneal, while easy to rust so they should be blackened.