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Why is the bit black, white, gold, what is the difference, which quality to buy(CNC prototyping)

Aug 13,21

Why is the bit black, white, gold, what is the difference, which quality to buy(CNC prototyping)

Drilling is very extensive in manufacturing a processing way, often believe in drilling line of friends won't be a stranger, and understanding of bit purchasing drill, can have different material different colors of drill bit, so different color bit exactly how to don't help, is there a link between color and the quality of the drill bit, which color to buy bit better?

Is there a relationship between bit color and quality
First: can not distinguish the quality of bit on simple from color, color with no direct relation to quality, different color bit mainly processing craft, can, of course, making judgments about from the color, only the poor quality of bit will put their own color for processing high quality bit appearance style.
What's the difference between different colored drills

High quality fully grinded HSS drill bits often appear in white, of course, rolled drill bits can also be refined by grinding the outer circle to achieve white, the reason why it is 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 burns. Black is a nitride bit, a chemical process used to improve tool durability by insulating the finished tool in a mixture of ammonia and water vapor at 540-560 ° C. Most of the black bits on the market are only made black (to cover the burn or black skin on the cutter surface), but the actual performance is not improved.
There are three processes for producing bits. Black is rolled, the worst. White for clear edge and grinding. Because, unlike rolling, there is no high temperature oxidation, the grain structure of the steel is not destroyed and is used to drill slightly harder parts. A tan bit, known in the industry as a cobalt drill, is the unspoken rule of the industry. Cobalt containing diamond is originally white, grinding production, later atomization, made into a tan (commonly known as amber), is currently in circulation the best. M35 (Co 5%) there is also a gold, this bit is called titanium plated drill, divided into decorative plating and industrial plating. Decorative plating has no effect, is beautiful, golden. The industrial plating is excellent, with hardness up to HRC78, which is higher than the hardness of cobalt containing drills (HRC54°).
Since color is not a standard to judge the quality of a bit, how on earth do you buy a bit?
As a rule of thumb, the white bits are generally full-ground HSS bits and should be of the best quality. The gold ones are titanium nitride plated, which is usually either the best or a very bad fool. And the quality of black is uneven, some are very poor carbon tool steel, easy to annealing, at the same time easy to rust, so black treatment.
Generally buy drill can see the trademark on the bit handle and the diameter tolerance logo, the logo is clear, laser or electrocorrosion quality is not too bad. If it is a molded word, if the edge of the word is bulging, the quality of the bit is poor, because the bulge of the word profile will lead to the clamping accuracy of the bit is not up to the requirements, and the word edge is clear, good and the cylindrical interface of the bit handle is good quality. In addition to look at the cutting edge of the bit tip, the edge of the full grinding bit is very good, the spiral surface meets the requirements, and the quality of the poor in the back corner surface is very poor