Which is better, a white drill or a black drill?
Most of the black drills in the market are only black (to cover the surface of the blade or black), but the actual use has not been effectively improved. The full grinding twist drill manufacturers, industry and trade, production, engineering, far east Lei this several quality have great advantages in the domestic bit. With imports, or quite a lot of difference, after all, a big difference in price. In addition, the quality of Taiwan's SUS Su is also good.
Another is between white and amber. Or above amber. This type of drill is called titanium drill, divided into decorative plating and plating industry. Decorative plating don't have any effect, is good-looking, golden. Very good industrial plating, hardness can reach HRC65 degrees, higher than cobalt drilling hardness (HRC54 degrees).
Black becomes nitrided and can be used to drill aluminum products, i.e., soft materials, after improved propertiesThere are 3 processes for producing drills, black for rolling and worst for rolling. White for clean edges and ground. Because, unlike rolling, no high temperature oxidation, the steel grain structure is not damaged, used to drill a slightly higher hardness workpiece.The yellowish brown drill, called cobalt cobalt drill in the industry, is the unspoken rule of the drill. Cobalt containing drills were originally white, produced by grinding, and when they were atomized at the later stage, they were made of yellow brown (commonly called amber), which is the best in circulation. M35 (Co 5%)
Black for rolling, worst. White for the edge and grinding, grinding than the edge of the better, grinding polished better, the price is higher
Color is not directly related to quality. High quality, fully ground, high-speed steel drills often appear in white. Of course, the rolling bit can also be made white by grinding the outer circle. The reason is that high quality, in addition to the material itself, in the process of grinding quality control is quite strict, the tool surface will not appear burns. Black is an oxygen treated drill. It is a chemical method to increase the durability of the tool after placing the cutting tool in a mixture of ammonia and water vapor and after 540-560C degrees of thermal insulation.
