How to recognize the quality of twist drills?
The first is the material: the market has 424160843416342934, 6542, M35, M42 in turn.The second is the process: straight drill are rolling, milling, grinding, milling and drilling are rolling. Ground is the best. The rolling efficiency is much higher than that of milling, so most of the bit is rolled. High quality high speed steel is generally used in grinding.
In addition, there are also listening to the sound, knocking glass, using a grinding machine to play sparks, see color, etc.. These need experience, like picking watermelon, each has its own coup, different varieties, methods are also quite different. Usually, the more crisp we are, the more glass we have, the slightest spark, and the more red the spark, the better the bit material.
Then the heat treatment: you can simply judge the surface texture of the drill with the naked eye, which shows the good heat treatment, and the worse the contrast. Especially the black drill, some heat treatment is not in place, and black treatment is used to cover the burn of the drill. Production of the giant black diamond quality is stable, the small factory to keep in mind the black diamond.
The drill industry is a mixed bag, but only for experienced people. If it is just a bit industry contact, may refer to the following recommendations: currently recognized brand: imported good bits such as YG, SUS, and so on, the domestic first-line work, the amount of Kazakhstan, second tier, such as a river of Guanzhong, like other workers, there are some small scale manufacturers such as: Germany Tong, Lei, Del, st..
General twist drill, a variety of points. It seems to be divided into two major groups. One is pumping out the twist, one is full mill. Now there is a knife bar slotted on top with knife particles. Called fast drilling, this is the high-speed processing of relatively large holes, pumping out the twist drill hardness is not so good, slightly better edge. As long as the mother material is good, the grinding accuracy is high. Now many are using this, relatively speaking, the price is much more expensive.
