What do you think the smallest drill bit is?I think the smallest drill bit is the micro drill.
Bit diameter less than 3.175mm, usually referred to as the micro drill ,and it is the smallest driil bit. To make micro drilling in the use of high efficiency, we must consider a series of factors: such as the drill itself, the various elements, processing parameters, Kong Shen, the installation of the perfect and the structure of the workpiece, etc..
To deal with these mutual influences and the process of drilling is very sensitive to the processing, it need to have a scientific spirit of innovation. Guhring (USA), the company's marketing manager, Megal Mark, said: "in many occasions, the use of micro drill you have to edge over the edge of the." Although the tool manufacturer has in micro drilling of material and geometric parameters completed many development, do not need everything from scratch test, but to the drilling of factors in the process are to be well controlled, is not a simple work.
The length diameter ratio of micro drill is significantly increased.
It is well known that the larger the ratio of the length and the diameter of the drill bit. Reducing the length to diameter ratio can reduce the bending force, thereby avoiding the drill bit breaking and the aperture error increasing. A deeper hole requires that the bit have a larger aspect ratio. Usually more than 3 times the diameter of the hole is a deep hole, and the hole depth of the smallest drill bit is generally more than this limit.
Such as the diameter 3.175mm of drill hole depth 31.75mm hole, length to diameter ratio of 10:1; and the diameter of the 0.508mm of drill hole depth 25.4 mm hole, the length to diameter ratio of 50:1. So, as the diameter of the drill bit decreases and the brittleness increases, the deflection becomes the root of many problems. To control the brittleness of the bit, it is to weigh the hardness and toughness of the tool base.
Generally, high-speed steel drill bits allow flexibility and can bear the corresponding bending force, however, high speed steel with the elastic deformation ability and lower hardness, also cause the decrease of the wear resistance, thus limiting the tool life. The cemented carbide has high rigidity and high hardness, so it can make the tool life longer, and the machining precision is high.And it is the feature od micro drill that we call it the smallest drill bit.