CNC drilling machine drill bit selection methods

1, to understand the types and characteristics of the drill:
PCB drilling with a drill with straight shank twist drill, twist drill set and fixed shank shank Spade (undercut) drill bit. Straight shank twist drill mostly for single head machines, PCB drilling relatively simple or single panel, now in a large circuit board manufacturing plant has been rarely seen in its drilling depth of up to 10 times the diameter of the drill. Laminated on the substrate is not high, the use of drill bit holder to avoid bias. At present, most manufacturers use CNC drilling machine, CNC drilling using a carbide shank drill set, which is characterized to  metal drill bits achieve automatic replacement drill. High positioning accuracy without the use of drill sets. Large helix angle, chip speed, suitable for high-speed cutting. In the range of the flute length, diameter of the drill is an inverted cone, when drilling with the hole wall friction is small, high quality drilling. Common drill shank diameter of 3.00mm and 3.175mm.
2, pay attention to the drill material:
PCB drilling with carbide drill bit is generally used as the epoxy glass cloth complex copper plate on the tool wear particularly fast. The so-called carbide is tungsten carbide powder as matrix, cobalt powder as a binder by pressurized sintering. Generally contain 94% tungsten carbide, 6% cobalt. Because of its high hardness, very wearable, a certain strength, suitable for high-speed cutting. But the toughness is poor, very brittle, in order to improve the performance of cemented carbide, and some use carbide substrate in a chemical vapor deposition on a 5-7 micron layer of special hard titanium carbide (TIC) or titanium nitride (TIN), to has a higher hardness. Some use ion implantation technology, titanium, nitrogen, and carbon injection the matrix certain depth, not only improves the hardness and strength and regrinding the drill can move into when they injected ingredients. There is a physical method to generate the bit at the top of a layer of diamond film, which greatly improves the hardness and wear resistance of the drill. Carbide hardness and strength, not only the ratio of cobalt and tungsten carbide, but also with the powder particles about. Carbide drill ultra fine particles, and its average grain size of tungsten carbide with 1 micron or less. This bit is not only high hardness and compressive strength and flexural strength are improved. To save costs Many drill shank welded structure, the original as a whole are carbide drill, drill shank back now made of stainless, but significantly reduced the cost of the  tile cutting blades material due to different concentricity less than its dynamic rigid whole alloy drill, particularly in the small diameter side.
3, choose a good brand to ensure product quality:
Currently, a lot of drill manufacturers, sub-national and imported. Domestic products and foreign products compared to a slight gap between the price of course, but also slightly more expensive imports, the market also has production from Taiwan and Hong Kong, as well as part of the production in Taiwan to fight the U.S. and European brands of drill bits, compared with Europe and the United States Japanese imports of drill and stone polishing pads  stable quality, although the price is a little expensive but is good value for money for craft workers, the actual use of the process due to quality problems that occur drill probability is very small, such as the production of products require a higher recommended the use of imported drill, Europe and Japan drill hardness softer, Europe drill rather break than bend in use but not prone to bias Kong higher probability of breaking some flexibility over the Japanese finally broken drill holes prone to bias, but especially the small side holes drill bit. In the actual use of the process can be chosen according to demand.