Type of drill

Is the most widely-hole machining tool. Diameter range of usually 0.25 to 80 mm. It is mainly the working portion and the shank by the drill portion. Working part has two spiral grooves, the  dry polishing pads shape of cannabis, hence the name. In order to reduce drilling holes intramural guide portion and the friction, twist drill tip to the shank from the direction of decreasing diameter inverted cone. Helix angle of twist drill cutting edge came principally affected the size of angles, edge flap strength and chip performance, typically 25 ° ~ 32 °. Available spiral groove milling, grinding, hot-rolled or hot extrusion processing methods, the drill bit tip is formed by grinding after the cutting portion. Standard twist angle of the cutting portion 118, a horizontal blade angle is 40 ° ~ 60 °, after the angle of 8 ° ~ 20 °. For structural reasons, a large rake angle in the outer edge, and gradually decreases toward the center, horizontal blade at a negative rake angle (up to about -55 °), when drilling from the compression. In order to improve the cutting performance of twist drills, according to the nature of the material to be machined part will repair ground cutting various shapes (such as drilling group). Form of shank twist drill straight shank and taper shank are two processing caught in the drill chuck the former, the latter inserted in the machine spindle or tailstock taper hole. Generally high-speed steel twist drill. Inserts welded carbide blade or twist the crown for machining cast iron, hardened steel and non-metallic materials, solid carbide twist drills for machining small parts and printed circuit boards and other instrumentation.
Flat drill
Cutting portion of the  industrial saw blades drill flat spade, simple structure, low cost, easily cutting fluid into the hole, but the cutting and chip performance is poor. Flat structure integral drill and assembly two. Integral mainly for drilling diameter of 0.03 to 0.5 mm pores. Fabricated flat diamond blade can be changed, can be cooled, mainly for the drilling diameter 25 to 500 mm large hole.
Deep hole drilling
Deep hole drilling is typically the machining hole depth is greater than the diameter of the bore of the tool 6. Commonly used gun drilling, BTA deep hole drilling, jet drill, DF deep hole drilling. Nesting also used in drilling deep holes.
Reamer
Reamer has three to four teeth, better rigidity than the twist, to expand the existing hole and improve the machining accuracy and finish.
Countersink
Countersinks have more teeth to the end of the stone polishing pads  hole forming method processed into the desired shape, for processing a variety of countersunk head screws countersunk holes, holes or flattened outer end face.
Center drill
Center drill for drilling holes shaft center of the workpiece, it is essentially a small twist by the helix angle and countersink drill