Use of bit and description

Bit is used to drill out the solid material through holes or blind holes, and is able to have a hole reaming tools. Twist drills are commonly used, flat drill, center drill, deep hole drilling and core drill. Reamers and countersinks although not drill holes in solid material, but will also be used to drill them into a class.
Twist drill
Twist drill through its axis fixed relative to the rotary cutting tool for drilling a workpiece hole. Its flute and shape into a spiral twist named. Spiral chute slot 2 slots 3 slots or more, but the  diamond bandsaw blades most common slot 2. Twist can be held in manual, electric handheld drill tools or drilling machines, milling machines, lathes and even use on machining centers. Drill material is generally high-speed tool steel or carbide.
Twist 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 portion. Working part has two spiral grooves, the 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.
Cutting portion of the 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 is typically the  hole saw blades 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 has three to four teeth, better rigidity than the twist, to expand the existing hole and improve the machining accuracy and finish.
Countersinks have more teeth to the end of the 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 for drilling holes shaft center of the workpiece, it is essentially a small twist by the helix angle and  tct circular saw blade countersink drill composite, so called composite center drill.
Center drill
Prefabricated hole machining for precise positioning guide twist drill hole processing, reduce errors.
Center drill is used in other parts of the end face of the shaft center hole machining.
The product is easy-cutting, chip is good. There are two kinds of center drill type: A type: without protecting chamfers center drill, B: with protecting chamfers center drill, machining diameter d = 1 ~ 10mm center hole, usually without protective dimensional center drill ( A type); step long high precision of the workpiece, the centering cone 60 degrees in order to avoid being damaged, the general center of the cone with a protective cone