1, twist drill

 

Twist drills are the most widely used hole machining tools. It mainly consists of the working part of the drill bit and the shank. In order to reduce the friction between the guiding part and the hole wall during drilling, the helix angle of the twist drill mainly affects the size of the rake angle on the cutting edge. The blade strength and chip removal performance are usually 25 ° ~ 32 °.

 

2, flat drill

 

The cutting part of the flat drill has a spade shape, the structure is simple and the manufacturing cost is low, and the cutting fluid is easily introduced into the hole but the cutting and chip discharging performance is poor. The integral type is mainly used for drilling micropores with a diameter of 0.03 to 0.5 mm. The assembled flat drill blades can be replaced by internal cooling, and are mainly used for drilling large holes with a diameter of 25 to 500 mm.

 

3, deep hole drilling

 

Deep hole drilling generally refers to a tool that machines holes with a hole depth to hole ratio greater than 6. Commonly used are gun drills, BTA deep hole drills, jet drills, DF deep hole drills, etc. Nesting drills are also commonly used for deep hole machining.

 

4, reaming drill

 

Reaming drills have 3 to 4 teeth and are more rigid than twist drills to expand existing holes and improve machining accuracy and finish.

 

5, boring

 

The boring has more teeth to form the hole end into a desired shape by forming, for processing the countersunk hole of various countersunk screws, or to flatten the outer end surface of the hole.

 

6, center drill

 

The center drill is used for drilling the center hole of the shaft workpiece. It is essentially a composite of a twist drill and a boring drill with a small helix angle, so it is also called a composite center drill.

 

When using a twist drill, it is necessary to pay attention to improve the cutting performance of the twist drill. Generally, the twist drill is made of high-speed steel, and the twist drill of the cemented carbide insert or the crown is suitable for processing cast iron hardened steel and non-metal materials. The alloy small twist drill is used to process instrument parts and printed circuit boards.