Do you know what types of threads are commonly found on the drawing of machining industry?

According to the different uses of the thread, it can be divided into:

1. International Metric Thread System:
The thread used by China National Standard CNS. The top of the tooth is flat, which is easy to turn, and the bottom of the tooth is arc-shaped to increase the strength of the thread. The thread angle is 60 degrees, and the size is expressed in M. Metric threads can be divided into two types: coarse and fine. Notation such as M8x1.25. (M: code, 8: nominal diameter, 1.25: thread pitch).

2. American Standard Thread:
The top and root of the thread are flat, and the strength is better. The thread angle is also 60 degrees, and the specification is expressed in teeth per inch. This kind of thread can be divided into three grades: coarse thread (NC); fine thread (NF); extra fine thread (NEF). Notation such as 1/2-10NC. (1/2: outer diameter; 10: teeth per inch; NC code).

3. Unified Thread:
It is jointly formulated by the United States, the United Kingdom and Canada, and is currently the commonly used inch thread.
The thread angle is also 60 degrees, and the specification is expressed in teeth per inch. This kind of thread can be divided into coarse thread (UNC); fine thread (UNF); extra fine thread (UNEF). Notation such as 1/2-10UNC. (1/2: outer diameter; 10: teeth per inch; UNC code)

4. Sharp V Thread:
Both the top and the root are pointed, the strength is weak, and it is not often used. The thread angle is 60 degrees.

5. Whitworth Thread:
British National Standard thread. The thread angle is 55 degrees and the sign is "W".
Suitable for rolling method manufacturing. Notation such as W1/2-10. (1/2: outer diameter; 10: number of teeth per inch; W code).

6. Knuckle Thread:
Standard thread set by German DIN. It is suitable for the connection of light bulbs and rubber tubes. The symbol is "Rd".

7. Pipe Thread:
Threads for preventing leakage are often used for connecting gas or liquid pipe fittings. The thread angle is 55 degrees, which can be divided into straight pipe thread code "P.S., N.P.S." and inclined pipe thread code "N.P.T.", the taper is 1:16, that is, 3/4 inch per foot.

8. Square Thread:
The transmission efficiency is high, second only to the ball thread, and the nut cannot be adjusted after wear, which is its disadvantage. Generally used for the screw of the vice and the thread of the crane.

9. Trapezoidal Thread:
Also known as Aikem thread. The transmission efficiency is slightly smaller than that of the square thread, but it can be adjusted with a nut after wear. The thread angle of the metric system is 30 degrees, and the thread angle of the inch system is 29 degrees. Generally used for lead screws of lathes. The symbol is "Tr".

10. Buttress Thread:
Also known as oblique thread, it is only suitable for unidirectional transmission. Such as screw jacks, presses, etc. The symbol is "Bu".

11. Ball thread:
As the thread with the best transmission efficiency, it is difficult to manufacture and the cost is extremely high. It is used in precision machinery. Such as the lead screw of the CNC machine tool.

Representation of inch bolts:
LH 2N 5/8 × 3 - 13 UNC-2A
(1) LH is the left thread (RH is the right thread, which can be omitted).
(2) 2N double thread.
(3)5/8 inch thread, 5/8” OD.
(4)3 Bolt length 3”.
(5) 13 threads have 13 threads per inch.
(6) UNC unified standard thread coarse thread.
(7) Class 2 fit, external thread (3: Tight fit; 2: Medium fit; 1: Loose fit) A: External thread (can be omitted)

B: Internal thread
Imperial thread:
The size of the inch thread is usually expressed by the number of threads per inch of length on the thread, referred to as "threads per inch", which is exactly equal to the reciprocal of the thread pitch. For example, with 8 threads per inch, the pitch is 1/8 inch.

Dongguan Yejia Precision Machinery Co., Ltd. has CNC large-scale gantry machining centers, CNC machining centers, precision CNC milling machines, lathes, large surface grinders, precision shape correction machines, CMM three-coordinate measuring machines, electronic altimeter and other advanced manufacturing and testing equipment more than 90 sets.The maximum size that can be processed is 5000×3200×1000mm, and the machining accuracy can reach 0.002.
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