What is the different of unf thread and unc thread?

What is the different of unf thread and unc thread?

1. UNF, UNC; is the identification of inch uniform thread

2. UNF is the abbreviation of "du" for the English Unified National Fine, which is the series of zhi unified spiral dao pattern fine teeth. UNC is the abbreviation of Unified National Coarse in English, which is a series of unified thread coarse teeth.

3. Coarse teeth seem to have large teeth, with fewer teeth per unit length, and fine teeth, with smaller teeth, and more teeth per unit length.

4. The difference between coarse thread and fine thread is the difference in pitch. Coarse thread is large thread pitch, and fine thread pitch is smaller. According to the principle of thread self-locking, it can be seen that the spiral angle of fine thread is smaller and more It is conducive to the self-locking of the thread, so the fine thread is generally used in places that need to prevent loosening.

5. The pitch of the fine thread is smaller. Compared with the coarse thread, the fine thread has more threads in the same thread length, which can reduce the fluid leakage, so it is used in the sealing occasion. Fine thread can also play a fine-tuning role because of the small pitch.

6. Marking method: thread diameter-number of teeth per inch series code-precision grade example: coarse thread series 3/8-16 UNC-2A

Fine tooth series 3/8-24 UNF-2A

Extra fine teeth series 3/8-32 UNFF-2A

Fixed pitch series 3/8-20 UN-2A

7. The first digit 3/8 represents the outer diameter of the thread, the unit is inches, and the conversion to the metric unit mm must be multiplied by 25.4, that is, 3/8×25.4=9.525mm; the second and third digits are 16, 24, 32, 20 is the number of teeth per inch (the number of teeth on a length of 25.4mm); the text codes UNC, UNF, UNFF, UN after the third digit are the serial codes, and the last two digits 2A are the accuracy grade.