Views: 296 Author: Site Editor Publish Time: 2021-07-01 Origin: Site
How fine can a thread be called a fine thread? The so-called coarse thread can be defined as a standard thread, while the fine thread is relative to the coarse thread. Under the same nominal diameter, the number of threads per inch is different, that is, the thread pitch is different. The coarse thread has a large pitch while a fine thread. The tooth pitch is small. In other words, for the 1/2-13 and 1/2-20 specifications, the former is coarse and the latter is fine. Therefore, they are expressed as 1/2-13UNC and 1/2-20UNF. How do we choose threads for high pressure quick release couplings and flat face quick release couplings?
The so-called coarse thread refers to the standard thread. Unless otherwise specified, the stainless-steel screws and other fasteners we generally buy are coarse thread. Coarse threads are characterized by high strength, good interchangeability, and standards for comparison. Generally speaking, coarse threads should be the best choice for metric hydraulic fittings and reusable hydraulic fittings.
Compared with fine thread, because the pitch of the coarse thread is larger, the thread lift angle is also larger, which leads to poor self-locking. Therefore, it is necessary to install anti-loosening washers and self-locking devices in the vibration environment. Its advantage is that it is easy to disassemble and assemble, complete with standard parts, and easy to interchange. Coarse threads do not need to be marked with pitch, such as M8, M12-6H, M16-7H, which are mainly used for connecting threads. Both our brass garden hose fittings and brass electrical fittings use coarse thread.
Fine thread and coarse thread are just the opposite, which is specified to supplement the special use requirements that coarse thread cannot meet. There are also pitch series for fine-tooth threads. The pitch of fine-tooth threads is smaller, so it is more self-locking and anti-loosening. Besides, the fine thread has more teeth, which can reduce the effect of leakage and achieve a sealing effect. On some precision occasions, fine-tooth stainless-steel screws are more convenient for precise control and adjustment. Therefore, hydraulic hose clamps and air compressor hose clamps generally adopt fine thread.
The disadvantages of fine thread are that the tensile value and strength are low, and the thread is easy to damage. It is not recommended to disassemble and assemble multiple times. The matching nuts and other fasteners may be equally accurate, with a slight error in size, which will easily damage the screws and nuts at the same time.
Fine thread is mainly used in hydraulic system metric pipe fittings, mechanical transmission parts, thin-walled parts with insufficient strength, internal parts restricted by space, and shafts with high self-locking requirements. When marking fine thread, the pitch must be marked to show the difference from the coarse thread.
Coarse thread and fine thread screws are used for fastening. Fine thread screws are generally used to lock thin-walled parts and parts with high requirements for vibration resistance. The fine thread has good self-locking performance, so it has strong anti-vibration and anti-loose ability. However, because the thread depth is shallow, the ability to withstand greater tension is worse than that of the coarse thread. When no anti-loosening measures are taken, the anti-loosening effect of fine thread is better than that of coarse thread. It is generally used for thin-walled parts and parts with higher requirements for anti-vibration. When used for adjustment, fine thread has advantages. However, the fine thread is not suitable for the application on materials with too coarse structure and poor strength. When the tightening force is too large, it is easy to slip.
After understanding the fine thread and the coarse thread, I believe you will know better how to choose 71 Series JIC Female One Piece Fitting and 90 Degree SAE Flange One Piece Fitting.
