The Difference And Application Of Coarse Thread And Fine Thread
As a common mechanical connection method, threads play an indispensable role in manufacturing. Among the types of threads, coarse threads, and fine threads are the two most common types. They have significant differences in pitch, strength, self-locking properties, etc., which also determine their selection and application in different application scenarios.
- The difference between coarse thread and fine thread
Different pitch sizes
Pitch refers to the distance between two adjacent thread crests. Coarse threads have a larger pitch, while fine threads have a smaller pitch. Due to the difference in pitch, the thread depth of coarse threads is correspondingly larger, while the thread depth of fine threads is smaller. This difference is particularly obvious in the appearance of the threads. Coarse threads look rougher, while fine threads appear more delicate.
Strength and force characteristics
Due to their large pitch and deep tooth profile, coarse threads have a relatively large stress area, so they have better performance when withstanding large pulling forces and impact forces. This makes coarse threads more suitable for applications that bear larger loads.
However, due to the small pitch and shallow tooth profile of fine threads. Their force-bearing area is small, and their strength is relatively low. However, in some special cases, such as when high self-locking properties are required, the advantages of fine threads can be reflected.
Self-locking performance
Self-locking refers to the thread’s ability to maintain a connected state without loosening when subjected to external forces. Coarse threads have relatively poor self-locking performance due to their large pitch and large thread lead angle. In a vibration environment, coarse-threaded threaded connections are prone to loosening. So, anti-loosening washers or self-locking devices need to be installed to improve their stability.
The fine thread has better self-locking performance due to its small pitch and small thread rising angle. They are suitable for occasions that require high self-locking properties.
Price and manufacturing difficulty
In terms of price, fine threads are relatively expensive due to their high manufacturing precision requirements and complex processes. The manufacturing process of coarse threads is relatively simple, and the cost is low, so the price is relatively cheap. This makes coarse threads more advantageous in mass production and cost control.
- Application of coarse thread and fine thread
Application of coarse thread
Due to its high strength and good interchangeability, coarse threads are widely used in the mass production of threaded fasteners, such as bolts, screws, nuts, etc. In situations requiring quick assembly or disassembly, coarse threads also show unique advantages. In addition, due to its easy disassembly and assembly and the complete set of standard parts, coarse threads have been widely used in machinery manufacturing, automobile maintenance, and other fields.
However, it should be noted that the self-locking performance of coarse threads is relatively poor. So, additional anti-loosening measures must be taken when used in a vibration environment.
Application of fine thread
Due to its small pitch and good self-locking performance, fine threads are widely used in situations that require high self-locking properties. For example, in metric pipe fittings, mechanical transmission parts, and thin-walled parts with insufficient strength in hydraulic systems, the application of fine threads can effectively prevent fluid leakage and loosening. In addition, fine threads also play an important role in internal parts and fine-tuning mechanisms where space is limited.
However, it should be noted that fine threads require high manufacturing accuracy and relatively high costs. So, cost-effectiveness needs to be considered when choosing to use them.
Conclusion
Coarse threads and fine threads are two common thread types, each with unique characteristics and applicable scenarios. In practical applications, we need to choose the appropriate thread type according to specific needs and scenarios. At the same time, with the continuous development of the manufacturing industry, thread technology is also constantly improving and enhancing quality.