1/4-20 UNC Thread: A Comprehensive Guide
What is a 1/4-20 UNC Thread?
A 1/4-20 UNC thread is a type of screw thread commonly used in various industrial and engineering applications. The thread is characterized by a major diameter of 1/4 inch (6.35 mm) and 20 threads per inch (TPI). UNC stands for Unified National Coarse, which is a standard thread form used in North America and other countries.
Features and Characteristics
Here are some key features and characteristics of a 1/4-20 UNC thread:
Thread Dimensions
- Major diameter: 1/4 inch (6.35 mm)
- Threads per inch: 20
- Pitch: 0.050 inch (1.27 mm)
Thread Form
- The 1/4-20 UNC thread has a coarse thread form, which means it has a larger pitch and fewer threads per inch compared to a fine thread.
- The thread form is designed to provide a strong and reliable connection between parts.
Materials and Applications
The 1/4-20 UNC thread is commonly used in various industrial and engineering applications, including:
- Machine building: The thread is often used in machine building and construction, where strong and reliable connections are critical.
- Automotive: The 1/4-20 UNC thread is used in various automotive applications, including engine mounts, suspension components, and other structural components.
- Aerospace: The thread is used in aerospace applications, where high-strength and reliable connections are crucial.
Thread Tolerances and Classifications
The 1/4-20 UNC thread has specific tolerances and classifications to ensure proper fit and function. The thread is classified into different classes, including:
- Class 1: This class provides a loose fit, which is suitable for applications where ease of assembly is important.
- Class 2: This class provides a free fit, which is suitable for applications where a slight interference fit is acceptable.
- Class 3: This class provides an interference fit, which is suitable for applications where high-strength connections are critical.
Conclusion
In conclusion, the 1/4-20 UNC thread is a widely used thread form in various industrial and engineering applications. Its coarse thread form and strong connections make it an ideal choice for applications where reliability and strength are critical.
