Threads are a key component of many products, from clothing to tools, and understanding the different sizes and types of threads is essential for a successful product design. A universal thread size chart helps to simplify the process of finding the right thread for each application. While there are many different types of threads, this guide will focus on the three most common: metric, unified, and American National.
Metric Threads
Metric thread sizes are based on the International System of Units, or SI, and are the most common thread type found in many parts of the world. Metric threads are identified by their nominal outside diameter (OD) in millimeters and their pitch, which is the distance between two adjacent threads in millimeters. The pitch is also referred to as the thread’s “count.”
Unified Threads
Unified threads are used primarily in North America and are based on the inch-pound system of measurement. Unified threads are identified by their nominal outside diameter (OD) in inches and their thread count, which is the number of threads per inch.
American National Threads
American National threads are used primarily in North America and are based on the inch-pound system of measurement. American National threads are identified by their nominal outside diameter (OD) in inches and their thread count, which is the number of threads per inch.
Finding the Right Thread Size
Using a universal thread size chart can help designers quickly and easily find the right thread size for their application. The chart will typically display the thread type and size, along with additional information including the thread’s major and minor diameter, thread depth, and pitch diameter.
Thread Tolerances
When selecting a thread size, it is important to consider the thread tolerances. Thread tolerances are the allowable deviations from the nominal thread measurements. Major diameter tolerances are the most critical, as they determine the fit between two threaded parts. For most applications, the major diameter tolerances should be as small as possible.
Using the Right Thread for Each Application
Using the right thread for each application is critical for creating a quality product. A universal thread size chart can provide designers with the information they need to select the right thread for their application. By understanding the different types of threads, designers can quickly and easily find the right thread size for their application.
