In mechanical engineering and manufacturing, threads are an important mechanical element used for connection,
fixing, and transmission. Understanding the parameters in a thread specification is essential for selecting
and using threads. Today we will explain the meaning of threaded TPI and its importance in thread specifications
for you in detail.
Ⅰ、Definition of threaded TPI
1. TPI is the abbreviation of Threads Per Inch.
2. TPI is a way of expressing thread density and refers to the number of complete threads
on a one-inch length thread.
3. The larger the TPI value, the finer the thread; The lower the TPI value, the thicker the thread.
Ⅱ、Relationship between TPI and pitch
1. Pitch refers to the distance between two adjacent threads, usually expressed in inch or metric units.
2. TPI and pitch are reciprocal to each other. Pitch = 1 / TPI (inches).
3. For example, if a thread has a TPI of 20, its pitch is 1/20 inch, which is approximately equal to 1.27 mm.
Ⅲ、Application of TPI in different thread standards
1. Inch thread: Commonly used TPI indicates thread density, such as 1/4-20 UNC for 1/4 inch diameter
and 20 threads per inch for uniform rough thread.
2. Metric thread: Usually used to indicate the pitch, such as M10×1.5 for the diameter of 10 mm,
pitch of 1.5 mm of the metric thread.
3. Some special threads, such as pipe threads, will also use TPI to indicate thread density.
Ⅳ、Effect of TPI on thread properties
1. Strength: Lower TPI (larger pitch) usually has higher strength and is suitable for occasions with larger loads.
2. Tightness: Higher TPI (smaller pitch) can provide a better seal, suitable for applications that require leak-proof.
3. Assembly speed: Low TPI threads allow for faster assembly, while high TPI threads require more rotation
to be fully tightened.
Ⅴ、Considerations for choosing the right TPI
1. Application scenario: Select the appropriate TPI according to the specific application requirements,
such as strength, sealing, assembly efficiency, etc.
2. Standardization: Whenever possible, choose standardized TPI values to ensure interchangeability
and easy availability of parts.
3. Material properties: Different materials may be more suitable for a specific TPI range, and the strength
and processability of the material should be considered.