# What is the number of threads per unit length of a screw called?

### What is the number of threads per unit length of a screw called?

The number of threads per unit length of a screw is commonly referred to as the "thread pitch" or "pitch." The pitch is typically measured in millimeters (mm) or inches (in), depending on the unit system being used. It is called simply "threads per length". In US it is threads per inch. It is the reciprocal of the pitch. For example, a screw with 32 threads per inch has a pitch of 1/32 inch. The pitch is the distance between threads

TPI stands for Threads Per Inch. This is simply a count of the number of threads per inch measured along the length of a fastener. The pitch of a screw is an important parameter that determines the amount of linear travel of the screw for each revolution. Specifically, the pitch represents the distance between two adjacent threads on the screw. For example, if a screw has a pitch of 1 mm, then it will travel 1 mm along its axis for each complete revolution.

It's worth noting that the pitch is not the same as the "lead" of a screw, which is the distance the screw advances axially with each complete turn. The lead is equal to the pitch multiplied by the number of starts (or "threads") on the screw. In other words, if a screw has a pitch of 1 mm and two starts, then its lead would be 2 mm.

In summary, the number of threads per unit length of a screw is called the pitch, and it is an important parameter that determines the linear travel of the screw for each revolution. The pitch of a screw is typically specified in the screw's technical documentation or on its packaging. It is important to choose a screw with the appropriate pitch for the application in which it will be used, as the pitch can affect the screw's speed, torque, and efficiency.

In addition to the pitch, other important parameters of a screw include its diameter, length, and thread form. The diameter of a screw is typically measured across the outer edges of the threads, and it can also be specified in millimeters or inches. The length of a screw is typically measured from the top of the head to the tip of the threaded end, and it is also specified in millimeters or inches.

The thread form of a screw refers to the shape of the threads on its surface. Common thread forms include V-shaped, square, and rounded threads. The thread form can affect the screw's performance in terms of its strength, resistance to corrosion, and ease of use.

Overall, the number of threads per unit length of a screw (i.e. its pitch) is just one of many important parameters to consider when selecting a screw for a particular application. By understanding the various parameters of a screw and how they relate to its performance, it is possible to choose the right screw for a given task and ensure reliable and efficient operation.