Nomenclature of Mechanical Threads- Diagram Of Threads

What is a Thread?

A Thread is simply a helical structured curve that is used to convert the the Rotational or Linear movement of the thread. It converts the Linear Movement of the thread to Rotational movement and the Rotational movement of the thread to Linear Movement. A screw thread is usually seen on the Cylinder of the screw that is in the shape of the helix. When the Screw Threads are on the cylinder, those are known as Straight Thread and when the threads are on the Cone, those are known as Tapered Threads.
terminology of threads
terminology of threads
We have two different threads in the screw. The first type of threading is the Internal Thread and the second type of threading is the External Thread. The External thread is known as Male Part and the Internal thread is known as Female Part. These can be both joined only with the help of threads on both the parts. The tightening or loosening of the screw also depends on the threading.

There are various design considerations to be considered while designing Screw Threads.


1. Gender-

The gender of the part must be determined first, so we can ensure the manufacturing of the part successfully with high accuracy.

2. Handedness-

There are two types of Handedness in the threading. Left Handedness and Right Handedness. The Left handed threading starts from left to right where as the Right handed threading starts from right to left.

3. Form Factor-

There are different forms of threading. Threads may be at an angle of 45 degrees with flat head on it. They may be at 45 degrees with pointed head on it. There are many forms of threading.

4. Angle-

The Angle alone comes under the main consideration for designing and manufacturing threading on the cylinder. Universal angle is 60 degrees.

5. Lead-

Lead is the distance a thread take for one complete revolution. There are many different leads depending on the size and shape of the threading.

6. Pitch-

Pitch is the distance between the two threads on the cylinder. It may be internal or external threading. The pitch that is considered for internal threads is known as internal pitch and for external is external pitch. Mostly, it varies for all the threads.

7. Diameters-

There are many types of diameters to be considered. Major Diameter, Minor Diameter and Pitch Diameter are the diameters to be considered.

8. Depth of cut-

Depth of cut is an important factor which involves the internal threading and external threading dimensions.
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