What is the difference between internal and external threading?

Internal threading and external threading are key concepts in machining that pertain to how threads are formed and where they are applied. Internal threading is the process of cutting threads inside a hole, creating a female thread that can receive a male thread, such as on a screw or bolt. This is typically done using tap tools specifically designed for this purpose.

On the other hand, external threading occurs on the outer surface of a rod or cylinder, where a male thread is formed, which can be used to screw into a tapped hole or to connect with nuts.

Understanding this distinction is vital in machining applications, as each type of threading serves different purposes and utilizes different tools and techniques. For instance, a tap is used for internal threading, while a die or lathe is used to create external threads. Recognizing the difference not only enhances knowledge of machining practices but also informs decisions related to component design and assembly techniques in manufacturing.