Internal and external threading tools are used in metalworking to create threaded holes or external threads on a workpiece. The main difference between the two lies in the direction of the threading operation and the design of the tools:
Internal threading tools, also known as taps, are used to create threaded holes inside a workpiece. These tools have cutting edges on the flutes that are designed to cut the threads as the tap is rotated into the pre-drilled hole. Internal threading tools come in various types, including hand taps and machine taps.
External threading tools, commonly known as dies, are used to create external threads on cylindrical workpieces, such as rods or bolts. These tools are applied to the workpiece to shape the threads. External threading tools come in various types, including hand dies, machine dies, and adjustable dies.
Adjustable Dies: Adjustable dies, also known as split dies, are used for threading operations where the thread diameter may vary. These dies have an adjustable feature that allows the user to change the size of the threading die to match the workpiece diameter. Adjustable dies are commonly used in repair work or for threading non-standard or custom-sized threads.
In summary, the primary difference between internal and external threading tools is in their direction of operation and the design of the tools. Internal threading tools (taps) are used to create threads inside a hole, while external threading tools (dies) are used to create threads on the outside of a cylindrical workpiece. Understanding the distinction between these tools is essential for selecting the appropriate tool and technique for specific threading applications.