A tapped hole has threads in the hole’s inside edges using the tapping process. A tapped hole is required for securing a fastener where a nut and bolt is not an option. Used when engineering metals; the threaded component is held with the machined internal tapped hole.
So, what is the difference? They are similar, but they are machined in two different ways.
The threading process creates threads outside of a hole with a die tool. The tapping process makes threads inside a drilled hole with a tapping tool.
One benefit of tapping rather than threading is speed. High-speed tapping centres with a rigid tap can thread holes much quicker than a thread mill would. Another benefit would be that tapping can be used to thread deeper holes in steel for example.
When it comes to a tapped hole; there is no adjustment of the thread fit, and a different size tap is required for each size of hole to be threaded, which can cause a delay in worktime due to the time taken to change tools.
A threaded hole compared to a tap is controlling the fit. A threaded hole is machined at a high RPM. The drill tool helix’s into an already made hole. So, the thread size can be adjusted.
In comparison to Tapping a single tool can be used in thread milling to make a variety of hole sizes. Reducing tooling costs and downtime. Thread mills can also create interior and exterior as well as right-hand and left-hand threads, and huge threaded holes.
However, threading holes requires a high-speed spindle, as well as taking a long time to ensure precision.
To Summarise, threading would be beneficial in high-volume production, where different sized holes or threads are required. Whereas a tapped hole would be beneficial when machining harder materials and is generally better for steel. Both tapped and threaded holes contain internal threads for fasteners to fit into, they can also both be used for through holes or blind holes.