1. Defining the Terms: Tapping vs Threading

In the most basic sense, tapping vs threading describes the relationship between a specific method and a general category. Threading is the broad, umbrella term for creating any helical groove on a workpiece. This includes internal threads (inside a hole) and external threads (on the outside of a cylinder). Tapping, conversely, is a specific subset of threading that refers exclusively to the creation of internal threads using a tool called a tap.

Every tapped hole is a threaded hole, but not every threaded feature is created through tapping. For example, external threads on a bolt are created through a threading process (using a die or a lathe), but never through tapping. Understanding this distinction is the first step toward professional machining mastery.

3. The Tapping Process: Precision for Internal Holes

When discussing tapping vs threading, the tapping process is highly specialized. It requires a pre-drilled hole, known as a pilot hole. A tap—a hardened steel tool with cutting edges—is then rotated into this hole. As the tap descends, it carves out the internal threads. This is the primary method used to create the threads inside a nut or a mounting hole in an engine block.

Types of Taps and Their Uses

To achieve the best results, machinists select different taps based on the hole depth and material:

• Taper Taps: Feature a significant lead-in taper, making them ideal for starting threads and ensuring alignment.
• Plug Taps: Have a shorter taper than the taper tap, used after the initial thread is started to cut deeper.
• Bottoming Taps: Have almost no taper, allowing them to cut threads nearly to the very bottom of a blind hole.
• Spiral Groove Taps: Such as our JlS spiral groove tap series, which excel at pulling chips out of the hole, preventing clogging in blind-hole applications.

4. The Threading Process: Versatility for External Rods

While tapping is for the “female” part of a connection, the broader term threading often refers to the creation of the “male” component. External threading is the process of putting a thread on a rod or bolt. In the context of tapping vs threading, the methods for external threads are much more diverse than the relatively singular method of tapping.

Common External Threading Methods

• Die Cutting: Similar to a tap but for external use. A die is a nut-like tool with internal cutting teeth that is twisted onto a rod.
• Lathe Threading: A single-point cutting tool moves along the length of a rotating workpiece. This allows for high precision and custom pitches.
• Thread Rolling: A non-subtractive method where hardened rollers press the thread profile into the metal. This makes the material stronger and is common in high-volume production.
• Thread Milling: A CNC-based method that uses a rotating multi-tooth cutter to move in a helical path. It can perform both internal and external threading.

5. Tapping vs Threading: Technical Comparison

The choice between these methods involves analyzing speed, cost, and the physical requirements of the part. Here are the core technical differences when evaluating tapping vs threading:

Internal vs. External Orientation

Tapping is exclusively for internal threads. Threading is the universal term for both but is most commonly associated with external threads when used in contrast to tapping. If you are making a bolt, you are threading. If you are making the hole it goes into, you are tapping.

Tool Geometry and Setup

Tapping tools (taps) are sized exactly to the thread they create. An M6 tap creates an M6 hole. Threading tools, particularly in CNC milling or lathe work, are more flexible. A single-point threading tool can create multiple different thread sizes and pitches by simply changing the machine’s program. This makes threading the preferred choice for non-standard or large-diameter workpieces.

Chip Management

Tapping produces chips inside the hole, which can be difficult to clear, especially in “blind” holes (holes that do not go all the way through). Using high-quality tools like those in our DIN371 German industrial standard range ensures efficient chip evacuation. External threading has the advantage of allowing chips to fall away freely from the workpiece.

6. Materials and Industrial Applications

Material selection plays a massive role in the tapping vs threading debate. Harder materials like stainless steel or titanium require premium tool steels and coatings to prevent tool breakage. Because taps are often thin and prone to snapping inside a part, threading methods like thread milling are sometimes used in expensive aerospace alloys to reduce the risk of scrapping a nearly finished component.

In the automotive industry, tapping is the workhorse of the production line. Millions of holes in engine blocks and transmission housings are tapped every year because it is the fastest way to create standard threads in mass quantities. Conversely, for the high-strength fasteners used in heavy machinery, thread rolling (a form of threading) is used to ensure the threads can handle immense stress without stripping.

7. Summary Comparison Table

The following table summarizes the primary differences between tapping vs threading for quick reference.

8. Frequently Asked Questions (FAQs)

9. References

• ISO 9001:2015 Quality Management Systems – Thread Tool Manufacturing Standards.
• American Society of Mechanical Engineers (ASME) B1.1: Unified Inch Screw Threads.