Tapping and threading!

Threaded hole machining is the creation of a hole with internal threads using a threading tool such as a thread turning tool, thread milling cutter, or with the help of a threaded insert. In engineering, a fastener part is incomplete without a threaded hole. Threads are often added during CNC machining for speed and accuracy. Threading is often one of the last steps in manufacturing a part, especially when threaded inserts are involved.

Tapping is just one type of threaded hole machining. More specifically, it is a threaded hole machined using a tap. These tools consist of a rod with a sharp edge or teeth that cuts into the side of the hole, creating an internal spiral groove (thread) as it cuts through the material. Tapping is a quick and convenient method of threading and is one of the most common techniques we see in hardware stores.

In short, tapping is a type of threaded hole machining, but there is more to it than just this one method.

As mentioned above, tapping is a threading method that creates internal threads in a hole. Threading is a general term used to describe the creation of internal or external threads using various types of cutting tools.

You can tap a hole or bore to create internal threads, but you can also tap external cylindrical features to create threaded rods or fasteners. External threads can be made using cutting dies, single-point cutting tools on a lathe, roll-forming tools, and more.

The processes of tapping and threading are similar in that they both create internal threads for a threaded fastener, such as a bolt, to fit into. They can also be used with blind or through holes. When the hole does not go all the way through the workpiece, the hole is considered a blind hole. As far as limitations go, we will focus on the limitations of tapping, as threading encompasses all other types of threading techniques. Here are the limitations to be aware of when tapping:

Thread Type: Tapping is limited to internal threads. For external threads, you will have to turn to other threading processes, such as using dies.

Thread Varieties: Taps are designed to create threads with specific sizes and pitches. This means that if you want to create a variety of threads, you will need a corresponding tap for each thread. Additionally, this rules out custom thread forms, which can be better handled by processes such as thread milling.

Tool Breakage: Taps are more susceptible to breakage than other threading tools. Damaged taps can become a machinist’s nightmare as they can be difficult to remove and in some cases even require the entire part to be scrapped.

Blind Hole Depth: Since most taps have a tapered lead on them to assist the cutting process, this means they can only go so deep before hitting the bottom of the blind hole. If you need the threads to be as close to the bottom of the blind hole as possible, you may need to resort to alternative methods such as thread milling.

Material Limitations: Taps don’t work as well when machining hard or brittle materials such as hardened steel. These types of materials tend to wear out the tap quickly, making it ineffective at producing good threads or requiring frequent tool changes, which increases costs. On the other hand, very ductile materials can also cause problems for taps as they can become “sticky” and stick to the tap during cutting, requiring frequent cleaning or tool changes.

Overall, tapping can be a good way to produce threaded holes in a part under the right circumstances, but other techniques may be necessary when dealing with certain materials and thread forms or when you want to reduce the risk of tool breakage.