Page 50 - CNC West Oct-Nov 2021

FIVE QUESTIONS TO ASK WHEN MACHINING THREADS
Supplied by Allied Machine & Engineering
There are many elements to consider when threading a workpiece. When is a solid carbide thread mill better than an indexable? How does the workpiece material behavior impact thread milling?
Understanding your program as well as diagnosing issues that arise are just as important. Luckily, thread milling can be better understood by asking five specific questions.
When would you want to thread mill instead of tap?
There are many instances where you would want to consider using a thread mill instead of a tap. In numerous cases, this comes back to one common issue: taps break. Because the tap is the exact same size as the hole, there is a lot of pressure when you are are forcing the threads into the hole— even more so in difficult-to-machine materials. Additionally, a tap’s cutting edges are constantly in the cut, thus generating more heat. A thread mill on the other hand has little contact with the material, and the heat generated is much lower—an added benefit in any manufacturing process. Finally, when using a tap, chips are more difficult to form and remove.
All of these things mentioned above lend themselves to tool failure. When the tap breaks off, it often results in a scrapped part, so using a tap works better when it is an inexpensive part being made. If it is a more
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