Therefore, they can be used for a wide variety of threads by varying the depth of cut and the pitch of the thread helix. Image courtesy of Lakeshore Carbide.Ī Single profile thread mill only has teeth to do one thread at a time. Single Profile Thread Mill (also called Single Point Thread Mills)Ī single profile thread mill. A Multi-form threadmill thus cuts faster than the Single Profile or Single Point threadmills we will look at next. You may only need a single pass for all threads in the hole if the thread length is the same or less than on the threadmill. They’re called “Multi-Form” because they form many threads per pass. The same Spiral Flute Thread Mill can cut lefthand or righthand threads and it can vary the diameter of the threads, but they are limited to a single thread pitch governed by the spacing of their teeth. Spiral Flute Thread Mill (also called “Multi-Point” or “Multi-Form” Threadmills)Ī Spiral Flute Thread Mill can cut faster than Single Profile (or Single Point) Thread Mills because more than one thread can be cut by the multiple rows of teeth. They need the extra rigidity and strength to do their job versus HSS. Thread Mill Cuttersįor starters, most threadmill cutters are made of carbide. That’s quite a long list of advantages for carbide thread mills that may make them perfect for your application instead of tapping. Otherwise, a good compressed air blast will be fine. Exceptions would be stainless steel (reduces work hardening), aluminum (reduces chip welding), and cast iron (to keep the dust down). While coolant can be used, most manufacturers suggest dry machining is the first choice when thread milling.At some point, threadmill cutters are cheaper than very large taps. Taps get increasingly expensive as size increases.This is an advantage on CNC Machines that lack rigid tapping capability. Thread mills have no need for special tension compression holders or tapping heads.A thread mill can be used to back chamfer the hole.You can thread mill odd-sized threads for proprietary applications.There is also savings in reducing the amount of tooling inventory that must be kept on hand for standard thread sizes. On parts with multiple threads, there can be considerable toolchange savings with thread milling. A separate tap will be needed for each thread size. A single threadmill of the right type can be used to cut many thread sizes.The lower cutting forces of thread milling can be advantageous in long reach and thin wall applications where tool deflection and chatter are problems.Thread Milling requires less horsepower than tapping, which may be an advantage for lighter-weight CNC machines.Chip clearance is easier because a threadmill generates short, comma-shaped chips whereas taps can create long stringy chips that “bird nest”.Their use in hard materials is another reason they’re almost always carbide. Thread Milling is better for harder materials because you can cut the material in smaller steps, and speeds and feeds can span a wider range than a tap, which is limited by the pitch of the thread being tapped.The teeth of a threadmill are larger and stronger than taps because of the reduced need for chip clearance.Thread milling is often preferred for expensive components and late stage machining for this reason. Removing broken taps is painful, especially if the tap is embedded in a part that’s already been machined at considerable expense. If you break a Threadmill, it won’t get stuck in the part.That being the case, you might wonder why anyone ever uses CNC Thread Milling? There are a number of advantages CNC Thread Milling has over Tapping that often make it the preferred choice including: Let’s get one thing out of the way up front– Tapping is faster than CNC Thread Milling. The popularity of these methods is Tapping, Single Point Threading, and Thread Milling in that order.Ī selection of threadmills. On lathes, single point threading (turned threads) and taps are used. Threadmills are cutters used in CNC millling machines to cut internal and external threads using a process called “thread milling.” The other threading process for CNC Mills is Tapping.