With the development of the CNC thread milling process, especially the advent of the three-axis machining center, the CNC thread milling process has gradually been widely recognized by the machining industry.
In addition, it is well known that threads can be obtained by conventional threading methods that we are familiar with, of which tapping is most similar to thread milling. Because they all form the thread through the relative rotational movement between the tool and the workpiece. So when faced with different working conditions, how to choose the appropriate method? This article tells you exactly what they are.
Conditions for CNC thread milling:
1. Three-axis linkage (or above) machining center
2. The length of the thread does not exceed 3 times the cutting edge of the tool
Advantages of CNC Thread Milling
1. The thread milling cutter can process threads of different diameters and the same shape.
For example, by changing the interpolation radius with a thread milling cutter to process M15x1.0, M18x1.0, M20x1.0 threads, it can reduce the number of tools, save tool changing time, improve efficiency and simplify tool management.
2. Improved thread precision and smoothness.
Thread milling is accomplished by high-speed rotation of the tool and interpolation of the spindle. The cutting method is milling, the cutting speed is fast, and the processed thread is beautiful; the cutting speed of the tap is low, and the chip is long, which is easy to damage the surface of the inner hole.
3. The inner thread is easy to discharge.
Thread milling belongs to chip breaking, the chip is short, and the diameter of the machining tool is smaller than the diameter of the threaded hole, so the chip is removed smoothly; when the tap is continuously cut, the chip is longer, and the diameter of the tap is as large as the machining hole, so the chip is difficult to remove.
4. If taps are used, of course electric sparks can be used to break off the broken part, but the process will be very complicated and there will be losses if there is damage to the parts.
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If you use a thread milling cutter, first of all, it is not easy to break due to the small force; even if it breaks, because the diameter of the machining hole is larger than the diameter of the tool, the broken part can be easily taken out. In terms of product throughput, thread milling is much higher than taps.
5. It is not easy to form sticky chips.
For softer materials, it is easy to produce sticky chips during machining, but thread milling rotates at high speed and breaks chips. The cutting speed of the tap is low, and the full thread and the machined surface work, which is easy to cause chip sticking.
6. The machine power is required to be low.
7. Due to the thread milling chip breaking, the tool is partially in contact, the cutting force is small, the tap is completely in thread contact, the force is large, and the machine requires high power.
8. Tool breakage is easy to handle.
First of all, the thread milling cutter is under little force and rarely breaks. If this happens, because the machining aperture is larger than the tool, the broken part is easy to take out; the tap is stressed, the chip removal is not smooth, it is easy to break, and the hole after breaking is large. It is a little easier to handle, but it is very troublesome if it is a small hole, such as:
When machining common threads, thread milling is not cost-effective considering the unit cost. Ordinary threads are classified as threads with a general hardness of less than 50HRC and a diameter of less than 38 mm, although this is not a clear dividing line. Ordinary taps are generally high-speed steel materials, and the market price is tens of dollars, but the price of thread milling cutters is more than 10 times the price, and the life of a single piece cannot exceed 10 times.
Second, the aspect ratio should not be too large, generally L/D <3 is required. Because the thread milling cutter has a one-sided force, when the thread is too long, the aspect ratio will produce a taper, and the tool will be easily broken.
Applications CNC thread milling
1. High-hardness material processing (hardness > 50HRC), suitable for thread milling, because milling chip breaking, local contact with the tool is small, the blade is made of cemented carbide, with little wear and long service life; ordinary high-speed steel taps cannot be processed at all, For example, the use of solid carbide taps is not cheap, and the price is similar to that of thread milling cutters. According to our existing processing experience, the efficiency and economy of thread milling are definitely higher than that of taps.
2. Compound hole (with chamfer) machining is also suitable for thread milling. Thread milling cutters have many functions that can be integrated into threads and chamfers.
3. Thin-wall processing is suitable for thread milling. The processing force of the thread milling cutter is small, so the deformation is small. In addition, the bottom hole can be made flat, and the thread can be close to the bottom hole, so that little space is required.
4. For the processing of high thread precision, thread milling has high thread speed, good chip removal performance, high thread precision and high finish, which is more suitable for thread milling.
5. The material is soft, titanium alloy processing, suitable for thread milling, because the thread milling cutter is not easy to produce sticky debris.
For unstable cutting, the thread milling cutter is fully able to adapt to this situation, because its cutting principle itself is intermittent milling
