Nowadays, manufacturers have more and more strict requirements on cutting tools. Maybe a small tool determines the quality of this product. The thread milling cutter has many advantages, which is much better than the wire tapping. The thread milling cutter is more than ten times faster than the wire tapping, and has high precision and good surface roughness. The same pitch can get large and small holes, which can be processed with one cutter. The drilling and milling thread chamfering can be formed at one time, and it will not be taken out like the wire tapping after it is broken, and the resistance of the machine tool is also small.
Thread milling cutter introduction:
The traditional thread processing methods are mainly turning thread with thread turning tool or manual tapping with tap and die. With the development of NC machining technology, especially the appearance of three-axis NC machining system, a more advanced thread machining method, NC milling of thread, has been realized. Compared with traditional thread processing, thread milling has great advantages in processing accuracy and efficiency, and is not limited by thread structure and thread direction. For example, a thread milling cutter can process a variety of internal and external threads in different directions. It is very difficult to machine the thread with transition thread or undercut structure by traditional turning method or tap and die, but it is very easy to realize by NC milling. In addition, the durability of thread milling cutter is more than ten times or even tens of times that of tap, and in the process of NC milling thread, it is very convenient to adjust the diameter of thread, which is difficult to do with tap and die.
Classification of thread milling
Clip on type:
Single tooth machine clamp: mechanical structure is similar to thread turning tool. The blade is connected with the turning tool and has only one thread processing tooth. The cutter can only process one tooth per spiral movement cycle, and the corresponding pitch decreases by one in the z-axis direction. The efficiency is lower than that of the multi tooth machine clip thread milling cutter
Multi tooth machine clamp: there are many thread processing teeth on the blade. When the cutter rotates for one circle, it can process many thread teeth by reducing the pitch of the corresponding number of teeth on the z-axis, with high processing effect
Integral type:
Integral type: there are many thread processing teeth on the blade, which is a kind of fixed pitch thread milling cutter. The cutter is made of integral cemented carbide, with good rigidity, high cutting speed and feed speed, wide processing range, compact structure, and can process small and medium diameter internal threads. But its price is more expensive
Characteristics of thread milling
1 stability
When machining difficult to machine materials such as titanium alloy, superalloy and high hardness materials, the tap will often twist or even break in the parts due to too much cutting force. In the process of long chip material, once the chip removal is not smooth, the chip will wind the tap or block the hole, which often leads to the tap crack or broken in the parts. Taking out the broken tap is not only time-consuming and laborious, but also may damage the parts. To solve this problem, we can use thread milling cutter. Because the thread milling cutter cuts into the material gradually, it produces less cutting force and seldom breaks. Even in case of tool breakage, because the diameter of the milling cutter is much smaller than that of the threaded hole, the broken part can be easily removed from the part without damaging the part
- High precision
Because the thread milling is through the tool high-speed rotation, spindle interpolation way to finish processing internal thread, chip removal is convenient. Milling thread belongs to chip breaking cutting, and the chip is short. In addition, the diameter of machining tool is smaller than that of machining thread, which can avoid the turning line formed by tap reversal (it is not allowed in the case of high sealing requirements). Because there is no turning line in the original milling cutter, and the tap can not be avoided. It is not easy to form sticky chips. For soft materials, chip sticking is easy to occur in the process of processing, but the screw thread requires low machine power. Because thread milling is chip breaking cutting, tool contact is local, cutting force is small, and tap tool damage is easy to deal with;
- High efficiency
Processing efficiency we know that in the mass thread processing, due to the low cutting speed limit of the tap and the reverse tool withdrawal after processing the thread, it is very difficult to improve the processing efficiency. However, if we use thread milling cutter, not only its own milling speed is very high, but also its multi groove design increases the number of cutting edges, which can easily improve the feed speed, which can greatly improve the processing efficiency. In the processing of long thread, we can also choose the blade with longer blade to reduce the axial feed distance (equivalent to making the thread shorter) to further improve the processing efficiency;
- Good finish
Due to the influence of low cutting speed and difficult chip breaking, it is very difficult to obtain good surface finish and thread precision when machining with tap. However, for thread milling, everything is not a problem! High cutting speed and small cutting force make the cutting surface smooth; The fine chips can be easily washed out by the coolant, and the workpiece will not scratch the machined surface. For the workpiece with high thread accuracy requirements, because the thread milling cutter relies on spiral interpolation to ensure the accuracy, only need to adjust the program to easily obtain the required high-precision thread. This feature has a great advantage in precision thread processing.
- Low cost
The thread milling cutter is flexible and can be used in various working conditions. For example, we can use the same thread milling cutter to process left-hand thread or right-hand thread; It can process both external thread and internal thread. All this just needs to be done by adjusting the interpolation program. If there are multiple threaded holes with different diameters but same pitch on the part, taps with different diameters are needed. This not only requires a lot of taps, but also takes a lot of time to change the tool. If the thread milling cutter is used, because it uses spiral interpolation to process, it only needs to change the processing program to complete the processing of all diameter threads, which greatly saves the cost of the cutter and the time of tool change. In order to ensure the thread accuracy, different types of taps are needed when machining different materials with taps. However, the use of thread milling cutter has no such limitation. The same thread milling cutter can process most materials and obtain high precision thread. This can also greatly reduce the cost of cutting tools. When the processing thread is close to the bottom of the blind hole, it is difficult to obtain the complete thread at the bottom if tapping with tap. And it is possible that the tool will continue to move forward a little distance (floating tapping) during the time when the tap stops at the bottom and is ready to reverse back, which is easy to cause the tap to break. This problem can be avoided by using the thread milling cutter – the thread milling cutter is smaller than the hole, there is no need to reverse the tool, and the thread shape is still complete at the tool tip. In this way, we can get complete and precise thread depth! In some processing, thread milling can help us solve many problems.
ken. tang@chengcg.com
