For the most part, improving productivity has focused on improving the ability of the cutting edge. After the cutting ability of the cutting edge is improved, the production efficiency can be continuously improved. However, due to the different characteristics of different parts, the tool overhang has become one of the important influencing factors in processing, and we pay more and more attention to the performance of the cutting edge during cutting vibration.

There is a tendency for vibration when there is tool overhang, but in most cases, this problem can be avoided by very slight cutting and the tool slowly approaches the workpiece, but it will sacrifice cutting efficiency. If the tool must enter a hole or cavity, a deflection force is generated which can cause a tendency to vibrate. Let's take a closer look.

In today's machining field, inner-hole turning, boring, cutting and grooving, and milling operations all require longer tool overhangs and are becoming more and more common. In some cases, the same workpiece may require multiple types of operations. So far, many long overhang applications have a low level of machining performance, which only meets the most basic requirement that parts can be machined, that is, no cutting vibration occurs, and it is impossible to talk about production efficiency. Because of the vibration of the tool, it is easy to cause the reduction of processing safety, the quality of the parts, the high noise level, the short tool life, and even the processing of waste products. Therefore, it is often only possible to use cutting parameters lower than the cutting edge capacity, which increases the processing cost and the production time.

In the milling process, due to the intermittent cutting action, vibration tends to occur during processing. Due to the use of long overhang tools, more and more milling operations are prone to vibration. Many methods can temporarily avoid the tendency to induce vibration, such as using the correct milling cutter and tool path. However, when the tool overhang (the distance between the spindle end shank flange and the cutting edge) exceeds three times the diameter of the adapter, if you want to produce a product that meets existing standards, other measures need to be taken.

As the demand for tool overhangs of four times or more during milling increases, we are eager to overcome the effects of vibration, which limits production efficiency. In particular, because the axial depth of cut and the amount of feed have to be kept low, the metal removal rate has not been as good as it should be. In many cases, whether milling or bore turning, long overhang tools must be used. For example, on multitasking machines, the B-axis spindle often prevents the tool from approaching the workpiece, so a tool with a long overhang must be used.

In order to overcome the tendency to vibrate, we need to use more high-tech methods to manufacture vibration-absorbing tool holders, which helps to better and more accurately minimize the amplitude. That is, we can very accurately determine the type of vibration in a field and the required damping setting. In the latest research and development work, when designing and applying vibration reduction technology, we combine a large number of professional technical means and experience to make it possible to achieve more stable metal cutting at higher processing rates.

It is not possible to completely eliminate vibration during processing, but it is now possible to reduce it to a minimum without affecting the processing process. Adopting advanced simulation methods, equipment and measurement systems, combined with a deep understanding of structural dynamics knowledge, can completely eliminate the adverse effects of the force on the tool. This research and development work not only realized the vibration reduction function, but also more accurately found the function of the specific tool overhang.

For milling operations, the use of new standard adapters will not affect the machining performance due to tool overhang. Standard adapters minimize typical amplitudes for two different overhang ranges. At present, there are two kinds of vibration-damping adapters with different lengths, which are respectively used for milling processes with overhangs of 4-5 times the diameter of the adapter and 6-7 times the diameter of the adapter. Custom-made vibration-damping shanks can make the overhang of the milling rod longer. (The tool overhang referred to in this article refers to the distance between the spindle end tool holder flange and the cutting edge.) These adapters are suitable for the most common areas of long tool overhang in milling work. The adoption of the new system can improve production efficiency and greatly reduce the time to return on investment for the shank.

This milling adapter allows for increased axial depth of cut and infeed. This can greatly increase the potential of production efficiency, and bring the possibility of high-efficiency milling for parts features such as cavities that exceed the machining range, such as when using a slot milling cutter with a diameter larger than the tool holder. The potential of new products can extend tool overhangs, or increase tool overhangs while increasing productivity.

Internal hole turning will involve tool overhang more broadly. Many parts have very deep holes and have strict requirements on the overhang of the boring bar. The overhang range is 4 times to 14 times the diameter of the boring bar. The correct tool selection and application play a decisive role in the results of the operation, as internal hole turning is sensitive to vibrations. One of the advantages of Silent Tools damping boring bars is that the damping mechanism is arranged as close to the cutting edge as possible. This mounting method can quickly respond to any vibration tendency.

Ordinary steel boring bars are ideal for overhangs of four diameters. The solid carbide boring bar is suitable for occasions with six times the diameter. For areas with longer overhangs, internal turning requires vibration-reducing boring bars. Steel damping boring bar is used for processing holes with overhangs of 10 times the diameter, and reinforced carbide boring bars are used for overhanging with 14 times the diameter. Grooving and thread cutting usually use lower overhangs. In addition, the vibration characteristics of the mechanisms of all machine tools are different, that is, the same cutting process vibrates at different frequency points due to the different characteristics of the machine tool itself. Therefore, it is important to develop a vibration-damped standard tool that can operate normally in the largest frequency range.

In the process of taking vibration reduction measures, the used bore diameter and boring rod diameter vary widely. The standard tool system has a processing diameter of 10-250 mm, while the custom tool product covers a larger diameter.

Vibration-reducing boring bars are used for internal turning for three reasons: maintaining small tolerances and excellent surface quality, minimizing machining time with a minimum number of passes, and using competitive and economical machining rates. At this time, production efficiency and safety are the most critical, because many parts are highly competitive in the manufacturing process.

The combination of boring bar and cutting head for internal hole turning now benefits the machining process. For small diameter machining with a diameter smaller than 20 mm, there are two types of inserts, T-shaped and D-shaped, which can be used to optimize the process at hand, for example, when the tolerance limit is small and hard part turning. For the hole diameter of 20 mm or more, interchangeable cutting heads can be used, which has great flexibility, high security, and convenient tool clamping.

When turning inside holes, it is important to use high-pressure cooling technology. By installing a coolant nozzle behind the cutting edge, chip control and discharge can be improved, with the aim of making full use of the coolant equipment on the machine. Tool holders with fixed nozzles ensure that the coolant is accurately sprayed into the cutting area, thereby improving chip breaking performance and ejecting the chip breaking out of the holes and conveying it to the conveyor. A quick-change tool holder system is used in the turning center. This system can usually be designed with high-pressure cooling water supply nozzles. Convenient to use high-pressure cooling water to blow iron filings away from the processing area. These units are equipped with built-in fittings and liquid supply pipes, and when external piping must be used, the tool change time can be long. The optimized cutting unit is equipped with preset fixed nozzles, thereby reducing machine assembly time.

Using the right method for internal hole turning can make a big difference in machining performance, safety, and machining results. For example, Sandvik Coromant's three-pass method, where the programmed part includes the programmed diameter is larger than the required diameter. When it takes more than 30 minutes to repeatedly process to achieve the finishing with a small tolerance range, the inner hole turning by Sandvik Coromant can be completed in less than five minutes, and the advantage is particularly obvious. The reason that the processing time can be greatly shortened is to avoid many unnecessary uncertainties caused by the trial cutting with a small depth of cut.

Because the cutting edge fails to participate correctly in cutting, and the measurement needs to be stopped many times, the low production efficiency and unstable cutting process will damage the machining accuracy of the hole. This machining method minimizes the correct number of cuts, and is suitable for internal hole turning overhanging at 3-4 times the diameter, where the tool diameter is ≥13 mm, which is suitable for various material types, and can use normal or recommended Cutting parameters.

The method used now is to solve the vibration problem that has a negative impact on the processing, which is completely different from the previous method. Although problem solving is still part of the application of these tools, our focus is on improving productivity, ensuring process safety, and quality consistency.

The system's overall stability can be improved by increasing the rigidity of the system or by increasing the amount of vibration reduction of the system by using vibration-damping tools. The use of the most sturdy and stable tool holder systems, such as the ISO-compliant Coromant Capto interface, has no effect on any part of the "system". The natural frequency of the machine tool is another important factor of the "system". In order to achieve comprehensive optimization, consider improving the different structures of a single machine to increase overall stability.

The large boring bar with the Coromant Capto C10 interface can be used for internal hole turning with a hole diameter greater than 100 mm and an overhang of 10 times the diameter, turning high-quality holes at high metal removal rates. Quick change function can quickly install boring bar with high accuracy. The boring bar is mainly used for flat-bed lathes and heavy-duty machining of relatively large holes on large turning centers.