In the highly competitive world of indexable tools, many recent developments seem to be gradual. The details of the others are shrouded in secrets. But because the choice of cutting tools can have a huge impact on productivity, it is always worth asking an expert what new changes are.

Let's start with the old question of deciding between indexable milling cutters and solid carbide milling cutters. As Luke Pollock, product manager at Walter USA, Waukesha, Wisconsin, puts it, the first thing to consider is "how much material need to be removed and how much work space do you have? ... the material to be removed, I definitely think it can be transferred Bit tools are a better method. We even saw the use of indexable tools on small parts in the previous operations, just to improve the material removal rate due to tool size and number of teeth."

Dan Tucker, Manager of Product Management Group at Sandvik Coromant in Fair Lawn, New Jersey, and a milling expert in the western United States, quantified the trade-off, saying that solid carbide is superior to indexable milling cutters with a diameter of 5/8" (15.88). mm) and below and "You can even say ¾" [19.05 mm] diameter solid carbide may exceed indexable in terms of productivity. It is often difficult to put enough indexable inserts into a smaller tool To compete, it depends not only on the number of inserts in the tool, but also on the length of the insert that matches the solid carbide." Tucker’s colleague and Eastern US milling expert Joe DeRoss said that in rare cases, the use of small diameters Indexable cutters are more cost-effective for roughing, even if it has fewer teeth than solid cutters of the same size. This is because the use of a double-edged indexable milling cutter to divide the material into pieces and then replace the insert when it wears out is cheaper ( At least from a tool point of view).

From an application point of view, Edwin Tonne, a training and technical expert at Franklin Horn USA Inc., Tennessee, said that slot milling or disk milling (face milling) is the best example of indexable tools defeating physical tools. "Another example is face milling in a smaller enclosed cavity. With the Horn 304 small milling cutter, the bottom of a deeper cavity can be machined without having to spend a longer solid carbide tool," he said.

For Sandvik Coromant’s DeRoss, the driving factor in choosing solid carbide tools instead of indexable tools was the need to achieve excellent surface finish. Wiper blades can be added to indexable tools to improve surface finish, but DeRoss said that the only way to compete with the high edge count of solid tools is to slow down the processing speed. Pollock explained that by its nature, indexable tools will never exhibit a continuous cutting edge as perfectly as a solid tool. "Even if the long-edged indexable tools may be arranged well, or even to the point where you can't feel the witness line, there is almost always a witness line.... Since the indexable tool is a component, there is always something wrong. Match. It is an insert [included] inserted into the steel body. It will never have a pocket in the perfect position, and you will never be able to grind the blade to the exact size. There will always be a little accumulation. For sturdy tools , This is not the case."

This is not to say that tool manufacturers are not trying to tighten these tolerances. Tucker said Sandvik Coromant was the first company to machine the valve body in a hardened state, making "more precise tools" (rather than heat treating it after cutting the groove). He added that Sandvik Coromant’s goal is to achieve 0.0005" (0.0127 mm) of radial runout of the groove. It is now looking for new materials and different processes to achieve tighter tolerances. It can be achieved when assembling the tools in the workshop. The goal "depends on," he said. For example, the blade needs to be ground to close to maintain the tolerance. Otherwise, they should all come from the same batch. But if it is a real indexable tool and use randomly selected production With the blade, "you" may see five-tenths of you from insertion to insertion and ground insertion," Tucker said.

"If the periphery of the blade is not ground," Walter USA's Pollock added, "the change will be on the order of ±0.001-0.0015" [0.0254-0.0381 mm]. This can result in total jitter as high as 0.003 [0.0762] "in the most extreme cases."

"Indexable" does not necessarily mean "simple" or "standard". For example, “gear milling used to require a dedicated gear hobbing machine,” says Tonne of Horn USA. However, advances in CAM software and cutting tool technology have made it possible to use the C axis to simultaneously produce the most complex gear shapes and splines on a standard lathe. Because of these advancements, Horn is also producing gear turning tools on indexable platforms. "DeRoss mentioned Sandvik Coromant's indexable milling cutter for the shape of the turbine root. They also made a special tulip cutter with indexable and solid carbide for the corresponding shape in the ring of the insert lock. It has a round shape. Railway tracks on the edges are another important application for special indexable tools.

Pollock cites custom blade shapes for crankshaft machining. "It is one of the most expensive components in internal combustion engines. Machining them consumes a lot of blades, so this field is of great concern." Pollock explained that the shape of the blade and the geometry of the end face are both important. "In order to process carbon steel, This produces long chips and can control them." He added that being able to suppress unique blade shapes and keep them within tight tolerances during the sintering process is "probably the biggest innovation in manufacturing these forming tools." "Starting from the sintering furnace, tolerances are sufficient. You don't have to come back to grind them, which makes complex geometries more possible. If they must be ground, then the shapes that can be produced are more limited."

Walter USA also produces indexable thread milling cutters with special inserts. (For tools up to 7/8 inch [22.23 mm] diameter, the tool can also be made in a solid carbide version.) According to Pollock, the design cuts the chip and folds it up to release it from the material. Pollock explained that the tool has a multi-row arrangement and requires multiple rotations to cut a complete thread. "Depending on the thread pitch, it may take up to four to five times to complete a complete thread. However, the resulting meshing force is lower. Through our design, we can feed the tool faster. In fact, we can shorten the cycle time to more than Cutting taps is faster. Generally, when switching from tapping to thread milling, one usually expects to improve thread quality, extend tool life, and increase the cost of each part. But it also means knowing that you will have to sacrifice cycle time , Because thread milling usually takes longer. This is not the case with this tool."

When should you consider customizing tools for your unique situation? Sandvik Coromant’s Tucker replied: “When the number of parts and the return on investment make sense....or, if a function on the part cannot be done with standard tools.” Tonne said that most of Horn’s sales are It is carried out by order or customized solutions, and the following standards are provided: "When the complexity or features of the part have stricter tolerances than the machine tool can handle. For example, if the groove pitch must be within micrometers, and the machine tool If there are some errors due to wear of the parts, then a custom solution will be a good choice. If the programming of features becomes too complicated, an indexable custom solution will be a good choice, [because it will] If you can operate at the same time , Such as chamfering, profile milling and groove milling."

Coating remains a key factor in improving the durability of blades and cutter bodies. The "secret recipe" used by OEMs to obtain the latest coatings is still proprietary and hidden. Sandvik Coromant has released a new version of its Inveio coating, which uses what Tucker calls a CVD process that can be controlled at the "molecular level" so that multiple layers can form uniform columns. "We have really mastered the consistency of how the width and length of each layer are aligned.... Our tool life has been greatly increased, and even the wear of the cutting edge of the blade has also been greatly increased." Sandvik Coromant's website does not tell you The composition of the coating, but Tucker reports that it is TiAlN.

Sandvik Coromant also released the PVD coating Zertivo that follows the same principle. Tucker once again stated that the differentiating factor is that Sandvik Coromant can "add greater strength at the micrometer or nanometer level of the edge line. We can bring the powerful particles to the edge line where we need them, and retain other materials." Where we need toughness." He also emphasized that 90% of the company's coatings are done in-house, using specialized processes, including secret edge preparation.

In the case of Walter USA, it has developed an ultra-low pressure CVD coating process, which Pollock says can “put more aluminum into the aluminum titanium nitride coating. We often recommend using aluminum titanium nitride for milling, Because it is very tough and very thin, it can handle the interruption of milling well. But by adding more aluminum to aluminum titanium nitride, you can run faster because aluminum is the heat-resistant part. It can It can withstand more heat like an aluminum oxide insert, but due to titanium, it is not as fragile as that coating." He described this method as a hybrid method that can achieve PVD at the same time.​​ Advantages of coating and CVD alumina coating. It requires modifications to the furnace, but naturally Walter will not say more, except for the name: Tiger-tec Gold.

Pollock said that Walter USA has also introduced a unique coating for its tool body "to help protect the steel and avoid chip washing." He said that the entire industry has transitioned from simple surface hardening and through hardening to steam oxidation. Produce a black surface to control rust, nickel plated, and produce a flat silver appearance. "Now the industry seems to be returning to black. But ours is not just the steam oxidation process; this is a harder, more wear-resistant actual coating called Walter BLAXX." Tucker mocked Sandvik Coromant's future In October 2022, a new milling cutter body was launched, and its service life was eight times that of the materials currently used.

Martin Dillaman, application engineering manager/project manager at Saegertown Greenleaf Corp. in Pennsylvania, observed that the improved CAM software has done a lot to increase tool life. "A greater focus on maintaining a consistent chip thickness helps to extend tool life and control wear on tool length. Whether it is an indexable tool or a solid tool, this helps."

Dillaman said that Greenleaf is also focusing on developing blade cutters with coolant lines to extend service life. "Whether it is used for liquid coolant or air coolant, you need to control the flow to the cutting edge to help prevent chip accumulation and expel the chips from the area where the next blade will pass for cutting. This prevents possible chip re- Cut or pile into grooves and contribute to overall performance and finish."

Ceramic molds are an important part of Greenleaf's business. For these tools, liquid cooling is not recommended due to thermal shock and the resulting loss of tool life. Interestingly, in its tests, Greenleaf found that it is not necessary to design a knife handle for air coolant that is different from liquid coolant. Many of its handles can use ceramic or cemented carbide blades.

But not everyone thinks that coolant is always or often needed, and high-pressure coolant (700-1,000 psi) seems to be controversial. In Pollock's view, high-pressure coolant is useful for grinding and turning, but it is not needed in milling. The high-pressure pump "brought a lot of vibration to the cutting", not to mention "screaming like a banshee" during operation. In fact, Pollock said, "There are some materials that we don't like to use coolant. Carbon steel is one of them. We prefer to cut it dry. If we need to evacuate chips, we might try to put some air on it." If the material Liquid coolant is required, such as titanium, Inconel, stainless steel or aluminum, low pressure coolant is sufficient.

On the other hand, Tonne said: “As more and more insert seats are added to each tool, high-pressure coolant becomes more and more common. If your tool has 20 slots, you need a high enough The inlet pressure and the amount of coolant supply each slot. The tangential milling systems such as Horn’s 610, 406 and 409 systems are also one reason why high-pressure coolant is beneficial. The strong core of the tangential tool, high feed rate and small Chip flutes require volume and pressure to discharge chips. When grooving and profiling difficult-to-machine alloys, the cooling and chip removal capabilities of high-pressure coolant are required.

"The standard coolant system on a typical machine may be in the range of 80 to 200 psi," he continued. "For each coolant outlet, the pocket pressure is separate. For a 100 psi system and 20 pocket cutters, this means that the outlet pressure for each coolant output is about 5 psi. There is no magic number for each application, but It must be as many as possible."

Accelerated settings have improved efficiency and profit margins have also improved. DeRoss said that Sandvik Coromant now uses larger screws on some of its milling cutters because "sometimes smaller screws are difficult to handle. After use, they can begin to lock in the tool. So, larger screws are more difficult to handle. Easy to disassemble."

Dillaman points out that Greenleaf usually uses a circular geometry, “because of the strength of the insert and its chip-thinning ability in milling. It also helps to index the insert faster and easier because you can use simple Rotate the blade to loosen the screw and index to the next good edge. Whether you rotate it 20 degrees or up to 90 degrees, it’s just a simple rotation, lock it back in place, and you’re ready to go." As mentioned earlier, Greenleaf offers ceramic and cemented carbide blades and handles, which can handle any kind. "In this way, you can use the same tool, especially in the workshop or where you move between multiple materials and multiple hardnesses. One tool can be used in many different grades, whether it is cemented carbide or ceramic."

Greenleaf also offers a series of knives with indexable inserts. Dillaman explained that they are called C4 and CP4 tools, and they allow users to easily switch between completely different blade geometries. "Whether it is a round blade, a square blade or an 80° diamond, you can change the nest according to the geometry of the machined part."

Tucker and DeRoss emphasized the advantages of rapid tool change change, such as Coromant Capto, which is safely integrated with the spindle and has high repeatability. The patent of the Capto interface is now expired, and various vendors provide many expansion and reduction adapters, as well as adaptations to other machine interfaces. DeRoss reports that approximately three-quarters of the new multi-tasking, multi-function machines with B-axis heads are now equipped with Capto spindles.