Tooling Up with Indexable Cutters

Simply put, steel costs less than carbide

Indexable insert cutting tools continue to evolve from predominantly roughing applications to finish machining, and are becoming available in smaller diameter tools. The most obvious advantages of indexables lie in their ability to multiply the number of effective cutting edges without the major commitment typically needed for solid-carbide round tools.

Indexable inserts, however, must be selected with careful attention to size, shape, geometry, and grade for the type of workpiece material and application, coatings, and nose radius for good chip control. Here's how products from leading suppliers are designed to meet customer requirements for optimum metal removal with indexable cutting tools.

Sandvik Coromant has introduced a new method called CoroTurn Y-axis turning for machining complicated shapes and pockets with a single tool with benefits that include reduced cycle time, improved component surface, and more stable machining. At the heart of the new turning method are two indexable cutting tools: the new CoroTurn Prime variant is suitable for shafts, flanges, and components with undercuts; while the CoroPlex YT twin-tool, featuring CoroTurn TR profiling inserts and CoroTurn 107 round inserts with rail interface, can be used for components with pockets and cavities.

The Y-axis turning development follows Sandvik Coromant's success with its innovative PrimeTurning, non-linear turning and interpolation turning for which two indexable inserts were developed: the CoroTurn Prime A-type tool with three 35° corners designed for light roughing, finishing, and profiling; and the CoroTurn Prime B-type tool with double-sided negative inserts with four cutting edges for finishing and roughing.

"One could say that these advances, together with advanced capabilities in modern machines and CAM software, have paved the way for the new Y-axis turning method," said Staffan Lundström, product manager, turning, Sandvik Coromant. "And with the tools and method now in place, we look forward to exploring the possibilities this method can present to our customers."

CoroTurn YT Y-axis turning is a method for simultaneous three-axis turning with interpolation of the milling spindle axis. The new tools can also be used in "static mode" with a locked spindle for flexible two-axis turning with fast insert indexing. The method is suitable for all materials and requires a multitasking machine with options to allow interpolation of the milling spindle axis during turning. All operations are performed with one tool, including roughing, finishing, longitudinal turning, facing, and profiling.

Y-axis turning, as the name implies, makes use of the Y-axis. All three axes are used simultaneously when machining. The tool rotates around its own center. The insert is placed in the Y-Z plane, and the milling spindle axis interpolates during turning. This allows intricate shapes to be machined with a single tool.

Benefits of Y-axis turning include the ability to machine several features with a single tool without tool changes, reducing cycle time, and minimizing the risk of blend points or irregularities between adjacent machined surfaces, Sandvik Coromant said. Wiper inserts can be kept perpendicular to the surface to also produce a wiper effect on tapered surfaces. The main cutting forces are directed into the machine spindle, improving stability and reducing the risk of vibration. A constant entering angle dramatically improves chip control and makes it easier to avoid chip jamming.

Tool path programming for PrimeTurning is supported by CAM partners for generating optimized NC codes to speed turning. PrimeTurning is recommended for mass production or components needing frequent setups and tool changes on machines, including turning centers, vertical lathes, and multitasking machines. For external turning, it is best suited for short and compact components and slender components using a tailstock. For internal turning, it is best suited for diameters above 40 mm and overhangs up to 8-10 XD. Combining Y-axis turning with non-linear turning or PrimeTurning further boosts productivity, according to the supplier.

For heavy-duty precision machining, Ingersoll Cutting Tools, Rockford, Illinois, provides custom-indexable tooling solutions for applications in aerospace, rail, oil and gas, and automotive drivetrain. This includes products designed for use with the latest CNC machine tools as well as legacy equipment.

Benefits of using indexable tooling (when compared to solid tooling), according to the supplier, include:

Cost per edge economy—Indexable inserts have multiple indexes and use less carbide.

Grade and geometry flexibility—Indexable inserts are offered with multiple corner sizes, geometries, and grades that fit the same pocket.

Higher productivity—Indexable inserts offer strengthened edge geometry for durability and higher chip load capability.

Indexables are traditionally used for most roughing applications. However, improvements in manufacturing accuracy and methodology also are increasingly opening doors for use in finishing applications, Ingersoll said.

Also, indexables are beneficial for cubic boron nitride (CBN) and polycrystalline diamond (PCD)-tipped inserts, where it's possible to eliminate integral brazed-type tools.

Trends in Ingersoll's indexable insert development include smaller indexable tools—as small as 0.250" (6.4 mm) for a single-effective indexable end mill, and 0.375" (9.5 mm) for three-effective units. Advances include reinforced edges for aggressive roughing applications, coatings with better adhesion, and hi-feed geometries in many milling and turning product lines. The new IN2055 grade will replace the current IN2005 for all deep hole-drilling families. IN2055 is said to enable four times longer tool life in machining steel, stainless, and high-temp alloys.

According to Ingersoll, as machines become more capable to run at higher rpm and table feeds, new indexable tool geometries such as hi-feed and barrel cutters produce greater productivity and quality. Ingersoll's SFeedUp products combine enhancements that focus on high speeds with high feeds. "Many new machines have higher speeds and lower torque, so we expect the trend of hi-feed machining with lighter Ap (depths of cut) or Ae (stepover) to continue," said Mike Dieken, milling product manager.

Advances in indexable cutter design have improved productivity throughput and piece-part quality. Some hi-feed insert geometries can be interchanged with standard insert geometries in the same pocket. Smaller lead angles promote aggressive feed rates using the chip thinning principle, according to Dieken.

DeepTrio indexable gundrills for machining centers, lathes, and gundrill machines are replacing brazed carbide tip gundrills. "DeepTrio indexable gundrills provide up to six times the performance as well as reducing downtime for tool changes," said John Lundholm, Ingersoll's DeepTrio and drills product manager. "When a brazed gundrill needs to be replaced, the machine is shut down for a long period of time. DeepTrio inserts have three cutting edges, so indexing the insert is accomplished in seconds instead of an hour. An added benefit is that the DeepTrio indexable gundrill uses the same guide bushings and support bushings as a brazed gundrill, so no machine component changes are necessary," he noted.

Successful machining with indexable inserts begins with a rigid toolholding connection, whether it's used on new or legacy machine tools for turning, milling, drilling, or reaming. Advanced machines might have a leg up, though, according to Kennametal Inc., Latrobe, Pa. New modern machining centers utilize system tools like the KM modular system that allows easy tool change and enables pre-setup in front of the machine with much less machine downtime.

Generally, new machines are more agile and have higher speed capabilities. System tools that serve as the link between the cutting edge and machine are a key factor for high performance and results. For example, development of the KM coupling for vertical turning machines, lathes, and multitasking machines provides secure access to performing almost any operation with no compromise in performance, according to Kennametal.

KM modular tooling offers a great deal of flexibility and allows customers to configure the machine to their needs. Higher speeds, rigidity, and agility are capabilities attractive to job shops that take on various types of work, enabling them to maximize return on their capital investments. Another addition to the KM system is the KM4X100 or KM4X63 coupling. This connection has been designed for heavy applications using both indexable and solid tooling. Wherever there is a need to increase bending moments or long reaches, KM4X100/63 would be the optimum connection, Kennametal said.

Advances in indexable cutter design have improved machining results from both legacy and advanced machines. New geometries, grades, and physical and chemical vapor coatings (PVD & CVD) have been introduced where improved chip formation, higher edge toughness, and more thermal and abrasion wear resistance are needed to meet a challenging material application. These include mitral-valve (MV) geometry for steel machining, High-PIMS KCS10B PVD grade for high-temp alloy turning, and KCK20B grade for milling applications, as well as KENGold KCP25C CVD-coated grade for steel machining. All of these reduce the risk of machine breakdown, increase output rates, and reduce machine downtime, which leads into overall productivity improvement, according to Kennametal.

In keeping with digitization and Industry 4.0 advances, there has also been a lot of work done with the machine controls as technology has evolved to use RFID, smart tools, and robots to enhance the tooling and bring more productivity to the machines, the company said.

Indexable cutting tools can offer significant advantages over standard solid-carbide round tools, depending on the application, according to Matt Hasto, applications engineer, Big Daishowa Inc., Hoffman Estates, Illinois. He cited applications for chamfering, back-spot facing, end milling, and face milling for the company's latest ACT 200 and ACT 300 grades and new PVD coating.

"The PVD coating is different from standard coatings," said Hasto. "It's a multilayer-nanoscale, titanium-aluminum-nitride coating that is impregnated into the carbide for better wear resistance, improved tool life, and increased productivity."

Big Daishowa's chamfering tools are offered in several different types to optimize performance for a given application. Small cutters with multiple inserts allow profile chamfering with optimal feed rates. Other cutters feature large chamfering inserts that permit inner diameter chamfering over a wide range of bore diameters.

Indexable centering tools feature solid tool performance with the economy of indexable tooling where only the cutting tip is replaced, according to the company. The C-Centering Cutter, for example, can face mill, back chamfer, and chamfer, making it a multifunctional tool.

The latest advancement for Big Daishowa's ultra-high-feed chamfering mill now has four C-Cutter Mini inserts instead of two, and a much smaller diameter that allows for higher spindle speed. An increased number of edges produces a dramatically faster feed rate, leading to shorter cutting times and cost savings, according to Hasto.

"Applications for the C-Cutter Mini are pretty universal, mostly chamfering and face milling with extreme efficiency and accuracy," Hasto said. "Back chamfering with the single insert style is easy by reaching through a tapped hole and chamfer the bore or counterbore the hole from the back of the workpiece."

The C-Cutter Mini features a sharp edge for smoother milling due to reduced resistance on the insert. The coating provides wear resistance, increasing the number of cycles that can be run before it's necessary to index the insert to a new edge, according to the supplier.

Big Daishowa also has a single insert type that can be offset and lowered through a hole and recentered to generate features, a centered tool for small front chamfering, and a universal tool that can change angles from 5° to 85° depending on the application.

Whether you’re end milling, pilot drilling, helical milling, or shoulder milling, Big Daishowa offers high-precision end mills that achieve smooth and quiet milling. Indexable mills provide sharp cutting edges in both high radial and axial directions that help maintain smooth and quiet end milling. BIG-PLUS dual-contact design allows for higher precision and rigidity in precision applications. All models also come in modular setups with additional inserts including CKB connections for long reach or heavy applications.

"The standard R-Cutter milling cutters use the inserts, which provide a sharp cutting edge to eliminate burrs along the part edges, providing superior surface finish of the workpiece," Hasto said. "This tool creates radial chamfers on the workpiece for back and front applications. The Speed finisher cutters are designed for high-volume applications allowing for four cutting edges on insert. This means ultra-fine finished with an insert that can be indexed four times before a replacement is needed, saving large amounts of time and money versus a non-indexable tool.

"Our BF (back spot facer) generally is used for workpieces that need back boring for counterbore generation without the operator taking time to flip a workpiece or fixture. The BF cutter is capable of offsetting to reach through the hole, recentering, and generating a counter bore before offsetting again to exit the bore. The BF-Cutter was exclusively designed for the back spot facing of capped bolt holes, sizes M6-M30, or 1/4"-1 1/8" (6.35-28.6 mm), and is ideal for all steels (including stainless), cast iron, and aluminum. The latest insert grades allow for in-depth selection based on material and conditions for the best surface finishes and run times," Hasto said.

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