Carmex Carbide Threading Inserts - NPSM - TiAlN Coated - threading insert size

Based on field reports, Iscar’s Gadzinski concurred that coolant pressure, as well as coolant selection, are major factors when turning heat-resistant alloys. However, high-pressure’s coolant role is not so much in breaking the chip but in enhancing lubricity and—more importantly—dissipating the heat. “It’s not that they’re so hard to cut, but what do you do with all the heat?” he asked. “If you can’t get the heat out with the chip, the only thing you can do is get rid of as much as possible with coolant.”

Added to titanium-carbide tooling to permit machining of hard metals at high speeds. Also used as a tool coating. See coated tools.

Substance used for grinding, honing, lapping, superfinishing and polishing. Examples include garnet, emery, corundum, silicon carbide, cubic boron nitride and diamond in various grit sizes.

Yes, there are various types of carbide inserts designed for specific machining applications. Some common types include turning inserts, milling inserts, and drilling inserts, each tailored to different cutting operations.

Although boosting productivity trumps extending tool life, controlling insert life is important. An end user turning superalloys should change or index an insert at the end of a radius or end of a part rather than in the middle of a cut to avoid creating stress points in the part, Loughney explained. “A stress point would be a possible failure point,” he said. “Especially in aerospace, you don’t want that to happen.” CTE

Cutting tool material consisting of polycrystalline cubic boron nitride with a metallic or ceramic binder. PCBN is available either as a tip brazed to a carbide insert carrier or as a solid insert. Primarily used for cutting hardened ferrous alloys.

“The selection process is based on whether you’re fine finishing or roughing,” he said. “If you find the right combination of DOC and feed rate, almost all chipbreakers are going to work fairly well as long as they are sharp enough.”

Hub Whitley, Mogas lead man, was instrumental in selecting the appropriate inserts to overcome the company’s challenges when machining Inconel 718.

Cutting tool material consisting of polycrystalline cubic boron nitride with a metallic or ceramic binder. PCBN is available either as a tip brazed to a carbide insert carrier or as a solid insert. Primarily used for cutting hardened ferrous alloys.

Microprocessor-based controller dedicated to a machine tool that permits the creation or modification of parts. Programmed numerical control activates the machine’s servos and spindle drives and controls the various machining operations. See DNC, direct numerical control; NC, numerical control.

He explained that chip formers are designed to break a chip at either a high DOC or a low feed rate. It depends on the proximity of the chipbreaker facet to the cutting edge as to how the chip coming off the cutting edge hits the facet, causing the chip to curl back over itself. Typically, a low feed requires a shorter distance from the cutting edge to the chip former’s facet.

In an application turning Inconel 718, Mogas Severe Service Ball Valves, Houston, effectively applies flood coolant to cool the insert, part and chips (see sidebar on page 60). “Typically, few cutting tool manufacturers would recommend using coolant in an operation like this with ceramic tools because of thermal fracturing of the ceramic when getting the tool hot and cold, hot and cold,” said Craig Kippola, sales engineer for Ingersoll Cutting Tools, Rockford, Ill. “But they do a very good job of this.”

Overall, carbide inserts play a vital role in modern machining processes, offering high precision, efficiency, and cost-effectiveness. Understanding the characteristics and applications of carbide inserts can help improve machining operations and achieve superior results.

Loughney noted that an insert’s entry angle has a direct impact on tool life, as well as chip thickness. A CNMG insert has a large entry angle of 95°, which makes it prone to notch wear and the DOC. That leads to premature insert failure. By switching insert shape to SNMG and selecting a toolholder with a 45° entry angle, there will be less heat at the cutting edge because a larger portion of the cutting edge is applied. That creates a chip thinning effect, resulting in longer tool life and less heat transferred into the workpiece.

Rotary tool that removes hard or soft materials similar to a rotary file. A bur’s teeth, or flutes, have a negative rake.

“The rule of thumb is you want 80 percent of the heat to leave with the chip, 10 percent stays with the part and 10 percent stays with the insert,” said Patrick Loughney, turning product specialist for Sandvik Coromant Co., Fair Lawn, N.J. “You don’t want to get the material so hot that you’re workhardening it.”

Cutting tool material consisting of natural or synthetic diamond crystals bonded together under high pressure at elevated temperatures. PCD is available as a tip brazed to a carbide insert carrier. Used for machining nonferrous alloys and nonmetallic materials at high cutting speeds.

Workpiece is held in a chuck, mounted on a face plate or secured between centers and rotated while a cutting tool, normally a single-point tool, is fed into it along its periphery or across its end or face. Takes the form of straight turning (cutting along the periphery of the workpiece); taper turning (creating a taper); step turning (turning different-size diameters on the same work); chamfering (beveling an edge or shoulder); facing (cutting on an end); turning threads (usually external but can be internal); roughing (high-volume metal removal); and finishing (final light cuts). Performed on lathes, turning centers, chucking machines, automatic screw machines and similar machines.

Kippola’s recommendation for turning and milling was to apply Ingersoll ½ " round, grade-AS20 silicon-nitride ceramic inserts and run them at about twice the speed of any other ceramic insert the company tried. Kippola attributes the enhanced performance to Ingersoll’s ceramic recipe. “It’s like the ingredients for a cake,” he said. “You can give them to 10 people and end up with 10 different cakes.”

Last August, Horton and Whitley turned to Craig Kippola, sales engineer for Ingersoll Cutting Tools, and Kirk Higby of tooling distributor Cutting Tools Inc., Houston, for recommendations on grades and machining parameters. “They solved past problems for us very well,” Horton said, “so they were the natural ‘go-to guys’ this time around.”

However, with superhard tools, coolant application isn’t an issue because superalloys are predominantly machined dry, according to Mastertech’s Frakes. Instead, high-pressure chilled air controls and clears chips. When the operations are run wet, he noted that the pressures can be as high as 3,000 psi. “The coolant pressure is high enough that it breaks chips up during machining.”

No fun! That’s the general sentiment when turning nickel-base, high-temperature superalloys, particularly Inconel but also Hastelloy, Waspaloy, Rene, Haynes, Incoloy and a host of others. That’s because the high nickel content—half or more—does not conduct heat well, so it builds up at the cutting edge and doesn’t transfer into the chips.

Tendency of all metals to become harder when they are machined or subjected to other stresses and strains. This trait is particularly pronounced in soft, low-carbon steel or alloys containing nickel and manganese—nonmagnetic stainless steel, high-manganese steel and the superalloys Inconel and Monel.

Rather than the nickel, it’s the chromium in high-temperature alloys that has a tendency to workharden, as well as become abrasive, according to Mike Gadzinski, national training manager for Iscar Metals Inc., Arlington, Texas.

Machining operation in which metal or other material is removed by applying power to a rotating cutter. In vertical milling, the cutting tool is mounted vertically on the spindle. In horizontal milling, the cutting tool is mounted horizontally, either directly on the spindle or on an arbor. Horizontal milling is further broken down into conventional milling, where the cutter rotates opposite the direction of feed, or “up” into the workpiece; and climb milling, where the cutter rotates in the direction of feed, or “down” into the workpiece. Milling operations include plane or surface milling, endmilling, facemilling, angle milling, form milling and profiling.

He emphasized that effective geometry begins with a highly positive top rake and rake face, as well as a positive, sharp cutting edge, to reduce tool pressure and minimize the amount of heat generated in the cutting zone. That allows a slightly higher cutting speed. “The flipside of the coin is that, unfortunately, the sharper and more positive your cutting edge is, the less tool life you’re going to get, but it’s the lesser of two evils at that point,” Gadzinski said.

Sandvik Coromant’s SO5F-grade CNMX insert has a 45° entry angle, allowing it to effectively turn heat-resistant superalloys.

When turning nickel-base superalloys, the material will start to string but break into manageable pieces because it becomes so hard, according to Frakes. “It workhardens as you turn it and then the chips break up.”

The flattop, uncoated turning inserts for roughing have a T-land, designated T6, with a 0.004 " width and a 20° angle. The cutting speed is 1,200 sfm and the feed rate is 0.01 ipr. For finish turning, Mogas applies flattop, uncoated inserts with a light hone to provide a cleaner, smoother cut, according to Kippola. The 1,200-sfm cutting speed is the same for finishing, but the feed rate is 0.006 ipr. “We’re getting a 32-rms finish,” Horton said.

To effectively turn these materials, applying inserts with the proper geometric features is critical. “The geometry, in our opinion, makes much more of a difference than the coating or the substrate,” Gadzinski said.

To control chips when turning superalloys, such as Inconel 618 and 718, Tungaloy America Inc., Wood Dale, Ill., recently introduced the AH905-grade insert with HMM chipbreaker. The ribbed chipbreaker diminishes heat in the gullet to keep it from penetrating the insert, according to Brian Sawicki, the toolmaker’s senior manager of engineering and products. Tungaloy reports that the chipbreaker sits flush against the shim seat to improve stability and extend tool life, has a sharp T-land to reduce cutting force and the rake surface geometry minimizes heat transferred from chips. “The chipbreaker produces less surface contact with the chip,” Sawicki added.

About the Author: Alan Richter is editor of Cutting Tool Engineering. He joined the publication in 2000. Contact him at (847) 714-0175 or alanr@jwr.com.

Tangential velocity on the surface of the tool or workpiece at the cutting interface. The formula for cutting speed (sfm) is tool diameter 5 0.26 5 spindle speed (rpm). The formula for feed per tooth (fpt) is table feed (ipm)/number of flutes/spindle speed (rpm). The formula for spindle speed (rpm) is cutting speed (sfm) 5 3.82/tool diameter. The formula for table feed (ipm) is feed per tooth (ftp) 5 number of tool flutes 5 spindle speed (rpm).

The principal components in the leakproof ball valves are balls and their mating valve seats. The valves help control hot, corrosive process fluids found in refining, chemical and mining operations. Each valve has one ball and two seats. The ball has a bore down the middle, and rotating the ball opens and shuts the flow.

“Anything that has a lot of nickel will normally give you problems with chip control,” Gadzinski said. “You’re never going to be really happy with it.”

One of the main advantages of using carbide inserts is their long tool life. Due to their hardness and wear resistance, carbide inserts can last significantly longer than traditional cutting tools, reducing the need for frequent tool changes.

The tools are kept just warm to the touch, which significantly shortens indexing time. “We deliberately accept high edge wear in exchange for higher throughput, which necessarily means more frequent indexing,” Horton said. “Naturally, we want to avoid indexing delays due to inserts becoming too hot to handle right away.” Kippola added that he has seen processing at other plants delayed for 10 minutes or more, waiting for the tool to cool enough to handle. Accordingly, Mogas applies flood coolant when turning.

Gadzinski added the DOC taken should be greater than the insert’s corner radius to prevent the chip from curling too fast and pushing the insert away from the part. As suppliers forge near-net-shape workpieces closer to a part’s final dimensions, a smaller radius than would typically be dictated by the part print might be required.

Carbide inserts are typically made of a combination of tungsten carbide, cobalt, and other materials. This unique composition gives carbide inserts their hardness, durability, and resistance to wear.

When selecting a carbide insert, factors such as material being machined, cutting speed, and feed rate must be considered. It's essential to choose the right insert geometry, coating, and grade to optimize performance and achieve the desired results.

Crystal manufactured from boron nitride under high pressure and temperature. Used to cut hard-to-machine ferrous and nickel-base materials up to 70 HRC. Second hardest material after diamond. See superabrasive tools.

According to Gadzinski, a 0.032 " corner radius on a typical diamond or square insert will be suitable for 75 percent of the applications. “It’s only when you get into very small-diameter parts that you need a smaller corner diameter,” he said. “Our general recommendation is to go with as large of a radius as you can tolerate and still stay within the part specifications.”

Substances having metallic properties and being composed of two or more chemical elements of which at least one is a metal.

Mogas previously machined Inconel 718 with carbide inserts and roughed at a cutting speed of 80 sfm and a 0.01-ipr feed. To boost throughput, Zach Horton, the company’s CNC programmer/supervisor, and lead man Hub Whitley determined ceramic inserts should replace the carbide ones. They tried ceramic inserts and achieved 50 to 100 percent productivity but edge failures were so unpredictable they defeated process stability.

High-pressure coolant can also aid chip control. According to Loughney, Sandvik Coromant’s tool bodies with built-in coolant nozzles direct high-pressure coolant to the tool/workpiece interface without any adjustment. “A lot of operators, when they have an adjustable nozzle, the first thing they do is adjust it,” he joked.

Fluid that reduces temperature buildup at the tool/workpiece interface during machining. Normally takes the form of a liquid such as soluble or chemical mixtures (semisynthetic, synthetic) but can be pressurized air or other gas. Because of water’s ability to absorb great quantities of heat, it is widely used as a coolant and vehicle for various cutting compounds, with the water-to-compound ratio varying with the machining task. See cutting fluid; semisynthetic cutting fluid; soluble-oil cutting fluid; synthetic cutting fluid.

Extremely hard material added to tungsten carbide to reduce cratering and built-up edge. Also used as a tool coating. See coated tools.

Runs endmills and arbor-mounted milling cutters. Features include a head with a spindle that drives the cutters; a column, knee and table that provide motion in the three Cartesian axes; and a base that supports the components and houses the cutting-fluid pump and reservoir. The work is mounted on the table and fed into the rotating cutter or endmill to accomplish the milling steps; vertical milling machines also feed endmills into the work by means of a spindle-mounted quill. Models range from small manual machines to big bed-type and duplex mills. All take one of three basic forms: vertical, horizontal or convertible horizontal/vertical. Vertical machines may be knee-type (the table is mounted on a knee that can be elevated) or bed-type (the table is securely supported and only moves horizontally). In general, horizontal machines are bigger and more powerful, while vertical machines are lighter but more versatile and easier to set up and operate.

Carbide inserts are commonly used in machining operations to cut, shape, or finish materials such as metal, wood, or plastic. They are inserted into a tool holder or cutting tool, providing the cutting edge needed to remove material efficiently.

Because heat-resistant alloys tend to produce long, stringy chips when turned, chipbreakers are generally employed to manage chip size. Similar to a tool’s rake angle, a positive chipbreaker is needed to shear the material as it forms the chip, according to Loughney.

Nonetheless, Frakes emphasized that machine tool rigidity is the No. 1 issue when turning challenging materials. “The machine tool has to be capable of keeping the toolholder and cutting tool rigid in the cut so there isn’t vibration, which dramatically decreases tool life,” he said.

Mogas makes the balls from chucked bar stock by boring the main bore, mounting the workpiece on a mandrel, turning the OD and then moving the part to another machine to pocket mill a rectangular slot. The valve seats only require OD and ID turning, with the ID being a spherical radius to mate with the ball.

Alan holds a bachelor’s degree in journalism from Southern Illinois University Carbondale. Including his 20 years at CTE, Alan has more than 30 years of trade journalism experience.

Loughney said the toolmaker witnessed “dramatic differences in chip control at 1,000 psi” when it conducted tests applying a sharp-geometry CNGP insert under normal and high coolant pressures. “We’ve also seen up to a 30 percent better tool life,” he said.

Cutting tool materials based on aluminum oxide and silicon nitride. Ceramic tools can withstand higher cutting speeds than cemented carbide tools when machining hardened steels, cast irons and high-temperature alloys.

The top face geometry puts more of the machining heat into the chip than in the tool, toolholder or workpiece, according to Ingersoll. This not only protects the inserts, but also helps quicken indexing. Horton noted that the 50 to 55 percent nickel content in Inconel 718 creates a lot of heat when machined, which helps ceramics produce thin, manageable chips. The ceramic insert “doesn’t quite melt the material, but flakes it off, if you will. It’s almost like snowflakes flying everywhere,” he said, adding that’s in contrast to other tool materials. “If you’re cutting with carbide, the nickel is horrible.”

Working in the machine shop at Mogas Severe Service Ball Valves, Houston, has its pluses and minuses. On the plus side, there’s plenty of work. The order backlog is so hefty at the process valve manufacturer, which is part of the global company Mogas Industries, that the CNC and manual machine departments must run 24/7 just to keep up.

The minus is that, to fill those orders, Mogas must machine a lot of “uncooperative” Inconel 718. The heat-resistant alloy is notorious for burning up cutting tools and generating long, stringy chips. This limits machining parameters and necessitates unpredictable and frequent stoppages for indexing.

Enlarging a hole that already has been drilled or cored. Generally, it is an operation of truing the previously drilled hole with a single-point, lathe-type tool. Boring is essentially internal turning, in that usually a single-point cutting tool forms the internal shape. Some tools are available with two cutting edges to balance cutting forces.

Angle of inclination between the face of the cutting tool and the workpiece. If the face of the tool lies in a plane through the axis of the workpiece, the tool is said to have a neutral, or zero, rake. If the inclination of the tool face makes the cutting edge more acute than when the rake angle is zero, the rake is positive. If the inclination of the tool face makes the cutting edge less acute or more blunt than when the rake angle is zero, the rake is negative.

He added that the high-pressure coolant will help during interrupted turning by keeping the insert cooler so it won’t experience as much thermal shock as moves in and out of the cut.

Engagement of a tool’s cutting edge with a workpiece generates a cutting force. Such a cutting force combines tangential, feed and radial forces, which can be measured by a dynamometer. Of the three cutting force components, tangential force is the greatest. Tangential force generates torque and accounts for more than 95 percent of the machining power. See dynamometer.

To help prevent chipping and reduce the tool pressure when turning nickel-base alloys with the superhard materials, Frakes recommends a neutral to -5° rake angle. He added that coatings, such as titanium nitride and titanium carbide, are often applied to PCD and PCBN inserts as edge wear indicators so operators know which edge has been used when indexing. The coatings also provide lubricity and extend tool life.

Groove or other tool geometry that breaks chips into small fragments as they come off the workpiece. Designed to prevent chips from becoming so long that they are difficult to control, catch in turning parts and cause safety problems.

And that’s essential because of the high amount of heat in the cut and the chips. “They’re on fire,” Kippola said. “Even with the coolant on it you can see the sparks flying.”

Similar to the negative cutting geometries sometimes found on superhard PCD and PCBN for superalloy applications, Kippola noted that “extremely hard” ceramic inserts have a negative land to provide edge strength.

Although Frakes noted that most of the chipbreakers found on Mastertech inserts are in PCD for machining nonferrous materials, mostly aluminum, they are also put into PCBN inserts. “That’s normally because our customers will run from less hard materials and then turn into hardened journals and welded areas,” he said, “and they want to break the chip up in the softer sections.”

In addition to radius hones, Thomas E. Frakes, president of Mastertech Diamond Products Co., Mentor, Ohio, noted that appropriate edge preparations on the company’s polycrystalline cubic boron nitride and PCD turning inserts include various K-lands and chamfers. A hone style that can be effective when turning high-temperature alloys is the waterfall hone, he added. “Instead of a conventional full radius hone around the edge, it creates a shape on the edge that looks like water falling over a rock,” Frakes said. “It creates a small chamfer with a radius hone on the cutting edge, which will increase as it goes along to strengthen the edge.”

He noted that the insert grade, which is the company’s hardest for turning high-temperature alloys, is designed for continuous cuts with a DOC from 0.020 " to 0.125 " per workpiece side and a 0.004- to 0.012-ipr feed rate.

Secures a cutting tool during a machining operation. Basic types include block, cartridge, chuck, collet, fixed, modular, quick-change and rotating.

Carbide inserts are a crucial component in many machining processes, but what exactly are they? Let's dive into the world of carbide inserts to understand their importance and functionality.

In addition, Loughney said, “Everybody runs into issues when they want to machine into a square shoulder.” That’s the domain of the semifinishing and finishing inserts, whereas roughing requires a strong edge and a strong insert shape. “When it comes to roughing the material, it’s always better to use a round insert,” he added, noting that ceramic ones are “your best bet” when roughing Inconel.