Walter WXN15 coated grade designed for machining ISO N materials - iso carbide insert

 2024-07-01 15:35:17

Particularly difficult-to-machine nickel alloys include Incoloy 901, Nimonic 80 and 105, and Inconel 625 and 718. The latter is a precipitation-hardenable nickel-chromium alloy with excellent creep-rupture strength at temperatures up to 1,300° F. It is used in gas turbines, pumps and rocket motors, according to ESPI Metals, Ashland, Ore., a supplier of high-purity metals and metal compounds for research purposes. The nominal composition of Inconel 718 includes, among other elements, 52.50 percent nickel, 19.00 percent chromium, 17.00 percent iron, 3.05 percent molybdenum and even a bit of titanium, at 0.90 percent.

Kern machines like this Micro are recommended for providing the productive, precise milling required to limit the need for diamond turning in the first place. This photo was taken at Kern's headquarters in Germany where, like Innolite, the company produces parts as well as machine tools.

The Innolite IL600 can be configured as needed with various tooling and gaging stations. Options include the Overdrive unit, milling spindles, and more. Machines can employ Nano-Grip zero-point clamping modules for easy changeover of tools and workpieces alike.

When reaming nickel alloys, the tool must remove sufficient stock so material that isn’t workhardened is removed, according to von Rohr. The starting point recommendations are 0.010 " for a ¼ " hole, 0.015 " for a ½ " hole and up to 0.025 " for a 1½ " hole.

Machine designed to rotate end-cutting tools. Can also be used for reaming, tapping, countersinking, counterboring, spotfacing and boring.

Coatings are also needed to protect reamers, as well as reduce friction, when cutting nickel alloys. “A coating makes the difference between an application working and not working,” said KOMET’s von Rohr. “You produce less heat and less stress, and it’s just easier for the chip to get out of the way with a coating.”

The first step in meeting this demand is changing old habits. To that end, Innolite and Kern offer Nanogrip, a spring-loaded, zero-point clamping system that enables swapping entire pallets of fixtures and cutting/measuring tools in seconds with no need for realignment. Repeatability is less than half a micron. Well-established in more conventional machining operations, such a system represents new thinking for diamond turning operations where painstaking, manual setup of tools and parts in vacuum chucks is common practice. Dr. Wenzel says.

The system also eases transfer of pallets from the three- and five-axis Kern milling machines recommended for “roughing,” which in this case can require machining surface profiles and shapes with peak-to-valley accuracy of less than ±10 microns. “Diamond turning is not very productive compared to conventional milling,” Dr. Wenzel says. “A Kern machine is going to be superb for providing the repeatability and accuracy required to limit the need for diamond turning in the first place.” However little diamond turning is required, Innolite’s DirectDrive3D offline CNC system ensures it proceeds as fast as possible.

When surface form accuracy is measured in microns and roughness is measured in nanometers, the CNC becomes a bottleneck, he explains. In any application, fluid, precise motion depends on lookahead functionality to scout ahead of the cutter and ensure ample reaction time to adverse conditions, all while the control is simultaneously engaged in other tasks. Diamond machining applications can require plotting motion in such detail that slowing down is the only way for the CNC to keep up.

Dimension that defines the exterior diameter of a cylindrical or round part. See ID, inner diameter.

To ensure the drive system can react dynamically enough, Innolite entirely decouples position and current control from the CNC or any other PC-based “master” computer. Instead, the work is done by field programmable gate arrays (FPGAs) embedded in each axis drive. Dr. Wenzel describes an FPGA as “a computer chip that is very stupid—there’s no Windows running in the background; it can’t execute Outlook or Word. But it can do just one thing and do it really fast: position and current control.”

In addition to running at the correct feed, applying reamers—which cut only on the bevel and taper leads and not on the lands—with up-sharp cutting edges and positive rake angles will shear nickel alloys rather than push the material. “The biggest concern is making sure you have a sharp tool geometry to minimize the amount of heat you produce,” said Allied’s Miller.

Hole or cavity cut in a solid shape that does not connect with other holes or exit through the workpiece.

With speeds maxing out at 3 or 4 khz (that is, 3,000 to 4,000 set points per second), most PC-based position-control systems are too slow. “The handshake that occurs when the CNC calculates and sends commands to the position controller is typically done online, but we do all of the work up-front,” he explains. “Essentially, we can feed more data from our offline CNC than (a PC-based system) could handle.”

While some recommend applying a sulfurized or chlorinated mineral oil to improve both lubricity and antiweld properties when reaming nickel alloys, others emphasize having the proper coolant mixture. “When you get into high-temperature alloys, the concentration of water-based coolants is important,” M.A. Ford’s Schmidt said. “We like to see 8 to 11 percent. With the normal 4 to 6 percent concentration, you have much less lubricity.”

Dr. Wenzel often refers to “diamond turning” because turning is the most common operation in diamond machining. However, Innolite systems like the IL600 are also capable of milling, ruling, fly-cutting and grinding. On this machine, the workholding spindle moves back and forth in Z and up and down in Y to present spinning parts to cutting tools and measurement equipment on the opposing X-axis slide. Periodic checks with both contact and non-contact probes keep the process on track, as do various temperature-control systems and hydrostatic, linear-motor driven axes leveraging high-resolution optical scales. With cutting edges so sharp—some turning insert edge radii measure only 20 nanometers—“everything must be perfect,” Dr. Wenzel says about the need for such features. “If you take a hair and cut it into 1,000 pieces, then take one of those pieces and cut it into four, that’s what we’re working with.”

The burden on the CNC is due more to the intricacy of diamond turned microstructures like these than stringent requirements for surface finish and precision.

Schmidt noted the coatings on M.A. Ford reamers are from 0.0001" to 0.0002" thick and are applied by outside coating companies via flash coat to reduce coating cycle time, and, therefore, coating thickness and the amount of heat entering the tools. The coatings for nickel-alloy reaming applications are primarily silicon-based, he added, noting TiAlN and AlCrN, which are not silicon-based, are also effective.

“Your CNC will allow you to run at two different parameters as you’re going through the workpiece,” Miller said.

When using BTA Heller’s float reaming system, coolant volume is more important than pressure, with 25 gpm per inch in tool diameter being the rule of thumb, according to Sollich. He recommends applying sulfur- or chlorine-based cutting oil and maintaining the oil temperature at 80° to 85° F with a chiller unit to extend cutting tool life 15 to 30 percent.

Because nickel alloys tend to workharden, a slower speed reduces friction and heat generation, von Rohr added. Just as a drilled hole guides a reamer, drilling speed can direct reaming speed. A rule of thumb is to ream at about two thirds the drilling speed, he noted.

Granted, any CNC could theoretically calculate any number of toolpath set points offline. The problem is that calculations take time—enough time to make doing the work in advance impractical. In one experiment, the company used a conventional CNC in offline mode to calculate the tool path for an LED headlight lens mold. With no need for lookahead to scout ahead of the tool in real time, the system ran at 10 kilohertz (khz)—that is, it was tasked with processing 10,000 toolpath set points per second. The calculations took more than 12 hours.

Iscar’s Edler agreed. “As long as you have a good concentration of water-based coolant, say 10 to 12 percent, everything will be fine.”

Hole or cavity cut in a solid shape that connects with other holes or extends all the way through the workpiece.

LED Headlight insert molds like this one are driving demand for increased diamond machining productivity. All photos and video courtesy of Innolite.

“The way I usually explain it to customers is it is very similar to reaming a casehardened material,” said Gary Schmidt of M.A. Ford Manufacturing Co. Inc. “You have the outer crust that’s very hard and you have a softer center. Metal-matrix composite materials are that way too.”

LED Headlight insert molds like this one are driving demand for increased diamond machining productivity. All photos and video courtesy of Innolite.

“Because inserts are not brazed onto the body, high-performance coatings can be considered,” he said, noting indexable inserts repeat within 0.0001 ".

Compared to reaming steel at a cutting speed of about 650 sfm, 200 sfm is appropriate for Inconel 718 when applying BTA Heller Inc.’s float reaming, or skive, tool, noted Mark Sollich, president and CEO of the Troy, Mich., company. BTA Heller states that the tool body holds a floating cutter magazine with two cartridges and two indexable inserts that oppose one another and have diametrical adjustment of 0.080 " to 0.118 ", depending on the tool diameter. Each insert has four cutting edges.

Condition of vibration involving the machine, workpiece and cutting tool. Once this condition arises, it is often self-sustaining until the problem is corrected. Chatter can be identified when lines or grooves appear at regular intervals in the workpiece. These lines or grooves are caused by the teeth of the cutter as they vibrate in and out of the workpiece and their spacing depends on the frequency of vibration.

Minimum and maximum amount a workpiece dimension is allowed to vary from a set standard and still be acceptable.

“Silicon-based coatings were originally designed more for high-speed machining and hardened dies,” Schmidt said, “but they found their way into [the machining of] some of these nickel materials as well.”

The Nanogrip zero-point clamping system's modular design enables users to quickly and easily swap not only workpieces, but also various, multi-station configurations of cutting and measuring tools. Additionally, parts can be moved from Kern machines to Innolite machines without losing location references.

The new S.C.A.M.I. replaceable-head reamers complement Allied’s monoblock and ring-style reamer offerings.

The burden on the CNC is due more to the intricacy of diamond turned microstructures like these than stringent requirements for surface finish and precision.

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

Machined directly in steel, LED headlight mold inserts require layering ridges and other microstructures directly atop complex, contoured surfaces.

Often used as a tool coating. AlTiN indicates the aluminum content is greater than the titanium. See coated tools.

LED Headlight insert molds like this one are driving demand for increased diamond machining productivity. All photos and video courtesy of Innolite.

In contrast, DirectDrive3D did the same work in less than 10 minutes. The difference between the two systems is how the calculations are performed, Dr. Wenzel explains. Running offline enables DirectDrive3D to use parallel processing, or the division of computing tasks among multiple cores (processing units). In contrast, CNC algorithms designed to work while the machine runs use a single core because the calculations are derivative—that is, adjustments made on the way to one toolpath set point can affect how the CNC might react when it responds to the next. “In the end we’re doing the same thing (as a CNC), but because we don’t need the online functionality, we can use different math and parallelize calculations,” Dr. Wenzel says.

Innolite equipment is available in North America as of late last year through Kern Precision, the Chicago-based U.S. arm of fellow German machine tool builder and long-term partner Kern Microtechnik. The two companies’ motivation here is the same as it is in their home market: to help manufacturers of parts with optical-quality surface finish adapt to the unfamiliar demands of new applications, particularly in the automotive industry.

Machined directly in steel, LED headlight mold inserts require layering ridges and other microstructures directly atop complex, contoured surfaces.

Similar to other machining processes, reaming nickel alloys requires a significantly slower cutting speed compared to most other materials, Miller noted. “Usually it’s between 60 and 80 sfm for coated carbide,” he said.

Iscar’s Edler indicated that BAYO T reamers have uneven flute spacing, with two flutes directly across from each other and the remaining ones varied. “It’s definitely to avoid harmonics,” he said.

Instead of removing 0.005 " to 0.008 " of material for holes under ½ " in diameter and 0.008 " to 0.012 " of material for holes ½ " and larger when reaming non-nickel-alloy materials, Iscar’s Edler recommends 0.004 " of stock removal for all nickel-alloy holes. An exception is when the drilled hole is egg-shaped, or out of round, more than 0.004 ". “You’re going to have an area that is not going to clean up,” he said. “You would then need to leave more material to have a completely finished hole.”

FPGA chips operate at 100 khz—that is, the query for position feedback happens 100,000 times per second in every axis, versus a few thousand in the most powerful CNCs. With tool paths pre-plotted, axis motion values precalculated and the CNC’s capacity freed, enhanced diamond machining productivity is well within reach. “Say we’re cutting a heads-up display mirror for a car,” Dr. Wenzel says. “Conventional diamond turning would take about 11 hours. On our IL600 machine, we can cut that to about three and a half hours.”

According to von Rohr, too low a feed rate results in glazing, or workhardening, of the workpiece and excessive tool wear, while an excessive feed reduces the accuracy of hole dimensions and surface finish quality. He recommends a feed from 0.0015 " to 0.004 " per flute per revolution when reaming nickel alloys.

Compared to reamers with brazed carbide tips, indexable-insert reamers offer more coating options, according to von Rohr. That’s because the carbide tip must be coated after brazing and the temperature used to apply the coating cannot be higher than what the brazed connection allows, meaning too high a temperature would cause the braze to fail.

To maintain a sharp cutting edge, the coating can’t be too thick. “A thick coating does not necessarily mean you have a better tool,” von Rohr said. “It’s actually the opposite; a thick coating may crack easier.”

Angle between the side-cutting edge and the projected side of the tool shank or holder, which leads the cutting tool into the workpiece.

“A float reaming tool is designed to follow the existing hole and give uniform size, finish and wall thickness from start to finish, producing a true round bore,” Sollich explained. “When you start into the bore, you introduce hydraulics to the tool, expanding the floating magazine, or cutters, to whatever size you require and skiving through the part with high-volume coolant running on the tool OD, which flushes chips away from the cutting edges. When you get to the end of the bore, you turn off the hydraulics, collapsing the cutters, and pull the tool back without leaving any scratches or marks inside the bore.”

Innolite machines work differently. Rather than relying on the CNC to work while the machine runs, the company’s DirectDrive3D software calculates the entire tool path offline, before the cycle begins. Moving the work of the CNC offline eliminates the need for (and the delays associated with) in-process CNC look ahead. Meanwhile, a decentralized servo-system architecture ensures the machine can respond dynamically enough to execute high-resolution toolpath data without compromising efficiency. “We want to make diamond turning productive as well as precise,” Dr. Wenzel says. “The market demands it.”

The float reaming tools, which can open existing bores up to 1⁄8 " on diameter, are applied only in a deep-hole drilling machine and can ream holes 100 diameters deep or more, according to the company.

Measure of the relative efficiency with which a cutting fluid or lubricant reduces friction between surfaces.

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.

“What we’re seeing on some of the newer reamers is just a bit of a cylindrical margin, so, if you have chipping, the cutting edges are backed up,” Schmidt added. With that design on a reamer with a smaller relief angle, toolmakers place more support on the back of the cutting edge, making the edge stronger.

Because chip control can be problematic when reaming nickel alloys, chipbreaker geometry is beneficial, according to Sollich. He noted BTA Heller’s float reamers have a manual chipbreaker held with an insert clamp. “The chipbreaker width can be adjusted based on the workpiece material,” he said. “If you’re reaming a material that tends to be tough as far as chip control, you tighten the chipbreaker to a smaller width, maybe 0.040 ".”

A reamer’s geometric configuration also helps minimize chatter—especially unwanted in a finishing operation. Reamers frequently have asymmetrical flute spacing to disrupt the natural-harmonic-frequency generation that causes chatter during machining, von Rohr noted. He added that the flute design can aid machinability when interrupted cutting, such as when reaming cross-holes. “Dihart always uses asymmetrical-flute spacing for our high-performance reamers,” he said.

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).

Tough, difficult-to-machine alloys; includes Hastelloy, Inconel and Monel. Many are nickel-base metals.

Others interviewed concurred that reaming nickel alloys is a slow process but some offered slightly different recommendations. Tom Edler recommends reaming Inconel at 80 to 100 sfm. He’s the national deep-hole drilling, reaming, thread milling, ITS bore and oil field thread chasers products manager for Iscar Metals Inc., Arlington, Texas. Iscar’s BAYO T reaming system is suitable for nickel-alloy applications. While the speed is slow, the feed can be a different matter. “The design of the tool allows for aggressive feed rates, typically 20 to 30 times faster than conventional reamers,” Edler said.

Click the image above for a video demonstrating an ALVAN replaceable-head reamer from Allied reaming an Inconel 718 workpiece.

The IL300 is designed for standard diamond turning as well as free-form and micro structure generation. ILSONIC models use ultrasonic assistance to diamond-turn steel and infrared materials.

Thin web or film of metal on a casting that occurs at die partings and around air vents and movable cores. This excess metal is due to necessary working and operating clearances in a die. Flash also is the excess material squeezed out of the cavity as a compression mold closes or as pressure is applied to the cavity.

Relieving the control of its calculation burden speeds production of complex, mirror-finish components machined with diamond tools.

Although sulfur has its benefits, workpiece staining can result if the oil and workpiece temperatures rise too high during reaming, KOMET’s von Rohr explained. Prior to heat treatment, users can remove the stain with a cleaning solution of sodium cyanide or chromic-sulfuric acid. “To avoid intergranular corrosion,” he cautioned, “the parts should be immersed in the cleaning solution only long enough to remove the stain.”

When controlling chips, a reamer’s lead angle also plays a critical role. In addition to possibly a 45° lead angle, a reamer might have a double, or compound, angle, with a 20° lead as well, to reduce the cutting force and enhance chip control by generating smaller chips, Edler explained. “The compound angle can be anything we need it to be to solve the chip control issue.”

DirectDrive3D outputs the same information as any CNC: Coordinated motion profiles for each individual axis, all precisely timed to ensure the tool follows the intended path. However, these calculations are performed offline, before the cycle starts. With no need to look ahead, there is no need for the CNC to slow down.

To support those sharp edges, the relief angles must be slightly less steep than on reamers for less demanding materials, according to M.A. Ford’s Schmidt. Reamers typically have 3° to 5° relief angles, whereas 1° to 3° is more appropriate on tools for nickel alloys.

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.

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.

Rotating cutting tool used to enlarge a drilled hole to size. Normally removes only a small amount of stock. The workpiece supports the multiple-edge cutting tool. Also for contouring an existing hole.

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.

Not all influential reamer geometries can be readily seen. Coolant channels facilitate metalworking fluid flow to effectively evacuate chips and can also vary in design depending on what type of hole is being reamed. When it’s a blind-hole, Schmidt pointed out that M.A. Ford engineers the though-coolant design so it directs the flow backward, whether through one central channel or two holes, and helps bring chips out the top of the hole instead of sending them to the bottom.

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.

With the CNC freed from much of its calculation burden, the bottleneck shifts to the drive system itself. Individual axes move via a feedback loop in which the motor adjusts power output as-needed based on periodic position checks from the encoder. Most machine tools use a centralized, PC-based system (often the CNC itself) to control and coordinate the axis positions, which are determined by precisely timed commands for position, speed, acceleration and jerk calculated from CAM data by the CNC (or by DirectDrive3D). If the coordinated feedback loops do not cycle fast enough, the machine cannot take full advantage of a system like DirectDrive3D, Dr. Wenzel says.

However, the properties that make nickel alloys desirable for extreme environments, such as those found in pressurized-water reactors at nuclear power plants and in aerospace turbocharger rotors, make the metals a challenge to machine. That’s because the high pressure the cutting tool exerts on the workpiece during machining produces a stressed and deformed surface layer, explained Adrian von Rohr, Dihart product manager for KOMET of America Inc., Schaumburg, Ill. This deformation causes the workpiece surface to harden, slowing the machining process.

Stringent specifications for precision and surface finish are not enough to make the CNC a bottleneck to efficiency, Dr. Wenzel says. Geometry creates the problem. If a turning insert is to machine non-rotationally symmetrical, freeform curvature and complex 3D shapes into the face of a spinning part, it cannot stay in one plane, like a needle on a record player. Following along the hills and valleys of the spiraling tool path requires moving in and out in Z in perfect synchronization with the main spindle’s rotation. However this functionality is achieved, oscillating the tool is a demanding task for an already busy CNC.

When a metal part must offer low weight, corrosion and oxidation resistance and high strength at high temperatures, part designers often turn to nickel-base alloys. These materials, along with iron- and cobalt-based materials, are considered heat-resistant superalloys.

“Even under the best conditions, stresses may be produced that distort the work,” von Rohr said. “For maximum dimensional stability, it is best to rough the part almost to size, stress-relieve it and then finish it to size.”

Sollich added that the tool’s double-effective cutting configuration allows users to substantially increase the feed rate versus a single-cutter reamer. For Inconel 718, he recommends a feed of 0.040 to 0.060 ipr.

Diamond turning is traditionally associated defense- and research-related work, such as missile or satellite guidance system optics. Such parts are expensive, application-critical and difficult to manufacture. However, a contract for an automobile rain sensor, or a mold for an LED headlight or a contact lens, requires prioritizing more than quality and precision, Dr. Wenzel says. New customers demand increased part volumes, faster deliveries and greater geometric variety.

More specifically, even the most powerful computer can only handle so many set points—the points in space that approximate the curves and contours of a tool path—in so much time. Spacing the set points closer together enables smoother tool motion around smaller, more complex shapes, but a CNC must work harder to plot that motion, particularly if real-time lookahead is required to ensure fluid point-to-point transitions. Beyond a certain number of set points (typically a few thousand), a conventional machine tool CNC must slow down to allow time for processing.

Reaming nickel-base alloys can be challenging enough, but add a dissimilar material into the workpiece, such as a composite in stacked arrangement, and the demands increase exponentially.

The IL300 is designed for standard diamond turning as well as free-form and micro structure generation. ILSONIC models use ultrasonic assistance to diamond-turn steel and infrared materials.

Although high-performance drills can produce high-quality holes, reaming is required for a tighter diameter tolerance. Indexable-insert drills typically achieve a tolerance as tight as 0.008 " and solid-carbide drills achieve a 0.002 " tolerance, von Rohr noted, but solid-carbide, carbide-tipped and indexable-inserts reamers attain a tolerance of 0.0004 ". KOMET makes solid-carbide, carbide-tipped and indexable-insert reamers.

Machined directly in steel, LED headlight mold inserts require layering ridges and other microstructures directly atop complex, contoured surfaces.

Grooves and spaces in the body of a tool that permit chip removal from, and cutting-fluid application to, the point of cut.

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.

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.

The burden on the CNC is due more to the intricacy of diamond turned microstructures like these than stringent requirements for surface finish and precision.

In addition to coolant concentration, applying it at high pressure is essential when reaming nickel alloys, Edler said. “The higher the pressure, the better the coolant penetration to get beyond that zone where the heat is being generated and to cool down the cutting edge, as well as the material.”

Because these extreme-environment parts often require high-quality holes—with an H7 international size tolerance grade or better—part manufacturers commonly employ reaming to meet surface finish, size and concentricity requirements. For example, an H7 tolerance for an 18mm-dia. hole is 0 "/+0.0007 ".

Nickel-base alloys and other heat-resistant materials certainly qualify as being difficult to machine, but effectively reaming them to improve hole cylindricity and surface finish is possible if users select the appropriate tools and make proper provisions. “If you want to run extreme, you have to take precautions,” Edler said. And when that’s the case, “high-temp alloys are basically the same as any other type of material.” CTE

Because nickel-base alloys withstand high temperatures, not much heat enters the material and the heat that does enter is carried away when chips are made. Therefore, coolant is needed to keep cutting edges from overheating and causing premature tool failure while helping to clear chips.

The IL300 is designed for standard diamond turning as well as free-form and micro structure generation. ILSONIC models use ultrasonic assistance to diamond-turn steel and infrared materials.

Miller pointed out that Allied offers coated and uncoated carbide and cermet reamers, and Allied generally recommends uncoated cermet tools for high-speed reaming. “There’s not a dramatic benefit to putting a coating on cermet as far as tool life,” he said, noting that cermet withstands tool wear from nickel alloy’s abrasiveness better than carbide.

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.

Space provided behind the cutting edges to prevent rubbing. Sometimes called primary relief. Secondary relief provides additional space behind primary relief. Relief on end teeth is axial relief; relief on side teeth is peripheral relief.

He noted TiAlN is the most common coating for nickel-alloy applications, but AlCrN is also suitable.

Any manufacturing process in which metal is processed or machined such that the workpiece is given a new shape. Broadly defined, the term includes processes such as design and layout, heat-treating, material handling and inspection.

He added that balancing tool geometries for both materials rather than optimizing them for one can prove effective.

Gary Schmidt, applications engineering for M.A. Ford Manufacturing Co. Inc., Davenport, Iowa, recommends basing reaming parameters on those for holemaking with carbide drills, cutting the reaming speed in half and doubling the feed. The increased feed will load the reamer and prevent it from rubbing and wearing prematurely, he noted. M.A. Ford produces standard solid-carbide reamers from 0.013 " to 5⁄8 " and specials up to 1¼ ".

However, optimizing the speeds and feeds for each material can also prove effective. Allied Machine & Engineering Corp.’s Jacob Miller emphasized this when reaming bimetal workpieces, such a thin Inconel explosion-bonded cladding on A 516 70 steel or 316 stainless. That might require starting at a slow surface speed and then increasing it once the tool passes the cladding.

On conventional reamers, a chipbreaker is effective for controlling chips but it reduces tool life compared to a reamer without one, according to KOMET’s von Rohr. A chipbreaker may not even be required to control nickel alloy chips. That’s because, as the material workhardens, it becomes more brittle and tends to break from the parent material before becoming long and stringy, he added. “The nickel itself almost acts like a chipbreaker.”

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

He added that the lead angle varies, depending on whether the hole being reamed is a through- or blind-hole. When reaming a through-hole, a 45° lead angle rolls the chips forward—ahead of the tool and out the hole. In a blind-hole, a 20° lead directs the chips back up the flutes and out the hole.

“As the hole gets bigger, the tolerance range gets larger,” said Jacob Miller, product manager for Allied Machine & Engineering Corp., Dover, Ohio. The cutting tool manufacturer recently added replaceable-head reamers from S.C.A.M.I. to complement Allied’s monoblock and ring-style reamer offerings from the same Italian manufacturer.

BTA Heller's float reaming, or skive, tool's body holds a floating cutter magazine with two cartridges and two indexable inserts that oppose one another and have diametrical adjustment of 0.080" to 0.118", depending on the tool diameter.

Lenses, mirrors, optics and the mold inserts that enable making such parts at scale have long been machined with tools made of solid diamond. Despite a well-deserved reputation for precision, however, diamond machining can be painstakingly slow, says Dr. Christian Wenzel, CEO of diamond machine tool builder Innolite.

Walter WXN15 coated grade designed for machining ISO N materials - iso carbide insert

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