Chip breakers are part of the macrogeometry of the insert. The size, geometry, and location of the chip breaker vary by material and depth of cut (DOC).

Because the back of the insert is used, the programmer is required to change toolpath methodology by selecting toolpaths that move the tool away from the headstock. Developing these types of toolpaths is somewhat unconventional, so CAM systems are not always cooperative. In response to these developments, toolmakers are working with CAM developers to create canned turning routines that allow easy toolpath creation, which makes adopting the new methods much easier.

Chip breakerin metal cutting

According to Geisel, long, stringy chips are an indication that either the cutting parameters are incorrect for the insert being used or an incorrect chip breaker is being used for the cutting parameters being run.

Plunge turning, groove turning and multidirectional turning are terms that describe the practice of applying rectangular grooving tools to create grooves, along with a multitude of other part geometries. Before the proliferation of affordable CAM software and advanced machine controls, complex groove geometries were made with form tools. Turning tools would be form-ground to match the desired geometry so the programmer needed only to position the tool in the correct axial location and feed it into the part.

Machining grooves and shallow channels. Example: grooving ball-bearing raceways. Typically performed by tools that are capable of light cuts at high feed rates. Imparts high-quality finish.

Turning insert chip breakerfor metal

One of the most effective, simple advances is used for heavy roughing of workpieces—such as large forgings—where high metal-removal rates are required and surface finish requirements and geometric tolerances are loose. Part manufacturers have applied rectangular inserts resembling large bricks of carbide with strong edge geometry. The inserts are held so the long edge is presented to the work in a tool body that creates a steep lead angle. Some manufacturers have demonstrated radial engagement of 1.3" with feed rates of 0.078 ipr. Compare these measures with the 0.187" DOC and 0.008 ipr feed rate of the standard CNMG inserts found at most shops.

The H-Carb Seven Flute High Efficiency Endmill specializes in deep axial trochoidal and high-speed machining applications. Offered at various lengths of cut, the 7 flute design creates a superior finish to conventional 5 or 6 flute tools.

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Bad chip breaking also affects productivity. Long chips take up more room in the hopper, which requires it to be emptied more often, but it’s not as full in terms of weight of chips. When combined with the time lost due to stopping the machine and removing chips, productivity is reduced and per-part costs are higher.

Cutting tool manufacturers have been designing milling tools to exploit chip thinning while machine tool builders have been creating more dynamic milling machines that allow users to capitalize on the advanced tools. As a result, milling operations that benefit from chip thinning have become common at many shops.

“Just by looking at the chip’s size and color, you should be able to tell how the cutting tool is running,” Geisel said. “These two factors will tell you if you are using the proper chip former for the DOC, spindle speed, and feed rate. It just gives you so much feedback.”

Turning insert chip breakercalculator

During the application of HPC, a jet of coolant creates a “hydraulic wedge” between the chip and the insert. Not only does this cool the zone better, it forces the chip away from the insert face quickly, and it breaks the chip into smaller pieces.

On a rotating tool, the portion of the tool body that joins the lands. Web is thicker at the shank end, relative to the point end, providing maximum torsional strength.

Turning machine capable of sawing, milling, grinding, gear-cutting, drilling, reaming, boring, threading, facing, chamfering, grooving, knurling, spinning, parting, necking, taper-cutting, and cam- and eccentric-cutting, as well as step- and straight-turning. Comes in a variety of forms, ranging from manual to semiautomatic to fully automatic, with major types being engine lathes, turning and contouring lathes, turret lathes and numerical-control lathes. The engine lathe consists of a headstock and spindle, tailstock, bed, carriage (complete with apron) and cross slides. Features include gear- (speed) and feed-selector levers, toolpost, compound rest, lead screw and reversing lead screw, threading dial and rapid-traverse lever. Special lathe types include through-the-spindle, camshaft and crankshaft, brake drum and rotor, spinning and gun-barrel machines. Toolroom and bench lathes are used for precision work; the former for tool-and-die work and similar tasks, the latter for small workpieces (instruments, watches), normally without a power feed. Models are typically designated according to their “swing,” or the largest-diameter workpiece that can be rotated; bed length, or the distance between centers; and horsepower generated. See turning machine.

Lathechip breaker

Although groove turning is effective, it has limitations—like causing chatter when applying small tools—that cannot be overcome by changing the design of the cutting tool alone. In the most recent advances, tool manufacturers have partnered with software developers to create tools and toolpaths that capitalize on axial and radial chip thinning, thereby reducing chatter. The techniques involve round inserts or large radii paired with light radial engagement and high axial feed rates. These methods not only reduce chatter but improve the mrr, impart finer finishes and often increase tool life.

Chip breakertool

Chips normally break off in one of three ways: they self-break, they break against the tool, or they break against the workpiece. Chips that are an ideal size pose no threat to the machine and will not damage the part, toolholder, or insert.

At Mitsubishi Hitachi Power Systems Americas Inc., we have successfully adopted some of these techniques, providing significant improvements to our machining processes. Safety is critical, and we address all situations that endanger our team. Our original machining processes produced bins full of stringy, unbroken chips. These placed everyone at risk of serious cuts but also created the risk of machinists being pulled into machines.

The chip breaker’s design is based on the DOC and also feed rate. For example, a roughing insert’s chip breaker must be designed is such a way that it can handle the high cutting force of the operation.

It’s when chips break poorly that birdnesting occurs. When the system produces long, stringy chips, commonly referred to as birdnests, the operator must manually clear them from the machining envelope, creating a health and safety issue for the operator, and also pause the machine, increasing the cycle time.

The two most important details to watch for during a turning operation are chip color and chip size. Photo courtesy of Seco Tools.

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.

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.

High-speed machining, high-feed milling and high-efficiency milling are terms that have been incorporated into the modern machining lexicon. While nuances make their meanings slightly different—depending on whom you ask—all the techniques take advantage of radial and axial chip thinning.

Turning operations that employ chip thinning have been slower to advance than milling operations. This lag is odd. After all, the chip morphology research that initially defined the characteristics of chip thinning was performed using orthogonal machining operations like turning and planing.

A common tool shape with a shallow lead angle produces a chip thickness roughly equal to the feed rate per revolution. Image courtesy of C. Tate

Exploiting chip thinning by purchasing new cutting tools or buying more CAM software can be daunting for some shops, but it does not mean they are excluded from the benefits of chip thinning when turning. All major cutting tool manufacturers have chip thinning formulas in their catalogs, and the web, such as at YouTube, has a ton of good videos that demonstrate the techniques. Research and creativity can allow any shop to begin adopting more efficient practices.

Chip breakertypes

With the evolution of affordable software, creative programmers and machinists began using standard grooving tools to create complex geometries and forgo form tools. Cutting tool manufacturers responded with designs that aided this practice. They provided improvements that increased insert stability and research that tuned speed and feed data.

For a long time, toolmakers have sold turning and facing tools that hold square, triangle or other common-shaped inserts in an orientation that offers large lead angles. These angles allow increased turning feed rates, which exploit chip thinning. However, only recently have the cutting tool manufacturers and CAM software developers started to sell tools and toolpath solutions that can be called innovative.

“This wedge action occurs because the coolant is directed at a very specific area,” explained Kevin Burton, turning product manager for Sandvik Coromant Canada. “For cutting materials that produce long chips, properly directed high-pressure coolant can have a dramatic effect on chip control and evacuation.”

Chip appearance will vary based on several factors, but workpiece material is the main driver. The two most important details to watch for are chip color and chip size. The sizes of chips produced when cutting cast iron are vastly different from those made when cutting steel. And, depending on the material you are machining, there are certain colors to look for as chips are created.

Of the six main workpiece material groups, steels (ISO P), stainless steels (ISO M), heat-resistant superalloys (ISO S), and nonferrous materials (ISO N) often produce chips that are not ideal.

Joe Thompson has been covering the Canadian manufacturing sector for more than two decades. He is responsible for the day-to-day editorial direction of the magazine, providing a uniquely Canadian look at the world of metal manufacturing.

Seco’s FF2 is a finishing chip breaker designed for smaller DOCs and relatively low feeds (f = 0.008 to 0.025 inch, ap = 0.020 to 0.157 in.). Its design features a dimple and a very large rake angle at the nose. It also has a short, positive protection chamfer and is “narrow” in the front.

“We like to think of this as high-precision coolant application,” said Burton. “When employing flood-style coolant, all you do is cool the chip. While cooling the chip can help it break, precision coolant application can cool it, break it, and move it out of the cutting area.”

“In turning we say that there are four types of operations: finishing, medium, roughing, and heavy roughing,” he said. “We design chip formers for all four categories, and it’s important to use the correct chip former based on your DOC; the feed rate you want to run at; the spindle speed; and, when finishing, the type of surface finish you are trying to achieve.”

Turning insert chip breakerpdf

By adopting newer methods, we have improved chip control that is much safer and makes chip disposal and handling much easier. Newer grooving techniques have reduced the need for specials, reduced machining times and improved surface finishes.

Chip breaker insert

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.

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“All of these things together -- the geometries, coolant, grade, and coating -- enable the chip to break easily and move out of the cutting zone,” said Miller.

An award-winning writer and graduate of the Sheridan College journalism program, he has published articles worldwide in a variety of industries, including manufacturing, pharmaceutical, medical, infrastructure, and entertainment.

“Chip breakers, or what I like to call chip formers, are designed to form the chip in such a way that it breaks into a manageable size,” said Geisel. “No matter what type of material you are cutting, the last thing you want to produce are long, stringy chips. There is no excuse for creating them.”

Newer tools and techniques capitalize on the step lead angle produced by using a common shape in a nontraditional way. The steep lead angle produces a thinner chip, thereby reducing forces and aiding chip control. Image courtesy of C. Tate

In a typical flood-coolant setup, coolant is sprayed from a location that typically is far away from the cutting edge. This causes the chip to act as an umbrella, deflecting the coolant away from the cutting zone. When this happens, the cut is not well-lubricated or cooled at the cutting edge.

In low-carbon steel, for example, the low carbon content makes it harder for chips to harden and break away. There is not enough martensite formation, which means that the material will stay soft and sticky.

Machining operation that creates flat surfaces. The workpiece is reciprocated in a linear motion against one or more single-point tools. Also used to create contours or irregular configurations.

“When chips form in these birdnests, they get wrapped up around the chuck and cause damage, but what we see shops most concerned about is the safety issue,” said Chad Miller, product manager – turning and advance materials for Seco Tools.

Heat absorbed into the insert will reduce tool life and create poor surface finishes. It also might harden the workpiece, reducing tool life even further.

Traditional toolpaths move the tool axially toward the headstock of the lathe with a relatively shallow lead angle. Improved inserts combined with the proper toolpath produce relatively large lead angles that result in thinner chips and lower cutting forces. However, there's a trade-off because a large lead angle increases a tool's surface area on a part and therefore increases the tool pressure. Reduced cutting forces allow deeper radial engagement and higher feed rates culminating in higher volumetric removal rates.

“If you are machining carbon-alloy steels, you don’t want to see dull gray chips; you want to see chips that are blue,” explained Steve Geisel, senior product manager for Iscar Canada. “When chips appear blue, it tells you that the heat generated in the cut is being directed into the chip and not being kept in the insert or the workpiece material.”

Another recent advancement utilizes inserts that resemble standard ISO diamond and triangular shapes. The inserts are held in standard orientations and are capable of being used in traditional ways. However, the inserts are slightly different from the standard shapes as they have a compound angle and built-in edge that creates a very large lead angle when programmed correctly.

It’s important to use the correct insert and chip former based on DOC, feed rate, spindle speed, and surface finish. Photo courtesy of Iscar Canada.

According to Miller, ID and OD turning with small DOCs, profile, and face turning requires a tight, sharp chip breaker (positive protection chamfer, relatively big rake angle, and a narrow nose design). A grooving operation has different requirements. Durring this process it’s preferable to produce small “comma” or “clock spring” chips that evacuate from the groove without scratching the side surfaces of the groove. You need to make chips that are smaller than the groove. You also need to get the right radius for the chip – how it curls – depending on the feed rate limits you set. The depth of the chip breaker’s pit affects both chip width and chip radius.

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