SUS Variable Lead End Mill For Stainless Series - end mill for stainless steel

End mills and face mills are both common types of milling operations. The choice between them can consider the following factors:

Powers a grinding wheel or other abrasive tool for the purpose of removing metal and finishing workpieces to close tolerances. Provides smooth, square, parallel and accurate workpiece surfaces. When ultrasmooth surfaces and finishes on the order of microns are required, lapping and honing machines (precision grinders that run abrasives with extremely fine, uniform grits) are used. In its “finishing” role, the grinder is perhaps the most widely used machine tool. Various styles are available: bench and pedestal grinders for sharpening lathe bits and drills; surface grinders for producing square, parallel, smooth and accurate parts; cylindrical and centerless grinders; center-hole grinders; form grinders; facemill and endmill grinders; gear-cutting grinders; jig grinders; abrasive belt (backstand, swing-frame, belt-roll) grinders; tool and cutter grinders for sharpening and resharpening cutting tools; carbide grinders; hand-held die grinders; and abrasive cutoff saws.

“For example,” Coomer said, “when you’re hard turning internal bores, even though the chips may be free flowing, you might get into some bird nesting issues where chipbreakers might help.”

“I prefer coding G96 for constant sfm,” Sawicki said. “Then, as the diameter changes and you get closer to the centerline of the spindle, it’s programmed to speed up the rpm to keep that sfm constant and to give you more consistent and predictable wear on your insert. If it were programmed in G97, which is a fixed rpm, it’s going to feel drag as the part gets smaller. And CBN is sensitive to drag.”    — Holly B. Martin

When selecting the right milling Tool for machining tasks, it's essential to consider various factors. The following are key points that require particular attention:

In general, chip control is less of an issue with hard turning due to high temperatures that cause ribbons of bright red, molten steel to flow off workpieces. Coomer said chips from hard materials are so brittle that they tend to crumble in one’s hand, so CBN inserts for hard turning don’t often come with chipbreakers.

Angle milling cutters enable the efficient generation of precise angles and grooves in diverse workpieces. The category encompasses two primary types: single-angle milling cutters[ ranging(18° - 90°) ; thickness(6 - 35mm)], and double-angle milling cutters[ ranging(30° - 120°) ; thickness(10 - 45mm)]

End mills, also known as straight shank mills, are the most widely used milling cutters on milling machines and are primarily used in small milling operations.  Since end mills have cutting teeth on both sides, they are highly effective in various drilling operations. It is suitable for processing workpieces that have one or more side walls perpendicular to the bottom surface.

Holly B. Martin is a science writer and technical copywriter based in Winchester, Va. For more information, visit www.hollybmartin.com.

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.

1.2 Roughing End Mills: Roughing end mills are designed with serrations or coarse pitch to remove material quickly. They are used for rough machining or large material removal where finish is not critical.

1.1 Square End Mills: These are the most common type of end mills and have a square end for milling square slots, pockets, and edges.

Ability of the tool to withstand stresses that cause it to wear during cutting; an attribute linked to alloy composition, base material, thermal conditions, type of tooling and operation and other variables.

The hardest material is diamond, and polycrystalline diamond cutting tools work well for turning nonferrous materials like ceramics and aluminum. But the iron in steel reacts to diamond at the high temperatures generated by hard turning, causing excessive tool wear.

Hard turning is commonly considered to start with materials of 45 HRC, with a transition zone up to 50 HRC. In that zone, some harder carbide and cermet inserts still work. Coated and uncoated ceramic grades work for a hardness range of 45 HRC to about 60 HRC while CBN inserts are designed for about 50 HRC to 68 HRC.

Product：Precision Machining Components. Material：Steel, Brass, Aluminum,etc.. Surface：Plating, Anodizing, etc.. Tolerance:±0.01mm. Craftsmanship: Turning, Milling. Services: OEM or ODM available.

“Depending on the specifics of the job, you could source a $500,000 grinding machine, or you could buy a $100,000 lathe and do the same thing with hard turning,” said Travis Coomer, national key account manager for GWS Tool Group in Tavares, Florida. “As long as you can attain all the tolerances given to the part, then it’s absolutely a no-brainer to use hard-turn inserts as opposed to grinding.”

Coatings are available for ceramic and CBN inserts to resist wear, prolong tool life and increase speed, which is all-important for production machining. Coated inserts are more expensive, but Wilshire said the increased cost for a CBN insert is not that much.

The above comprises some basic types of milling cutters, but this is just the beginning. In the following sections, we will delve into the characteristics of each milling cutter. Continuing to read will provide a deeper understanding of how each tool plays a crucial role in the machining process.

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.

It’s important to match the combination of the CBN grade and the edge preparation to the application, said Brian Wilshire, technical center manager for Kyocera Precision Tools Inc. in Hendersonville, North Carolina.

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.

For rough machining, it is recommended to opt for pressed blades. This choice helps reduce processing costs, as these blades exhibit higher edge strength, impact resistance, and can withstand larger cutting depths and feed rates during coarse machining.

“You may start to see a change in surface finish that tells you this edge has reached its (end of) life,” said David Essex, turning product manager at Tungaloy America. “Typically, operators will have worked out a part count and know, for example, this grade on this part will give you 50 pieces easily. So they change the insert at that point because it is predictable.”

Many CBN grades are available and often are designed for continuous-cut steel, heavily interrupted steel or moderately interrupted steel. Once a grade is selected, Coomer said choosing the right edge preparation and hone for the insert can minimize tool wear, lighten tool pressure, improve crater wear resistance and help a tool last longer.

Machining operation in which material is removed from the workpiece by a powered abrasive wheel, stone, belt, paste, sheet, compound, slurry, etc. Takes various forms: surface grinding (creates flat and/or squared surfaces); cylindrical grinding (for external cylindrical and tapered shapes, fillets, undercuts, etc.); centerless grinding; chamfering; thread and form grinding; tool and cutter grinding; offhand grinding; lapping and polishing (grinding with extremely fine grits to create ultrasmooth surfaces); honing; and disc grinding.

“Most ceramic grades don’t have a high breaking strength,” Sawicki said. “Whisker-reinforced ceramics generally have the highest breaking strength. But through an interrupted cut, it’s way more predictable to run CBN than ceramic because once a ceramic insert starts to show flank wear, many times it just chips out due to excessive tool pressure.”

However, even during hard turning, there are cases when chips may wad up and create issues with fixturing, workholding or surface finish — and harm tool life as well.

Milling tools, also called Milling cutters are essential tools used in milling machines or CNC centers for material removal operations. These rotating cutting tools consist of one or more teeth, each tooth intermittently removing a portion of the workpiece during the milling process.

The keyway milling cutter, also known as T-slot cutter closely resembles the plain milling cutter in appearance. However, a key distinction lies in the fact that the former is a double-edged tool, lacking a center hole on its end face. Designed for machining keyways and grooves, it is not suitable for flat surface milling.

A face mill has a relatively short cutting edge and is primarily used for machining flat surfaces. The cutting edges are consistently positioned on its side, requiring a horizontal entry at a set depth. The tool features a robust inserted-tooth structure, facilitating easy blade sharpening and replacement, long lasting.

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.

Chips entangling on workpieces or piling up at the bottom of machine tools can be prevented with the HP-style chipbreaker on the BXA10 range of coated CBN-grade inserts.  Image courtesy of Tungaloy America

The KBN05M indexable insert works for high-speed finishing, as well as interrupted machining of hardened steel. Image courtesy Kyocera Precision Tools

Metal-removing edge on the face of a cutter that travels in a plane perpendicular to the axis. It is the edge that sweeps the machined surface. The flat should be as wide as the feed per revolution of the cutter. This allows any given insert to wipe the entire workpiece surface and impart a fine surface finish at a high feed rate.

“You’re safe 99.5% of the time running those operating parameters in any hard turning application for most materials above 50 Rockwell C hardness,” he said. “If you’re closer to 50 Rockwell C, start with 500 sfm (152 m/min.). And if you’re hard turning D2 tool steel, start at 300 sfm (91 m/min.) or 350 sfm (107 m/min.).”

Workholding device that affixes to a mill, lathe or drill-press spindle. It holds a tool or workpiece by one end, allowing it to be rotated. May also be fitted to the machine table to hold a workpiece. Two or more adjustable jaws actually hold the tool or part. May be actuated manually, pneumatically, hydraulically or electrically. See collet.

“Because the material is much harder, the cutting forces in hard turning are much higher, and any play in the ballscrew or in the ways of the machine is going to be magnified,” Wilshire said. “So select the most rigid machine available and go up to the largest shank on the toolholder, with the shortest overhang, the strongest insert shape and the biggest corner radius possible for the part.”

“This lets the hard-turn insert ease into the cut from a lighter depth of cut to the full depth of cut without hitting that hard corner,” Wilshire said. “That minimizes the shock as it goes from no load to cutting loads, which can help prolong tool life — and it’s less machining they have to do in the hard turn.”

Thread milling is a precision thread processing method completed on a three-axis machine tool (machining center). Unlike traditional machining methods, it is not limited by thread structure or thread rotation during machining.

Saw blade cutters feature slender teeth and are suitable for cutting and removing materials up to medium hardness, particularly in narrow and deep groove machining applications. After usage, the milling cutter can be easily restored to its original effectiveness by utilizing a grinding machine for sharpening purposes.

Chip Formation: In conventional milling, chips move away from the cutting edge, whereas in climb milling, chips move away from the uncut material.

Gear milling cutters, employing the profile-milling method, engage in cutting movements along the contour of the gear to achieve precise machining. The process is straightforward, making it particularly suitable for single-piece manufacturing requirements.

“If you double the speed from 400 to 800 sfm (244 m/min.), you’ll get far fewer parts per corner and perhaps less than five minutes of in-cut time,” Sawicki said. “You may get done much faster, but you’ll need to offset your tool more frequently in order to compensate for the tool wear that higher speeds induce.”

1.3 Ball End Mills: These end mills have a rounded end, resembling a ball. They are used for contouring and producing curved surfaces. Ball end mills are often used for 3D profiling and finishing operations.

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.

Consider the number of teeth. A coarse-tooth milling cutter with only 6 teeth for a 100mm diameter performs better in handling cutting loads due to its larger chip groove than a fine-tooth milling cutter with 8 teeth of the same diameter.

“If the size of the workpiece you’re turning is 1.25" (31.75 mm) or greater, I prefer using an 80-degree rhombic insert with a 32nd nose radius, which is the most common type of CBN insert,” he said. “As the diameter gets smaller, you want to transition into a screw-down positive insert with a front relief angle because it’s more important to be on centerline on smaller components than it is larger components. You’ll be able to hold size and finish better.”

The three basic types of milling machines are vertical milling machines, horizontal milling machines, and machining center.

The tool profile of a form milling cutter is crafted in accordance with the intended final shape. These milling cutters may feature various tip shapes, numbers of edges, and tool materials, allowing them to accommodate complex, curved, or three-dimensional machining requirements. Most form milling cutters are specialized tools that require custom design tailored to the specific shape of the workpiece.

There are two distinct ways to cut materials when CNC milling:  Climb Milling and Conventional Milling. The crucial distinction lies in the cutter's rotation relative to the feed direction. Conventional Milling witnesses the cutter rotating against the feed, while Climb Milling involves the cutter rotating in harmony with the feed direction.

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

“There’s a fine balance you walk to pick a large enough edge preparation so that you get standard wear and no chipping,” he said. “But if you pick too large an edge preparation, it’s not going to last as long. You can consider it almost pre-worn because you’re grinding a portion of the cutting edge away to strengthen it.”

Hardness is a measure of the resistance of a material to surface indentation or abrasion. There is no absolute scale for hardness. In order to express hardness quantitatively, each type of test has its own scale, which defines hardness. Indentation hardness obtained through static methods is measured by Brinell, Rockwell, Vickers and Knoop tests. Hardness without indentation is measured by a dynamic method, known as the Scleroscope test.

1.4 Radius End Mills: Similar to ball end mills, radius end mills have a rounded end, but with a specific radius. They are used for milling rounded corners, fillets, and complex shapes.

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.

During milling, the tool rotates to perform the main movement, while the workpiece is fed in a straight line or curve. It can accurately realize milling operations such as planes, steps, grooves, vertical surfaces, and formed surfaces.

“Nowadays,” Sawicki said, “a lot of high-production cells use robots to take parts out of one chuck and put them into another chuck or onto an inspection table, so you cannot afford to have chips hanging up on the workpiece. The ultimate chip control is using a chipbreaker plus high-pressure coolant at the tip with a coolant-through toolholder, so you’re pretty much guaranteed the chip is going to go into the bed of the machine.”

Due to the diversification of machining processes, various types of cutting tools have emerged to serve specific purposes. The following are common types of specialized milling tools:

GWS Tool Group’s custom high-performance ISO inserts with various tip options, including single tip, double tip, full top and special, can accommodate any hard turning application.  Image courtesy ofGWS Tool Group

An alternative to ceramics and diamond, cubic boron nitride is the second-hardest material, and CBN tools of many grades have been developed for hard turning applications like transmission shafts, constant-velocity joints and toolholders. These inserts are used to finish-turn hard materials and produce fine finishes and tight tolerances, replacing grinding, which takes longer and costs more.

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.

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.

Distance between the bottom of the cut and the uncut surface of the workpiece, measured in a direction at right angles to the machined surface of the workpiece.

“When you put CBN in a soft material,” Sawicki said, “it begins to feel drag, which quickly erodes the insert, so your in-cut time is much lower in softer materials.”

Selecting the appropriate milling tools involves understanding their individual capabilities and matching them with specific machining tasks and materials. That's it! Thank you for joining me on this exploration of milling tools.   Feel free to reach out if you have any more questions or need assistance with your machining needs. Happy crafting!

“Our ceramics definitely get better tool life running dry,” Wilshire said. “So in most cases, when we recommend ceramics for hard turning, we prefer no coolant.”

Face Mills yield relatively rougher surfaces; however, their capability for extensive surface milling enables faster material removal.

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.

Hollow milling cutters consist of a cylindrical body with cutting teeth on the outer surface. The center of the cutter is hollow, allowing it to be mounted on an arbor. It can rapidly create uniform pre-thread diameters, thereby enhancing productivity.

The design of chamfer mills is specifically intended for the removal of sharp edges during the cutting process, leading to the creation of a bevel or rounded corner instead of a right angle. This type of milling cutter typically features one or more blades, the shape and angle of which can be selected based on the desired chamfer design.

Common milling cutter materials include cemented carbide, high-speed steel, ceramics, PCD, and CBN. The hardness of the material directly influences the selection of the tool material. For instance, cemented carbide is suitable for machining materials with high hardness, high-speed steel for materials of moderate hardness, and ceramics or PCD for processing high-hardness and brittle materials.

End Mills produce high surface smoothness, exceptional precision, and neat edges, suitable for workpieces requiring superior surface quality.

Corner rounding milling cutters, sometimes referred to as bullnose cutters, are designed to round off the sharp corners of a workpiece. They have a semi-circular cutting edge that is used to create a smooth, rounded corner.

The cylindrical milling cutter, also known as a plain milling cutter, is utilized for machining flat surfaces on a horizontal milling machine. Divide the gears into two types: spur gear and helical gear based on the tooth shape. Classify the gears into coarse-pitch and fine-pitch based on the number of teeth.

The three-edge milling cutter is a standard machine tool cutting tool, commonly used on horizontal milling machines, and is generally used for milling grooves and steps. Its blade incorporates three cutting edges, enabling simultaneous cutting on three surfaces during machining.

Cutting tool repeatedly enters and exits the work. Subjects tool to shock loading, making tool toughness, impact strength and flexibility vital. Closely associated with milling operations. See shock loading.

In milling cutters, a flute is the groove or channel on the tool's cutting surface that helps in evacuating chips during the cutting process, providing space for the coolant to reach the cutting edges, and determining the number of cutting edges on the tool.

A milling Tool is a rotary cutting tool used in milling operations. It consists of multiple cutting edges that aid in the removal of material from the workpiece. These tools encompass a wide array of types, engineered to fulfill distinct machining tasks. Here are several essential types of milling cutters:

For precision milling, it is preferable to choose ground blades, which offer high positional accuracy within the milling cutter, resulting in improved machining precision and surface roughness.

“To protect the cutting edge,” he said, “we can vary the angle coming off the top of the insert anywhere from 10 degrees to about 35 degrees down from the horizontal to direct the cutting forces into the tool and away from the edge.”

The choice of tool diameter depends on equipment specifications and workpiece dimensions. For example, for face milling, a diameter of D = 1.5d (where d is the spindle diameter) is suitable. In mass production, the tool diameter can also be chosen as 1.6 times the workpiece cutting width. For end mills, the diameter should primarily meet the requirements of the workpiece dimensions.

Face Mills are better suited for surfacing larger areas and deeper cuts, commonly employed in plane milling and substantial material removal.

Interrupted cuts don’t fare well with coolant, however, due to rapid thermal expansion and retraction as the tool moves in and out of the workpiece material.

Brian Sawicki, business development manager for the Northeast region at Tungaloy America Inc. in Arlington Heights, Illinois, shared best practices for hard turning.

Replaceable tool that clamps into a tool body, drill, mill or other cutter body designed to accommodate inserts. Most inserts are made of cemented carbide. Often they are coated with a hard material. Other insert materials are ceramic, cermet, polycrystalline cubic boron nitride and polycrystalline diamond. The insert is used until dull, then indexed, or turned, to expose a fresh cutting edge. When the entire insert is dull, it is usually discarded. Some inserts can be resharpened.

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.

“Using coolant for an interrupted (cut) will create thermal shock in the CBN,” Wilshire said, “which will cause small fractures and quickly destroy your edge. We always tell customers, if they are running coolant, to make sure the stream is not interrupted, which could happen if the pump cavitates or if the geometry of the part shields the coolant line from the insert itself.”

Concave milling cutters, on the other hand, have cutting edges with a concave or inwardly curved profile. The concave mill tool is employed for machining bosses with a semicircular top.

Main body of a tool; the portion of a drill or similar end-held tool that fits into a collet, chuck or similar mounting device.

Two clearance angles are provided in milling cutters to ensure proper chip evacuation during the cutting process and to prevent rubbing, minimizing tool wear.

Convex milling cutters are cutting tools with a curved or rounded shape on their cutting edges.  Used for creating concave features, including grooves with a concave semicircle at the bottom.

For parts with ultratight tolerances, Sawicki said CBN holds size much longer than ceramics. The lubricating and cooling effect of coolant helps with tolerances while providing a better finish, he said, and wiper flats on the inserts may improve the finish and reduce cycle times as well.

“If there’s gauging immediately after machining, it’s easier to get a true measurement if the part stays cooler,” Wilshire said. “But if you run without cooling, the part heats up and tends to expand. So the part may be in tolerance when it’s gauged, but as it cools off, it may shrink enough to go out of tolerance.”

“I would say 90% of the time coated is going to be better,” he said. “But I have seen in some cases where uncoated might give a slightly better surface finish than coated, especially with the ceramics.”

Group of alloy steels which, after proper heat treatment, provide the combination of properties required for cutting tool and die applications. The American Iron and Steel Institute divides tool steels into six major categories: water hardening, shock resisting, cold work, hot work, special purpose and high speed.

The best milling method depends on the specific requirements of the task. For instance, face milling is suitable for flat surfaces, and end milling is used for creating various contours and profiles.

Conditioning of the cutting edge, such as a honing or chamfering, to make it stronger and less susceptible to chipping. A chamfer is a bevel on the tool’s cutting edge; the angle is measured from the cutting face downward and generally varies from 25° to 45°. Honing is the process of rounding or blunting the cutting edge with abrasives, either manually or mechanically.

For precision milling, opt for fine-tooth milling cutters. Since the cutting depth is shallow (typically 0.25 to 0.64mm) and the cutting load per tooth is small (approximately 0.05 to 0.15mm), the required power is relatively low.

Aluminum oxide, also known as corundum, is used in grinding wheels. The chemical formula is Al2O3. Aluminum oxide is the base for ceramics, which are used in cutting tools for high-speed machining with light chip removal. Aluminum oxide is widely used as coating material applied to carbide substrates by chemical vapor deposition. Coated carbide inserts with Al2O3 layers withstand high cutting speeds, as well as abrasive and crater wear.

Before delving into specific classification explanations, it is necessary to provide a brief introduction to the structure of milling cutters in order to better understand the subsequent classification content. The milling cutter is mainly composed of three key parts: the shank, the body, and the cutter edge. These three parts work together to complete milling operations.

When turning metal, the tool material must be four times harder than the workpiece. This becomes a problem when cutting metals with a hardness greater than 45 HRC, such as alloy steel, high-speed steel and chilled cast iron.

1.5 Drill End Mills: These end mills have the functionality of both drills and end mills. They are used for drilling and milling operations in a single tool. Drill end mills are versatile tools that can create holes and perform various milling tasks.

“The outer surface is hard,” he said. “But as you get deeper into the part, it gets softer, and a chipbreaker can help curl the chip to keep it from scratching the softer surface underneath.”

“Certain aluminum oxide ceramic-grade inserts can be used for hard turning, but not all ceramics can hard-turn,” said Brian Sawicki, business development manager for the Northeast region at Tungaloy America Inc. in Arlington Heights, Illinois. “Sometimes you can get away with using ceramic inserts, but you can’t use them in interrupted machining, such as face turning gear teeth, because they will fracture.”

Coarse-tooth milling cutters are often employed in rough machining due to their larger chip grooves, which excel in carrying cutting loads.