DNMG 431-SF GS3115 Turning Insert - dnmg insert
Graham said the company’s TH carbide can successfully turn materials up to 65 HRC and, unlike PCBN, is available in a range of geometries and chipbreaker configurations. And carbide is less prone to breakage in some applications—a casehardened shaft, for example, where it’s possible that softer material might be encountered, which would quickly dissolve the cutting edge and spell near-certain doom for the PCBN insert.
“Alternatively, when the machine architecture allows, a combined configuration of turning and grinding can become very attractive for mid-volume requirements, an architecture that EMAG machines inherently provide.”
We liked the pointed tips on this set of bits as they kept the bit from skittering across the material when we started drilling, which made the process much easier. If you need to drill different size holes in masonry, these Bosch Bulldog bits are just the ticket.
This set from Owl Tools includes 10 drill bits at an affordable price point. With its broad range of sizes, this set can handle most concrete drilling needs; bit sizes range from 1/8 inch to 1/2 inch in diameter, and we found them all to be durable and of good quality.
Tom Sheehy, applications engineering manager for Hardinge Inc., Elmira N.Y., said hard turning can be performed on virtually any lathe and provides many benefits.
You can drill as soon as the concrete is completely hardened, but pros often wait a couple of days to ensure the concrete is ready. Unlike needing to wait before painting or applying a sealer, you don’t have to wait 28 days to drill.
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.
Masonry drill bits are specifically designed to tackle stone and can bore through these hard surfaces with ease. Often featuring tungsten carbide tips that can endure drilling through hard stone surfaces, masonry drill bits have wide flutes that allow them to pull away large amounts of material as they drill to prevent debris from jamming the bit. Some bits even use diamond-encrusted blades to cut through this material. They come in a wide range of sizes to suit different needs.
Some machine builders, Hardinge included, offer turning and grinding machines, making them trusted advisers on which process is most suitable for a given part. Another is EMAG LLC USA, Farmington Hills, Mich., which also offers machines that grind and hard-turn. The company’s director of sales, Kirk Stewart, agreed that hard turning offers many opportunities for improvement in productivity and part quality, and proper machine design is critical to success.
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.
Secures a cutting tool during a machining operation. Basic types include block, cartridge, chuck, collet, fixed, modular, quick-change and rotating.
With extra-wide U-shaped flutes, these drill bits from WorkPro effectively ejected masonry dust as we drilled in concrete, brick, and stone. The bits have Luxembourg carbide tips that are made to be tough, hard, and durable, and they drilled quickly in our tests.
Before selecting the concrete drill bit sets we wanted to test, we researched more than 20 sets, looking for high-quality bits made from steel with carbide tips. We considered brand to an extent—after all, manufacturers like Bosch and Makita have top reputations for producing high-end power tools and accessories. Still, we didn’t automatically eliminate smaller or niche manufacturers if their masonry drill bit sets were highly rated by customers.
We tried out a 1-inch hole bit, although these bits are available in several sizes to suit your specific needs from just under 3/4 inch to 4 inches in diameter. This is a diamond-coated drill bit; tiny diamond shards are laser welded to the tip, making it easy to drill through concrete and other types of masonry.
If you have additional questions about how to drill into concrete or choosing a drill bit for concrete or a drill bit for brick, you’ll find answers here.
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.
In addition to drilling through masonry, we tried out this set of bits on dimensional lumber and 8-gauge sheet metal. They were slightly slower on masonry than some of the dedicated bits we tried, but they still did the job. They excelled as drill bits for metal as long as we drilled nice and slow. It’s not every day you can pick up a set of good metal drill bits and use them to drill a hole in brick or concrete, but it’s possible with the EZArc bits.
Hard turning is used to finish a variety of parts, such as bearing journals and races, brake drums and rotors, cylinder bore liners, gears, pinions and splines—or to semifinish those same components prior to grinding. Properly applied, it achieves an accuracy best measured in microns and, in many cases, is faster and more cost-effective than cylindrical grinding.
Despite these capabilities, some parts are not suitable for hard turning. Bearing seals, for example, often call for ground surfaces, which eliminate the possibility of fluid escaping through what is essentially a microscopic thread-wide channel produced by single-point turning. And the “white zone” created when material softens and subsequently rehardens during turning (and grinding to a lesser extent) may cause premature component failure. Sheehy said both of these situations can be minimized with the right tooling and a few process adjustments.
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.
This set comes with five bits, ranging in size from 3/16 inch to 1/2 inch. An included plastic bit case provides convenient storage.
Indexable ceramics are another option. Jack Kohler, applications engineer for Greenleaf Corp., Saegertown, Pa., said the cost of ceramic cutting tools falls somewhere between PCBN and carbide, and offers equivalent or better performance in some applications. “Ceramic does quite well in the 50-HRC to 65-HRC range,” he said. “Cutting speeds would be comparable to PCBN. Figure around 700 sfm on a 55-HRC A-2 tool steel, for example, with only slightly lower tool life.”
Masonry drill bits need to be hard enough to endure the rigors of drilling through concrete. With that in mind, most masonry drill bits have steel shafts with a cutting tip made of tungsten carbide, which is much harder than steel and can grind through stone without dulling quickly. Some drill bits use diamond particles, which are welded to the cutting edge to chew through hard surfaces such as marble and granite.
A durable hard-plastic storage case keeps the bits organized and protected when in a tool box or on the workbench. Thanks to the visual holes in the holder that show the exact size hole each bit will drill, we found it easy to pick the correct-size bit at a glance. If you regularly drill into any type of masonry, you won’t go wrong with this set.
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).
Like higher-end bits, this set of Owl Tools bits comes with pointed tips to help keep the bit positioned when starting the hole. We tested the bits by drilling into brick, concrete, and stone, and they fared well. We felt they were just slightly slower than some of the other bits we tested, but drilling into masonry isn’t something to hurry along. We mainly wanted to see if they could withstand repeated drilling without breaking, and they did.
“A significant benefit of changing from grinding to hard turning is the reduction in capital investment,” Stewart said. “Grinding, however, does have its place and is, in some instances, a faster process when multiple features are ground simultaneously—a situation that is ideal for high-volume applications. Thus, in a high-volume environment, when there are only one or two features that require finishing, hard turning might be the better process for overall capital investment.
This kit includes eight bits, ranging from 1/4 inch to 1/2 inch in diameter. The bits have SDS-plus shanks, so the user will need a rotary hammer drill to use them.
CNC grinders are routinely called upon to produce part roundness of 1μm (0.00004"), maintain diametral tolerances of ±2.5μm (0.0001") and impart surface finishes as fine as 8 rms or finer. Sheehy said the only way a CNC lathe can compete in this arena is if it is designed from the ground up for hard turning.
Some drill bits have coatings to improve their performance. Black oxide coatings are more durable than high-speed steel, as they resist rust and corrosion. Tungsten carbide coatings enhance the drill bit’s strength, enabling it to bore through stone and concrete.
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.
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.
Condition whereby excessive friction between high spots results in localized welding with subsequent spalling and further roughening of the rubbing surface(s) of one or both of two mating parts.
While there is no single chuck or drill head for concrete bits, many concrete bits have a slotted drive system (SDS), which means they have slots on the ends of the shanks for use in rotary hammer drills. SDS bits came out decades ago, and today, an improved version (SDS-plus) is standard on bits for hammer drills. You can still find smooth-shank bits for standard drills and hex-shank bits that will fit standard drills and impact drivers.
Drilling through masonry can be tough, requiring special drill bits for concrete that will hold up to the job. We recently tested seven different types of concrete drill bits in various sizes—using them to drill holes in concrete, brick, and stone.
Turning with ceramic inserts is usually done dry. Here the toolholder is mounted face up, driving cutting forces down into the machine’s load-bearing surfaces. Image courtesy Greenleaf.
When buying any type of drill bit, it’s important to consider its compatibility with the drill. Not all drill bits fit all drills. A 1/2-inch-size drill will fit drill bits with a shank up to 1/2 inch in diameter, while a 3/8-inch-size drill will only fit drill bits with shanks up to 3/8 inch in diameter.
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.
These are slotted drive shaft (SDS) bits, meaning they will fit SDS-plus hammer drills, so we used a cordless Milwaukee rotary hammer drill for testing. This set has five pieces, including a 3/16-inch, 3/8-inch, and 1/2-inch bit and two 2¼-inch bits of different lengths. The carbide tips are rugged, and we could easily drill through concrete, brick, and stone.
Ceramics should be run dry in hardened materials, Kohler said. He recommends Greenleaf’s WG-600 silicon-nitride grade—a CVD-coated version of the company’s whisker-reinforced WG-300—as a good starting point for most hardened steels, as well as its new XSYTIN-1, a phase-toughened ceramic grade designed specifically for high-performance roughing and interrupted cuts.
“An often-overlooked component of ID work is accounting for the axial, radial and tangential cutting forces produced when turning,” said Mike Csizmar, regional sales manager at Horn USA Inc., Franklin, Tenn. “This is also true on external operations, but due to the increased L:D ratios associated with boring, these forces become more pronounced, affecting dimensional qualities. If you have a choice, axial (Z-axis) cutting force is preferred. A rule of thumb is that DOC should be equal to or greater than the tool nose radius, thus generating greater axial force. This provides the ability to control chatter, diameter and taper in a more efficient manner, and allows you to get the most out of your cutting tool.”
With carbide tips and a fluted design that bores through masonry, these Bosch Bulldog drill bits are some of the best on the market. Their four-flute design brought concrete dust up and out of the holes as we drilled, making the process smooth and quick.
The bits feature SDS-plus shanks, and users will need a hammer drill to use them. The set comes with seven bits, ranging in size from 3/16 inch to 1/2 inch in diameter, making this a highly versatile set of masonry bits.
For drilling jobs that require drilling through concrete or other stone surfaces, it’s important to use a drill bit that’s strong and sharp enough to bore through especially hard, dense material. Read on to learn about materials, bit type, drill compatibility, and other crucial factors to consider when choosing a masonry drill bit.
For most standard bits, you don’t need to use water. However, if you’re using a large hole bit, spraying the surface of the concrete with water can reduce friction and help keep the bit cool as you drill.
When drilling, a force that is directed axially—along the direction of machining. The magnitude of an axial force rises with the drill’s diameter and the chisel edge’s width. Axial force is also known as thrust. When turning and boring, the term “feed force” is commonly used instead of “axial force.” See cutting force.
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Initially, carbide is also less expensive, although Graham pointed out that cost per edge favors PCBN. “PCBN might cost 10 to 25 times more than carbide, but you’re also going to get 50 to 100 times the tool life. Certainly, for high production, PCBN is the way to go.”
Our favorite, thanks to its four-flute design and carbide tips, is the five-piece Bosch Bulldog Carbide Set for use in hammer drills, which are often used as masonry drills.
Spending money on specialty concrete bits that see infrequent use may not be the most economical way of expanding one’s collection of drill bits. This EZArc multipurpose bit set offers an excellent alternative. The bits’ design and carbide tips make them suitable for drilling through tile, concrete, and stone plus metal, wood, and even plastic.
Start by drilling a small guide hole at a low-speed setting for very hard concrete. Once you’ve established a 1/8-inch hole, remove the bit, blow the dust out of the hole, and use a larger bit at medium speed while applying steady pressure. It’s also a good idea to wear hearing protection—concrete drilling can be loud.
The Owl Tools bits have standard smooth shanks to fit a regular drill. We didn’t notice any of the bits slipping as we applied pressure while drilling, as some smooth-shank bits tend to do.
Opinions vary on the definition of hard turning. Some industry experts say it’s the single-edge cutting of hardened steels from 58 to 68 HRC, while others suggest hard turning begins at 45 HRC and includes hardened irons and superalloys. All, however, agree it presents difficulties but is quite manageable provided the right cutting tools, machine and process parameters are used.
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.
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Angle between the side-cutting edge and the projected side of the tool shank or holder, which leads the cutting tool into the workpiece.
“Hardinge Super-Precision lathes offer 0.1μm programmable resolution,” he said. “Axial errors are mapped and compensated for electronically. All mating surfaces within the machine are hand-scraped, the linear guide ways and ballscrews are oversized, and the base of the machine is filled with composite polymer for vibration damping. Not only does this produce the accuracy and rigidity needed to replace many grinding operations, it also increases tool life during hard turning by up to 30 percent.”
The SHDIATool core bit excelled in our tests. To extend its useful life, users can spray the surface of the material they’re drilling with water, which will help keep the bit cool and reduce friction. This is the bit to have for drilling larger holes in concrete.
Repeated drilling through dense concrete and stone puts drill bits to the test, often wearing them down quickly. While these drill bits from Makita are more expensive than some masonry drill bit sets, in our tests, their thick tungsten carbide tips held up well for drilling several holes.
Each bit has a wide spiral flute that bores evenly through stone, concrete, and brick. These bits will easily handle tough concrete-drilling jobs, but you’ll want to use a good drill for concrete—and it will need to be a rotary hammer drill with a minimum 7/8-inch chuck. We drilled several holes in quick succession, and the Makita bits performed flawlessly.
Kohler said he’s seeing increased use of ceramic in high-temperature alloys, such as Inconel 718 and Hastelloy, although he warns shops to steer clear of titanium, as this presents a fire risk because titanium chips can burst into flames at the high cutting speeds common with ceramics. Regardless of the metal being cut, ceramic inserts usually come with a slight hone, land or combination of the two at the cutting edge to prevent chipping and increase strength.
A durable hard-plastic carrying case keeps the bits organized and easy to transport to the worksite. It was one of the better cases we saw, as it held the bits securely and came with a sliding lock. This is an all-around great little set of drill bits for anyone who regularly needs to drill into concrete or other masonry materials.
Glenda Taylor is a BobVila.com staff writer with a background in the residential remodeling, home building, and home improvement industries. She started writing for BobVila.com in 2016 and covers a range of topics, including construction methods, code compliance, tool use, and the latest news in the housing and real estate industries.
Glenda Taylor is a product tester and writer specializing in the construction, remodeling, and real estate industries. She and her husband own a general contracting company, and Taylor is experienced in both residential and commercial building applications. She tests a wide range of power tools as well as other home improvement, household, and lawn-and-garden products.
Masonry drill bits come in a variety of sizes to suit a broad range of needs. The smallest masonry bits are around 3/16 inch in diameter, with larger bits topping out at the 1/2-inch size. Hole saw bits have sizes that go up to 4 inches or more.
Substances having metallic properties and being composed of two or more chemical elements of which at least one is a metal.
In actual testing, we drilled through concrete, stone, and brick to see how well the drill bits fared. We used a standard DeWalt drill and a Milwaukee rotary hammer drill (depending on the individual drill bit shanks), and we drilled dozens of holes. We noted how well the bits performed and awarded points based on a rubric. After testing, we averaged the points to determine our best overall pick, and then we categorized the rest of the drill bits by their best usage.
The solution, experts agree, is to apply the shortest tool possible relative to tool diameter, preferably no greater than a 4:1 length-to-diameter (L:D) ratio. Boring bars should be on center or, in some cases, a few tenths (0.0003") above center to allow for deflection. And use a boring insert with a 0° lead angle whenever possible, so cutting forces are directed opposite the direction of cut.
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.
Some might wonder about the difference between hard turning the inside of a part (boring) and its outside. Most agree that boring is generally more difficult than OD turning, regardless of material hardness. That’s because boring bars are less rigid than other turning tools, creating problems with chatter and tool deflection. Because quarters are often tight in a bored hole, chip evacuation can be a challenge, leading to coolant starvation and workpiece galling. In addition, achieving sufficient surface speeds becomes increasingly difficult for small part features, such as bores, and PCBN and ceramic inserts require high cutting speeds.
The following drill bits are well suited for drilling into concrete and other masonry materials. They withstood rigorous hands-on testing, and each set of bits performed well enough to make our list. You’ll find different sizes and types that fit different drills. There’s sure to be one for your concrete-drilling project.
Masonry drill bits come in several variations, including rotary percussion, double flute, and saw drill bits. All bit types use large carbide tips that can penetrate stone. Some bits have spear-shaped tips that allow for precision drilling, while others feature a crown-shaped tip that can efficiently grind through masonry.
Most masonry drill bits are used in hammer drills or standard drills, but not all. The SHDIATool core bit is designed for use with an angle grinder, and we were impressed at how well it drilled.
When purchasing and using a drill bit for masonry, there are several important guidelines to follow to ensure a successful outcome.
“Hard turning offers lower machine investment, reduced setup and tool inventory, fewer operations, faster cycle times and greater process flexibility,” he said. “Unfortunately, many shops can use it only for semifinishing of parts prior to grinding, primarily because the majority of CNC lathes are unable to achieve the extreme tolerances and form accuracy produced by cylindrical grinding machines.”
Sharpening drill bits manually with a file or bench grinder is a complicated process. You need a machine specially designed for drill-bit sharpening to do it yourself. It’s usually easier to buy new drill bits.
To cover all bases, we tested bits that fit standard drills and impact drivers, as well as rotary hammer drills. We also tested a hole bit that fits a grinder. Ahead, learn which factors to consider when shopping for a cement drill bit, and find out how the following products earned a spot in our lineup of the best drill bits for concrete.
Horn added to its Supermini line for boring workpieces as hard as 66 HRC without the use of PCBN. Image courtesy Horn USA Inc., Nico Sauermann.
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.
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.
In addition to carbide tips, the EZArc bits have multigrind sharp edges and double-flute design, which make them well suited for drilling in various materials. A hex shank adds even more versatility—these bits are compatible with standard drills and impact drivers. The kit includes five bits: 5/32 inch, 3/16 inch, 1/4 inch, 5/16 inch, and 3/8 inch.
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.
Grinding operation in which the workpiece is rotated around a fixed axis while the grinding wheel is fed into the outside surface in controlled relation to the axis of rotation. The workpiece is usually cylindrical, but it may be tapered or curvilinear in profile. See centerless grinding; grinding.
“A cutting speed of 600 sfm is a good starting point for PCBN,” he said. “We recommend a double-sided round insert where possible, carefully rotating it as the tool wears. Depending on depth of cut, this might provide 10 to 20 uses per side. Some shops are scared off by the relatively high price of these inserts, however. In these cases, we’d likely suggest a PCBN-tipped insert —or even one of our new superhard carbide grades.”
This is the second set of Bosch drill bits to make our lineup, and we found these bits highly efficient. Their four-flute design excelled at ejecting dust and debris as we drilled, which made the drilling process smooth and quick. Their pointed tips kept the bits centered as we started the holes. We were able to drill clean holes in concrete, brick, and even dense stone without problems.
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.
Let’s start with cutting tools. Don Graham, manager of education and technical services for Seco Tools LLC, Troy, Mich., said that if the setup is fairly rigid and the correct cutting parameters can be achieved, indexable PCBN inserts are generally the best bet for hard turning.
Kip Hanson is a contributing editor for Cutting Tool Engineering magazine. Contact him by phone at (520) 548-7328 or via e-mail at kip@kahmco.net.