Once again, in these applications “a lot of people will start out with coated carbide, and if they have a short run, that will get them through and give them a good finish,” he said. “But if the volume is high, then CBN is something to look at.”

Other best practices when using boring tools involve coolant-related issues. For one thing, it’s advisable to keep boring coolant clean.

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.

The three highly stable cutter body designs incorporate Short Type ‘E’ ‘EL’ and Shell Type ‘F’ which uses a smaller Sumitomo AXMT06 insert that has a high rake ‘wave’ style precision cutting edge. Inserts can be specified from seven substrates ACP, ACK and ACM and three chip breaker geometries –L with 25°, -G with 20° and higher edge strength –H which has 5°. Each is segregated to maximise performance when used respectively on high speed/light cutting, general purpose or roughing applications

For boring applications with depth-to-diameter ratios greater than 5-1, Allied Machine & Engineering offers Novitech, a mounted module that reduces vibration when machining hole diameters. Wise said this improves the surface finish of bored holes and increases tool life.

ANT Industries, a leading manufacturer of aero engine and gas turbine components in Atherstone, Warwickshire, has announced a significant milestone in its commitment to quality and excellence.

The ACK200 geometry with its ‘Super FF’ CVD coating is for use in more general machining tasks involving grey and ductile cast irons and when milling the same materials and heavy interrupted cuts are involved, the ACK300, which is coated with Sumitomo’s ‘Super ZX’, provides a solution able to generate even greater levels of productivity.

Meanwhile, ACM200 is coated with ‘Super FF’ to provide high orders of wear resistance when machining PH stainless steels and ACM300 should be the first choice with its ‘Super ZX’ coating when highly balanced wear and fracture resistance is required on materials such as stainless steel.

“So a key is to get the chips out of there so you can ensure a good finish and not have any interference with the cutting edge,” White said.

Due to its importance during boring and other cutting operations, better coolant delivery has been a focus of Scientific Cutting Tools.

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Another coolant-related problem can arise during the use of CBN-tipped boring bars. White said CBN is hard but also brittle, so big temperature swings can crack the material. To prevent this, there can be no interruption of coolant delivery to the tool during a boring process.

These tools can require “a good deal of technical knowledge to set up, run and make those final finishing adjustments,” she said. “So we (offer) digital adjustment instead of an analog vernier scale.”

She added that digital components also can be damaged by high coolant pressures, so she recommends limiting these pressures to 500 psi.

Essentially a cantilever beam that holds one or more cutting tools in position during a boring operation. Can be held stationary and moved axially while the workpiece revolves around it, or revolved and moved axially while the workpiece is held stationary, or a combination of these actions. Installed on milling, drilling and boring machines, as well as lathes and machining centers.

“When you’re done making the adjustment,” Wise said, “you just take that digital module off the boring head and you’re ready to go.”

“Some people that are newer to the industry don’t even know how to read a vernier scale,” Wise said. “So digital adjustment is becoming a lot more common.”

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.

“We need to have seals in place to protect the digital components,” said Wise, whose company makes such tools. “But really nasty coolant can eat up those seals and completely damage those components.”

The AXMT inserts extend the range of Sumitomo’s successful WEX Wave Mill Series of milling cutter bodies by introducing the WEX Type 1000 for 90° shoulder milling applications that also enable pocketing, helical boring, slotting, shoulder milling and ramping cycles to be carried out with the same tool.

In addition to coolant delivery advances coming from toolmakers, White stressed the importance of the high-pressure coolant capabilities of current machines. Today, he pointed out that many machines are equipped with pumps that can produce coolant pressures ranging from 300 to 1,000 psi, which is a big help to tools and toolholders designed to get coolant to places where it will be most helpful.

ACP100 has the latest ultra-smooth Sumitomo ‘FF’ chemical vapour deposition (CVD) coating giving excellent wear and thermal resistance for high speed and light cutting of steel. ACP200 uses Sumitomo’s ‘Super ZX’ physical vapour deposition (PVD) coating on a tough carbide substrate enabling milling to be maintained at rates up to 1.5 times faster than conventional inserts.

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For boring operations, Allied Machine & Engineering provides two digital tooling options. One is a tool with a built-in digital component: a display fixed to the boring tool. As a user adjusts the tool’s finished diameter setting, the adjustments are shown on the display, Wise explained.

Another key factor that comes into play when choosing a boring tool is the ratio of hole depth to diameter. If that number is high, Scientific Cutting Tools can provide boring bars with a helical flute, White said, which minimizes deflection during the boring process.

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.

So even though a solid-carbide bar costs $25 and a diamond-tip option costs $150, “your cost per piece is going to be way less,” he said.

White said machine shops cutting very abrasive nonferrous materials might get through 5,000 parts with a diamond-tipped boring bar compared with 10 or 15 with a solid-carbide bar.

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.

He explained that stringy chips made of these materials can accumulate in blind holes where they are re-cut by the tool and often end up damaging the cutting edge.

Although some shops know enough about boring tools to make specific requests of suppliers, the majority rely to some extent on recommendations from toolmakers.

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

“The boring head is going to last a lot longer because it’s not vibrating,” she said, “so there’s not a lot of radial deflection or pressure.”

In addition, Wise said her company’s digital technology makes it easier for operators to use boring tools.

The seven grades: ACP100, 200 and 300, ACK200 and 300 and ACM 200 and 300 can cut to depths up to 5mm. ACP100 has the latest ultra-smooth Sumitomo ‘FF’ chemical vapour deposition (CVD) coating giving excellent wear and thermal resistance for high speed and light cutting of steel. ACP200 uses Sumitomo’s ‘Super ZX’ physical vapour deposition (PVD) coating on a tough carbide substrate enabling milling to be maintained at rates up to 1.5 times faster than conventional inserts. This also has the added benefit of high wear resistance. ACP 300 too has ‘Super ZX’ coating and is designed for use under more arduous roughing applications.

The other digital option is the company’s 3E Tech display, a small module that can be mounted on a boring tool for diameter adjustment.

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“In small-diameter boring with certain materials like 1018 steel, 316 stainless and 304 stainless, you can get really stringy chips,” White said. “So if you can get that coolant right to the cutting edge and keep it flowing, it could be really beneficial.”

The new inserts bring processing benefits with the ability to maintain high levels or surface finish and each insert has a high rake with a curved wave form to the cutting edge. With a greater width to the insert this creates a more stable seating to support the cutting action. The seven grades: ACP100, 200 and 300, ACK200 and 300 and ACM 200 and 300 can cut to depths up to 5mm. ACP100 has the latest ultra-smooth Sumitomo ‘FF’ chemical vapour deposition (CVD) coating giving excellent wear and thermal resistance for high speed and light cutting of steel. ACP200 uses Sumitomo’s ‘Super ZX’ physical vapour deposition (PVD) coating on a tough carbide substrate enabling milling to be maintained at rates up to 1.5 times faster than conventional inserts. This also has the added benefit of high wear resistance. ACP 300 too has ‘Super ZX’ coating and is designed for use under more arduous roughing applications. The AXMT inserts extend the range of Sumitomo’s successful WEX Wave Mill Series of milling cutter bodies by introducing the WEX Type 1000 for 90° shoulder milling applications that also enable pocketing, helical boring, slotting, shoulder milling and ramping cycles to be carried out with the same tool. The three highly stable cutter body designs incorporate Short Type ‘E’ ‘EL’ and Shell Type ‘F’ which uses a smaller Sumitomo AXMT06 insert that has a high rake ‘wave’ style precision cutting edge. Inserts can be specified from seven substrates ACP, ACK and ACM and three chip breaker geometries –L with 25°, -G with 20° and higher edge strength –H which has 5°. Each is segregated to maximise performance when used respectively on high speed/light cutting, general purpose or roughing applications Each of the three variants of cutter body provide greater resistance to abrasion and corrosion with enhanced chip evacuation through internal coolant feed. Short Type ‘E’ is available from 10mm to 25mm diameter and has between two and seven insert pockets. Short Type ‘EL’ in diameters between 10mm and 20mm has between two and four teeth and Shell Type ‘F’ has outside diameters between 32mm with eight teeth to 63mm with 14 teeth. ACP100 has the latest ultra-smooth Sumitomo ‘FF’ chemical vapour deposition (CVD) coating giving excellent wear and thermal resistance for high speed and light cutting of steel. ACP200 uses Sumitomo’s ‘Super ZX’ physical vapour deposition (PVD) coating on a tough carbide substrate enabling milling to be maintained at rates up to 1.5 times faster than conventional inserts. The ACK200 geometry with its ‘Super FF’ CVD coating is for use in more general machining tasks involving grey and ductile cast irons and when milling the same materials and heavy interrupted cuts are involved, the ACK300, which is coated with Sumitomo’s ‘Super ZX’, provides a solution able to generate even greater levels of productivity. Meanwhile, ACM200 is coated with ‘Super FF’ to provide high orders of wear resistance when machining PH stainless steels and ACM300 should be the first choice with its ‘Super ZX’ coating when highly balanced wear and fracture resistance is required on materials such as stainless steel. www.sumitomotool.com

But while shops always are concerned about price, “when customers come to us with a very important operation like finishing, it’s more important that the tool does what we say it’s going to do,” Wise said, as long as the extra cost is “within reason.”

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

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.

“When you have excessive vibration, it’s really hard on the customer’s machine as well,” she said. “So it’s a win-win when you include some type of vibration-reducing technology.”

You probably know that boring tools are used to bring holes to the desired size and finish, straighten drilled and cored holes and correct casting defects. But you may not know what to do — and what not to do — to get longer life and better performance out of boring tools, as well as improve the user experience. This knowledge falls into three categories: tool selection, best practices when using the tools, and developments that have had a positive impact on boring tools and processes.

In some cases, however, “customers want to change that angle, so we make special tools for them based on their preferences and R&D that they have done,” he said. “For one customer, we make the front angle 8 degrees instead of 2 degrees because they find that works better for the materials that they cut.”

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.

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The new inserts bring processing benefits with the ability to maintain high levels or surface finish and each insert has a high rake with a curved wave form to the cutting edge. With a greater width to the insert this creates a more stable seating to support the cutting action.

To improve coolant delivery, Scientific Cutting Tools has developed a toolholder featuring a ring around the tool shank. Instead of just directing coolant to a point at the tip of the tool, he said this ring produces a coolant “halo” that surrounds the entire tool.

This works because CBN “can take a lot of heat, but it can’t take the big thermal change from hot to cold,” White said. “So as some people move toward dry machining, they’ll just shoot air through their lines to help with the chips. But that (prevents) that thermal up-and-down condition that can crack CBN.”

Each of the three variants of cutter body provide greater resistance to abrasion and corrosion with enhanced chip evacuation through internal coolant feed. Short Type ‘E’ is available from 10mm to 25mm diameter and has between two and seven insert pockets. Short Type ‘EL’ in diameters between 10mm and 20mm has between two and four teeth and Shell Type ‘F’ has outside diameters between 32mm with eight teeth to 63mm with 14 teeth.

In some cases, White pointed out that price considerations lead shops to the least expensive option: an uncoated boring tool. But when those customers cut metals like stainless steel and Inconel, Scientific Cutting Tools urges them to think longer term and opt for a coated tool. He reports that his company has had “great success” with a high-performance AlTiSiN coating called nACo, which provides excellent wear resistance and lubricity.

Coolant delivery advances aren’t the only ones boosting boring operations. Allied Machine & Engineering, for example, has come up with boring tools that have a self-balancing feature. This automatic mass balancing is meant to compensate for imbalances that occur as the diameter of a boring tool’s insert holder is adjusted. The idea is to reduce vibration in order to optimize finish machining.

Once a boring tool has been acquired for a particular application, users should be aware of practices that will help get the most out of that tool. For example, Wise recommends that users make sure they’re removing enough material when boring to completely cover the nose radius of the insert. If this isn’t the case, she said, radial deflection or pressure will cause chatter, which in turn results in poor hole quality or surface finish.

In situations like this, she said shops can do two things. One is to make the pre-drill hole size a little smaller so more material is left for the finishing operation. If this can’t be done, the other option is to swap out the tool insert for one with a smaller nose radius while leaving everything else in the boring tool setup the same.

“Most of the time, when customers are looking at a finishing operation, they want a little bit of guidance,” said Natalie Wise, manager for finishing products at Allied Machine & Engineering Corp. in Dover, Ohio. The reason, she explained, is that “those are later operations in the manufacturing of their part, so it’s very critical that they get it right the first time. If something goes wrong with those finishing operations, they could be scrapping something very expensive that they’ve spent a lot of time on.”

“Then if they’re using them up too fast, they’ll call and I’ll say, ‘You should probably bite the bullet and get a diamond-tipped bar for those materials because they’ll last a long time,’” he said. “Even though they’re quite a bit more expensive, the (number of) parts you get out of them can be phenomenal.”

Single- or multiple-point precision tool used to bring an existing hole within dimensional tolerance. The head attaches to a standard toolholder and a mechanism permits fine adjustments to be made to the head within a diameter range.

William Leventon is a contributing editor to Cutting Tool Engineering magazine. Contact him by phone at 609-920-3335 or via email at wleventon@gmail.com.

When it comes to selecting the best boring tool for an application, some users are knowledgeable enough about the subject to request tools with specific features and characteristics. For example, Scientific Cutting Tools Inc. in Simi Valley, California, normally makes boring tools with a 2-degree front angle across the face that facilitates efficient cutting, said Sales Director Todd White.

To come up with the right boring tool for a particular application, White asks customers for basic information, such as the hole diameter, machining speeds and feeds and the part material. If the material is hard and abrasive, Scientific Cutting Tools can supply diamond- or CBN-tipped boring bars. Sometimes, however, he reports that customers dealing with such materials may start with conventional solid-carbide boring bars rather than pay extra for diamond- or CBN-tipped tools.

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

“If you’re running nasty, dirty coolant through the tool,” Wise said, “it’s going to get into internal components and start wearing them down more quickly.”