“For example, I have this complex part, and what I’m doing is opening up cycles and filling in the blanks adding turning to a mill,” he continues. “Tool orientation is managed by the cycles and the cycles manage the tools so I don’t have to. All I have to do is run the part. Visualization will show what’s going on.”

Y-axis turning can also be used in static mode with a locked spindle for flexible two-axis turning with fast insert indexing. The method is suitable for all materials and requires a multitask machine, turning centers or vertical lathe with options to allow interpolation of the milling spindle axis during turning.

For Hainbuch America Corp., Germantown, Wis., the acquisition of Vischer & Bolli Automation (VBA) expanded the automation technology available for turning and milling robot cells. VBA robot cells for turning and milling small parts up to 10 kg, VBA Robilo cells for 80-kg workpieces and even modular cells as large as 500 kg are available.

■ Once you have set up and used a tool, do yourself a favor: When you remove it from the lathe, record at least the X-axis offset on the storage tube or directly on the tool. This will speed the setup of that tool the next time you use it. The offset won’t be perfect, but it can be darn close.

Walter’s latest innovation is the Tiger-tec Gold CVD grade, which can be used for applications from low-carbon steels to high-alloy steels. Steel and cast-iron solutions are closely related.

With the expanded expertise in automation, Hainbuch is able to support its customers throughout the entire manufacturing process. The modular design of the cells lends itself to choosing the extent of functionality. Options include pallet-, workpiece- and toolholder-handling systems, as well as a master computer for entire cells.

“The difference between the two is that FANUC uses software to achieve its high-frequency cutting action, while Mitsubishi uses hardware to achieve the same results,” Zunis says. “The technique is achieved by oscillating the cutting axis at a frequency in the kilohertz range. It isn’t something that you can easily program using traditional programming practices. The action is to feed a little bit in any axis that is cutting, dwell or reverse a little, then feed a little more, then dwell and reverse, etc. A traditional program would be extremely long and labor intensive to prepare.”

ThriftPoint—approaching from the end, this single flute inserted tool will profile the part with the support of a bushing. Think face, radius/angle, similar to a needle valve.

Software provider Open Mind Technologies AG engineered hyperMILL software to expedite trochoidal turning on conventional CNC turning machines, enabling easy programming of trochoidal turning on standard three-axis turning machines. Using a multitasking machine with B-axis capability enables a shop to take full advantage of the benefits of trochoidal turning strategies.

ThriftTurn—approaching from the end, this two-flute inserted tool will profile the part with the ability to adjust each insert independently. Think face, radius/angle and a thread blank, similar to a welding tip.

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.

Aimed squarely at the job shop market, the QT-Ez is “putting Mazak quality and reliability within reach for virtually any shop with productive, space-saving efficiency at an affordable price,” according to Greg Papke, vice president, sales and marketing for Mazak’s Advantec Product Group. The QT-Ez fills a niche right below Mazak’s ubiquitous Quick Turn machines.

CNC turning, on all of its machine platforms—Swiss, conventional and multitasking—is getting smarter, faster and more versatile through cleverly designed tools and software combinations. Which companies and solutions are vying for leadership all depends on what knotty problem is being addressed.

“One mechanism is achieved by introducing elasticity with a layered coating that includes TiCN that helps resist crack formation. Additional grain-oriented Al2O3 coating layers further improve crater wear resistance, allowing the grades to run much faster cutting speeds. The benefits to the shop are high process reliability, excellent surface finish and dimensional stability over the production run of steels or cast irons,” Garud says.

■ If you have enough machine X-axis travel and the control will allow it, you can run the spindle in reverse and take a light test cut on the OD of a part with an internal tool to set an accurate X offset without having to make and measure a bore. On my machine, I enter the offset as a negative X value because the tool is into the negative X quadrant. Be sure to check the control to see if it will accept a negative value and still correctly do the offset math. It’s almost always easier to accurately measure an OD than a bore or hole.

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Tom Lipton is a career metalworker from the San Francisco Bay area who has worked at various job shops. For more information, visit his blog and YouTube video channel.

“The biggest challenges that shops face are still feeds and speeds, chip breaker and chip control, tool life and productivity improvement,” Garud notes. “Multilayer coating technology has introduced sophisticated ways to combine single coatings into multilayer coatings to target specific machining problems. So instead of a single layer of TiCN, AlTiN, Al2O3 and TiAlN, multilayers of these coatings used in various combinations and thicknesses are able to reduce cracking that leads to tool breakage and flaking. A cobalt enriched substrate also adds to a tough substrate, further preventing chipping while not compromising the hardness and high-speed capabilities of the grade.

■ For all my external boring tools, I add a back stop screw that butts against the turret. This allows me to retain an accurate X offset if I take the holder out of the machine. During the next setup of that tool, I retain the X offset.

Chip control, especially for difficult-to-machine and so-called “gummy” materials, is always a prime target for ways to break bird-nesting chips into easy-to-handle, tiny, steel-mimicking chips. Unique, high-frequency cutting capability on CNC controls is leading the way. New tooling concepts for high-volume turning operations and automation are always welcomed into shops looking to increase productivity or enter into new markets.

Absolute Machine Tools’ solution is offering three of its CNC turning machine lines with CNC control options that feature oscillation cutting. All three Absolute brands—Nexturn Swiss machines, LICO CNC screw machines and Quick Tech hybrid-production turning machines—feature either the Mitsubishi CNC or the FANUC CNC with their oscillation cutting technology capability called Vibration Cutting Control (VCC) and Servo Learning Oscillation (SLO), respectively.

Another important benefit of form tooling is that with all geometries and profiles of the part in the form tool, inspection can be done without checking every feature. “First and last piece inspection (per insert change) are enough to guarantee that all the parts in between were up to spec,” Freeze says.

Walter’s turning tools cover ISO turning, grooving and parting off, as well as thread turning. Precision turning tools, boring bars and parting blades are available with standard ISO square shanks, as well as with all interfaces that are standard in turning applications.

Development of CNC control technology for multitasking machines brought turning and milling together on one platform for Siemens, according to Daniel Vitullo, business development territory manager for Siemens Industry Inc., Elk Grove Village, Illinois. “We developed turning and milling on a single platform, which makes transition from one technology to the other seamless,” he says. “Whether a turn-mill or a mill-turn, depends on which is primary functionality.”

■ Setting the fine serration top jaws in a CNC lathe power chuck is a common challenge. The 1mm serrations make it easy to set one tooth off and screw up the centering on a blank. Also, it’s difficult to measure three jaws and set them to the middle of the jaw travel. I made special labels that have the basic sizes engraved on them so I can quickly set the jaws to a diameter range and hit all the serrations at the same radius. It cost $5 and a little time to engrave on a mill. Be sure to thoroughly clean the part of the jaws where these labels stick on. Make it a habit to remove the fine jaw serrations from the jaw with a scratch brush when reinstalling the top jaws.

As the name implies, the new method makes use of the Y-axis and all three axes used simultaneously when machining. The tool rotates around its own center. The insert is placed for machining in the Y-Z plane and the milling spindle axis interpolates during turning. This allows intricate shapes to be machined with a single tool.

Trochoidal turning is essentially separated into two strategies: “simple” done on conventional turning machines, and “simultaneous” performed on machines with B-axis movement. These turning strategies are similar to trochoidal milling, which combines a spiraling cutting path with straight-ahead motion. Turning similarly features lower depths of cut, higher feeds and faster cutting speeds than conventional turning.

Runs endmills and arbor-mounted milling cutters. Features include a head with a spindle that drives the cutters; a column, knee and table that provide motion in the three Cartesian axes; and a base that supports the components and houses the cutting-fluid pump and reservoir. The work is mounted on the table and fed into the rotating cutter or endmill to accomplish the milling steps; vertical milling machines also feed endmills into the work by means of a spindle-mounted quill. Models range from small manual machines to big bed-type and duplex mills. All take one of three basic forms: vertical, horizontal or convertible horizontal/vertical. Vertical machines may be knee-type (the table is mounted on a knee that can be elevated) or bed-type (the table is securely supported and only moves horizontally). In general, horizontal machines are bigger and more powerful, while vertical machines are lighter but more versatile and easier to set up and operate.

Two new tools have been developed to support Y-axis turning. The new CoroTurn Prime variant is suitable for shafts, flanges and components with undercuts. The CoroPlex YT twin-tool, featuring CoroTurn TR profiling inserts and CoroTurn 107 round inserts with rail interface, can be used for components with pockets and cavities.

Applications for trochoidal turning include high-volume production operations such as manufacturing traditional automotive components, including axles and shafts.

A combination of more capable modern machine tools and sophisticated CNC programming are driving the search for improved part quality. All-directional turning enables finishing complex shapes in a single cut without blend points. Wiper inserts can be kept perpendicular to the surface to also produce a wiper effect on tapered surfaces, the company says. In Y-axis turning, the main cutting forces are directed into the machine spindle, offering high process stability. Maintaining a constant entering angle during machining means chips can be optimally controlled.

Using a turning tool, scratch a line a tenth or two deep along the turret axis. It allows you to twist a boring bar around and have something for lining up the cutting edge.

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).

Finding cutting solutions for precision turning applications—whether for conventional CNC, multitasking machining of complex workpieces or high-volume, Swiss-style production—means considering all relevant parameters of the application, says Sarang Garud, product manager, turning, drilling, boring, Walter USA LLC, Waukesha, Wisc. “I don’t take the shotgun approach. I prefer the rifle when it comes to formulating a cutting solution strategy with our latest technologies,” Garud says.

Applications for profiling with form tools include aerospace components, automotive workpieces such as bearings and shafts, hydraulic components, medical components and industrial products.

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.

For CNC turning, whether Swiss-style or multiple spindle machines, GWS Tool Group, Nashville, Tenn., has developed a custom profiling inserted tooling system that replaces standard, single-point indexable tools with form tools. Cycles on CNC machines are reduced by replacing single-point tooling with toolholders that hold form or profile tooling that make a plunge move rather than making several passes with IC indexable inserts.

Increased feed rates put greater stress on machine tool components. Feed rate is directly proportional to metal removal rate and higher metal removal rates place larger demands on the machine tool spindle. However, round positive style inserts generally are softer cutting, so in most cases trochoidal turning is suitable for lower power machines.

■ Sometimes it’s hard to align a boring bar with the machine axis and centerline when the manufacturer doesn’t provide flats on a tool. To get around this problem, I face the end of a setup bar and darken it with a marker. Using a turning tool, I scratch a line a tenth or two deep along the turret axis. This line is pretty accurately on center and aligned with the turret X-axis angle. It allows me to twist the little boring bar around and have something for lining up the cutting edge. I use a mirror so I can see upside down to align the tool with the scribed centerline.

■ For bar pulling operations, it’s better to have a spindle liner that is close to your raw stock size. I made single spindle liners that drop into the headstock. They use common off-the-shelf pipe and tubing sizes. Have the waterjet or laser cutter zip out a bunch of disc blanks next time you have less than a minimum cutting order. Toss them on the shelf, and the next time you need a special liner diameter, half the work is already done. Chop off a piece of tube and weld the discs in place. A couple of quick welds and you have an inexpensive spindle liner for that oddball size you need to run. CTE

Chip breakage of exotic materials, stainless steels and those with high nickel content is always a challenge in turning operations, according to David Zunis, director of service and applications engineering, Absolute Machine Tools, Lorain, Ohio. “When turning these materials, chips tend to ball up and nest up, leading to insert and tool breakage, causing all kinds of problems, including broken tool arms for cutoff detection. The best condition you can have is breaking those chips into tiny little chips so that they fall away much like chips for carbon steel,” Zunis says.

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.

For multitasking processing capability, Papke cites the QT-Ez’s milling and Y-axis off-centerline capability. “For still more productivity, QT-Ez machine seamlessly integrates with a range of automation solutions. These include simple bar feeders and parts catchers as well as full cooperative robot installations such as Mazak’s Automation Systems Cobot Cell,” Papke says.

Cutting tools that can improve quality, reduce cycle time and handle the most complicated shapes and pockets are difficult—if not impossible—to find, unless you are looking at the latest iteration of all-directional, Y-axis turning with a single tool from Sandvik Coromant US, Mebane, N.C. The Y-axis turning method continues to add to the company’s earlier capabilities, such as its all-directional Prime Turning, non-linear turning and interpolation turning.

Both controls are actuated by G-code, Zunis adds. There is a syntax that tells the number of vibrations, the frequency, the length of cut and how far the tool moves in one rev of the spindle. “Experience will help determine parameters to get in the ballpark,” Zunis continues. “It’s related to how far the tool moves in one revolution of the spindle to the feed rate. You want to break the chip at least once per revolution. That’s a good starting point. Some materials you can go around hundreds—or even thousands—of revs before chips become a major problem. Oscillation cutting capability works well on smaller machines where chips can have a major impact on machine operations.”

The benefits of highly engineered form tooling for turning include shorter cycle times, fewer tools, reduced number of setups and significantly improved tool life, according to Johnny Freeze, business development director at GWS.

■ Try turning off the constant cutting speed when turning tricky plastics. Having manual control over the cutting speed can provide better control of the stringy chips. Chip control in a CNC lathe can be a real roadblock to unattended machining on some types of plastics. You can increase the chip load by slowing the spindle or increasing the feed rate to thicken the chip. Even a simple task like turning off the coolant can sometimes help with chip control.

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.

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GWS’s form tools include all geometries and angles of the workpiece. Carbide form tools allow more intricate profiles with tighter tolerances and improved cutting geometries, resulting in two to three times faster cycle times, Freeze says. Form tools that replace multiple IC indexable inserts reduce the chance of error and improve tool life, with form tools lasting for 1,500 to 5,000 parts compared with only several hundred for IC indexable inserts. Form tool life is two to three times that of single point tooling, according to Freeze.

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 it comes to turning machine solutions, it’s hard to argue with Mazak Corp., Florence, Ky. The company supplies sophisticated Integrex five-axis, multitasking machines to produce complex workpieces for aerospace, as well as its most recently introduced QT-Ez 12MY multitasking systems.

To Vitullo’s way of thinking, the seamless connection is a major enhancement for machine-tool builders when it comes to adding processes like skivving, hobbing, grinding and other processes for customers. Adding functionality is a matter of opening up cycles and filling in the blanks. Simulation on the SINUMERIK ONE control helps operators know what’s going to happen when they run a complex part, Vitullo notes.

To learn the ins and outs of the shop’s turning application, Garud advocates an extensive checklist of questions about a shop’s process capabilities and operations. What kind of machine? How old? How robust? What kind of cut finishing/medium/roughing? Interrupted or not? Coolant? Material (steel, cast iron, stainless)? Difficult to machine? Chip control, chip breaker?

A significant piece of the machining puzzle is provided by the Digital Twin that resides within the SINUMERIK ONE CNC. “We’re not talking about conventional two-axis lathes. These machines represent million dollar and more investments in advanced machining technology,” Vitullo points out. “Our digital twin is native to the control. It simulates the operation of the multitasking machine. If I flip a tool around, the digital twin will recognize it and simulate the operation of the machine.”

“You can eliminate fear about running a complex part because all the travels, axis values and centers of operation are set up the same as the physical machine,” he continues. “By combining cycle support and the digital twin, you get almost a fully closed loop process from development and testing of the part to running the part. The only thing that’s missing in this scenario is inspection.”

Standard round turning inserts increase toolpath flexibility and permit smooth entry and exit from the workpiece. The insert is always in the cut, eliminating the time lost returning to a set point after every pass. Trochoidal turning performs longitudinal and face turning as well as radial and axial grooving. Because of the possibility of using high feed rates to get good chip breaking, the approach is also beneficial when turning soft but tough ductile materials that normally produce long chips that endanger operators and wrap around the tool.

“Turning is very specific,” Garud notes. “Everything matters and there are many parameters to consider. It all comes down to feeds and speeds and how our newest technologies fit the application’s specific requirements.

1. Process of locating the center of a workpiece to be mounted on centers. 2. Process of mounting the workpiece concentric to the machine spindle. See centers.

Manufacturing processes can be completely flexible with the automated changing of mandrels and chucks. Clamping device changeover includes zero-point clamping systems for both turning and milling. In addition, Hainbuch’s intelligent IQ clamping devices, both as a chuck for O.D. clamping and as a mandrel for I.D. clamping, facilitate upstream and downstream measuring processes. Workpieces are continuously measured for diameter, temperature, workpiece contact and clamping force. Measurement data are relayed to the machine controller for analysis via contactless data and energy transmission, closing the production loop.

GWS offers a number of profiling products, each featuring quick change replaceable heads and adjustable movements. They include:

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.

Targeting the growing market for high-mix/low-volume production of small and slender precision parts, Mazak has introduced its Syncrex series of Swiss style machines also manufactured in the Florence facility. The Syncrex machines feature improved design for machining of smaller parts from 12'- (3.66 m-) long bar stock in diameters of 1.5" (38.1 mm) or less. The series features one-piece-polymer, casting-machine base that is said to be 10% more rigid than cast iron with thermal control that reduces part variation by 25%. In addition, Mazak Dynamic Chip Control reduces long, stringy chips that can foul tooling and mar surface finishes, according to the company.

For bar pulling operations, it’s better to have a spindle liner that is close to your raw stock size. Pictured is a simple spindle liner.

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.

Programming the additional axis is somewhat more complex than that for a three-axis machine, but the moving axis provides greater accessibility when turning complex parts and as a result is faster and more efficient. The round inserts combined with light depths of cut and the ability to rotate/swivel the cutting tool relative to the workpiece axis effectively creates more cutting edges and increases tool life. Regarding insert geometry and style, global toolmaker Ceratizit Inc. typically recommends its RCMT and RCGT inserts for trochoidal turning and GX24 inserts for trochoidal grooving using 4-6 mm nose radii and M3 chip breakers.

Vitullo says, “It’s physically the SINUMERIK ONE control which is driving the machine, and the digital twin is driving that simulation with the same control. The digital twin and the physical machine use the same parameters and settings, this also includes travel limits and drive settings. For us, the digital twin is a true real-world simulation. This means when using the SINUMERIK ONE digital twin you have full-cycle support. If you call up the cycle for drilling or high-speed milling, the machine operator doesn’t have to guess about the outcome. What happens in simulation is what will happen at the machine. It’s not your machine’s control. What most others do, they look at how our cycle works and they emulate it off the code from the post we run the same cycle in both simulation and at the machine,” Vitullo explains.

Thrift Edge—approaching from the side, this inserted tool will profile the part. Think multiple grooves, cornerbreaks/radii, similar to a piston (four grooves at once).

Few among us would turn down turning results that produce a much higher metal removal rate when cutting difficult-to-machine materials such as stainless steels and nickel and titanium-based alloys. That is the promise of trochoidal turning, a machining strategy in which tool paths and the entry and exit movements are optimized to maximize metal removal rates. The simultaneous use of different axes in combination with round indexable inserts and advanced CAM software are the keys to trochoidal turning’s success.