Nothing seems so obvious in subtractive machining than that milling and turning processes really are very different: single point vs. multipoint tools; rotating workpiece vs. rotating tool; static tool vs. rotating tool, etc. And yet we have witnessed the harnessing of these two very important and dissimilar processes to work together on the same machine; alternately on mill-turn-type machines or simultaneously on so-called multitasking machines. The magic that has made this possible is found in the programming capabilities of advanced CNC controls as well as in machine design that accounts for the forces at work in removing material in the most efficient way possible. So whether you are talking about entry-level machining or sophisticated multitasking solutions, the requirements always involve choosing the right machine technology.
To reduce manufacturing costs and improve overall workpiece quality for the aerospace and related industries, Mitsui Seiki USA Inc. (Franklin Lakes, NJ), has developed and added a full line of five-axis machining centers with turning capability to its three-axis and four-axis machine lines using similar technology. “To reduce manufacturing costs, the biggest saving is related to workpiece setup times. When parts have to go to separate machines for milling and turning, they generate handling, setup, and increased work in process,” said Tom Dolan, vice president sales and marketing.
“Mitsui Seiki customers typically occupy the high-end aerospace market where workpieces are rather expensive and are often made in significantly lower quantities than other industries like automotive.” Typical parts include aero engine related components, such as gear cases, fan frames, compressor housings, as well as critical rotating parts i.e. blisks, impellers, and turbine disks.
“Workpiece tolerances are very tight. Our customers’ parts usually have some relatively straightforward turning requirements, but very accurate and challenging milling requirements. It’s to their and our advantage to be able to perform these processes on a dual-purpose machine,” said Dolan. “However, when you rotate a workpiece, work fixture, pallet, and a rotary table at a relatively high speed, heat is generated that can adversely affect the machine tool’s geometry and accuracy.
“Keep in mind the types of applications that we’re talking about, particularly in the gearbox application. Milling tolerances are measured often in the micron range; 10 µm or less isn’t uncommon on many high-precision aero gearboxes,” Dolan said. “The gearboxes we’re machining are predominantly aluminum and magnesium. Our customers with blisk, turbine disc and impeller applications are machining titanium or Inconel nickel-based alloys. Cycle times can range from an hour-and-a-half to 30 hours per workpiece and volumes are relatively low but climbing rapidly as the aero industry increases production rates.”
Another significant challenge on turning and milling machines is that the milling spindle has to be able to operate correctly in a nonrotating mode to manage precision turning effectively. The effects of fixed tool (i.e. single point turning) must not cause premature spindle wear, damage, or failure. “We have designed a whole new system for locking up that spindle properly and isolating it from the bearing system to allow precision turning on a milling machine without damaging the spindle. Isolating and clamping our unusually stiff spindles properly allows us to avoid inducing undue stress to the spindle bearings during fixed tool turning applications,” Dolan said.
As with the turn mill, Mitsui Seiki is high on key hybrid manufacturing processes including additive/subtractive technology, mill/jig grind, superabrasive, and GE’s Blue Arc technology. For example, at IMTS, Mitsui Seiki introduced their new hybrid additive/subtractive, and hybrid G mill/grind centers and explained their work with GE on the Blue Arc technology for high-speed low-cost roughing of tough materials such as nickel-based alloys and titanium and others. The expectation is that with all these very productive processes, combined with the same machine and setup, precision five-axis machining will have a significant impact on manufacturing going forward.
At DMG Mori (Hoffman Estates, IL), the Ecoline product line is gradually becoming a holistic solution with more technology options for global manufacturing. The series comprises the CLX series of basic universal lathes, the CMX V series of basic vertical machining centers, and the basic universal milling machines of the CMX U generation. The CMX V series will be manufactured in DMG Mori’s state-of-the art manufacturing facility in Davis, CA.
Today, DMG Mori points to the global market where the overall performance of a machining solution is most important for the users of today. This applies worldwide and independently of the performance class of a machine or the industry segment of the customer. The new basic machine program will feature a new portfolio of technology, software solutions, and applications that will be expanded into a comprehensive modular building block system offering a multitude of possibilities.
As a result DMG Mori’s entire range of technologies will be opened up for the users of CLX and CMX machines. This includes the extensive options in the field of spindle technology, for example. The evolution of the new basic machines will be seen in a number of developments: the optional Y axis with its 60-mm travel path for milling operations on the CLX 450 lathes, the optional NC rotary table for efficient four-sided machining in the case of the CMX V, or the accelerated rapid traverse and the tool magazine that virtually doubles the capacity of the new design of the CMX U.
And it also applies to the multitude of 3D control options including access to the exclusive DMG Mori technology cycles as well as other innovative software options. DMG Mori will equip its machines with the leading 3D control systems from Siemens, Heidenhain, FANUC, and Mitsubishi. This is a particular benefit for the CMX V series, which can, as of now, also be equipped with a Heidenhain control, in addition to access to advanced automation.
At Mazak Corp. (Florence, KY), the three new versions of its innovative Smooth CNC control (i.e. X, G, and C versions) lie at the heart of the value and performance of its milling and turning machines in job shop applications, according to Rick Bramstedt, product manager for small lathes and verticals. Mazak’s SmoothX CNC is designed for those machines with five or more axes; the Smooth G for mid-level machines with onboard PCs similar to the SmoothX; and the SmoothC control for the company’s cost-effective Kentucky-built machines.
Of those Kentucky machines, Mazak’s QTU and VCU series machines feature the SmoothC, a much more powerful version as compared with its predecessor the Smart control. “The QTU is our competitively priced turning machine, while the VCUs are their vertical milling machine counterparts,” explained Rick Bramstedt.
“Both the QTU and VC series machines feature specific design features that help make them high value machines, but without sacrificing performance,” said Bramstedt. “For instance on the QTU, we’ve incorporated an innovative roller gear cam-style turret indexing system together with hydraulic clamping capability – all of which eliminates the use of turret couplings.” The QTU is offered in 6, 8, and 10″ (152, 203, 254-mm) chuck versions and models from two-axis up to those that feature dual turning spindles, milling spindles and Y-axis off-centerline machining capability.
With roots in Mazak’s popular Quick Turn Nexus machine series, the company’s Quick Turn (QT) series for job shops encompasses two versions of the Smooth control—SmoothG and SmoothC. The new QT 250 MSY, for example, comes with the SmoothG control or, as optional, the SmoothC. “The QT series is our bread-and-butter lineup of turning machines that offer today’s job shops multitasking and Done In One part processing capabilities. The machines feature either 8 or 10″ [203, 254-mm] chucks and 2 or 3″ [51, 76-mm] bar capacities.”
On the vertical machining center side, Mazak offers its VC machines in three and five-axis versions. The full simultaneous five-axis version with a trunnion table takes full advantage of the extremely powerful SmoothX control that gives the machine a high level of functionality. This includes, according to Bramstedt, two-pallet changing capability and digital connectivity with MTConnect and Mazak’s SmartBox.
Toyoda Americas (Arlington Heights, IL) has equipped its new GS300H5 gear skiving center with a skiving function for mass production of gear parts. “The GS300H5 can act as a lathe, HMC, can replace a hob, a shaper, and also roll in chamfering,” said Will Terry, product manager. “I’ve just replaced five pieces of dedicated equipment with it. For job shops that have to outsource their gears, this machine is perfect. This is going to give the job shop control over the entire process, in addition to allowing them to quote broader work and to diversify their portfolios,” said Terry.
The single-chuck machining of the GS300H5 gear skiving center integrates all gear part machining processes for a more functional and cost-efficient shop floor. Individual, conventional machining processes of lathe, hobbing, gear shaping, chamfering and drilling machines are essential for the gearmaking process.
“What we bring to the table is our high-speed axis synchronization. We have been accurately synching axes since 1986 with our cam grinders and 1998 with our crank grinders. We took that same PLC, a proprietary control, not an off-the-shelf CNC control. It’s fast and able to control up to 18 axes. Nine can move simultaneously. We’ve got crankshaft equipment in the field on which I’ve seen roundness of 0.6 µm—dead round crankshafts that are finished in 2–3 minutes. We took the same concept and threw away all the ancient mechanical implementation and synched the axes together to achieve high speed and quality on gears,” said Terry.
Toyoda’s GS300H5 Gear Skiving Center features a high-speed rotation workpiece C axis made more compact with a built-in motor while supporting automatic hydraulic fixtures. The newly developed TOYOPUC-GC70 control technology displays content of NC programs by using an intuitive proprietary flow-chart-style menu and simplifies inputting gear data, tool data and cutting conditions shown on the screen.
Gear tooth geometry can be readily programmed with Toyoda’s conversational control while all other processes can be programmed using CAM software like Esprit or Mastercam. “I can machine a gear from 30 to 300 mm on one piece of equipment which is dramatically more flexible than most hobs that I’ve seen, eliminating the need to have a number of different hobs to handle a family of gears,” said Terry.
At IMTS, Hermle Machine Co. (Franklin, WI) introduced its entry-level C 250 five-axis machining center to the US market, joining its successful C 400 model that has been delivering precision five-axis machining since 2012. Both the C 250 and C 400 machining centers are designed to offer an affordable way for job shops and contract manufacturers serving the aerospace, medical, die/mold, and general engineering market to enter the five-axis machining capabilities.
“Hermle is a high-end machine tool builder,” said Gunther Schnitzer, vice president sales and engineering. “The C250 five-axis model allows us to offer an entry-level five-axis machining center to job shops with a lot of options integrated into the machine achieving an overall favorable return on investment.” Both the C 250 and C 400 are capable of machining superalloys, titanium, Inconel, and other nickel-based alloys, as well as high-speed machining of aluminum.
The C 250 is a dynamic machining center built for the most challenging five-axis/five-side machining applications. The C 250 package includes but isn’t limited to options including a Heidenhain TNC 640 control, a tool magazine with 30 tool pockets, an 18,000-rpm HSK-A63 spindle connection, an NC swiveling 450 × 360-mm rotary table, an ICS 40 bar, a Renishaw or Heidenhain touch probe, and a Blum laser. The C 400 machine has the same number of options and features an increased payload in a larger working area.
“For some manufacturers, initial entry into this space can be intimidating and there is a learning curve, but the benefits of stepping up to five-axis machining are tremendous,” said Schnitzer. “We help our customers achieve optimized results through comprehensive process consulting and project management. Our commitment to provide training onsite and ongoing support sets us apart.”
“Everyone is asking for five-axis, multipallets and expanded ATC magazines. Flexible machines and easy change-over are extremely important, as well as untended operations,” said Dale Hedberg, Feeler product manager at Methods Machine Tools Inc. (Sudbury, MA) “Methods offers a full range of five-axis machining solutions.”
To achieve the best of both worlds, Methods Machine Tools imports a Japanese horizontal class of machines, the Kiwa KH4500 series that allows customers the flexibility to add additional rotary tables to a four-axis horizontal, and make it a 4+1 axis machine, which covers most applications, according to Bernie Otto, Kiwa product manager.
“Customers can expand the pallet changers and ATC tool changers either up front or later on to meet further production demands and run more untended for longer periods of time, extending working hours,” Otto said.
Other state-of-the-art technologies being offered by Methods include the Nakamura-Tome NTRX-300, a multitasking turning center that features complete parts machining in one operation, a built-in load/unload automation system, a compact footprint, and advanced operator recognition management software.
Younger people are stepping into operator roles and shops are looking for new software programming technology to assist these operators who may lack the experience and knowledge of G-code programming on CNC machining, but are comfortable with intuitively-designed, icon-rich software programs, according to Richard Parenteau, director of application development, Nakamura-Tome. Seeing a need, Nakamura-Tome introduced a new, powerfully intuitive “Smart X” multitasking operating system for their PC-based control that is fully loaded with a Fanuc 31I-A5, five-axis control but with many new Nakamura features such as an icon menu, production monitoring, trouble guidance and an operation-level control function.
With regard to turning, there’s a growing demand for increased automation or total lights-out manufacturing both for improved profitability and because shops can’t find experienced and qualified machinists, according to Courtney Ortner, chief marketing officer, Absolute Machine Tools Inc. (Lorain, OH). “Running unattended second and third shifts boosts production, increases the capacity of current employees and can provide owners and managers more time to continue to look for and train new people,” said Ortner.
“The trend in milling that we see is that our customers want to put as many workpieces on the table as possible to get as many parts off the machine as they can at one time, hence the increased popularity for the Johnford bridge mills with generous tables and travels. Further, the pricing of bridge mills is competitive and comparable to today’s bigger C-frame machines and the ergonomics of a bridge mill are much better than a C frame,” said Ortner.
“For example, getting to the spindle or ATC on a C-frame machine often requires stepping on the table to get inside the machine. This is dangerous. On a bridge mill operators don’t have to climb into the machine interior to get to the spindle or ATC. Bridge mills are more aligned with OSHA regulations and guidelines and are less of a potential liability to shop owners,” said Ortner.
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