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Advanced Technology Guarantees VMC Performance

Jim Lorincz
By Jim Lorincz Contributing Editor, SME Media

It doesn’t seem as if you can ever count the vertical machining center (VMC) out when it comes to being the favorite workhorse of any shop, whether mold/die, aerospace, medical, or just plain hard-charging job shop. The iconic three-axis machine has morphed into the versatile platform for high-speed, high-precision five-axis machines capable of machining the most complex molds and dies, as well as the highest precision parts for the aerospace, energy, and medical device industries. VMCs are meeting precision manufacturing requirements through a combination of advanced technologies, including machine construction, the latest controls and CAM programming software, and cutting tool and toolholding technology that is delivering high performance in the most challenging applications.

Die/Mold Demands Precision Technology

Makino’s D200Z five-axis vertical machining center sets standards that are widely representative of today’s VMC technology.

According to William Howard, vertical product line manager, Makino Inc. (Mason, OH), here’s what you should expect from the high-precision die/mold machining technology: “Machine design that provides stiffness/rigidity for 3D contouring blends matches, tight tolerance machining typical of the die/mold marketplace requirements but is also designed for speed acceleration required for high-speed finishing and reducing complex, contoured 3D component production. Die/mold manufacturers are facing stiff competitive challenges and the need to reduce costs, shorten lead times, and be more responsive to customer delivery and design changes,” said Howard.

“In addition, there is pressure to increase their machine utilization, spindle production times, and reduce or eliminate time-consuming and costly post-machining finishing work.” To meet those requirements, Makino’s D200Z five-axis vertical machining center sets standards that are widely representative of today’s VMC technology. The D200Z features the latest high-speed servo technology delivering 60 m/min rapid traverse and feed rates on X-Y-Z axes; 1.5 g on X and Y and 2.0 g on Z axis. Its integral five-axis table with DD motor technology provides 100 rpm on the tilting axis and 150 rpm on the rotary axis.

“In addition to highly productive feed rates, today’s customer is demanding unencumbered access to the various facets of a die or mold, multi–side approach which minimizes setups for high-speed, 3D contouring of complex geometries, with tight blends and matching surface finishes. To accomplish this, many manufacturing shops are turning to five-axis machining with shorter, stiffer more rigid cutting tools for a better positioning relationship between the tool cutting edge and work surface. This facilitates processes running at higher spindle rpms and higher feed rates with less tooling deflection and runout. The result is that we can maintain very good surface finishes and outstanding tool life,” said Howard.

Advanced control technology is provided by Makino’s Professional 6 control and Super Geometric Intelligence 5 (SGI.5) software. Features of the control include an “operations flow” approach providing a seamless transition for the operator to the machine through screen layouts, operator assistance, including access to Makino’s proprietary Data Center and new machine functions such as Collision Safeguard. “SGI.5 combines the rigidity of the machine structure, superior kinematics of the machine drive systems and the latest advancements in servodrive technologies with Makino’s proprietary software. The result is unmatched speed, high feeds and tight accuracies when executing NC programs with micro blocks whose movement value is 1 mm or less. SGI.5 can provide 20–60% faster cycle times while maintaining accuracy and surface finishes,” said Howard.

“The SGI.5 system can virtually eliminate part gouging caused when a cutter overshoots the programmed path due to servo error,” said Howard. “Even at higher feed speeds, the SGI.5 control can correct servo droop. A combination of highly refined AC digital servos and proprietary software make it possible to feed at rates faster than standard CNC systems while maintaining high accuracy. The high-resolution, three-million pulse per revolution feedback system ensures that the servo system operates at optimum performance.” The proprietary Makino Data Center, which provides flexible program and data management and enhanced networking capability, is the single source for all files on the machine and network, providing the ability to run directly from memory, internal/external card, full DNC, or from a network.

Cutting tools and toolholding technology continue to play leap frog with advances in machine technology and developments in cutting tool technology, challenging the other to catch up and move ahead. “From what we’ve seen, our machines have been pushing the envelope of cutting tool capabilities,” said Michael Fecteau, Makino application engineer. “We’ve been able to achieve higher feed rates with tools like the six-flute solid-carbide ballnose end mills from Mitsubishi-Hitachi Tool, and now other cutting tool manufacturers who are developing multiflute cutting tools. With these new developments in cutting tools we are able to reduce the machining times even more,” said Fecteau.

“For finishing and some semifinishing, we recommend shrink-fit toolholding and have been using MST and Haimer systems. MST has released its submicron UNO shrink-fit holder with less than 0.001-mm runout. We have been utilizing these holders for achieving longer tool life and better surface finishes in high-speed and micro cutting with very noticeable results.”

CNC, Motion Control Set Machining Agenda

The YASDA PX-30i, a five-axis, high-precision, automated vertical machining center.

Hurco Companies Inc. (Indianapolis, IN) numbers among its customers those that manufacture parts for the automotive, aerospace, medical equipment, energy, injection tool and molding, transportation, and computer equipment industries. Known for conversational programming, Hurco’s NC control features complete compatibility with the most commonly used CAM systems and comprehensive FANUC integration. “Our customers have grown accustomed to the ease of use and versatility of the Hurco control,” said Michael Cope, product technical specialist. “The WinMax software allows the user to benefit from a powerful control that allows them to run G-code, program conversationally at the machine, or combine both programming disciplines for the ultimate in flexibility, for three-axis and five-axis configurations.”

Hurco’s VMCs are designed to give customers the ability to eliminate process steps and increase efficiency during the 60% of noncut time that accompanies most jobs, especially helping customers efficiently produce a high mix of parts at lower volumes profitably. According to Cope, “Thermal stability of the Hurco BX40i three-axis double-column, bridge-style machine, coupled with the faster 18,000-rpm spindle, makes it well suited for the die/mold industry.” Hurco also offers this machine model in a five-axis configuration (BX40Ui) as well. “Our motion control technology, called UltiMotion, is a software-based system that provides better surface finishes, shorter cycle times, and smoother overall motion of the machine tool. Some customers are experiencing more than 30% reduction in cycle times over the same processes running on machines without the UltiMotion technology.”

“High-speed machining toolpaths are becoming more and more prevalent in the moldmaking industry all the time,” said Cope. “These high-speed algorithms, coupled with the ever-faster spindle speeds, and better cutting tool technologies, allow molds to be finished in much less time than previously possible.”

Hurco has released a set of conversational high-speed toolpath routines for pocketing, called AdaptiPath. “This new control technology allows our conversational users to also benefit from the same type of roughing algorithms as CAD/CAM software offers, and to rough-out pockets in a fraction of the time that it would take with normal pocketing routines,” said Cope. AdaptiPath is designed to allow the programmer to easily control the amount of material the tool will engage, even in corners. This type of toolpath control allows for deeper cuts and faster speeds when pocketing. AdaptiPath also offers a “rest machining” process prior to finishing the pocket.

Full Five-Axis Contouring Machining Centers

The MU-V series of five-axis vertical machining centers from Okuma America Corp. (Charlotte, NC) is designed for stability, accuracy, and reliability. “The MU-V platform utilizes double-column construction giving it the best possible stability, with the trunnion turned 90° from previous models which allows for easy automation,” said Wade Anderson, product specialist and Tech Center manager.

“All the high-tech bells and whistles really don’t mean anything, absolutely nothing, if you have to have a service truck in your parking lot every month,” said Anderson. “Okuma customers know they will run the machine hot for several days straight, then shut it down one evening and come in the next morning on a cold machine and the first part will be mind-bogglingly close to where it was from a hot machine the night before. Okuma’s Thermal Friendly Concept that encompasses the engineering of the machine design and the control algorithms from the intelligent technology our machines bring to the market eliminate worries and chasing offsets,” Anderson explained.

Automation is absolutely a factor today. Anderson said: “Every manufacturer is looking for more and more automation. If you’re not, you soon will be as competitors find new ways to be more productive.” The MU-V series can be automated via a 2APC, robot, pallet pool, FMS system, among others. “With the power of the control, you’re only limited by your imagination. IIoT [Industrial Internet of Things] has been such a large focus for us. Our customers range from small shops utilizing free productivity tracking apps from our App Store to large-scale manufacturing utilizing GE’s Predix for complete and global data capture. This allows for real-time monitoring and real-time decision making,” said Anderson.

“One of the best tools I’ve seen lately that helps bridge the skills gap most machine shops experience today is via Velocity’s Smart Tool technology. This is developed through our partner Velocity and is an Okuma exclusive. You can purchase a complete tool assembly that includes the pull stud, Big Plus toolholder, and cutting tools, that are a complete assembly that has been tap tested on your specific machine model. It is guaranteed to run in its optimal performance level without chatter with the speed and feeds provided via their software interface. It’s an ingenious idea and takes all the guesswork out of your roughing operations. It enables the user to reduce setup time, knowledge level, and optimize cutting performance the first time—every time,” said Anderson.

Value Is In How Efficiently Parts Are Machined

The new Feeler HV-800 vertical machining center from Methods Machine Tools Inc. (Sudbury, MA) was recently featured at Methods’ Advanced Milling and High Speed Machining Expo. The event allowed attendees to explore advanced techniques in hard milling and high-speed machining and ways to optimize existing machine tools for higher productivity and profitability. The HV-800 was machining high-quality demo parts at the event. “Customers typically expect quality parts of this caliber off a high-end machining center,” said Dale Hedberg, Feeler product manager at Methods.

Construction of the Feeler HV-Series features a reinforced, cross-ribbed column structure and no counter-balance weight design that dramatically improves torsional torque resistance and reduces low frequency resonance for optimal stability in high-speed machining. “The new design delivers 30% increased rigidity for higher accuracy, better workpiece finishes, and less waste,” said Hedberg.

At the Methods’ event, attendees gained an insight into how small process improvements, when coupled with the highest precision machining technologies, can significantly increase performance and cost savings. Dale Mickelson, specialist die/mold and precision machining of Methods Machine Tools, presented results of his research into the effectiveness of high-feed cutters, particularly in handling difficult-to-machine aerospace materials like Inconel 718. Keys to success include using the latest trochoidal circular interpolation machining strategies and spindle interfaces that deliver the necessary rigidity. His research included the comparison of the spindle interfaces, including CAT, BT, BIG PLUS, and HSK and shrink-fit toolholders as well as the effectiveness of thermal control achieved by cooled spindles like that of the Yasda PX-30i.

Dave Lucius, Methods Machine VP-sales and marketing discussed the true cost of ownership and how shops can benefit, as an example, from one high-precision multi-pallet five-axis single-spindle machining center vs. three lesser priced machining centers. The Yasda five-axis PX-30i with a self-contained, 33-pallet multi-pallet stocker system delivers impressive ROI by reducing the single greatest drain on profitability—the cost of labor. Precision five-axis machining reduces part handling, results in superior geometric accuracy, better part finish, and increased tool life for shops that adequately plan for it. “Five-axis machining centers continue to be among the fastest growing machine tool categories,” said Lucius. “When you add multi-pallet capability, and 314 tools to these five-axis workcenters, they now deliver unmatched machining and throughput capabilities for shops.”

Advanced Technologies Provide Smart Connections

One of the latest machine technologies from DMG Mori (Hoffman Estates, IL) is the Celos control platform. DMG Mori’s new HMI (Human Machine Interface) gives users the ability to monitor and control their processes. The Celos control platform also incorporates many new features that take advantage of the Industry 4.0 initiative including machine diagnosis, remote monitoring and data acquisition. This technology applies to almost all of DMG Mori’s machining platforms, including three-axis, five-axis, lathes and mill turns, as well as its Ultrasonic and Lasertec (Shape, PowerDrill and 3D) platforms. This also includes large machining platforms for molds that are 2, 3 and even 6 m in size.

“Customers are looking for ease of use, intuitive interfaces and automation. The new generation of engineers and users have had a major paradigm shift and are coming into the industry expecting an HMI that allows them to be creative as well as being functional. With DMG Mori’s Celos control and HMI, we are addressing these needs and we are staying on the cutting edge of technology to deliver world-class solutions to today’s users as well as the next generation,” said Jeff Wallace, manager-five-axis Center of Excellence.

“As in the past, moldmakers are looking to reduce polishing and hand work and to increase consistency and accuracy in their product,” said Wallace. “Advanced control functions, such as the ATC Technology Cycle [Automatic Tuning Cycle] allows the user to choose between multiple roughing, semifinishing and finishing cycles utilizing the same CAM programs and not having to create additional programs for these operations. This gives the CAM programmers the opportunity to concentrate on the manufacturing processes and optimize the NC code before it is executed on the machine. This also allows the moldmakers to utilize their knowledge of moldmaking and leverage the abilities of the machine and optimize the cutting process in real-time, without having to make modifications to the CAM program.” This function enables users to optimize the new generation of linear motion die/mold machines and realize the benefits of high-speed and high-accuracy machining.

“We have also seen an incredible increase in automation inquiries from our customers. With today’s intuitive robot solutions, such as DMG Mori’s Robo2Go platform, we are providing mobile automation solutions that can be programmed from an ‘app’ within the Celos control and gives the user, that is not a traditional ‘robot programmer,’ the ability to quickly and easily program a robot,” Wallace said.

“New CAM routines, such as VoluMill, which is integrated into several CAM packages, such as OpenMind and Siemens NX, allow the programmer to optimize the toolpath and take advantage of the increased velocities of the new generation of linear drive die/mold machines. This, naturally, has pushed the cutting tool manufacturers to develop new geometries and coatings that can withstand the increased velocities. With the combination of all three of these technologies [machine/control, CAM programs and tooling technology], we are achieving results that were not even considered five years ago. The advances continue to accelerate as we incorporate the Industry 4.0 initiative into the machine designs and the manufacturing processes,” said Wallace.

Features Produce Dynamic Five-Axis Machining

The QP5X-400 five-axis vertical machining center from Chevalier Machinery Inc. (Santa Fe Springs, CA) scores high in versatility and is well-suited for precision machining applications in aerospace, automotive, moldmaking or job shops. The QP5X-400 A is engineered for better accuracy, greater productivity, using less manpower, and producing higher profitability. The QP5X-400 features a 15,000-rpm spindle for high-speed dynamic machining, which involves taking fast, small cuts, rather than the old way of taking large cuts of metal. The QP5X-400 is capable of five-axis simultaneous or 4+1 axis machining. The standard machine is fitted with a two-axis 12.6” (320-mm) rotary table.

Construction of the QP5X-400 features highly rigid Meehanite cast iron for the machine’s major parts. The column design features one-piece inverted Y-shape construction for rigidity and stability. The pre-tensioned, Class C3 ballscrews are used in all three axes. All servomotors are directly coupled to ball screws, increasing movement sensitivity while dramatically reducing backlash. An efficient chip-disposal design includes an automatic chip-flushing system that brings cutting chips to the center of the machine base. A screw-type chip conveyor option is available to deliver cutting chips to a conveyor, which is located at the front of the machine’s base.

The machine has a table load of 220 lb (99.7 kg) with a 12.6″ (320-mm) trunnion table for workpieces measuring 15.7 × 13.7″ H (400 × 350 mm). The series offers a two-axis rotary table with a heavy-duty, three-piece, cross-roller bearing that provides part loading and machining capability and a ±10″ (254-mm) angle encoder for the A axis. A large-diameter BBT spindle design uses four-piece, P4 Class, high-precision angular-contact ball bearings to increase spindle rigidity and loading capability and maintain high accuracy during high-speed machining.

A direct-drive spindle is standard for low noise, vibration, and thermal expansion. The series provides fast interpolation, maximizing machining time, with a high-linear rapid speed of 1417 / 1417 / 1181 ipm (36/36/30 m/min). The spindle taper is #40; spindle power is 15 hp (11- kW) FANUC, with a spindle speed of 10,000  rpm (optional 12,000 and 15,000). Tool capacity is 30+1, with a maximum tool diameter and adjacent tool of 3 or 4.9″ (76, 124 mm) without an adjacent tool. The series includes a FANUC 0i-MF control for 4+1 applications.

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