Technology Drives Cell Success
Advanced machining concepts boost productivity, quality
By Jim Lorincz
Manufacturing solutions that are based on today’s advanced machining centers and cells are readily available for the most troublesome jobs. In the aerospace industry, these jobs may involve awkward and complex parts in medium to large sizes made from difficult-to-machine materials like titanium or Inconel as well as complete assemblies.
For Hansen Engineering Co. (Harbor City, CA), a supplier to Tier One aerospace customers, the challenge was to provide the same quality, precision, and on-time delivery for these challenging parts, which today account for 20% of the shop’s output, as it did for its competitively priced airframe and jet engine parts.
The solution, according to Jody Lay, Hansen CEO, was adopting advanced machining technology that not only increased production efficiency for all the shop’s jobs and a variety of materials, but also allowed for untended operation. The technology selected was a fully automated Palletech Manufacturing System from Mazak Corp. (Florence, KY) consisting of two CNC machining centers, a rail-guided pallet transfer vehicle, part load/unload station and multiple pallet-stocking stations.
Initially, Hansen Engineering started with a five-axis Mazak Integrex e-1060V/8 II multitasking machining center, a load/unload station, the pallet transfer vehicle and 12 pallet-stocker stations. The modular, pre-engineered Palletech System allowed Hansen to add a second machine, a Mazak Horizontal Center Nexus (HCN) 8800-II machining center with high-torque spindle. There is space for the future addition of an Integrex e-1060V machine and the 16-pallet stocker capacity has room to expand to 36 if needed when the third machine is installed.
Currently, the Palletech cell runs, for the most part, nonstop during Hansen’s two 10 to 12-hour daily shifts, six days a week. “The key to the system’s untended operations is the reliability, precision and performance of the Mazak machine tools,” said Lay. “The repeatability of the machines is phenomenal. Once we know our programming and tooling are good, we don’t worry about the Mazaks. They give us good parts every time,” said Lay. “Plus they feature large tool storage capacities—120 tools on both the e-1060V/8 II and on our HCN 8800-II, for extended run times.”
Hansen has so much experience in machining titanium that it touts itself as a “titanium expert” that has perfected its machining of the material in particular during lights-out operations. According to Lay, processing titanium efficiently requires a combination of machining techniques and advanced machine tools like the Mazaks. The two techniques used most often by Hansen are high-speed machining and what Lay referred to as “sneaking up on a part.” The part is rough machined, checked and straightened, then machined some more, checked and again straightened. Roughing is done on the HCN 8800-II and finishing is done in single setups on the Integrex e-1060V/8 II using five-axis cutting and the machine’s 5000-rpm, 50-hp (37-kW) high-torque milling spindle. Surface finishes achieved range from Ra 125 to 63 and tolerances can be as tight as ±0.0004" (0.010 mm).
Cells Are Only as Good as the Machines in Them
“What’s happening today is that the aerospace OEMs want to build airplanes like cars, and to do that production has to be consistent and predictable,” said Scott Walker, president, Mitsui Seiki (USA) Inc. (Franklin Lakes, NJ). “The days of taking an aerospace engine part from the machine to buffing and measuring to final assembly are coming to an end. In the future, you’re going to have 15 machines lined up and a robot will feed parts in and out. The process will be basically hands-off for machining, inspection, buffing, and the part will go into the box ready for assembly,” said Walker.
“The same is true for hardened nickel-based IBRs [integrally bladed rotors]. Typically, IBRs are EDM’d, ground, or CBN ground, going back and forth. They want to automate all of that and know that they will get a certain number of IBRs a day. Based on that they will need to build X number of engines a day and put them together like car engines,” said Walker. For example, Mitsui Seiki has just converted a production line to a fully automated FMS cell which provides complete machining and inspection for 63 new part numbers, magnesium or aluminum castings for gearboxes for the new 737x.
“Mitsui Seiki’s technology developments are aimed at providing solutions for engine, structural, and gearbox machining,” said Walker. “Our new machining center, the HU63EX series, is aimed at second and Third-Tier job shops. There is a lot of development aimed at blisk machining, especially for the new jet engine programs that are being developed to be 20% more fuel efficient. These new fuel efficiency engines will be used to re-engine the global fleet of 737s and Airbus 320s.”
To meet this new generation of engine technology, new machine tool technologies are being developed to manufacture blisks with a much better surface finish and improved production rates. “Surface finish and high production rates have not historically gone together,” said Walker. “We’re focusing on technologies like direct drive-motor based machines that make the machines very agile so they can drive a very thin tool around the blade profiles of IBRs and blisks and keep it bent the same as it goes through big changes in acceleration and deceleration. The goal is to eliminate markings and poor surface finish so that parts come off the machine ready for assembly without benching,” said Walker.
At EMO Hannover, Mitsui Seiki will present its most recent developments for the European market, including the Vertex 550-5XB Blade Center, for the production of turbine blades; the large capacity HU100-5XL and HU100-5XLL five-axis trunnion horizontal machining centers for hard metal aerospace, power generation, refrigeration, mold and die, and off-road equipment applications; and the VGE60A universal vertical thread grinder.
Machine Evolution Continues for Heavy-Duty Cutting
Machine tool technology continues to evolve in ways that serve a broad range of industries in untended operations. For applications that require large, complex parts like those found in the energy, automotive and general commercial markets, the new Feeler SDM-G/GA series double-column machining centers from Methods Machine Tools Inc. (Sudbury, MA) offer the ability to machine five sides of the workpiece in one setup, a capability which is especially critical when working with very large parts.
The SDM-GGA machine line takes its machining capability one step further by offering automatic head-changing capabilities, which allow longer untended operation because heads do not need to be changed manually. A vertical/horizontal automatic toolchanger provides fast tool changes, and the SDM-GGA Series’ automatic attachment changer makes head changing fast and easy without requiring operator assistance.
“The Feeler SDM series offers a rigid structure to minimize vibration during cutting and ensure stability and accuracy in greater cutting depth and efficiency,” said Dale Hedberg, Feeler product manager. “Three oversized boxways are designed for heavy loading without deformation and, combined with a great span between slide ways, provide stable operation. An all box-way design provides dampening characteristics that are well-suited for extremely demanding applications that include heavy cutting,” said Hedberg.
The 6000-rpm spindle of the SDM series includes a 22/26-kW motor and a two-speed gearbox. The low range speed produces the 699 N•m torque required for making heavy cuts in parts such as castings, forgings and plate work. For further rigidity and stability, the ram design features a patent-pending four-sided enclosure to offer greater force distribution on the Z-axis boxway.
VMCs Designed for Heavy-Duty and Die-Mold Machining
Hwacheon Machinery America Inc. (Vernon Hills, IL) offers machines well-suited for demanding oil and gas, aerospace and die mold machining applications. Hwacheon’s machine technology features well-proven designs based on the parent company’s experience as a supplier of cylinder heads, blocks, crankshafts, gears and spindles for the Korean automotive industry. Machining centers are designed for heavy-duty machining and pocket milling with Hwacheon’s Optima cutting feed optimization, and HTLD tool load detection software.
Hwacheon’s Vesta 1050B vertical machining center features four wide hand-scraped box guideways in the Y axis and wide box ways in the X and Z axes for machine rigidity. A two-speed gear-driven spindle with integrated drive provides high-speed cutting and delivers high torque. All Hwacheon spindles are oil-cooled, including the gearbox to minimize thermal displacement and promote long spindle life. The geared headstock machining center is capable of heavy roughing cuts as well as fine finish machining. The Vesta universal machine is available with 40 or 50-taper, 6000 or 8000-rpm spindles that produce micron accuracy in heavy-duty cutting.
Hwacheon’s tool load detection (HTLD) software provides real time measurement of tool load constantly monitoring tool damage and deterioration for prevention of complete tool failure causing workpiece damage for consistent and safe machining. The HTLD system measures tool load frequently, as often as every eight msecs.
Optima cutting feed optimization software uses an adaptive control method to regulate the feed rate in real time to sustain a consistent cutting load while machining. As a result, cutting tools are less prone to damage and machining time is reduced. The system controls the feed velocity to maintain consistent cutting load. Features include a graphic display of tool load and feed rate, convenient operation using G-code programming, and a number of data sets for specific tool and process control.
For die-mold applications Hwacheon’s Sirius three-axis vertical machining centers feature 20,000-rpm high-speed spindles for the UM and UL+ models and 12,000-rpm spindle for the UX model. The machines are equipped with integral motor spindles with jacket cooling and oil-jet cooled bearings and rigid roller linear guide ways for stable performance over long cycles. The cooled jets of oil are injected directly onto the spindle bearing for effective cooling and a suction pump is employed to remove the heat oil quickly. The motor and spindle assembly are jacket-cooled to limit displacement caused by heat.
Advanced CNC Milling CNC Control
When Tom Barr, owner of TK Mold and Engineering (Romeo, MI) needed to increase capacity, he purchased a Hurco VMX24HSi machining center for its higher spindle speeds and stronger controller. Barr, who had experience with a VMX24 mill, says that higher spindle speeds and advanced controller on the new machine have produced the better finishes and tighter tolerances he sought.
When Hurco Companies Inc. (Indianapolis, IN) launched its VMX 24HSi and VMX42 HSi machining centers, equipped with UltiMotion technology, it had every confidence that they would improve productivity up to 40% in cutting parts. The reason is found in Hurco’s advanced proprietary CNC control technology that features a new way of controlling motion. Position loops that normally would be on third-party cards have been moved into the core CNC, producing dramatic improvements in performance. Simply put, when in the middle of a tapping cycle, for example, UltiMotion lets the user dynamically adjust the cycle while it’s in operation.
The Hurco control gives the user both conversational programming and standard NC that supports ISO/EIA standards, which means the user can take any Fanuc program or G code program and run it on fully Fanuc compatible Hurco machines. This versatility is especially important to shops that run a high mix of parts, because it allows the user to approach each job in the most efficient way that increases productivity, whether they are using NC, conversational, or both control strategies.
3D Printing and Milling Produce Metal Parts
The latest addition to manufacturing metal parts combines 3D printing with milling. The SonicLayer 4000 from Fabrisonic LLC (Columbus, OH) combines a three-axis milling head with ultrasonic additive manufacturing (UAM) capability in a mid-size fully automated 3D printing machine that can create deep slots, hollow, latticed or honeycombed internal structures in metal components and other complex geometries that can’t be made using conventional subtractive machining processes.
The SonicLayer 4000 is a mid-sized machine with 2500 lb (1134-kg) load capacity, positioned in between the SonicLayer R200 for universities and R&D and the SonicLayer 7200 which has a load capacity of 5000 lb (2268 kg). The SonicLayer 4000 features a three-axis CNC mill with dimensions of 40 × 40 × 24" (1016 × 1016 × 610 mm) and a 25-hp (18 kW) 8000-rpm spindle for machining near-net-shape parts that are produced by the UAM 3D printing process to produce final parts.
3D printing with the SonicLayer machines (see video at http://www.fabrisonic.com/video.html) is produced using a patented 9-kW UAM welding head that additively manufactures solid metal parts by welding 1" (25.4-mm) strips of metal ranging from 0.002 to 0.020" (0.05–0.51-mm) thick together at 200 ipm (5 m/min). Alloys including high-strength aluminum, stainless steel, and titanium can be combined to form sandwiches of metals for rapid prototyping, metal matrix composite workpieces and other applications. Fabrisonic’s custom G-code CAM software automates the CAD-to-part process. When CAD geometry is imported into the SonicCAM, the software generates the toolpath for both welding and machining.
Universal Post Processor for CAM Output in Mori-APT
DMG / Mori Seiki (Hoffman Estates, IL) is releasing a Mori-APT toolpath-based postprocess to allow machine tools to be put into service as soon as the machine lands on the shop floor. Traditionally, customers are required to purchase machine tools and CAM/postprocessing software from different vendors, possibly leading to discrepancies in quality, thoroughness and timely delivery. Part of a powerful suite of applications called Manufacturing Suite, this universal postprocessor will be available for all Mori Seiki machines and will work with any CAM software that outputs toolpaths in Mori-APT standardized format.
Customers can continue to use multiple CAM software solutions in conjunction with Manufacturing Suite Post Processor to generate NC code, avoiding the need to obtain postprocessors for individual CAM software and with the added benefit of a single support contact.
The Mori-APT toolpath format is an extension of APT CLDATA standard (based on ANSI NCITS 37-1999 and ISO 4343:2000). The Manufacturing Suite Post Processor can import the standardized toolpath from any CAM software and generate NC code using the proven DMG / Mori Seiki post templates. For the process to work, customers need to acquire the Mori-APT CLDATA interface-enabled version of the CAM software from their respective CAM vendors and acquire the Manufacturing Suite Post Processor software from DMG / Mori Seiki. Interfaces to output Mori-APT CLDATA are available or in development. ME
This article was first published in the August 2013 edition of Manufacturing Engineering magazine. Click here for PDF.