Precision Solutions are Productivity Enhancers
Design advances combine speed, power and innovative software-controlled functions
By Jim Lorincz
Manufacturers from general engineering job shops to high-precision die mold shops have a wide range of machining centers to choose from to meet their machining customer requirements. Advances in technology can be found in virtually every facet of machine design from finite element analysis (FEA) construction to software control of machine movement and compensation for machine thermal growth. Machines can be found in families ranging from general purpose to moldmaking, with variations in design that are capable of heavy-duty metal removal without sacrificing fine surface finishes or the ability to handle a wide range of materials. Here are examples from the end-user point of view and that of the designers, builders, and distributors of advanced machine technology to meet these challenges shops face on a daily basis.
There Must be a More Efficient Way
When OVM Design and Manufacturing LLC (Westminster, MD) was awarded a contract for a job consisting of 49 different components that would run over 18 months, Bob and Rob Baird, father and son and OVM co-owners, respectively, looked to their machine tool dealer for help. “We were running the part on a nonpalletized vertical machining center and thought there must be a more efficient solution,” said Bob Baird. “Our customers were driving us to produce parts faster and with extreme accuracy.” Their machine tool dealer, MTA Co. Inc. (Ellicott City, MD), recommended the Fanuc RoboDrill PC2, from importer Methods Machine Tools Inc. (Sudbury, MA) as a way to significantly improve productivity.
The RoboDrill is a vertical machining center with a heavy-duty, high-speed 30-taper, 24,000-rpm spindle and an integrated pallet-changing system for pallet changes in seven seconds. OVM, which is a general job shop that manufactures a variety of metal and plastic components for recurring or one-off jobs, ranging from small lots to quantities of several thousand, took the recommendation and purchased the RoboDrill.
“The RoboDrill is great for making fast, light cuts including drilling, tapping and light milling,” said Rob Baird. “The palletized machine allows us to load parts or change fixtures on one pallet while machining is done on the second pallet. And the toolchanger is very fast.” For example, one of the components they produced was an aluminum side plate for an assembly. This operation included 10–12 tools, which took eight seconds each to change prior to the RoboDrill. With the RoboDrill, tool changes were drastically reduced to only 1.5 seconds each. “We reduced machining time on this job by 30% and met our delivery with a high-quality part,” Rob said.
OVM again turned to its dealer on a recurring job for a housing chassis made of 2024 aluminum that OVM needs to run to produce a quantity of 35 parts daily to fill orders of 250 about twice a year. MTA recommended the Feeler VMP-580 APC from Methods Machine Tools with an automatic pallet changer (APC) and a 24-tool ATC. “We use two vises on each pallet. On the first vise, we mill the pockets and part profile; then we move the part to a second vise to position the 2.0" [51 mm] of height, as well as drill and countersink a few holes. Every time we change pallets we have a completed part. With the Feeler VMC, we estimate we are saving about 25% of time on this job alone because the pallets allow one operator to load and unload parts while the VMC is running,” said Rob Baird.
The experience of the Bairds is typical of many shops that don’t have the luxury of long lead times to produce the parts their customers require. Shops are always looking for a better way of meeting their customers’ requirements. They make their choices based on the performance, reliability and reputation of their machine tool suppliers.
Control Technology Drives Machine Development
A distinguishing characteristic of machining centers and CNC lathes manufactured by Hurco Companies Inc. (Indianapolis, IN) is differentiation of its products through development of its own advanced CNC control technology. “Machining centers from Hurco can be found in any shop that values a machine that’s easy to program for getting jobs done quickly in virtually any product category,” said Greg Volovic, executive vice president-technology and operations. “Our engineers can add new features to our controls, almost on a daily basis, to meet specific customer requirements and we drive future development of machine models through our control technology,” said Volovic.
“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 our machines, which are fully Fanuc compatible. This versatility is important to our customers because they run a high mix of parts. They know the best way to approach each job and we make sure our control technology supports that approach so they can increase productivity and profitability whether they use NC, conversational, or both. Our NC/Conversational Merge feature lets the user combine both programming types into one program. It enables the user to call an NC subprogram from any conversational program, or add the simplicity of conversational features, such as transform plane, pattern operations, or scaling, to NC programs. In addition, our UltiMonitor feature has remote monitoring and remote diagnostics capabilities. It’s a very smart intuitive system that lets us identify and solve a customer’s problem, often even before the service man arrives,” said Volovic.
At Hurco, evolving control technology is driving machine development. “Our new line of machining centers will feature high-speed spindles 18,000–30,000 rpm, and a new five-axis large machining center will join the three-axis 3.2-m DCX machine.” Two new Hurco machine introductions, the VMX24 HSi and VMX42 HSi machines, equipped with its patented UltiMotion technology, are showing “improvements in productivity up to 40% relative to cutting the part,” said Volovic. “It’s a brand-new way of controlling motion. We’ve taken the position loops, which normally would be on third party cards, and moved them into the core CNC. This enables us to dramatically improve performance. For example, if you’re in the middle of a tapping cycle, UltiMotion lets you dynamically adjust the cycle while it’s in operation. You can tap at one speed going in and come out many times faster, or continue a cycle after an e-stop and power up without redoing the cycle.”
Builder Benefits as User and Automotive Manufacturer
Hwacheon Machinery America Inc. (Vernon Hills, IL) benefits from the manufacturing experience of its Korean parent company by being both a machine tool builder and a machine tool user. Hwacheon is a supplier of cylinder heads, blocks, crankshafts, and other precision components like gears and spindles to the Korean automotive industry. Hwacheon is also a major supplier of precision machining centers specifically developed for the Korean die-mold industry.
“Our moldmaking machine tools feature standard integrated software developed in conjunction with Fanuc for thermal displacement control and compensation. We’re not only thermally measuring the machine throughout its use, but we’re using the information collected to dynamically verify and control accuracy,” said Michael Huggett, president, Hwacheon Machinery America Inc. (Vernon Hills, IL). “We are able to control the kinematics of the machines for contour machining, allowing us to optimize machine performance for roughing, semifinish, and finish machining without going back and forth through a number of different programs.”
“While some machine tool builders are getting away from box-way geared headstock machines, Hwacheon is committed to supplying both the heavy-duty geared headstock machines, as well as integral spindle motor, linear guideway machines. There’s a need in the market for manufacturers who want to have heavy-duty reliable machines that are able to take a crash and are powerful for heavy-duty machining as well as able to hold high accuracies in both positioning and finishing,” said Huggett.
Hwacheon’s Vesta 1050B box-way geared headstock machining center is capable of heavy roughing cuts as well as fine finish machining. “The 1050B is a true universal machine available with 40 or 50-taper 6000 or 8000-rpm spindles with hydrostatic bearing guideways that produce micron accuracy in a heavy-duty machine,” said Huggett. For high-precision die-mold applications, Hwacheon’s Sirius machines feature 20,000-rpm high-speed spindles for the UM and UL+ models and 12,000-rpm spindle for the UX model. The Sirius machines have integral motor spindles and roller linear guideways and are oil-jet cooled.
For five-axis machining, which is gaining popularity and use in the die-mold market, Hwacheon offers the M-2 machining center. “The advantage of five-axis machining for die-mold work is the ability to use shorter tools, gaining more rigidity and accuracy for fine surface finishing. Also we are able to do a dynamic reset of kinematics before taking the final finish passes that can compensate for any changes in the machine due to temperature, vibration or changes in the tool itself,” said Huggett.
Five Face/Five Axis Machining Centers
JapanTek’s 5X-410 machining center from SB Machine Tools (Schaumburg, IL) provides a unique five-face/five-axis machining capability that can be configured in four different ways: five-axis machining with APC; five-face machining with APC; horizontal machining with APC; and vertical machining with APC. Unlike cradle or trunnion types, the 5X-410 maintains original strokes and part size/weight envelopes, while offering better accessibility. Contrasted with tilting table/articulating head types, the 5X-410 is said to be much easier to program and operate. The 5X-410 is well suited for aviation, aerospace, medical, automotive, and die and mold applications, among others.
The 120° (90° ±15°) tilting spindle makes the 5X-410 well suited for aerospace, medical, automotive, and die and mold applications, among others. Design intention is to combine a fully controlled, double-wormgear driven pallet and extended linear strokes in XYZ axes to provide an enhanced, yet simplified approach to simultaneous, multiaxis machining. The 16" (406-mm) square pallet accommodates a 16 × 16" (406 × 406-mm) workpiece and allows for full four sides and top surface machining on any 16" cube part. A 30-hp (22-kW) main motor, a 60-tool magazine with ATC and coolant through the spindle are standard. The standard speed of the CAT-40 spindle is 12,000 rpm; 15,000 rpm is available as an option.
Large Capacity Mold and Die Machining
Two all new CNC vertical machining centers for machining large industrial molds and dies from Hyundai WIA (Carlstadt, NJ) feature XYZ-axis travels of 61 × 29.5 × 28.5" (1550 × 750 × 725 mm) for the F750M model and 96.5 × 37.4 × 33.5" (2450 × 950 × 850 mm) for the F960M model. Standard features found on both M-Series machining centers include; 12,000-rpm built-in spindle with Big Plus 50-taper spindle nose, thru spindle coolant with chiller, hardened and ground box guideways and HW MP II CNC mold package included in the control. Ultraprecision class angular bearings of the 2000-rpm built-in cartridge type spindles minimize noise and vibration at high cutting speeds and thermal transmission to the main spindle.
Big Plus spindle system (BBT #50) provides dual contact between the spindle face and the flange face of the toolholder. This greatly increases tool rigidity, reduces run out and adds significant productivity to any machining application. Spindle motor is 16–25 hp (11.9–18.6 kW) with spindle torque rated at 893/732 N•m. The Big Plus spindle offers machine users fast material removal rates, as well as high accuracy and rigidity. It guarantees stability when run at high spindle speeds for high-rpm precision machining. CNC control is the Fanuc 31i.
All guideways are hardened and ground, wide box type for long-term rigidity and machining accuracy. By adapting the “semi-rising sliding ways” system the load on the X and Y-axis slide way is decreased dramatically enabling the M-Series VMC’s to hold tolerance and repeatability over longer cycle times. The F960M table is further supported at all times by the use of four boxways and two supplemental ways. This allows for a maximum table load of 4500 kg without any table distortion.
To aid in the machining of molds, the Hyundai WIA Mold Package is applied as a standard feature for the F750/960M Series machines. This ensures accurate and high-quality surface finishes and contouring. Main points of the Mold Package include a Fanuc 31iA control, AICC II package, featuring machining condition selection function, AI contour control II, smooth backlash compensation, thermal displacement feature and automatic power-off feature.
Evolving Designs for Universal Machining Centers
Grob Systems Inc. (Bluffton, OH) has evolved its universal machining centers in milestones that began with the first appearance of the G350 in 2007, followed by the launch of the much larger G550 in 2009 and then in 2011 EMO and 2012 AMB showcasing the G550T five-axis universal mill-turn machining center. To meet the demand and sustain the evolution of the G series machines, Grob has expanded its manufacturing locations in the US, Germany and China by more than 600,000 ft2 (55,472 m2).
Grob engineers are adding options to the standard components to meet demand from medical technology, tool and mold making, aerospace and automotive industry applications, among others. The growing Grob customer base includes a printing machinery manufacturer, the Swiss company Liechti, which specializes in the supplying turnkey solutions for the production of turbine blades and impellers. An order from a leading aerospace parts manufacturer totaled 28 G350/G550 machines equipped with pallet changers and Siemens 840D sl CNC controls.
A hunting rifle manufacturer was recently looking for an automated machining cell to produce high tensile strength aluminum parts for its rifles. The process originally utilized four-axis machines, but the company wanted to progress to five-axis machines to reduce the number of machining setups. The machines also needed to be capable of deep-hole drilling, have excellent chip evacuation and be capable of holding tolerances to ±0.005 mm. The tombstone setup provided by Grob allows parts to be completed in only two setups while the original process took five different setups. Four GROB G350 machining centers with 205 tools each were purchased for the application along with a pallet pool system to have lights-out production.
The Diamond Cut milling series of vertical machining centers from MC Machinery Systems Inc. (Wood Dale, IL) comprises five series of VMCs and drilling and tapping machines. The MC Milling line covers a broad cross section of machining operations including general engineering, mold and die, drill/tap, and heavy-duty machining. The MCV Series general-purpose machining centers feature two spindle/tooling systems, CAT-40 8000-rpm and CAT-50 6000-rpm motor, for applications like fixtures, mold base, and secondary operations. The DV Series general-purpose machine features a 15,000-rpm direct-drive spindle and CAT-40 tooling for intricate milling work in job shops.
The DM Series features a 20,000-rpm HSK-A63 spindle for die mold, hard milling, as well as graphite machining with two models. For large-part machining, the SV Series features heavy-duty box-way construction for large-part machining with large tools, with a 10,000-rpm belt-driven CAT-50 spindle. The TV Series drill/tap machines feature 24,000-rpm high-speed BBT-30 dual-contact spindles driven by a 5-hp (3.7-kW) motor. Design intent of each of the machine models in the MC Milling line is to make selection of the right combination of features for the job at hand easy to make for the customer. In addition to its high-end Roku-Roku machining centers for mold and die work, shops are familiar with all of its product lines including Mitsubishi EDM, waterjet, lasers, consumable products, and press brakes. ME
This article was first published in the April 2013 edition of Manufacturing Engineering magazine. Click here for PDF.