Advanced simulation, new toolpath techniques aid programming of highly complex machinery
CAD/CAM software developers continue to refine simulation capabilities and toolpath techniques that enable programming highly complex equipment including multiaxis and multitasking machine tools.
As manufacturers face increasingly difficult conditions, CNC programmers seek out the best tools and tricks to efficiently tackle the most complicated programming tasks. Key advances in programming for five-axis and multiaxis machining, as well as multitasking or multifunction machines, are helping manufacturing operations set up jobs much more quickly and meet production goals.
“Complex machines are offering manufacturers the chance to reduce setups and improve surface quality,” notes Glenn McMinn, president, Delcam North America (Windsor, Canada, and Birmingham, UK). “Machines such as multiturret lathes, lathes with B-axis milling capabilities, high-speed machining centers, and five-axis mills are now coming down in price and offering productivity enhancements to more and more manufacturers. Finding a CAD/CAM company that can support this entire range of machines is becoming a requirement.
“Manufacturing also is now being performed more often from solid models. Companies need solutions that allow them to quickly program their parts directly from these solids using the original native CAD data. Reliable data import, feature recognition, and solids-based machining are becoming a necessity.”
Building on its broad base of CAM solutions, Delcam is adding to the capabilities of its PowerMill precision milling package for three and five-axis machining focusing on aerospace; the mid-range production shop with its FeatureCAM package for multiturret turning and five-axis simultaneous milling; and also its Partmaker package for Swiss turning. “Our goal is to become the single source for CAM solutions,” says McMinn, noting CIMdata ranks Delcam as the largest CAM specialist worldwide.
Simulation and verification tools are critical for complex machining tasks on today’s multiaxis and multitasking machine tools. With the latest Vericut NC simulation, verification, and optimization software from CGTech Corp. (Irvine, CA), users can now take full advantage of the 64-bit Windows operating system, enabling use of larger computer models and simulations.
“The wide availability of fast, affordable computers running the 64-bit Windows operating system has helped several of our customers better utilize Vericut,” notes Bill Hasenjaeger, CGTech product manager. “The main advantage of a 64-bit system is access to a very large amount of memory. Vericut immediately takes advantage of the extra memory due to its scalable design. Some CAD/CAM systems also benefit from 64-bit, but not to the extent Vericut does. Our CNC machine simulation requires the hardware to do several concurrent computer-intensive tasks: fast digital animation, accurate solid modeling arithmetic, and fast, reliable handling of very large datasets. Other applications typically do not have to deal with all this at once, with sub-second response.”
Simulating directly from NC code also offers Vericut users very accurate simulation. “Our customers want CNC machine simulation as close to the shop floor as possible, simulating a multitude of processes and their different machines, directly from the NC programs that will run on the actual machines,” Hasenjaeger adds. “This requires us to have very robust control emulation, for multiple brands and models of controls, flexible enough to be configured for multiple types of CNC machines and machining operations. Often these machines are unique variations, or there is some unique process twist or company ‘standards’ requirement which the customer would like the simulation to validate. Many of our customers rely on Vericut’s simulation to allow them to start cutting immediately, and not speculate on the validity of the NC program.”
Composite machining for aircraft is a growing business for CGTech, as well as simulation for waterjet-cutting operations. “Many CGTech customers machine composite parts and usually simulation requirements are similar to traditional metalcutting,” notes Hasenjaeger. “But sometimes they aren’t, such as composite trimming with a waterjet machine, or machining with a lightweight parallel-kinematics machine [PKM] like SMT’s [Vasteras, Sweden] Tricept. The trend seems to be towards specialty or purpose-built machines and techniques specifically for machining composite structures. We’re also asked more and more to simulate assembly machines, most commonly in aerospace applications, attaching aluminum or composite skins to the underlying structures. While these machines do not typically do metal removal, we are asked to simulate adding material such as fasteners or rivets.”
In aerospace, more composites means more machining of titanium parts, since titanium is required for internal structures, Hasenjaeger adds. “The titanium used is changing as well, from the traditional 6AL/4V grade to stronger grades such as 6AL/6V 2Sn and others. These new stronger materials can be used to design lighter structures, but they also tend to be more complex and the materials more difficult to machine,” he notes. “This has instigated an increase in the use of Vericut’s OptiPath feed-rate optimization software. The tougher materials require closer control of the feed rates when cutter contact changes during cutting. The spike in composite-related demands has also led CGTech into simulating composite layup for automated fiber-placement machines, and even into NC program path generation and postprocessing for fiber-placement.”
In the latest Vericut 6.2 package, CGTech has added more NC program-checking tools, with a user-configurable syntax checker in addition to the program’s already supplied control emulation. “We’ve found that syntax checking not only has to do with checking what’s valid for a specific brand or model CNC control’s logic, but also what meets a specific company’s standards and preferences,” Hasenjaeger says.
In past releases, Vericut added the ability to automatically generate process documentation from the simulation, including pictures and information on the in-process workpiece. “It is now possible to add dimensions to the pictures, thereby creating graphical setup plans in the process documents,” Hasenjaeger says. Other new functions include Vericut’s simulation of tapping operations, reading the machine’s tap cycle commands, and applying a parametric tap tool to create a tapped hole feature in Vericut’s simulated cut part. “This also allows several error checks for common tapping problems such as wrong spindle direction, wrong feed rate for the tap’s lead, missing or undersize drilled holes, and improper motion.”
A new waterjet cutting tool has also been added, providing accurate simulation of waterjet cutting. “The waterjet tool has parameters to define minimum and maximum cutting lengths,” says Hasenjaeger, “and the simulation checks for errors such as the jet cutting through multiple sections of the workpiece, cutting through fixtures when it should not, and cutting either too close or too far from the jet nozzle. There are also special ‘deflector’ fixture components that allow the waterjet to pass over them without cutting through.”
More advanced simulation and NC programming tools are required today to pay back manufacturers’ investment in complex machines. “One important trend is that users are investing in more productive machine tools that require more advanced NC programming and simulation systems to deliver a good ROI,” says Eric Sterling, vice president, Siemens PLM Software (Plano, TX), a division of Siemens Automation and Drives (Nuremberg, Germany). “These machine tools include high-speed mills, multiaxis machines for mold and die, as well as multifunction mill-turn machines. For mill-turns, we see new machine tooling processes, such as milling and turning functions in the same machining strategy.” Benefits include faster material removal, he says, adding these new machining strategies require new NC programming techniques.
“Another key trend is industry-focused process changes,” Sterling states. “For example, in aerospace, we see a move to manufactured blisks requiring advanced multiaxis combined with on-machine probing and adaptive machining techniques to machine welded assemblies. We’re also focused on the increased focus on programming automation for faster programming and consistent, proven methods. A great example is feature-based machining that is becoming more common and effective. Finally, advanced machining simulation, or ‘controller-driven simulation,’ is a critical trend. It more completely validates the machining process using technology from the machine tool controller.”
In future developments, Siemens PLM Software plans to forge tighter links between its PLM and NX 5 CAM machining environments and its machine controls offerings, in which the digital manufacturing tools in PLM solutions combine with control automation on the factory floor (see our cover story “Enter the Virtual World” in the October 2007 issue of Manufacturing Engineering). “We will continue to provide leading-edge manufacturing technology,” Sterling says, “and new developments will deliver even tighter integration between CAM software and the machine-tool controller, which will enable our customers to better use their machines and controllers for higher performance and greater quality. We’re also focused on more extensive connections to the shop floor and production systems from the PLM-based manufacturing environment. This will reduce errors by providing more data on the shop floor to assist and support production.”
Support for high-end machines has evolved slowly, notes Bill Gibbs, president and founder, Gibbs and Associates (Moorpark, CA). “I always suggest potential CAD/CAM buyers focus first on what a product can do with their people, parts, and machines,” states Gibbs. “What goes on inside the CAD/CAM after these issues are covered is of little or no importance to a user.
“The CAD/CAM market is slowly responding to the customer’s need to support high-productivity CNC machines,” he adds. “This class of CNC includes multitask machines [multispindle, multitool, mill-turn, and Swiss machines], pallet-changing mills, and five-axis simultaneous milling. All these machines can produce parts in fewer setups, with less human intervention, and therefore less human error, and less labor cost component.”
Last month, Gibbs and Associates merged with CAD/CAM software developer Cimatron Ltd. (Givat Shmuel, Israel), which purchased the assets of Gibbs and will now operate the company as a new Cimatron subsidiary (see NewsDesk Software story on page 32).
“Another trend is the continuing specialization of specific CAD/CAM products for more focused users, such as the difference between mold, tool, and die versus production part shops,” Gibbs says. “There are significant differences between these two groups of manufacturers that a specialized CAD/CAM solution can service better than a jack-of-all-trades product.”
While GibbsCAM continues to specialize in production machining, ranging from entry-level to high-productivity production manufacturing, Gibbs notes that the company has added new three-axis HSM and five-axis milling capabilities in the next GibbsCAM. “The three-axis capabilities are a maintenance upgrade, the five-axis capabilities are a new option,” Gibbs says. “We have new simulation tools to prove out setups off the machine. We have new lathe improvements including turn-roughing functions for self-grip grooving inserts, modeled after Iscar recommendations to compensate for deflection. Providing continuing value to our customers is very important.”
Continuous updates are required by CAM developers to keep pace with the industry. “The trends in the CAM business are most commonly driven by the latest CAD data formats, machine tools, controls, cutting tools, operating systems, and computer hardware,” states Chuck Mathews, vice president, DP Technology Corp. (Camarillo, CA). “All these require CAM vendors to continually update software to keep pace. Direct requests from customers for more specific productivity enhancing functionality for part programming, such as simulation and postprocessing, also influence CAM vendors.”
Mathews notes CAM developers have been affected by changes with the new Windows Vista operating system, and also by increasing demands for more sophisticated postprocessing to keep pace with the increasing number of multitasking mill-turn machines installed around the country. “Our extensive collaboration with leading machine tool builders, such as Citizen, Mazak, Mori Seiki, and Sodick, along with close relationships with many of our customers, helps us drive our product innovations,” he adds. “As an example, we are introducing programming for the new ‘Spinning Tool’ cutting process that was developed jointly by Mori Seiki and Kennametal.”
With the Spinning Tool programming capabilities, DP Technology’s Esprit CAM users employ a rotating milling tool while performing traditional turning operations. “This new cutting technique is well-suited for use on millturn and B-axis machine tools and promises shorter cycle times, longer tool life, and improved surface finishes.”
Feature-based machining heads a list of key trends cited by Mark Summers, president, CNC Software Inc. (Tolland, CT), developer of Mastercam software, who also sees embedded products and HSM developments as key for CAM suppliers. “Feature-based machining is a way that software packages automate the machining process,” Summers says. “Automated machining is an important trend today in the CAD/CAM market. More people are getting into prototyping that are ‘nontraditional’ machinists and CAM users. Feature-based machining is a way for people to machine solid parts without extensive CAM training.
“More shops now recognize that high-speed cutting is a valuable and crucial element of machining—even on conventional machines,” Summers adds. “HSM can streamline processes and provide a quicker time-to-market. Harder materials can be cut more efficiently, and because HSM tool control eliminates any inappropriate motion such as angular moves, shops can see longer tool and machine life even on conventional machines. HSM toolpaths can also produce an extremely fine finish, dramatically reducing or eliminating secondary work.”
The available 3-D HSM toolpaths in Mastercam have been refined, he adds, and are also being applied in all milling environments including 2-D milling. “High-speed machines are more affordable than ever, and more people are taking advantage of the efficiencies of the process, and also the multiple benefits, including longer tool and machine life.”
Reducing machining time is crucial for manufacturers today, notes Stephen Crane, vice president, Surfware Inc. (Westlake Village, CA), developer of SurfCAM Velocity software. “For years, the CAD/CAM industry has predominantly focused on reducing programming time,” Crane states. “Today, we’ve gotten to the point where all products have the similar Windows interface and ease of use, programming processes can be automated at will, and seamless importing and machining of solid model features is the norm. The key trends moving forward will focus on reducing machining time, because an hour of machining time is more valuable than an hour of programming time. However, the inherent problem with reducing cycle times with traditional programming methods results in reduced cutting tool life and other limitations.”
Since introducing its patent-pending TrueMill toolpath engine, Surfware has been working toward that goal, notes Crane. “By precisely and predictably managing the load on the cutter, TrueMill boosts milling production by 30–70% on most manufacturers’ existing CNC equipment,” he says. “Another benefit is extremely low cutter vibration and heat buildup resulting in two-to-four times longer cutter life—especially on harder materials.”
While initially leveraging TrueMill within its SurfCAM Velocity package for mainly prismatic parts in the production industry, in the past year and for 2008, Surfware has been working to add more functionality to TrueMill’s simultaneous five-axis toolpaths for aerospace, Crane says. “For the moldmaking industry, TrueMill results in an optimally roughed-through-pre-finished mold core and cavity,” he observes. “We have determined the best techniques which will boost our three-axis operations to yield superior surface finishes while reducing tool breakage.”
Moving toward 3-D tools for facility planning has helped manufacturers digitally design and implement new plant-floor layouts, notes Marc Rakowski, manager, market development, Delmia Corp. (Auburn Hills, MI), a brand of Dassault Systèmes SA (Paris). “Manufacturers are continuing the move to 3-D facility planning from the traditional 2-D approach,” Rakowski says. “While 3-D has been long recognized as a more effective way to design products, it has been slow to be adopted in manufacturing planning. We have seen tremendous growth and success in utilizing 3-D digital manufacturing tools to address critical areas in the production process to improve operations and identify deficiencies before physical commissioning, and we see a trend in using the same tools even earlier in the planning phases.”
At Delmia automotive customer MAN Nutzfahrzeuge AG (Munich), the company has deployed Delmia Process Engineer to help design a new truck factory near Krakow, Poland. “MAN Nutzfahrzeuge began by developing an initial draft plan of the new plant in Process Engineer using different assembly lines complete with line balancing on the various stations, such as framework construction, painting systems, wheel, cab, and motor assembly,” he says. “The company used the software to configure alternative manufacturing designs, systems layouts, material handling, tests for use ability, and the supply concept. Line balancing and cycle periods placed in context, then visualized and optimized. Through 3-D visualization of the building and work-cell layout, the company minimized costs and potential production problems.”
In December, Dassault and Delmia inked a partnership with Rockwell Automation (Milwaukee) to tie Delmia’s 3-D digital manufacturing solutions with Rockwell’s automation and control offerings, similar to the offering envisioned with Siemens’ purchase of UGS in January 2007.
With virtual commissioning, Delmia Automation offers users digital manufacturing tools enabling manufacturing engineers to debug code on PLCs that will be on the shop floor weeks, or months, before integrating devices such as tooling, robots, clamps, safety devices, electrical, hydraulics and pneumatics on the shop floor, Rakowski notes. “It significantly reduces product launch time by identifying control logic errors well before implementation on the factory floor,” he adds. “The ability to test the actual controls [PLC and HMI] against a virtual factory months before anything is built not only reduces development time, but also reduces the risk and cost involved in a production launch.”
This article was first published in the February 2008 edition of Manufacturing Engineering magazine.
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