How new CAD/CAM programming and simulation software can help address additive manufacturing processes.
In the manufacturing realm, additive manufacturing (AM) processes are still the new kid on the block. Although additive’s been around for several decades, until relatively recently it’s been relegated mostly to prototyping applications and short-run production use. With newer metal additive processes, however, the potential for AM has dramatically expanded. It has stretched from what’s been seen as an intriguing technology to a more realistic production process that’s now more widely used by major manufacturers like GE and Lockheed to make metal AM parts for aircraft engines and other mission-critical components and assemblies. As AM processes have become more popular, new CAD/CAM programming software and related simulation packages are addressing some of the issues with additive’s layer-by-layer processes, adding additive workflow tools with generative design and much more extensive 3D visualization and topology optimization techniques for manufacturers. Many of these new software packages also aim to help manufacturers with the new class of hybrid additive/subtractive machine tools.
Making the Impossible Possible
One of the key goals for new additive solutions is generating much improved designs. CAD/CAM programming in additive can make it easier for product development engineers to design parts that were previously considered impossible to manufacture. “Autodesk has built a complete end-to-end workflow for additive manufacturing, from design optimization to build preparation, simulation and post production, helping designers and engineers move from prototyping to serial production,” said Duann Scott, business development and strategy, Additive Manufacturing and Composites, Autodesk Inc. (San Rafael, CA). “We are now adding Generative Design to allow designers to explore and realize the full potential [of AM] in ways that were not possible before.”
AM’s new capability in serial production is a key development, Scott noted. “As the industry evolves with new materials and processes, so will the use cases broaden from small, complex and/or customized parts, to larger parts as lower cost machines and materials enter the market,” he added. “We have seen the cost of hardware dramatically drop as key patents expire, first in the polymer space with FDM [fused-deposition modeling] machines dropping from $40,000 to $400, then SLA [stereolithography apparatus] machines dropping from similar prices to $3000, and now SLS [selective laser sintering] machines dropping from $150,000 to $10,000. We are now seeing a new wave of additive metal processes. Where formerly it would cost $1 million to set up a single machine, new machines can now be purchased for around $100,000. This massive reduction in the investment required to produce parts will dramatically broaden what is currently a relatively small market.”
Adding generative design capabilities to software for AM processes will give designers substantial advantages, Scott contended. “Generative design allows designers and engineers to explore solutions based on design constraints and manufacturing processes that would be impossible to conceive or execute with traditional CAD software,” he said. “More than just topology optimization, which takes existing geometry and reduces mass based on FEA [finite element analysis] solvers to a single optimized design, generative design creates geometric solutions based on multiple objectives and multiple manufacturing processes to provide multiple solutions. These solutions can then be iterated upon to further refine the geometry, which can then be manufactured as is, or used as a guide, to inform the designer’s approach to the design, based on the solutions they provide.”
Early next year, Autodesk will release the next version of its Netfabb 2018 additive/3D printing software, currently in beta-testing, which will add new features including generative design capabilities. “The link between traditional subtractive processes and additive manufacturing is that both require deep understanding of the specific machine and material combination to create optimal machine control to meet the design engineer’s requirements,” Scott said. “It is also critical for most metal AM parts to be subtractively machined after printing to ensure surface quality and tolerances on parts that interface with other parts in an assembly.” Autodesk is offering the complete workflow, he added, to use the same CAD file for both additive and the essential subtractive post-process.
“Combining separate processes like additive and subtractive in a manufacturing workflow typically involves multiple steps, often on different machines. This needs to be accurate and automated. There’s a digital process thread that starts with the design and engineering intent and simulates what should happen at each step in the process—you need to build on the original data,” Scott stated. “You also have to monitor the progress in the real world, using inspection and adaptive or feedback loops to detect and compensate for variation. These processes also need to be joined up.”
Last fall, Siemens PLM Software (Plano, TX) announced its “Additive Manufacturing with NX” solution, and early this year the company added the Siemens Part Manufacturing Platform, an online collaborative service aimed at matching buyers and sellers of additive components. In April, the software developer, owned by Siemens AG (Munich), also announced an extensive technology partnership with longtime additive/3D printing software provider Materialise NV (Leuven, Belgium) under which the Materialise Magics 3D Print Suite AM software will be fully integrated with Siemens’ NX software. The combination brings the expertise of Materialise with Siemens PLM’s NX core CAD/CAM/CAE strengths, including extensive design capabilities with simulation-based optimization tools, noted Aaron Frankel, senior director, marketing, manufacturing engineering software, Siemens PLM.
Siemens’ additive strategy features three pillars, starting with Additive Manufacturing with NX, which includes the company’s NX and Teamcenter PLM offerings, noted Andreas Saar, Siemens PLM vice president, Manufacturing Engineering Group. “That’s what we call the digital chain and the core moving into the future,” Saar said. Siemens will be releasing three- to six-month updates of the software, with new printer interfaces working with many additive players, including EOS, Stratasys, DMG Mori, HP and others, he said.
“Our intent is to bring additive forward into an industrial phase,” Saar said, integrating Materialise into Siemens’ large NX industrial installed base. An example is GE, which uses additive to produce large nozzles for aircraft engines. “There was a small group, maybe 20–30 people, between design and simulation engineers, who made this happen, and there are probably 4000 design engineers there. Our goal is to greatly expand that. We have 10,000 design seats in GM. These guys have to rethink additive manufacturing.”
“What we see in the market is medium and large companies are creating additive manufacturing workgroups to understand the technology,” said Frankel. “There’s a big learning curve. Companies are picking up various disparate technologies to see what will work, but that ad-hoc environment will not scale. Companies need to have an end-to-end solution, and they need to be able to manage that data and process with a single solution.”
The Rise of Hybrid Additive Machining
Many newer CAD/CAM solutions for additive focus on programming or simulation of the latest crop of hybrid additive/subtractive machine tools, including entries from DMG Mori and Mazak. Since AM components are not nearly net shape and require moderate to extensive finishing, hybrid is a practical approach for many machine tool users. Hybrid machines, while pricey, have recently become more affordable.
Siemens’ strategy aims to support all AM machines, especially hybrid units from some of the company’s partners, such as DMG Mori and Mazak. “We support existing solutions, such as direct energy deposition, laser beam welding and power bed fusion,” Siemens PLM’s Frankel said. Of those technologies, Saar said the most common one is powder bed fusion, and Siemens supports the newer Multi-Jet Fusion from HP, which uses 2D printers with nozzles. The machine has 3D voxel technology that prints in just one color but will be able to print in multiple colors. “The future is very scalable,” Saar said.
Hybrid machines are attractive to many CAD/CAM developers, and Vero Software (Reading, UK) is planning to release a hybrid additive machining module in the future, possibly around April next year, for its Edgecam and other CAM software, said Raf Lobato, strategic products director. Direct energy deposition, repair, growing features, and cladding are all areas of focus for this type of software, he noted. “To get the most out of additive, it cannot really live on its own; the ‘adding’ area occasionally needs to be prepared by subtractive and then finally, after material addition, usually needs to be finished with subtractive,” Lobato stated.
More research is needed to refine many additive processes, he noted. “They actually don’t know how to add material effectively yet,” Lobato said in describing direct energy deposition. “When you add some material to a component, it doesn’t come out perfect.” The material deposited is not close to near-net shape, requiring subtractive finish-machining processes to complete the parts. “The great news is that the tests show that the additive material deposited in this process is harder than the base materials, in some cases,” with close to 100% dense metals added to these metal components in such cladding operations, Lobato said.
In one example, repairing aircraft turbine blades required cutting a V-shaped piece of material out of the part instead of just adding metal where a crack on the blade was. “There again you can see where a subtractive operation is required,” Lobato said, agreeing that, at times subtractive and additive processes are both needed to complete the job. “That’s our belief. Also, it would take a bloody long time—adding material is not quick.”
Improvements in technology, both software and hardware, plus speed, flexibility, and of course, cost, are critical to additive’s growth, Lobato said. “We are involved in the Kraken Project, http://krakenproject.eu/, which is about additive manufacturing on large parts by a robot with a higher accuracy solution than traditionally available.”
Another new entry comes from CAD/CAM developer DP Technology Corp. (Camarillo, CA), which in August announced its Esprit Additive Software suite for metal additive manufacturing. The software is said to help simplify the time-consuming additive programming process into just a few simple steps.
“Today’s CAD/CAM software should provide powerful programming for multitasking, multifunction, multichannel, mill-turn, additive and subtractive machine tools, with additive and subtractive processes being programmed, optimized, and simulated together in a single user-friendly interface,” said Chuck Mathews, executive vice president, DP Technology. The new Esprit Additive module is expected to be available in mid-2018. DP Technology has strong partnerships with DMG Mori and Mazak and the module will offer additive programming for users of those companies’ hybrid machines.
In Creo 4.0, PTC (Needham, MA) released an Additive Manufacturing platform that includes functionality to better design and optimize lightweight structures, define new assembly sub-types that can store the parts to be printed, their position, materials, colors, and more, noted Jose Coronado, product manager of Creo Manufacturing and Simulation applications. The additive solution also includes a connectivity feature to provide direct feedback to the designer about the 3D printers’ capabilities, which will be considered in the design phase.
“A high percentage of Creo users have said that they are currently implementing, or are considering implementing, pilot projects in additive manufacturing,” Coronado said. “Also, many plastic printers already in customer premises are shifting from prototype work to fabrication of tooling and fixtures, or directly to produce final parts. One of the enablers of this shift is the new functionality available in Creo, enabling engineers to design optimized lattices and directly connect with Stratasys and 3D Systems plastic printers.
“PTC’s roadmap for Creo includes more lattice types, topology optimization integrated into the B-Rep [Boundary representation] model, support of metal printing processes and more, all without leaving Creo,” he continued. “But our users don’t need to wait; PTC’s current additive and subtractive functionalities coexist, seamlessly integrated with the CAD model. Using the same 3D model, we can prepare a tray assembly to print one or many parts. Then, if post-processing like drilling, face milling or deburring is needed, the same 3D model is used to create the corresponding NC toolpaths.”
An early pioneer in additive, 3D Systems (Rock Hill, SC) also offers its additive and subtractive manufacturing expertise along with its 3DXpert Metal Additive Manufacturing software introduced last year, according to Daniel Remenak, product manager, GibbsCAM 3D Systems. “3DXpert is an all-in-one software solution for metal additive manufacturing with advanced capabilities in print preparation, supports and structure optimization, slicing, and even post-printing operations.”
Although CNC Software, developer of Mastercam, hasn’t released an additive-specific module, the company is “evaluating what additive software approaches are the most useful for our customers both now and as the technology continues to expand,” noted Ben Mund, senior market analyst, CNC Software Inc. (Tolland, CT).
“The initial issue of surface finish has seen dramatic improvement, as have the available materials, with more development going into high-temperature and structural materials, flexible materials, and composites. As these issues are improved, the process will be used in more and more places,” Mund said. “More affordable metal printing will also move the industry forward. We’re seeing that happen now with new types of more affordable substrate-infused metals.
“There are also many places where additive and subtractive will be used in concert,” he said. “This can range from producing additive fixtures for subtractive machining, to creating additive parts that need to be finished machined. And, of course, there will always be parts that are impossible to produce through subtractive, where additive is the only choice.”
At Open Mind Technologies USA Inc. (Needham, MA), developer of hyperMill CAD/CAM software, the company has the capability to support AM processes using an additive-specific module which is an option within hyperMill, noted Alan Levine, managing director. Open Mind has been involved with additive machining for nearly 10 years, Levine added. “Our focus is programming support for laser-based metal deposition processes. This effort is consistent with our advanced five-axis focus, and includes feedback from our customer base. Today we are working with machine partners and key end users on projects and to implement and confirm new technology. Our processes are aligned with ongoing developments in hyperMill, our package for subtractive machining, so this work is streamlined and can be done elegantly within our current approach.”
Though additive powder-bed machines may comprise a larger segment of the market today, Open Mind’s focus is on laser deposition, as applied to building new parts (often with five-axis machines) and maintenance and repair in mold and die and energy, according to Levine. “Laser deposition processes generally do not require in-process structures to support overhangs that later have to be removed,” Levine said. “Also, laser deposition is well-suited for hybrid machining.”
About a year ago, Open Mind added new simulation support for additive from its partner and component module developer MachineWorks (Sheffield, UK). “Our software development for additive processes is based on our experiences and cooperation with key users and machine partners. The various parts being made today lead to refinements to the software and process workflow. The fundamental requirements for additive processing—regarding filling and bounding paths, controlling start points, and laser triggers—have already been implemented in the software,” Levine said. “Collision-checking procedures also need careful attention as the workpiece model is constantly growing, and also deposition heads require specific focal lengths for proper powder deposition.”
Simulating NC and Additive Processes
As in any manufacturing process, accurately simulating metalcutting and metalforming motion is critical for ensuring manufacturing quality and safety of the tooling, fixturing and machine tool. Until recently, simulation software solutions have been scarce for adequately visualizing AM processes.
At the Rapid/TCT show in Pittsburgh, the latest Vericut Version 8.1 NC simulation, verification and optimization software introduced new capabilities for simulating additive and hybrid manufacturing operations as well as for continuous dressing while grinding, said Gene Granata, product manager for Vericut at CGTech (Irvine, CA). “These new methods can be used in any order, with any traditional cutting method [such as milling, turning and five-axis machining] and on virtually any brand CNC machine. The new software also has enhancements for sectioning the workpiece, X-Caliper measurement tool, Force toolpath optimization, and setting up reports to automatically document the manufacturing process.
“The lure of additive manufacturing brings with it many unique challenges for designers and NC programmers,” he continued. “People are retraining themselves to think, design and program parts differently, to make a superior product as efficiently as possible. Simulation software, such as Vericut, is an invaluable tool for NC programmers to visualize and verify each process in the order used, compare manufacturing strategies, and prevent costly crashes or damage to machines, tooling and parts being made.” Hybrid machines are typically expensive, and usually in limited supply at a given company, he added. Repair parts or technicians for laser and other additive equipment can also be hard to find. “Simulation software offers a cost-effective safeguard to mitigate potential problems before they occur.”
Finding novel ways to program parts produced via additive processes presents a new challenge for NC programmers. “Having options to employ additive, subtractive, or hybrid methods often pushes programmers to think beyond their previous ‘comfort zone’ to do things not previously thought possible,” Granata noted. “New Design for Additive Manufacturing [DFAM] and additive NC programming capabilities seem to arrive in each new CAD/CAM release. While these enhancements are intended to provide additive NC programmers with more options, this also increases the learning curve. Mentally keeping track of where material has been deposited and where it hasn’t is challenging.”
Incorporating additive in any production process creates multiple issues, Granata said. “A mistake in planning and sequencing of NC operations can damage machine components, additive equipment, or the part. Simulation removes guesswork and minimizes risk, showing how parts will be made and the exact representation of the part throughout the process.” The Vericut Additive module simulates both additive and traditional machining capabilities used in any order on hybrid machines. “Simulating all operations can identify potential problems that can occur when integrating additive methods. The user can access a detailed ‘history’ stored with Vericut’s realistic droplet technology, saving programmers time by identifying when part features have been machined and the source of errors, in most cases, using just a single mouse-click.”
This additive capability checks accurate laser cladding and material deposition, detects collisions between the machine and additive part, and finds errors, voids and misplaced material, Granata noted. “For the highest accuracy, Vericut simulates the same post-processed NC code that will be used to drive the CNC machine and ensures proper usage of AM functions and laser parameters. Users can virtually experiment with combining additive and metal-removal processes in any order to determine optimal safe hybrid manufacturing methods.”