By Leslie Langnau
Choices, such as whether to use one material over another, whether to include a subassembly, or accommodate a wide or narrow range of loads directly affect a product’s total cost. While CAD programs can influence choice, market forecasters claim that Product Lifecycle Management (PLM) programs will have the greatest affect on controlling total product costs — from procuring materials, manufacturing the product, through ongoing support and recycling. Market analysts also say that companies that design in 3D CAD programs will gain the most advantage from PLM software.
According to these analysts, however, only half of all 2D CAD users have moved on to 3D CAD. The reasons why more engineers have not switched include cost, not seeing the need, and unfamiliarity as to how 3D programs have evolved. However, to hustle product development, eventually 3D systems must replace 2D programs.
Combined with 3D data, PLM software displays a product design in a way that 2D drawings cannot, helping non-engineers see and understand the concepts behind the design. Such understanding is vital for customers, investors, as well as suppliers and manufacturing personnel who will convert the design illustration into a physical object. Together, 3D CAD and PLM programs accelerate the process of turning an idea into a product and bringing it to market.
Kässbohrer engineers must meet legally stipulated dimensions. The Solid Edge program lets the engineers use a modular process to ensure that total weight, axle loads, width, height, and length meet the required dimensions.
Pros and cons
With 2D programs, drawing is fast and easy. But the output is still a 2D drawing, which does not readily work with downstream systems like purchasing and manufacturing. These 2D drawings do not contain all information needed to develop a three-dimensional product. It is usually during the manufacturing stage that problems arise, particularly with material or matching and mating assemblies.
Most 3D CAD systems generate dimensioned 2D drawings almost automatically, but they also include a virtual prototype that offers unambiguous data for subsequent processes. Viewing 3D models on screen helps identify errors early. These systems also promote innovation; recognition of good ideas is fast. Just as important, recognition of unsuccessful ideas is swift too. This ability to explore many good and bad ideas in the time it usually takes to explore one is what leads to rapid delivery of better products.
Converting from 2D to 3D programs is easier with hybrid 2D-3D systems. When budgets permit, engineering departments can convert to pure 3D CAD systems. The newer versions are affordable, Windows based, and support component as well as assembly modeling. In addition, many 3D CAD packages include features specific to cooperative situations, such as data management, revision status tracking, change order management, and bill of material data to name a few.
Evolving to 3D
Converting from 2D to 3D is becoming easier thanks to the hybrid systems and companies that promote an evolutionary path to 3D. Such programs permit stand-alone 2D design and drafting while offering plenty of opportunities to explore 3D tools.
3D CADprograms ensure a design has sufficient room for cylinders, hoses, cables and other components needed in Kassbohrer’s truck chassis designs.
Then, as engineers reach sufficient familiarity with 3D tools, they can turn a simple 2D geometry into an accurate 3D part. Next, by mixing and matching 2D layouts with 3D components, engineers can quickly generate enough information to accurately define the necessary proposal detail. Once this step is finished, the acquired skills can be applied to a full 3D process.
The ability to consider alternatives
The engineers at Kässbohrer Transport Technik, in Eugendorf, Austria, one of Europe’s most renowned automotive manufacturers, preferred a step-by-step move to 3D CAD. Said Christian Winkler, CAD administrator/development, “The foundation for our present success with this program was laid in the introductory phase. Thanks to the clearly structured approach, unpleasant surprises that might occur during 3D CAD implementation were avoided.” For more than fifty years, Kässbohrer has designed vehicles to meet customers’ unique requirements. The company has an extensive product line that covers just about any conceivable requirement for its line of Metago, Variotrans, Supertrans, Citytrans and Ecotrans vehicles. Every year, approximately 1000 units are produced and marketed worldwide. When it was time to upgrade to solid modeling, the company chose Solid Edge software after testing it for two months. The development department purchased 13 seats. In use for several years now, the designers learned to use the software by working with the program’s tutorials.
A fresh start
”We use a large number of Solid Edge’s features,” said Winkler. The structured process includes a manual for the creation of vehicle prototypes. All parts designed in Solid Edge now have an article number and are stored on a server, providing access for all authorized users. “In the past, the assembly structures were only parts lists,” Winkler continued. Using the 3D CAD program, the team changed to precisely structured plans that included the complete steel structure, the hydraulics, lines, and the entire electric and cabling systems. “One essential advantage now is that a drawing is produced for everything, even the smallest part, down to the pure metal sheet cut to size,” Winkler added. “In this way, every change can be tracked and there are installation drawings for everything. This wasn’t possible before because we didn’t have the capacities to plot everything in 2D CAD.”
Modular design process
Depending on the customer, Kässbohrer vehicles are made through a modular process that handles legally stipulated dimensions. Total weight, axle loads, width, height, and length are crucial. “A truck chassis with a cargo of cars must be able to transport this load within the scope of legal requirements,” explained Winkler. “We need to adjust the superstructure when load dimensions change, a process no longer feasible without a 3D system.” Designers must find room for cylinders, hoses, cables and other components. “Solid Edge assists us with this because you can clearly see everything in the design,” Winkler added. “On a computer screen, we can simulate hydraulically raising our transporters, and moving them longitudinally.”
The program assists with the development of “intelligent” assemblies by placing emphasis on function as well as on how parts fit together, creating digital prototypes that emulate real-world situations. “Sensors” monitor critical variables keeping projects on time and on budget by checking for manufacturability, build errors, and cost increases. Solid Edge supports both top-down and bottom-up design methods where it is important to create links with adjacent components to accommodate changes that ripple through an assembly. In addition, the program tests product alternatives quickly. Integrated kinematics analysis helps avoid errors. The Simply Motion kinematics feature automatically generates dynamic results for mechanical motion and collision analysis from Solid Edge data. If individual parts within a design are moved, Solid Edge automatically detects collisions, marks the areas involved and issues an audible warning. For electric and pneumatic diagrams, the SmartSketch 2D CAD system works with parametric drafting block diagram functions to aid cargo-loading simulations. Overall, Kässbohrer finds that Solid Edge, with its tools for modeling, administering, and mapping modules, creates a productivity advantage.
Rethinking the internal combustion engine
For Bradley Howell-Smith, 3D CAD helped him modify a design and have it ready for presentation to a customer within seven months. In 1995, Howell-Smith designed and patented a radically different internal combustion engine. He called his concept the “Controlled Combustion Engine” (CCE) and formed Revetec Holdings, Ltd., located in Gold Coast, Queensland, Australia, to bring it to the market served by conventional combustion engines. “The controlled combustion engine can be used in motor vehicles, trucks, buses, motorcycles, pumps and generators and light aircraft engines as well as diesel and marine engines,” said Howell-Smith.
The ability of 3D CAD programs like Solid Edge to show potential part collisions or interference saves confusion during actual assembly.
The CCE offers increased power/torque ratios. This engine consists of two counter-rotating “trilobate” (three lobed) cams geared together. Thus, both cams contribute to forward motion. The engine has a higher bottom-end mechanical advantage over equivalent conventional engines for improved fuel-efficiency. It produces fewer emissions and is smaller, lighter, and less expensive to manufacture than conventional engines.
In the summer of 2006, while evaluating the needs of the aircraft industry, Howell-Smith conceived of a variation on his original design. Called the X4, the new design’s physical size is about 40% smaller and half the weight of similar capacity engines. The concept was enthusiastically received, but Howell-Smith needed to take the idea from concept to working prototype in a few months. “One interested company was not expecting to see a working model,” he explains. “But we wanted to impress them with what we could do.”
“We” is really only two people. Howell-Smith does the design work and a machinist builds the prototype engines. Solid Edge software allows them to accomplish a lot quickly. Howell-Smith chose this CAD system when he started Revetec and has been using it ever since. “Before then, I had never touched a CAD package,” he said, “so, I needed something I could learn quickly. Within two weeks of purchase, I learned most of the major features and was modeling engine components.” Over the years, he has used the software to create digital component models from which he builds sub-assemblies and then virtual mock-ups of entire engines.
Thanks to 3D CAD, a modification to a proprietary Controlled Combustion Engine design was finished in seven months.
Integrated analysis improves the design When Howell-Smith started work on the X4 engine, the release of Solid Edge included Femap Express structural analysis software. This feature eliminated the frequent outsourced analyses and subsequent delays of working with a contractor for finite-element analyses. “Each time I changed the design and sent it back, it took about two weeks for results,” he said.
With Femap Express, he could do the structural analysis himself. “I opened a Solid Edge piston model and the software asked where I wanted to put the loads,” he explained. “I entered the location (the top of piston) and the amount of the load. Then it asked where the design was constrained so I put in that, along with the material associated with the part. Then I clicked ‘Analyze.’ It was really that easy.” Now, what used to be a two-week process is done in half an hour.
The finite element analysis feature of Solid Edge saves Revetec Holdings Ltd. more than $1000 per consultant fee.
Looking good is part of the benefit
The ability to analyze a design in house saves Howell-Smith the $1,000 to $2,000 per analysis the contractor charged. More importantly, he can perform more analyses and use the results to improve his designs. “On the X4, I was able to analyze certain components that I wouldn’t have analyzed in the past,” said Howell-Smith. “The overall design is better because of this ability. In fact, I brought some old models back into Solid Edge and checked out areas where we had outsourced the analysis. Through Femap Express I was able to remove about half the weight while making the parts stronger. I wish I had this capability earlier.”
Howell-Smith started designing the X4 on July 10, 2006 and finished modeling the entire engine before the end of the year. He figured the Solid Edge work took him about 1,000 hours, which includes all the analysis. The prototype was built and running in time for the customer meeting. However, Howell-Smith has really come to rely on the ability to produce highly realistic-looking images from 3D CAD data in his efforts to sell his engine. “We are a small operation but we like to have people see us as a larger operation. I find the rendering capability in Solid Edge very useful for this,” Howell-Smith says. “I generated attractive high-resolution images that were so realistic, people thought the engine was already built. They didn’t realize they were looking at a computer rendering.” It is this fully dimensional, realistic rendering of an idea that is one of the crucial benefits of 3D CAD modeling over 2D drafting, and one of the reasons all 2D systems should migrate to 3D.
UGS Corp. provided information for this article.
UGS Corp. www.ugs.com
Revetec Holdings Ltd. www.revetec.com
Kässbohrer Transport Technik GmbH www.kassbohrer.at
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Filed Under: 3D CAD, Automotive, Industrial computers