Simulation Strategies

Dec. 21, 2004
Software allows companies to take designs through a dry run, eliminating error and saving time and money.
Planning. Testing. Prototyping. Ever since humans began to build things, they have embraced the idea of creating a model before making the real product to see how it would work. Today, as manufacturers seek to set up their production lines in the optimum layout and create new products free of "manufacturability" problems, the ability to simulate how things will work is more important than ever. "Every dollar spent at the front end is worth $6 to $7 at the back end, especially if you have a robot out of place on the line," says Joe Fallert, general supervisor of vehicle and powertrain inspection at DaimlerChrysler AG's Auburn Hills, Mich., Technology Center. Many companies are finding one of the best front-end solutions is software for simulation. In manufacturing there are numerous uses for simulation, most notably product design, production-line streamlining, and supply-chain optimization. By eliminating potential errors in a dry run using software, companies can save time and money, while ensuring that their processes and products are laid out and engineered in the most efficient way. At Schneider Automation Inc., for instance, simulation has become a byword for creating machine programs. "We're better able to create machine programs with relative ease and in a more timely fashion than we could before," says Chuck Babcock, manufacturing engineering manager. Schneider's North Andover, Mass., manufacturing plant makes programmable logic controllers (PLCs) and motion-control systems used in process automation and industrial control. Schneider uses software from Tecnomatix Technologies Ltd. to simulate the design and layout of the PLCs' printed circuit boards without having to make a prototype. "It allows the engineering group to evaluate designs and layouts upfront, without even seeing the product being made," says Babcock. "We've seen a time reduction to the new-product-introduction cycle." He figures that through the use of simulation software Schneider has been able to eliminate 98% of all potential manufacturability problems before making a single product. Another Tecnomatix simulation software user is DaimlerChrysler. One of the cornerstones of the auto manufacturer's Chrysler Development System, whose goal is to compress the time it takes to build a car, is digital simulation. Several DaimlerChrysler engine plants are using Tecnomatix's Valisys package (now called eMPower/Quality) to simulate the inspection systems for checking quality of powertrain components, including engines, castings, transmissions, crankshafts, and engine heads, both in the U.S. and abroad. "One of our key goals is to get away from product validation to process validation," says DaimlerChrysler's Fallert. In other words, rather than inspecting a sample of parts for quality measures as they come off the end of a production line, DaimlerChrysler's aim is to build in quality inspection all through the process. This approach is superior to end-of-line inspection, especially since it allows for greater traceability of quality problems that may arise. "If you wait and save all the inspections for the end of the line, you lose some traceability-the ability to find the machine that created the problem," Fallert says. DaimlerChrysler typically will simulate the inspection activities for a manufacturing line six months prior to the plant's construction. The goal is to make sure that the inspection systems exactly fit the work process, so that when they are actually put in place, they effectively validate the quality of the parts the line produces. By reducing or eliminating the need for time-consuming final inspections, the auto manufacturer is able to reduce its cycle time. Since installing the inspection simulation software at several new plants, managers at some of the older plants have expressed interest in using it to bring their inspection processes up to the same level, Fallert adds. All programming for the coordinate measuring machines that track quality data on the production line is done offline at a CAD terminal. Offline programming allows companies such as DaimlerChrysler to pursue a more process-centric view of inspection. "A lot of people say they can program the inspection system at the plant, but with the solid CAD models used today, this is very difficult," Fallert says. "You end up with six different programmers at six lines in the plant, each with a different style. It's difficult to develop a naming convention and a common reporting structure." Moving inspection closer to design with the help of simulation has other benefits. A major one DaimlerChrysler has identified is the time saved whenever a design or engineering change is made in the preproduction phase, such as changing the size of a hole or its location. Since the Tecnomatix software is integrated into the company's Catia CAD system via a direct link to the master CAD model, the inspection stage is automatically updated-thereby eliminating a lengthy revision cycle. Tecnomatix executives believe the demand for simulation capabilities is increasing as more manufacturers move toward mass customization, offering different options and product variations to meet customer needs. "This move to mass customization is spurring sales, because simulation software helps manufacturers cope," says Eli Dahan, marketing director at Tecnomatix's U.S. headquarters in Novi, Mich. "They can do process planning, as well as detailed layout of production processes." With more than 2,000 customers worldwide, Tecnomatix is best known in the automotive industry. But in the last year or so, the company, based in Herzilya, Israel, has been expanding into heavy industry, aerospace, and electronics. Another manufacturer that is using simulation software to improve the product design process is Lockheed Martin Corp. In an engineering simulation application, the aircraft maker is using software from Virtual Prototypes Inc. to create a virtual cockpit for F22 fighter pilots to try out. "We can make changes in the cockpit displays and show the different variations using the virtual prototyping system," explains Ralph Bell, manager of Lockheed Martin's F22 Advanced Development Laboratory in Marietta, Ga. "Using Virtual Prototypes software, we were able to generate code for cockpit displays that may be used on the airplane," Bell says. "The advantage is the speed and the ability to see what you [are] doing-that, and the fact that the customer can be assured that we can put this code in the aircraft. We've cut out several processes that previously were done by several vendors." And that meant a big savings in time. Using the simulation software, Lockheed Martin was able to push its F22 project to what is called Block 3, meaning that the company has built an advanced version of the fighter, basically a laboratory test plane including radar and cockpit displays. "This tool," says Bell, "gave us the ability to get Block 3 out the door and in the air this year." Bell and his engineering team like the simulation capability because it simplifies their task of making changes that pilots may want to see on the aircraft displays. "It's low risk when you show the customer exactly what he is going to get," he says. What's more, the code used for displays on one aircraft may be reused on others, saving a lot of time and money. Says Bell, "We can reuse the code each time we design an aircraft." Bell says the simulation technology will most likely be used on other aircraft design programs as well. "We're looking to propagate it onto the JSF (joint strike fighter) to use the same tools. The reasons are compatibility, and the ability to use existing software." The Virtual Prototypes software also may find its way into use as a tool to help redesign the cockpit for the B2 bomber, which was built before this kind of simulation technology became available. In yet another potential use, Bell says NASA is considering upgrading the cockpit on the Space Shuttle, which would be a likely application for simulation. Based in Montreal, Que., Virtual Prototypes provides reconfigurable flight simulators for both fixed-wing aircraft and helicopters. Yet another application for simulation software is optimizing the supply chain. In March, software firm Gensym Corp. began offering its e-SCOR system that enables companies to perform "what-if" analyses on their entire supply network, including vendors, inventory, costs, and equipment. Based on the Supply Chain Council's SCOR standard, it includes both financial and operational metrics, so that a manufacturer can look at the impact of a supply-chain adjustment versus the current supply chain, and see the effect on cash flow. "Manufacturers can test alternative strategies and make quantitative comparisons against other supply chains," says Mark Whitworth, vice president of e-Infrastructure planning at the Cambridge, Mass., software firm. The software allows companies to simulate various configurations and identify possible shortcomings and areas that need improvement. For example, Hitachi Ltd. is using e-SCOR to model and simulate alternative material-flow configurations and inventory strategies for its production of thin-film-transistor displays for notebook PCs and flat monitors.

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