Driven by design

In the automotive industry, design is now becoming an integrated part of the entire production cycle - and even of the factories themselves, reports E&T.

For any engineer the topic of the best designed sports car is sure to set the pulse racing. My own personal favourite was, and I suppose still is, the Lotus Elise Series 2. The British manufacturer Lotus Cars has a unique concept for its sports car: "Performance through light weight." Introduced in 2000, the Lotus Elise Series 2 definitely took the Lotus family to a whole new level.

The Elise packs an aggressive design, despite its small frame. The car is 3.8m long and it weighs less than a ton (from 860 to 910kg). It also comes with a fibreglass body shell. But, of course, everyone has their own favourite. Some would opt for the AC Cobra 427, others the Porsche Carrera GT, the Chevrolet Corvette 1968 L88, or even the Bugatti Veyron.

But it matters little what car you select, they are all beautifully crafted engineering masterpieces. The automotive industry has never been shy when it comes to pioneering new design technology, and the minds behind such classics as the Elise have now turned their attention to using the tools that deliver today's stunning road cars to design the manufacturing layout of factories. 

At Lotus Engineering, they are integrating digital assembly situations around the design environment. Within the design process at Lotus a whole host of software is encountered - ICEM Style, Catia, Unigraphics, all the CAE (computer-aided engineering) programs and even dynamic analysis.

That is important because, historically, manufacturing has been a poor relation to the design activity. Designs were passed to manufacturing, which then had to find a way of making that vehicle. "But as we have gradually introduced those processes into the design process, we have made that more efficient and learnt things about that manufacturing process much earlier," David Jenkinson, manager of body assembly systems at Lotus Engineering, says. "We really wanted to reduce our product delivery time, we needed to improve the efficiencies of our processes, we had to improve the quality of the product because our customers demanded it, but most of all we had to have a cost effective process."

The design process that Lotus used at that time was a standard configuration - styling, design, CAE, dimensional management, process planning and feasibility, and although it was using some digital simulation, it was as a validation tool rather than influencing the design. "We decided that the first improvement that we should make was to bring that simulation into the design process," Jenkinson continues.

To allow this simulation to collaborate with the Catia design tools that Lotus uses, it opted for Delmia, enabling it to speed up the process of feeding information back to the design team. So it became an integrated part of that design.

"The value added was very important - we now had an integrated system that was within Catia, we had eliminated all the translation time, current and live data was being used, and because we weren't losing any time with translation our responses were much quicker, our communications were more accurate and the clarity of communications through the dynamic visualisation really helped to speed things up," Jenkinson says.

"Because we were doing all this work, we had much more confidence in committing to our tooling programmes, as a result our overall product delivery time has been reduced. This also gave us improved process planning because our assembly engineers were preparing the family trees and process sequences that were being passed straight to the simulation engineer who could very quickly confirm the feasibility of assembly, time analysis and any ergonomic considerations."

Lotus has already experienced demonstrable improvements. The time from concept to prototype has been reduced, the actual prototype build time has been reduced, which means that they get to testing quicker and that has all helped to reduce the product delivery time. There have also been fewer changes due to assembly issues, and the number of confirmation prototypes for manufacturing has been reduced.

"We feel that we have done the right thing by bringing all that simulation into the design environment, but we still seem to have a mismatch between process planning and simulation," Jenkinson says. "This part of the process is working well but process planning and simulation are still not a seamless activity. The simulation is working straight off the CAD model, but the process planning is still being done manually.

"So when we looked at our process planning, things such as plant layout are done with AutoCAD, there is the simulation that is part of Catia, and then presentations and reports that are sometimes produced in Word or Excel. There was great scope for error in transposing all this information, so we realised that we had to combine all this planning within the CAD environment.

"We looked at various systems, but having learnt from using Delmia and making sure that it was integrated within Catia, we did a line trial with DPE, which is a process engineering package that is part of the Delmia suite."

It all saves Lotus a lot of time and ensures that the engineers are engineering and not just copying data. As a value-added proposition, it now has a totally integrated manufacturing and design system that will help reduce time to market and further reduce costs. "And for us, because we have to spend our money wisely it is going to build on our current investments and that it is going to help us to survive," Jenkins concludes.

Simulating a Mercedes

Mercedes Benz is another company that has pushed the boundaries of digital simulation within the manufacturing process. In a world where greater complexity of product is a given and increasing productivity a must, the role of production planning has taken on even greater importance.

Common themes are the drives to standardise assembly methods in facilities spread around the globe, in order to minimise the number of tools and processes, and gain a handle on vehicle complexity by introducing modular design. All those issues are familiar to Mercedes and are being tackled via digital simulation, not just in isolated islands of technology, but in an all encompassing cradle to grave philosophy that is fundamentally changing the way it designs and manufactures cars.

The man charged with this task is the vice-president of production planning, Gunter Walz, a veteran of production, research and development roles at the Stuttgart-based carmaker. Over his time at the company, Walz has got to know its cars pretty well and is using that knowledge at the interface between development and production, where he has been instrumental in developing Digital Factory as a production simulation tool.

"Production planning at Mercedes is a growing department, having recently taken over a lot of responsibility that in the past resided in the plants," Walz says. "It has always been responsible for developing new technologies, making them feasible for production, making new concepts, and of course planning all the facilities - the buildings, bodyshop, paintshop, assembly and logistics. We are also responsible for series planning; we are a kind of turntable between development and production."

The challenge in production planning, according to Walz, is that it needs to be involved much earlier in development, and that involvement must continue throughout the car's lifecycle. He explains that the planning involvement would encompass the strategy phase, technology phase, vehicle phase and the current series.

"The use of simulation is still in development," he says. "It began over ten years ago with the actual development of the car and we have now had to adopt that in production and the Digital Factory is the tool on our side. So when the digital car arrives, the Digital Factory has to be ready and we can make the digital car in the Digital Factory and discover all the problems, which traditionally we would not find until we started production.

"We have developed the tool of the Digital Factory to contain all our standards. We use that as a simulation tool and also as a planning tool; we also have other planning tools such as FACT, but this will be replaced by Digital Factory over the coming years. So Digital Factory and the tools that we are developing now are then our standard tools for simulation, planning and even documentation."

Another key task for Digital Factory is to assist Mercedes with its standardisation of processes and increased modularisation of products. "At the beginning we had only Sindelfingen, then Bremen, then Rastatt, but we are adding other sites around the world - at Tuscaloosa in the US, East London in South Africa, and China," Walz says. "If you want to have the same procedures you have to standardise. We make sure that the production system is the same. At Tuscaloosa the production system is exactly the same as it is in Germany, but we have to be aware that we have different locations, different educational capabilities, so they may need more training but the production system is and will remain the same, even in China."

Digital Factory is also helping modularise car development, for example with roof, rear-end and front-end modules. "This same concept is carried over to the interiors on components such as air conditioning and seats, in order to develop building block systems and facilitate design and manufacturing and planning," Walz adds.

Modularisation concerns the production facility too, he says. "The Digital Factory is such a vital tool, allowing us to implement the principal of operating robots, from the car body-in-white, up to the assembly phase, to increase flexibility to reduce cost and also to increase availability and process ability, to aim at offering a higher quality for the customer. The focus is on six elements of car production - the press shop, body-in-white, paintshop, assembly, measurement and test, and logistics."

The future vision of the Digital Factory is to plan all production facilities digitally, and to simulate and validate the manufacturability of the product as well as planning results, Walz concludes.

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