Visions of a digital factory
Warwick, U.K.--In the same way that digital prototypes are being used to cut down on the costly process of making physical prototypes for new models, car companies are starting to plan the complete production system of a vehicle digitally. The U.K. car company Rover, now owned by BMW, is one good example.
For the launch of Rover 75, a saloon car on sale this spring, Rover has introduced an electronic build, or E-Build, process which enables prototype vehicles to be built, component-by-component, in the virtual world. The virtual vehicle construction phase takes place three months prior to any physical cars being assembled, so changes can be made without incurring investment in manufacturing tooling or equipment, says Paul Towers, IT manager, Rover large car projects.
During the E-Build process, a multi-disciplined team of engineers and managers meets in a specially built E-Build theater where they don stereoscopic glasses to view the assembly process in full 3D stereo. A specially trained E-Build engineer then constructs the car virtually in front of them. "Having all the people present, you can actually solve problems in the most dynamic way," Towers says.
During development of the Rover 75 saloon, 500 electronic builds were conducted, resulting in more than 750 significant changes. One of these changes, for example, required the sequence of the rear suspension assembly processes to be adjusted because the original process precluded tool access for tightening the rear caliper bolts.
"In the past," Towers explains, "we would have discovered the problem during the early pre-volume build phase. Using the E-Build process, we highlighted the problem three months earlier." This allows significant potential savings, he notes, for if the tooling for a bumper or fascia should have to be changed, the cost incurred is likely to be "as much as 500,000 British pounds."
Applying process simulation tools from Tecnomatix to the Rover 75 allowed body-side assembly robotic simulation (above) and rear-suspension dynamic simulation (right)
Having created the E-Build process, Rover then had the confidence to fit a one-piece exhaust for the first time ever. Previously, a two-piece exhaust had been preferred because it simplified the final fitting and adjustment of the exhaust mounting locations at the vehicle prototype stage. "On the Rover 75, the one-piece exhaust fit exactly, the first time," claims Towers.
Behind the E-Build process is a mass of IT tools and methodologies. Rover already had a strict CAD modeling strategy in place and the whole vehicle was developed in 3D CAD using Catia and CaddsV software from Dassault Systemes. Suppliers also had to conform to the strategy. In total, the number of Rover 75 components modeled in CAD exceeded 2,000.
Integrated with the CAD software is a suite of Tecnomatix (Novi, MI) process simulation tools. Dynamo is the visualization tool for dynamically packaging components into assemblies, defining insertion and extraction paths for parts, and checking service and maintenance procedures. Robcad is used for modeling critical manufacturing processes as a three-dimensional computer simulation.
|The Hawk Tailplane cell as situated on the Brough site. Quest-a QUeueing Event Simulation Tool developed by Deneb Robotics-was used within the area to optimize cell layout.|
Robcad/man is the ergonomics tool for performing driver studies and assessing the efficiency of manual production tasks. To analyze tolerance stack-up and assess critical areas such as gaps between panels, Rover is applying the Valisys tool, also from Tecnomatix.
Computing power for the graphical manipulation of the vast amount of engineering data was achieved using Silicon Graphics Indigo2, Octane, and Onyx workstations.
As this was the first application of the new E-Build process, Rover only fully modeled 12 key stations in the trim and final production facility: those where assistors or kinematic devices help production associates maneuver components. These include the station where seats are mounted, doors are put on and taken off, the heater assembly inserted, the sun roof assembly fitted, and the rear suspension mounted.
In addition, E-Build exercises served a variety of purposes. One application was to optimize the layout of a station, to ensure that it took up a minimum amount of floor space without compromising quality. "It was critical to evaluate the materials handling operations and ensure that when associates moved components from their line-side palletization systems over to the vehicle, they had enough space to maneuver without risk of damaging and impacting quality," Towers explains.
Optimized production facilities
Brough, U.K.--For British Aerospace, factory modeling plays a major role in enabling the company to handle an unexpected volume of orders. Sales of Hawk aircraft are almost double their expected level and British Aerospace has launched a 29-million-British-pounds project known as Showcase to restructure the manufacturing site at Brough to cope with the increase.
Layout of the existing area would not achieve the projected output without a major reorganization, says Mark Tomlinson, development engineer. "By physically changing the layout we can produce better process flows. We are creating lean production lines and arranging machines so that parts don't travel as far as they previously did," he says.
Like other British Aerospace sites, Brough has turned to Quest modeling and analysis software to help plan its re-organization project. Developed by Deneb Robotics (Troy, MI), now part of Dassault Systemes, Quest is a QUeueing Event Simulation Tool designed to help manufacturers set up models of production systems and optimize them by trying out different scenarios.
With Quest, Tomlinson's team first set up 2D layouts of manufacturing cells using the CAD functionality within the simulation software and then translated them into 3D models. In some cases, it was possible to use geometric models of components from Quest's own library.
In other cases, it was necessary to develop the models from scratch. The result, however, was a very good representation of reality, including not only the buildings and equipment but also the operators and workpieces, Tomlinson reports.
At Brough "cell design sessions" held to assess the proposed layouts, as many as 15 people from different functions, including operators, fitters, and maintenance personnel, participated. "The Quest models enabled us to show the cell designs to the shop-floor people so we could argue out all the issues together and ensure that no major changes would be needed once the cells were implemented in reality," Tomlinson explains.
A particularly useful application of the 3D Quest models, he adds, was the ability to generate "fly-through" views of a cell by specifying camera angles and viewing the cell as the system passes smoothly between cameras. Using this feature, it is possible to zoom into critical areas such as the space between machines to check out maintenance access, for example, or collisions between large workpieces like wing skins, machines, or buildings.
The Brough site has also invested in virtual reality equipment which Tomlinson says is useful in cell-design sessions. "When the operators don their headsets, they can walk around the cell and get a far better impression of space than when they are just looking at an image on the screen."
Less materials handling
Murray Hill, NJ--Like British Aerospace, U.S. optical fiber manufacturer Lucent Technologies was faced with increasing demand. With output expected to double at one of its U.S. production sites over the next five years, virtual manufacturing tools were brought in to help.
"Lucent wanted to verify how the expected expansion would impact the site and whether it would be possible to fit all the production equipment into the same area by locating it more astutely," explains Ray Alexander of Lockwood Green Consulting (Atlanta, GA), the company which performed the simulation project. In addition, Lucent wanted to examine the costs of different materials handling systems for the new site layout.
Using data about the products and their manufacturing processes, as well as the volumes and materials flow, it was possible to set up a 2D model showing the site layout and the paths of material flow necessary for the planned production levels.
This was accomplished using the VisFactory virtual manufacturing package from Engineering Animation Inc. (EAI; Ames, IA). With the FactoryFlow module, facilities drawings and material flow paths could be integrated with production and material handling data. With FactoryPlan it was possible to develop relationship diagrams illustrating important activity relationships on the shop floor.
The modeling software enabled about 35 different scenarios to be created and assessed during the three month project period. Result: selection of the materials flow which generated the lowest materials handling and production costs.