Reverse engineering: the catalyst behind the next big aerospace leap
by Ping Fu, CEO & President, Raindrop Geomagic
Ten years ago, Boeing Commercial Airplane Group’s 777 division created the first airplane that was 100 percent digitally designed and pre-assembled on computer. From that achievement has come two basic facts: using digital processes accelerates design and increases quality, and new technologies need to be adopted to make the next big automation steps.
In creating the 777, Boeing used new approaches to designing and building an airplane. The 777 program established design/build teams to develop each element of the airplane's airframe or system. Under this approach, all of the different specialists involved in airplane development – designers, manufacturing and tooling engineers, finance, suppliers, customers and others – worked jointly to create the new airplane. Based at the same location, team members worked concurrently, sharing their knowledge rather than applying their skills sequentially.
Communication among the program's 238 design/build teams was enhanced by sophisticated computers linked by the largest mainframe installation of its kind in the world. Using three-dimensional, digital software, designers could see parts as solid images and then simulate the assembly of those parts on the screen, easily correcting misalignments and other fit or interference problems.
As a result of these digital processes, the 777 program has exceeded its goal of reducing change, error and rework by 50 percent. Parts and systems fit together better than anticipated and at the highest level of quality. The first 777 was just .023 of an inch – about the width of a playing card – away from perfect alignment, compared to a half inch for most airplanes.
Boeing has been able to achieve these milestones by using standard forms of data representation and computer-aided design (CAD) tools. In recent years, Boeing and other aerospace companies are finding that modern reverse-engineering systems can extend digital technology into areas such as recreating legacy parts and comparing as-built parts to CAD models for quality assurance.
Reducing hard-tooling costs
One of the biggest challenges facing the aerospace industry is reducing costs associated with hard tooling. Many airplanes built 30 years ago are still flying, and hard tooling for spare parts is critical for repairs. Tooling is the standard for manufacturing parts because drawings and digital models either do not exist or are not accurate enough.
Keeping aging aircraft flying is as critical to aerospace as keeping computers running is to information technology. From an economic point of view, less than 10 percent of the investment in a new airplane can keep 80 percent of aging airplanes flying. Reducing hard tooling costs is a sure way to boost profit margins.
Boeing has again taken the lead in addressing the hard-tooling problem. In 2000, Boeing launched a test project to digitally duplicate a 747 wing tip, create a CAD model, and manufacture the part within one working day. The completed part needed to meet tolerances of three-thousands of an inch.
The wing tip was mounted on a platform for scanning by Boeing’s custom-made system, comprising a line-laser scan head and a mechanical motion controller. Several types of reverse engineering software were used to create the CAD model, and the part was manufactured on site with a process that is consistent with Boeing’s new product design.
Boeing’s goal was that once the CAD model was obtained, the manufacturing process would be the same whether it was for a new airplane or for the spare parts of an aging airplane. If this process was relatively easy and cost effective, there would be a huge potential to reduce the costs of hard-tooling maintenance.
Using the reverse engineering process, a database of 3D CAD files for hard tools can be stored in the computer. If an airplane is on ground for repairs, parts can be made on demand.
At the time of Boeing’s wing-tip project, software vendors were offering a fraction of the functionality available today. The Boeing team was using pre-release betas of first-generation reverse-engineering software. Although the old wing was replicated within the tolerance, the process took more than a day. Simply put, the technology was not mature enough for prime time.
Today, reverse engineering technology can reproduce a part like this within one working day. But so far, the new generation of software has not been used widely to reduce the costs of hard-tooling maintenance. One of the reasons is that the process has not been tested in a real production environment.
Despite the huge cost-saving potential, companies are more reluctant to spend money on spare parts then they are to spend on development of new products. Nevertheless, there is real value in creating digital inventory of hard tooling, especially in an economic climate where profit matters. Digital hard tooling inventory is one area in which return on investment can be measured and both short- and long-term benefits can be realized.
Verifying CFD accuracy
Reverse engineering also shows promise in aerodynamic computational fluid dynamics (CFD) applications.
In the early 1990s, NASA conducted a major study to achieve an accurate match between a physical prototype of an X-38 Autonom Crew Return Vehicle and its digital counterpart. This would allow the agency to verify the accuracy of CFD simulations.
Images courtesy of Capture3D and NASA
A company called Capture3D was contracted by NASA to create CAD models from point cloud data that resulted from scanning a working X-38 prototype. A combination of a white-light scanner and a photogrammetry system were used to capture the data.
Measurement, data calculation and data post-processing took just four days. For the CFD analysis, a CAD model was derived in eight hours based on decimated polygonal data. For detailed analysis, a CAD model based on the dense polygon data was built in five days.
A color visualization showed very little deviation between the actual model and the CAD data. Only the symmetry of the wings was slightly out of tolerance. In addition, the CFD analysis showed that a simulated hard landing had not caused damage to the model. Based on its findings, NASA was able to make some corrections to the prototype to improve performance.
The success of this project has led NASA to adopt reverse engineering as part of its processes, providing the agency with the equipment to digitize an entire full-sized X-38 CRV in house.
Removing the inspection clamp
As Matt Reinhard sees it, better digital processes have improved manufacturing reliability and speed tremendously, but one area lags behind: quality inspection.
“Manufacturing has a fire-house capacity,” says Reinhard, CEO of Aerospace Manufacturing Technologies (AMT), “but quality inspection clamps it to a trickle.”
AMT manufactures parts of all sizes for the aerospace industry. Recently, the company turned to non-contact laser scanning and computer-aided inspection (CAI) to speed its part verification.
Before implementing the laser scanner, AMT’s first-article quality inspection could take half a day to set up and hours to run. By changing to non-contact part verification and automating much of the work, inspections can be set up in as little as half an hour. The actual inspection might take only a few minutes. The reduced time saves manpower, cuts costs, and adds flexibility for design changes
Data from the scanning is fed into the CAI software, which compares it to the CAD model. AMT is able to run graphical comparisons for dimensions, datums, features and other quality factors. The software automatically records the session for reports that help with design alteration decisions, making changes to milling machines, and certifying that a part is suitable for further production.
Behind the scenes, a template of information gathered by the scanner and the CAI software during the first inspection of a particular part allows subsequent inspections of the same part without a new set-up. AMT is using this capability to develop a library of 200 different part inspection profiles that will further automate its processes.
Once the library is implemented, AMT will be able to put a part on the scanner, hit a barcode, and automatically scan the part. The CAI software will bring in data from the inspection library and then develop a finished inspection report without any user intervention.
AMT expects that its CAI system will eventually extend beyond first-article inspection and dimensional verification to encompass the entire quality inspection process. The obstacle is familiarizing customers with the first-article inspection process.
Reinhard would like to see an industry standard for non-contact parts verification. This would improve the flow of the supply chain and relieve pressure on aerospace suppliers’ customers as they move to just-in-time inventory and other cost-saving measures.
The next leap
The next major step for Boeing and other aerospace companies is a much higher level of integration for the design process and the parts used for new and aging airplanes.
Reverse engineering holds the potential to provide a closed loop among CAD, CAM, CAE, hard tooling and inspection, making it much easier to exchange data. Even the seemingly simple process of measuring, modeling and verifying a physical part requires companies to look beyond traditional solid modeling systems to new reverse engineering technology that can capture the physical world and represent it with accurate, manufacturable digital models.
Aerospace engineers view this step as an enormous challenge – the sheer scale of tracking millions of components can be conceptually and computationally overwhelming – but one that must be faced.
It helps to take a deep breath and look back at the 100 years of aviation. It's an amazingly compressed success story, from the early days of skepticism about the Wrights' initial flight, to the development of the Boeing 777.
Aviation has progressed in leaps and bounds since 1903, pushing flight beyond the skies and into space. Over the next decade, sights will be set on the frontier traversed by reverse engineering: conquering the divide between the physical and digital worlds and creating full integration among all facets of the aerospace manufacturing process.
Ping Fu is president and CEO of Raindrop Geomagic Inc., which provides patented software that transforms physical products into accurate digital models, enabling closed-loop processes for design, engineering, mass customization and quality assurance.