SME Speaks: Revisiting Reverse Engineering
The term engineering has a positive meaning, typically describing the act of creating something beneficial to industry or society. But add the word reverse, and it becomes something quite different. Reverse engineering is often associated with the sometimes-illegal act of copying an original design for competitive purposes, but this perception is quickly changing.
A new, more-positive definition of reverse engineering is unfolding. For many modern manufacturers, the term now describes the process of capturing a part with a 3-D scanner, reconstructing the measurement data (point clouds) into highly accurate polygon or NURBS surfaces, and using the resulting digital model for applications such as product design, tool and mold design and verification, customized manufacturing, recreating legacy parts, engineering analysis, and computer-aided inspection.
Reverse engineering is fundamentally different from traditional CAD/CAM. With its roots in drawing, CAD/CAM software is limited to prescriptive modeling methods. In other words, pre-defined geometry must be prescribed by an expert to a software tool for the purpose of modeling. CAD/CAM starts in the virtual world with a goal to produce better products in the real world.
With its roots in imaging, reverse engineering offers descriptive modeling methods. The software extracts geometry and topology information from measurement data and describes it to a user. Reverse engineering starts in the real world with a goal to produce high-quality digital models in the virtual world that can be used by CAD/CAM/CAE applications.
Combining the two methods creates a complete closed-loop solution-from real to virtual to real.
Dual representations of data and physical phenomena have been behind many scientific breakthroughs. Take physics, for example. Maxwell, Hertz and others made great progress in understanding light as part of an electromagnetic spectrum. But it wasn't until discrete-particle models (photons) were set side-by-side with their continuous brethren that physics made a quantum leap. Today, models of light-as-a-wave and light-as-a-particle work side-by-side.
Engineers routinely examine mechanical and electrical events (signals, noise, vibration) in both the time and frequency domains. Problems that are extremely difficult to solve in one domain are often simple to solve in the other. The invention of the Fourier transform, which allows any time domain measurement to be examined in the frequency domain, has driven spectacular progress in many fields.
The two digital domains in the manufacturing world could be thought of as the shape domain (traditional CAD) and the point domain (reverse engineering). Traditional CAD is based on mathematics that define continuous curves and surfaces. It's great at modeling new products, particularly those with simpler boundaries. But, it's cumbersome for capturing the complexity of the existing world.
The natural complement to continuous mathematics is discrete mathematics--handling geometry as sets of discrete points. This is what reverse engineering does. Discrete modeling bridges the gap between the point domain of measurement and the shape domain of design. When combined with the continuous mathematics of CAD/CAM, discrete modeling represents the next quantum leap in product design and manufacturing.
Reverse engineering aligns the physical and digital worlds, ensuring that the design model is an accurate representation of the as-built product. This alignment is often missing in CAD/CAM, where changes required to adapt a design to manufacturing create differences between the CAD model and the physical product. Accurate alignment between the digital representation and as-built product provides major benefits, including the following:
- Faster development cycles due to fewer design iterations
- More accurate computer-aided engineering analysis
- Better fit and finish of final products
- Less manufacturing waste
- The ability to customize products in mass quantities
- Faster and more accurate quality inspections
Here are just a few examples of how reverse engineering is making its presence felt in today's manufacturing environment:
- In the automotive world, Japanese manufacturers are using reverse engineering to shorten the process of developing a full-scale car design from three months to three days. Racing teams are using new digital processes to capture, recreate, and test engine and body parts that are critical to a car's on-track performance.
- Aerospace companies employ reverse engineering to create digital inventories of legacy parts, and to cut first-article inspection of turbines and other parts by 40% or more.
- In the medical market, reverse engineering processes are the foundation for mass manufacturing of hearing instruments, orthodontic devices, and dental appliances that are custom-made to fit an individual perfectly. These new products look better, feel comfortable, and are more effective in treating medical conditions.
And there are many more uses. My company, Raindrop Geomagic, has helped designers and engineers capture scan data from physical parts and create highly accurate digital models for applications such as digital dentistry, the historic preservation of the Statue of Liberty, the redesign of a retro Harley-Davidson gas tank, and quality inspection to ensure that circuit breakers will last 400 years. The possibilities are virtually endless.
Over the last several years, 3-D scanning and software vendors have often had to fight the stigma attached to the term reverse engineering. But the name hasn't affected the impact of the new technologies associated with reverse engineering. They have proven their worth in customizing products, automating processes, and increasing manufacturing throughput. And, if the rate of adoption by manufacturers is any indication, this new form of reverse engineering is just scratching the surface of its potential.
Our language is constantly evolving, with new words continually being invented to describe new technologies and the activities associated with them. It's time to develop a term that gives dignity to what we've been calling reverse engineering. Your suggestions are welcome.
Those wishing to learn more about "Reverse Engineering," should visit www.sme.org/rtam, the homepage for SME's Rapid Technologies and Additive Manufacturing Technical Community, where they can connect with SME's 3-D Data Capture/Reverse Engineering Technical Group. New members are always welcome.
This article was first published in the April 2005 edition of Manufacturing Engineering magazine.