Laser Scanning Improves Parts Production

Here's a riddle worthy of the Sphinx - how do you construct a part without access to any up-to-date information on it? Can't be done, right? Well, imagine being asked to develop parts for a customer having no material characteristics or generated CAD drawings in hand by which to steer your work. Imagine being able to create a part drawing functionally and dimensionally where no formal specifications existed before. Still can't be done you say? well it can, because you've just described the process of reverse engineering (RE).

Reverse engineering is being embraced in scores of tools and technologies and is utilized in the redesign process as well as new parts introduction. Let's face it, the parts business is not an easy one and competition is usually fierce, where the quality of the part is assumed and its price negotiable. To get these parts to market fast, those in the industry are bending over backward to compress the time it takes to design and build them. That's where RE comes into play.

For RE to work, you must have a physical model of some type. RE helps when there are no product drawings or the drawings are incomplete; where a physical industrial design model exists without a CAD model; where a prototype has been modified to optimized fit, form and function; where a production process yields a part that does not match or print; or, where an older product does not have CAD data and a new tool needs to be created.

As those in the industry will tell you, the first step to any RE project is determining what is needed when the project is completed. A number of different software and hardware solutions may be used to collect this data. The geometry of the part to be "reversed" and the desired end result will dictate what RE methodology is used to obtain accurate results.

Traditional methods usually called for an engineer to sit down with a set of calipers and a ruler to gather some measurements, but this is labor intensive, slow, inaccurate and almost always never provides enough data. To add to the difficulty, organic shapes can be extremely difficult to measure in this manner. However, with the arrival of 3-D lasers and optical scanners, RE is easier to master and the final results are much more reliable.

Embracing these new technologies allows businesses to meet the challenges and survive, but where will RE's options take product development, engineers and time compression in the near future? What trends will impact the industry and what major developments will open the door to even the average user?

"Reverse engineering is best described in light of advancement," says Mark Carlson, vice president of Advanced Design Concepts (Pewaukee, WI) - a full-service engineering firm. "In the last couple of years advances in optical and laser technologies have made it possible to quickly and accurately replicate any physical object digitally. Additionally, computer hardware has improved such that it can quickly manipulate the large amounts of data generated by these technologies. Software is now available that will allow for Class A surface generation, Computer Aided Inspection and easy input into other CAD tools. These advances have substantially redefined the term reverse engineering. Continued developments will automate this process. There may be a time not too far into the future where you simply push a couple of buttons and a completed CAD model is created, much like a 3-D copier. The level of automation will bring the time and cost down dramatically."

More automation techniques are the mantra being chanted by many in the RE industry because rather than starting from scratch and sketching a model out, designers and engineers want devices that will put their model right into their computer files - be it STL, DXF or IGES - where they can easily manipulate it. Many companies want this capacity so that they can take an STL file and simply send it off to a milling machine.

One device that is proving to be an answer for RE folks is laser scanning. Scanners sweep a continuously varying beam via rapidly rotating mirrors and capture the return by way of a receiver that detects the reflected energy. The receiver matches the return waveform to the output modulation and calculates the distance to the object. Laser scanning can be used for re-engineering previous product designs and easily scans product models into a computer file. There are some scanners that have intolerance to metal, others have built-in trackers, several can be hand-held, and still others can "auto-stitch" - meaning the scanner can digitize in real time to create an instant 3-D model. As RE follows the rest of industry, manufacturers want more and more to stretch out the life of their design.

"Laser scanning certainly speeds up the reverse engineering process," says Bill Panepinto, vice president of sales and marketing at Polhemus, Inc. (Colchester, VT) - a global provider of 3-D position/orientation tracking, motion capture and digitizing technology solutions. "There is a glaring need in RE to have the ability to create 3-D digital models quickly and cost effectively. The convergence of laser scanning and tracking enables manufacturers to scan an object or part in minutes, producing watertight STL files that can be exported immediately into almost any industry standard software. Portability of the scanner is key - it saves manufacturers time and money, as they aren't required to transport the object to their facilities. The scanner can be hand carried directly to the object where you can set up and scan it in minutes. This scanning process is amazingly simple."

In fact, scanning hardware has progressed to the point where it's now reliable and repeatable. One team can be designing a part in one area of the world, another team engineering it in another and a third manufacturing the part in still another - and have it all come together via computer. These individual factions can create their own CAD drawings and do things internally - whether tracking full engineering specs or draw tooling for the mold. When beginning with a physical prototype and then scanning it, that model can be sent all over the place with everyone working on the same project in real time - which translates into a serious quality control factor as well as cost savings.

For example, one RE firm working with a toothbrush company took a month to design just one toothbrush using traditional CAD methods and two of their top engineers. But with RE, the firm now scans a physical design, creates a surface and has a surface to draw tooling from in just 48 hours. Some of these factors have been around for several years, but computers were simply not heavy-duty enough to handle large-file data. Thanks to the increased processing speeds of today's hardware, all that has changed.

The number of non-contact scanners on the market has increased in the last few years - from the larger scale white scanners to smaller, more portable systems. Each scanning system has its niche, which is due to the particular software being utilized for it. While most hardware vendors need some basic capabilities, more software is becoming hardware-independent and able to be used for a variety of scanners. It used to be there was only one game in town for software. Today, there are several good products on the market, but the development curve is steep and more work is required for these newer packages to even come close to providing all of the needed tools.

"RE offers a whole host of options that are not embedded in the traditional CAD method," says Lisa Federici, president of Scansite (Novato, CA) - a full-service 3-D scanning facility. "Because of RE, the versatility of the average engineer will have to increase. There is going to be an expansion of industry's knowledge base to incorporate these new technologies and thinking three-dimensional. One RE industry trend is that the worlds of design and manufacturing will become much more open to using everything out there. The ability to tweak a design will become traditional. But perhaps most important is that industry is now cooperating with each other - with the flow of information becoming much more pervasive. In the past it was never the twain shall meet - or even talk to each other. They were tools being used in one industry that would have transferred well to another, but for some reason never happened. There is much more crossover going on today."

RE - Just One Tool

RE is regularly performed for the purposes of creating a complete CAD model. Few projects are completed with rapid, wrap-type surfacing. Most projects require the additional design intent. This is the analysis of the project and incorporation of true engineering design requirements and parameters in terms of the function of the part and the needs of the customer. This can be as simple as making corners square and sides parallel and perpendicular or even number hole spacing and diameters. Or this can be as complicated as determining the most accurate, smooth, machinable and appropriate contour for a customer product that should be symmetric - all based on measurement data from both sides. Many parameters must be understood before true RE can be performed. There is no one method, tool or technique that can fit all cases. It is this difficulty that can often take years to master.

"Awareness is probably the biggest contributor to the growth of RE today," says Michael Raphael, president of Direct Dimensions, Inc. (Baltimore, MD) - a provider of 3-D measurement, digitizing and reverse engineering services and products. "In the past, we found that few understood what tools and methods existed. The process was very often unique for each customer. Each project required a new combination of techniques, tools and solutions to achieve an accepted RE model. Today, with many projects under our belt, the process is becoming more defined in terms of types of projects, the requirements for the job and the deliverables [IGES, solids, native formats]. We provide a variety of services using many tools, but still are only a subset of all of the RE out there. In the near term the biggest impact will be from some of the newer software and hardware products created specifically for RE."

RE also opens the door to "knock-off" or poorly copied products. The concern - especially with those in aerospace - is that people will scan and manufacture components that have not been through all of the regulatory tests necessary to ensure their safety. If these manufacturers scan a replacement part, which for all intents and purposes resembles the original, those buying the part may find it difficult to tell whether the treatments have been done right or if the proper tests were performed. That is a worry that has not yet been addressed by those working with the technology. There is increased interest in aerospace RE as of late, with companies creating digital designs of original aviation parts then modifying and revising them to produce new parts. This ability to take old designs and bring about entirely new parts and designs via RE affects not only people working in environments that have only recently become digital, but designers working for high-tech companies working with low-tech equipment.

"Reverse engineering is a very intriguing technology, but also is a very disturbing one for many because of the danger involved in unauthorized copying of original parts," says Mervyn Rudgley, software analyst for 3D Systems, Inc. (Valencia, CA) - a rapid prototyping and 3-D printing technology provider. "Let's face it, with broadening RE applications there are more possibilities with RE than those in the industry ever imagined -good and bad."