How 3D Scanning Technology Impacts Product Development
Introduction:
In order to meet the challenges of today's rapidly changing business landscape, companies are taking a close look at their processes, adopting new techniques, and looking for ways to make product development more efficient and cost effective. Among the recent technological advances, is optical range scanning. Manufacturing companies in particular are looking to the scanning industry for increased productivity and an effective means of creating a 3D digital file for an existing product or component with little or no design documentation.
Scanning a 3D object and sending the scan data to prototyping or CAD software programs saves not only hours of painstaking work, but thousands of dollars in iterative redesign and prototype costs. Reproducing an object by physically drawing it CAD software is difficult, and the result often does not match the original design. Although reverse engineering is a method companies have used for some time, a truly cost and labor effective method has not existed until now. Laser scanning also opens the door for many firms that initially prefer to sculpt objects in traditional mediums to retain the tactile and visual advantages that CAD systems lack.
More than three-quarters of the Fortune 100 companies depend on visual computing to help them design their products. Embracing this new technology allows firms both large and small to meet the computing challenges that are pivotal to their competitive strength. Laser scanning can provide a measurable difference for improved quality and accelerated time-to-market, while reducing costs for new products.
Laser scanning is accomplished by using a laser device that collects range data. The most common method for acquiring range data is active optical triangulation.
Generally, a 1D or 2D sensor is swept linearly across the object or circularly around it. As this is not usually enough information to reconstruct the entire object being scanned, multiple passes must be made in different orientations. Data matching algorithms are required to merge multiple images into a single representation of the surfaces being scanned. Although this technology has been in use for over twenty years, the continued improvements in CCD's and lateral effect photodiodes has increased its speed and accuracy dramatically.
There are several different types of scanners that work this way, and their primary differences are in the structure of the illuminant (typically point, stripe, multi-point or multi-stripe), dimensionality of the sensor (linear array of CCD grid), and the scanning method (move the object or move the scanner hardware).
One of the most obvious benefits to 3-dimensional scanning is the tremendous increase in speed with which a prototype can be reproduced. Traditional methods call for the object to be measured and redrawn in a CAD program. This is extremely time-consuming, and organic shapes are almost impossible to model using this method. Objects such as an ergonomically designed handle or new toy design can easily be sculpted and then scanned to insure the intended result. The merits of laser scanning are best appreciated when dealing with shapes of this type.
Often, the time to market can make or break a new product. It is much easier to predict the future when the future is a few weeks away rather than a few months away. In some cases, the resulting time savings can allow a manufacturing project to start later. This means that companies have a longer time to work with clients in the conceptual process. Details can be fully explored, and customer requirements clearly understood before committing to the production stage. The entire scanning and post-editing process can happen in as little as 4 to 5 hours. This kind of time savings also means that companies have the ability to respond rapidly to changes in the market place. And because the laser scanning process is relatively quick, it is generally much cheaper than other types of scanning.
A couple of scanning hardware manufacturers have developed white light scanners that accurately digitize the human body. Companies that need to produce ergonomically designed products such as safety helmets, orthopedic braces, prosthetic devices, or even blue jeans, use this technology as a fast and safe method for collecting surface information of the human body.
Yet another advantage for the manufacturing community is that, in many instances, code for CNC milling can be created directly from scan data. This means that a prototype can be made and approved, scanned, and tooled in a matter of days. Scan data can be translated to nearly any file format: DXF, OBJ, 3Dstudio Max, IGES, ASCII, STL, Inventor and others.
Product verification is another example of the benefits of scanning. After a product has been produced, it can be scanned and the resulting data compared to the CAD drawing. Deviations from the specifications can then be accurately determined. Another routine use for scanning is periodic inspection of multiple parts to analyze how closely the product adheres to the original design. This allows for greatly improved quality control, and helps to detect flaws in the manufacturing process.
Another benefit that is not so obvious, but that can have a far-reaching effect on a company, is that once the object is in a digital format, complex ideas can be conveyed accurately and easily. In today's world, manufacturing processes are carried out by multiple parties, often from different locations around the globe. The client and the design process can be in one place, while the manufacturing occurs in another. The synergistic effect of having several people collaborating on the development of an idea substantially broadens the scope of the design and manufacturing process. Once a prototype has been scanned, the engineering, finite element analysis, and various other functions that used to take place consecutively, can take place concurrently before committing to manufacturing. All parties involved with the project can work from the same digital file. The result is a shortened development cycle, improved product performance and greater flexibility at every level.
When looking at this technology for use in the manufacturing industry, it is important to know how the surface information is gathered, and what its advantages and limitations are. There are many variables that affect the laser, and subsequently affect the quality of the information. Reflectivity of the surface, color of the object, undercuts, narrow opening, and sharp edges can all pose challenges. Other things to consider are placement of the object in relation to the scanner, and operator experience. These challenges are greatly reduced with the right equipment and an experienced operator.
Operator experience is a critical factor with optical laser scanning. The operator must follow certain guidelines and be able to predict how the laser will react. The individual scans must be viewed carefully before merging, so that any errant data can be eliminated. And the operator must have a clear understanding of how lasers work. Competing lighting in the room, the distance the object is from the scanner and the color of the object can all affect the laser. The technician needs to be able to clearly distinguish acceptable form unacceptable data, and needs to be able to accurately analyze the point cloud-the native product of scanners.
In the case of reverse engineering, it is important to establish what it is you want to do with the data, and just as important, what is, or is not, important to you in terms accuracy. Accuracy is the primary question of concern in the manufacturing community. It is important to understand the range of accuracy for the particular scanning hardware being used, and then to take into consideration the factors already mentioned above. Both file translations and certain types of files have a margin of error. In applications such as STL, where the product will have finishing work done after being produced, this may not be an issue. And in most cases of CNC milling, the tool diameter is larger than the error.
Many companies want to use optical laser scanning for inspection purposes. In these instances, a software package especially designed for interpreting point cloud is needed. It is then imperative to gather the cleanest, most accurate data possible. Sometimes the manufacturer does not want the data altered in any way, so it is critical to choose scanning hardware or service bureau that can produce proven results.
If the desired result is to get a fully modifiable 3D file, then a surface must be created over the point cloud. There are many programs and methods that make this possible. The point cloud data can be sliced in order to generate B-splines, and a surface lofted from there, or a surface may be generated right over the point cloud.
To determine whether optical laser scanning is right for a project, the end use of the data must first be determined. Next, the object should be evaluated to understand whether the benefits of 3D scanning provide an advantage. Finally, the cost, timeline, and alternative methods should be considered. The benefits of laser scanning when properly applied can make the seemingly impossible to measure product or component a routine component of the product development process.