The goal in most design projects—find a way to develop the most accurate products, quickly and easily (or easily enough) and run with it. The need for speed, however, often conflicts with the need to take accurate measurements along the way—an integral but often time-consuming part of the process. These days, a growing number of engineers use laser scanners to expedite measurements, as well as take them in three dimensions, to create prototypes for new products.
One such firm, Synergeering, Farmington Hills, Mich., uses handheld 3D laser scanners to deliver rapid prototyping and rapid manufacturing services to customers in the automotive, aerospace, media, and consumer products industries. The Synergeering team produces functional parts using the highest resolution process of Laser Sintering (LS) of glass-filled nylon material.
In the past, the team used mostly hand gauges and calipers to measure and inspect parts of all sizes. These old-school methods resulted in less accurate measurements, or incomplete measurements that did not provide the level of precision many customers demanded.
Therefore the team embarked on a search for an alternative that would allow them to complete measurements for rapid prototyping jobs more quickly and easily than with traditional methods. The team researched multiple potential systems including fixed coordinate measuring machines (CMM). Though accurate, the devices proved too cumbersome and inflexible for many rapid prototyping applications.
Ultimately, the team decided upon a portable CMM that was both accurate and flexible. Several were considered before the FARO ScanArm was selected. FARO’s current generation scanner, the Laser Line Probe (LLP) for the Edge arm, produces a nearly 4-in. wide laser strip and scans at a rate of 60 frames per second. The 2.7-oz device produces roughly 45,000 points of 3D data over that same period.
The team uses Polyworks® point cloud software to process the scanned data. Together with the ScanArm, the engineers use that data for reverse engineering, 3D modeling, point-cloud generation and part inspection. The combination of FARO hardware and Polyworks software gives the team a comprehensive, high-resolution scanning system capable of creating NURB-based surfaces that can be imported back into native CAD systems as .IGES or .STEP files.
A typical scanner like the one used by the team attaches to a portable CMM, or a measurement arm, which in this case was a Quantum FaroArm. The device then projects a laser line on the subject and uses a camera to look for the location of the laser line silhouette. Depending on how far away the laser strikes a surface, each point on the laser line profile appears at different places in the camera’s field of view.
Data are collected one “slice” or cross-section at a time and triangulated. The CMM acts as a referencing device, or “localizer,” that tracks and communicates to the host application software the position of each cross-section in space. As the laser stripe is swept across an object, hundreds of cross-sections are captured and rendered collectively in a CAD environment. The result is a full 3D digital representation of the object.
Since their acquisition of the new technology, the team has used it on a number of prototyping applications for automotive OEMs. One such project involved the prototyping of a fully functioning, four-cylinder intake manifold that could be engine-mounted and tested on a Dyno. The orientation of the project required exact geometries to allow the part to fit within the surrounding obstacles of a vehicle engine, and to allow for airtight fittings and precise through holes to permit full assembly later on.
The manifold was built using laser sintering and RapidNylon (glass filled Nyon-12) material in a process unique to Synergeering. Using their FARO device, operators scanned and inspected the manifold in three dimensions with a high degree of accuracy. Wall thickness, hole diameter and other geometries were all compared against the original design to ensure fit and function.
Another recent application led the team to produce a full-size (roughly 7 x 3 ft) SUV bumper fascia that included underbody panels, grille and headlight buckets. The trick here was that the part was to be built in six pieces and bonded back together after the fact. Because of the nature of the part, the finished product needed to be as strong as if it had been a single-piece construction. Again using laser sintering and RapidNylon, the team completed the six pieces quickly. To ensure fit, they used their ScanArm to create 3D scans of the parts and obtain exact geometries. The individual bumper parts were bonded together and again, inspected with the laser scanner to verify the finished piece’s accuracy.