Portable 3D Scanners Take the Floor
Category: Manufacturing Technology • Jun 29, 2021
Structured light scanning technology – better known as 3D scanning – recognizes part contours by triangulating two camera lenses and beam(s) of light that project a pattern on the part surface. Software then compiles and converts millions of images into a point cloud, creating a 3D representation. The majority of scanning devices generate points or measures of extremely high density when compared to traditional “point-by-point” measurement devices.
Any visitor to the IMTS 2018 Quality Assurance pavilion would have seen a multitude of scanning demonstrations, which begs the question: which is “the best” scanning technology? For those interested, here’s some sage advice from a scanning technology leader: Don’t worry about technology details. Rather, consider how portable 3D measurement and analysis technologies could increase productivity and profitability.
Creaform, a 3D scanning pioneer located in Lévis, Quebec (just outside Quebec City), works with companies to help them take their manufacturing and quality control processes to a new level in accuracy and efficiency. The company develops, manufactures, and sells portable 3D measurement solutions, application software platforms, and dimensional metrology services for industrial applications.
“Choosing a portable 3D scanner is easier than you might think. It’s not a question of what’s the best technology. It’s more a question of what you want to measure and for what purpose,” says Daniel Brown, Director of Product Management, Creaform. He has been with the company for 15 years, starting shortly after the company released its first portable scanner in 2005.
Moving into Production
Traditional metrology equipment, and even shop floor CMMs, measure parts once they come off the production line or machine. Measuring extremely tight tolerances remains the domain of the metrology lab and CMMs such as touch probes, optical gaging products, or X-ray/CT scanners. However, using a portable 3D scanner on the shop floor to measure parts “in-situ” (e.g., without removing them from production) will often bring efficiencies to the metrology and production teams. Complementing a CMM with scanners alleviates bottlenecks in quality control, as only the most critical parts get sent to the metrology lab for inspection.
“For parts measuring from 10 cm to several meters, 3D scanning becomes extremely efficient. Even better, you don’t need a metrologist to learn how to operate a 3D scanner,” says Brown.
To verify geometry, dimensions, and tolerances (GD&T) on the production line, Creaform offers the MetraSCAN 3D. Products in this category are about the size and shape of a soccer ball and use multiple laser crosses (15 in this case) to scan with an accuracy/volumetric accuracy and resolution of 0.025 mm. The measurement rate is 1.8 million points per second. This particular device uses blue laser technology, which is ideal for shiny and reflective surfaces.
As an example, a company operating deep draw forming machines uses the MetraSCAN to scan parts before removing them from the die. By using a “scan-to-CAD” comparison combined with “color mapping” (which highlights deviations in geometry and textures with different colors), a technician can easily make a go/no go decision.
“Users just have to scan, run the inspection, create a report, and then they have everything required for the metrologist or QC department,” adds Brown. “This brings up another key benefit of using 3D scanning for production: you don’t need to be a metrologist to operate a scanner.”
Brown says that it takes one-half to a few days of training before a technician is ready for production work with a 3D scanning device. To become proficient with scanning, the associated software and fully integrating the two takes a few weeks to a few months. If the scanner is needed for a time-sensitive project, online training and support services with application engineers are available.
While 3D scanning offers accuracy for measuring rigid, fixed objects, shop floor vibrations, and part movement lead to accuracy and repeatability issues in a production environment. To address the issue, MetraSCAN and similar “tracked 3D scanners” can pair with an external optical tracking device to establish positioning. They usually use fiducial markers (such as passive or active targets) that optically bind the tracking device to the scanner.
Called dynamic referencing, the process makes measurement accuracy insensitive to environmental instabilities. For example, measuring the fit of an airplane door requires the technician to be inside the plane, which will bounce from the technician’s movement. Dynamic referencing makes it possible to obtain a precise, repeatable measurement without a rigid setup in a metrology lab, using a touch probe or working from a ladder.
The auto industry, noted for the high cost of production disruptions, is embracing 3D scanning. As an example, Flex-N-Gate, a supplier of stamped metal and welded components, assemblies, and plastic parts for car manufacturers, equipped 22 of its factories across five countries with MetraSCAN 3D. Flex-N-Gate’s production teams can scan a part or sub-assembly in real time and get a precise image of the root cause of quality issues.
“Measuring parts where they are, with no special preparation, quickly resolves quality challenges, supports just-in-time production goals, and reduces costs for manufacturing companies,” says Brown.
Whether for metrology equipment or software programs, manufacturers implementing digital technologies often experience trust issues.
Brown says that one of the most asked questions is, “How do I know a 3D scanner is accurate?”
To that end, scanners are tested with a ball bar. This consists of two spheres with a known distance between them that has been measured with a very high accuracy CMM – the type of product users already trust. Each scanner comes with a calibration certificate that shows an acceptance test (based on VDI/VDE 2634 Part 3 standard ISO 17025 accredited laboratory), performed in production to ensure the scanner achieves the stated specifications.
A premium multiple stripe 3D laser scanner and software start at $20,000 and a tracked system can run $100,000 or a little more.
“Payback is really fast, especially in applications where scrapped parts or production downtime is extremely valuable,” says Brown. He says that the savings of moving metrology to the production floor and freeing up the lab for other tasks should not be under-estimated either, nor should the cost savings associated with digital data generation, file management, and traceability.
3D scanners have evolved rapidly, and companies adopting the technology understand they are the best solution for portable measurement.
“Compared to the first scanners back in 2005, what we have today is probably 20 times faster and at least five times more accurate and with more resolution,” says Brown. “It pays to take your scanning to the floor.”