GE Appliances (GEA) has been designing and manufacturing consumer appliances for over 125 years. The iconic brand, headquartered in Louisville, KY, employs nearly 6000 people, a number that rose to 12,000 employed globally after its acquisition by Haier, making the company part of the largest appliance manufacturer in the world. According to the company, it is committed to quality and technological innovation and sharing available knowledge to optimize manufacturing processes.
One recent example was when GE Appliances implemented precision optical metrology systems distributed by Capture 3D, the exclusive North American certified partner for GOM GmbH. When engineers from GEA saw ATOS and TRITOP from GOM in action, they knew that adding 3D metrology capabilities would improve their processes and efficiency significantly compared with using traditional CMMs and handheld or mounted laser scanners for part inspection.
After conducting initial scans through its partners, GEA made its first purchase in June of 2016. “It was easy to make the business case to purchase the systems,” said Dave Leone, director of dimensional control for GE Appliances, who regards the GOM systems as more than just a stand-in for the traditional CMM. He described ATOS as a powerful engineering tool.
ATOS is a 3D scanner that uses non-contact optical technology to collect millions of X-Y-Z coordinate points in a given volumetric area with high-speed scanning. The projector in the center of the 3D scanner projects a fringe pattern onto the object being measured using structured blue light. Two high-resolution measuring cameras on each side of the projector capture the fringe pattern during each scan, using the displacement to calculate the 3D coordinate measurements. A 3D visualization of the entire part’s shape is created without any programming, resulting in a complete inspection color map that indicates areas that fall within the proper tolerances as well as areas of deviation.
GEA often uses ATOS in conjunction with TRITOP for larger appliances for even greater accuracy because it creates a global reference to eliminate stacking error across larger complex objects. TRITOP is a hand-held photogrammetric technology that obtains measurements using a single high-end camera to snap pictures of the object from various angles. Using the principles of triangulation—the same principles that are used in calculating ATOS measurements—points are calculated onto the 3D coordinate plane. TRITOP can also be used as a standalone measuring system for inspection and deformation analysis.
“If you can digitize a part, there’s a lot you can do with that data,” Leone said. “We saw it as an opportunity to close the loop between virtual and actual, and take actual and put it back into CAD space.” ATOS and TRITOP have been used for part inspection, large scale digital assembly studies, tooling inspection, reverse engineering, and virtual reality rendering.
With part inspection and assembly analysis for product development and quality control as the main focus, GE Appliances has been using the ATOS and TRITOP systems as diagnostic tools to pinpoint dimensional issues to make improvements before production. In one instance, a pre-production top load washer basket had excessive runout, which can cause vibration. GEA used ATOS and TRITOP to perform a root cause analysis. First, GEA’s metrology team scanned the basket to dimensionally compare it to the CAD file. The bright green 3D model indicated very little form error and that the part matched nearly perfectly—no issue there.
Next, the washer basket was aligned virtually to the input shaft, which holds the basket in place, in the GOM software. That alignment indicated that the basket had a high degree of orientation error causing a runout condition—too high on one side, too low on another. The GEA team decided to collect detailed data from the entire assembly to discover the root cause, and added in TRITOP photogrammetry to achieve higher accuracy over the larger surface area to be scanned.
Engineers used TRITOP to shoot the assembly in its entirety for a global reference, then used ATOS to scan each part individually, creating a digital assembly by combining all of the data. Digital assembly allows data from scanned parts to be integrated with data from CAD nominal parts to diagnose assembly, fit, form, and function issues. Using this method, the GEA team discovered that the problem stemmed from the aluminum hub that is integrated in the base of the washer basket. The part which goes through an overmolding process was misaligned.
Scan data of the aluminum hub were aligned to CAD data of the overmolding tool in the GOM software. By taking a cross section of the data, GEA engineers could see that the form error of the part created a gap between the tooling pads, causing the part to be overmolded at the wrong orientation. By adjusting the datum scheme of the tooling pads used in the overmolding process for the aluminum hub and correcting its orientation, the runout issue was resolved.
In this case, the data collected previously with a traditional CMM were misleading and didn’t highlight the issue with the parts. “CMM data can be very inconclusive,” Leone said. “You end up using the scan data to show what you really have, because the scanner doesn’t lie. Additionally, with CMMs if you don’t probe it, you don’t know it. We let the scan data highlight the problem areas”
Leone said that the adoption of 3D scanning has contributed to the growth of the innovation culture at GEA, too. “It has created this acceleration of learning and technical growth,” he said. Partnerships with other companies, benchmarking and sharing best practices have caused GE Appliances to embrace other new technology—and question the limits of older technology—in other areas as well.