While 3D scanning has already been adopted by many automotive part manufacturers, the use cases in Quality Control (QC) have been limited. This is primarily due to the following limitations:
1. 3D scanning has been manual.
2. Existing “so-called” automated 3D scanning systems tend to be unproductive.
3. 3D scanning attempted to be an all-in-one solution, while there still are reasons to use contact devices (CMMs) for certain types of measurement.
Typically when a manufacturer buys a stand-alone 3D scanner, it must follow through with add-on purchases of 3D image processing software such as Geomagic or Polyworks, two-axis turntable, 3D scanner tripod, or others. After such purchases, a worker had to be trained on:
–How to operate a 3D scanner (e.g. turn on/off, change settings, etc.).
–How to take the right scans from the right angles and distances for a specific part to be scanned.
–How to account for the surface characteristics of an object (e.g. set the right exposure based on the reflectivity of the surface).
–How to combine multiple scans into one file and process the scanned data.
–How to perform image processing techniques to complete the scanned data to CAD comparison.
–Other how-to’s such as calibration of the scanner, mastering of the fixture, etc.
This meant that there always would be a new learning curve for trained labor for a new project. First, for a new part inspection, the worker must learn how to scan that specific part. Second, if the company is reproducing an old model, the worker must either revisit the old project to remind himself/herself or relearn how to scan the part from scratch. Even though there have been incremental improvements in the off-the-shelf software to increase worker productivity, there still is no solution that fundamentally removes this steep learning curve.
Collaborative ARIS system, supported by ARIS software’s simple user experience (UX) empowers an easy setup of a new part.
Many companies have introduced solutions to improve the labor intensity of 3D scanning by utilizing robotic automation. However, currently available solutions out there have the following limitations:
–Most existing solutions are provided by 3D OEM scanner hardware, locking you into a specific brand or type of 3D scanner. As an example, there is a popular 3D scanning automation solution, which is developed and promoted by a 3D scanner manufacturer. The 3D scanners used in this solution (1) are structured blue-light which is not great for shinier surfaces forcing the users to spray the part; (2) have long standoff between the eyes limiting its capability to scan narrower holes; and (3) many times require putting markers on the part which ironically makes the automation very manual.
–Most existing solutions are not built to be flexible. In other words, the system may become obsolete as soon as the user has to repurpose the system for a new production line. When a manufacturer decides to repurpose the automated 3D scanning system for a different application, it may require a swap out of the 3D scanner, robot, and/or image processing software. Such a swap typically requires a totally new systems integration, retraining and recalibration.
–ARIS resolves these limitations, by utilizing its proprietary software products.
–Modular integration platform: ARIS recommends any optimal market-proven sensors and robots and then performs integration and implementation.
–Automation (Run) Software: ARIS provides software for minimally trained workers to run programmed inspection repeatably.
–Setup Software: ARIS provides software which enables easy setup of new programs and post-scan analytics as manufacturers’ needs evolve.
3D scanning can collect millions of measurement data in seconds and thus has high resolution and fast cycle time. However, it does not perform as well as CMMs in measuring transparent/translucent, shiny surfaces or internal details. For this reason, even to measure all the required annotations (points of interest) for one specific part, it may be more desirable to use both CMM and 3D scanning.
Recognizing this, CMM OEMs have mounted 3D scanners on the CMM arm, though this is a very slow and unproductive process. On the other hand, going through the complexity of having an industrial robot in an inspection lab doesn’t seem so optimal.
How ARIS overcomes this issue is by integrating collaborative robots with a fast multi-line laser scanning. Such a system has slightly lower accuracy compared to ARIS systems with 3D area scanners (e.g. structured blue light), while it maximizes the speed and productivity, and also outperforms other types of 3D scanning for reflective surfaces.
Moreover, it can scan bigger parts significantly more effectively without losing precision, as you can use external tracking mechanisms to stitch images live as the robot is in motion (capturing the data).
Finally, by using collaborative robots, this system can be deployed in areas with existing human processes and therefore, can be set up right next to a CMM complementing CMM measurements in real-time.
A full inspection report is generated for a die cast part using a reference ARIS system, with a range of annotations that are needed to ensure quality. Then, a Gage R&R study is performed on the measurements, where the precision (repeatability and reproducibility) is tested and compared against well-accepted industry standards.
This precision test seeks to inform whether automated 3D scanning systems can be deployed in production, instead of just in the lab, for both FAI (First-Article Inspection) and in-production inspection, leading to significant cost savings.
The choice of 3D scanners is usually more important than that of the robotic arm, as varying tolerances, surface finishes, and part sizes may require different optical accuracy and/or field-of-view devices. Usually, the more accurate and bigger field-of-view devices are more expensive; and it is due to this price factor that the ability to plug-and-play various 3D scanner types offered by the ARIS integration software is important in accomplishing a required accuracy and cycle time under the allocated budget. As an example, there are 3D scanners that are accurate to the ±2.5-μm level, but these would easily cost more than $100,000.
Once the scanner and the robot are placed and wired, an initial setup of calibrating the relative positions of the 3D scanner and the robot is performed. This is handled by the ARIS automation software, in which the operator, with just one click, can perform the needed calibration automatically. In some cases, the 3D scanner also needs to be calibrated as frequently as daily (especially with temperature changes) and this again is handled automatically through ARIS’s automation software with minimal human input. For the reference system used, the initial calibration process took less than 15 minutes of manual operator time.
The result shows that even in an in-production environment, with minimal investment, the solution is capable of providing similar accuracy to CMMs. It showed a slightly worse precision compared to in-lab CMMs but proved to be superior to portable ones. Especially since many in-lab, high-accuracy CMMs require controls such as a concrete floor and a temperature/vibration-controlled room, 3D scanners being less susceptible to such externalities manifests in the flexibility and efficiency that an automated robotic 3D scanning quality control solution can offer.
ARIS system can work with automotive manufacturers’ existing infrastructure, and provide a strong return on investment (ROI). Such ROI can be yielded without having to replace existing CMM processes by utilizing collaborative ARIS systems.
Edited by Yearbook Editor Bill Koenig from information supplied by ARIS Technology.
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