In this blog, we are going to demonstrate how to process 3D scan data using Artec Studio and Geomagic Control X. We are going to scan a control arm that has been cast. It has a machined stud on one end, a pressed-on stud on the other, and a tapped hole that we inserted a bolt into to more precisely capture the void in the threaded hole. We are using the Artec Space Spider for this application because this scanner is perfect for capturing intricate details in high resolution with exceptional accuracy. After scanning the control arm, we will be post-processing and aligning the data using Artec Studio, and creating an inspection report using Geomagic Control X.
Post-Processing Scan Data in Artec Studio
Now that we collected our data using the 3D scanner, we will use Artec Studio to process the data. First, we will change the color-mode to scan color to make it easier to interpret what is what. Next, we are going to delete the table that the control arm was scanned on. For this step, we are using the eraser tool and using it on one scan at a time. The cutoff plane selection tool allows us to do this easily by suggesting the area to delete. After we delete the table, we can exit the editing tools.
Next, we are going to bring all four scans together using the alignment tool. We are going to select the main scan in blue and following that with a floating scan that appears in green. We can select common pairs of points and align the markers. We use the align tool to let the software do the work and make the final alignment for us. This process is repeated with the other scans until they are all aligned. Now that all the scans are aligned, we need to register the scan data. Registration is the process that takes all the individual scan frames and moves them to the nearest neighbors to remove duplicates and ensure the scans are all in agreement with each other. There is some noise from the table left over, and some hanging data around the edges of the scans, but we can remove this noise by running the outlier removal tool.
The last step is to run the fusion tool. Sharp fusion takes all the individual scan frames, compares them against their neighbors and generates the mesh file. Once the Sharp Fusion algorithm is complete, it generates a fifth item in our object list. It is a 15-megabyte mesh file and contains all the surface accuracies from the original scanned data. We can see all of the fine details such as the RN99 stampings, as well as the masking tape over the threads.
Using Geomagic Control X for Inspection
Now we will export the mesh as an STL file in preparation for inspection and we will use Geomagic Control X for the inspection portion. We will begin building our recipe by importing the native CAD. In this case, it’s a SOLIDWORKS file. In general, to begin the alignment process, we always add an initial alignment to the recipe.
After that, you can use any combination of other alignment structures. For example, the Best Fit Alignment makes sense for organic parts, but in other cases, you might use a Datum Alignment to build a datum structure from features from the CAD or constructed features. Or you could build a three-two-one alignment.
Now that our alignments have been added, beginning our inspection routine, we’d like to continue building our recipe by adding some geometric comparisons. The first is a 3D compare, this generates a false-color heat map showing where the measured data is higher or lower along the surface normal to the CAD data. We assigned a color bar range of plus-minus two millimeters and an acceptable tolerance of plus-minus half.
Next, we will add some geometric dimensions to our inspection routine. The first is a radial dimension on the upper stud. The nominal reference dimension is called out here, and we can assign any tolerance we want. We’ll keep both views in the same group. This means that these will be captured in the same image on the actual report. We can add other features that should display in the same plane to the same group. We can add a radial dimension to the inside of the hole. We can also add a circularity on that cylinder and because those two features are defined by the same basic geometry, they will appear linked in the tolerance.
Now that we’ve chosen our alignment routine and selected our comparisons in geometric dimensions, we can import measured data to compare against the CAD. In this case, we are selecting the STL file we exported from Artec Studio.
We will rebuild the document to allow the evaluation to occur. First in green, we have the three radial dimensions each passing. The deviation is below the tolerance value that we have associated with those holes. We note that the circularity that we set for that hole has failed.
Further, let’s review the 3D comparison. In red we would see parts of the data where the data is high. In blue, we expect to see areas of the STL file where the data is low. In this case, we can see that most of the part is green, within the acceptable tolerance that we set. Let’s review the report we’ve created. The comprehensive report includes our company logo, scan data, the measured data, the best fit alignment and statistical information about the alignment’s performance, 3D comparison, and the geometric information that includes the three radial dimensions. Now that the report is complete, we can save it as a PDF. One final note, we can return to Control X after the report is complete. If we have more scan data, we can replace the measured data with additional STL files and generate reports. This allows us to reuse the routine we’ve built and reuse the report structure generating reports quickly and easily.
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