Advertising in MoldMaking Technology offers
Issue link: https://mmt.epubxp.com/i/706095
Inspection/Measurement 22 MoldMaking Technology —— AUGUST 2016 With model-based definition, everything that defines the part exists in a single digital archive, including how to manufacture and inspect the part. Image and figures courtesy of Verisurf Software Inc. Capturing and then processing data using reverse engineering software is very straightforward (see Figure 2): • Measure. A suitable CMM or scanner is used to measure and capture 3D surfaces as point clouds, including planes, cylinders, cones, spheres, lines, splines, circles and slots. As the term "point cloud" infers, the collected data is a group of relative points in space without any connecting structure or geometry among them. • M esh. Reverse engineering software "connects the dots" of the point cloud data, applying geometry to create a water- tight mesh or STL model ready for surfacing also suitable for 3D printing. This process includes alignment and merging of meshes, filtering, smoothing, and filling holes. For some applications, like 3D printing and additive manufacturing, this step is as far as is needed. • Model. Reverse engineering software automates the conver- sion of mesh models to 3D non-uniform rational basis spline (NURBS) surfaces and solid models. The solid models can be made intelligent by adding associative GD&T; annotations before they are exported to any popular CAD format to sup- port other manufacturing applications and databases. Quality Inspection Quality inspection and reporting used to be a disparate pro- cess isolated in a quality lab. Today, in-process inspection is much more integrated with the production floor. In the MBD process, it is the job of inspection software to align and com- pare the nominal CAD model with measured points collected from the finished part, whether that includes a relatively small number of manually triggered contact points or non-contact, scanned data containing millions of points. For example, model-based inspection software uses a simple FIGURE 1 process of align, inspect and report for quick in- process inspection of mold cavities or machined parts, without requiring that the part be removed from the CNC machine. The same principles apply in a production-run environment in which many finished parts are inspected using pre-programmed inspection routines on automated CMMs. Each part is compared directly to the MBD nominal for quality assurance (see Figure 3). Align. Inspection software quickly aligns the part to the CAD model by creating targets on the model and guiding the user through auto alignment by probing each target on the part. Inspect. Real-time part-to-CAD-model deviation can be seen when probing the part surface, while virtual targets guide the user through automated inspection plans. Real-time visual and audible indicators combined with color-deviation displays provide instant part-quality feedback. Report. Inspection software uses the 3D CAD model as the inspection nominal and quickly generates custom reports in industry-standard formats with GD&T; constraints. Color-deviation maps, and in- or out-of-tolerance indicators provide clear, practical analysis. Maintaining the Digital Thread Standardizing on one inspection software across the manufactur- ing enterprise should result in consistency of operation, quality reporting, data management, and reduced training and support costs. Buyers should be sure the enterprise inspection software they select is open and offers the necessary level of interoperabil- ity to support their current and future manufacturing inspection requirements. The following questions should be considered: • Is the inspection software based on a CAD platform, and does it include 3D modeling capability? • Does it import and export all CAD files and models seamlessly? • W ill it import and allow annotation of GD&T; data? • Does it accept measurement data from all digital measuring devices? • Is the software capable of controlling all popular digital mea- suring devices? • Does it have the flexibility and embedded tools to handle the range of inspection data, from manual contact probing to non- contact point clouds? It also is important to insure that all planned-use digital mea- suring devices support open-system, non-proprietary controls and communication protocols. Virtually all portable CMMs and 3D scanners in use today are open, however, many older and larger fixed CMMs still have closed proprietary controls and communication protocols. Open protocols can provide integra- tion with otherwise closed systems, but it is important to con- firm whether or not it is available on a particular fixed CMM.