Application Engineer, 3D Solutions
Roland Inc., Irvine, Calif.
Edited by Leslie Gordon
Manufacturers must often reverse engineer existing products to improve them. But reverse engineering can be complicated. Manual tasks involve technicians scanning in objects, perhaps in multiple part orientations, to get raw point-cloud or polygonal data. Then someone knowledgeable in scanning software must align and merge individual scans or meshes, repair meshes by, for instance, filling holes, and create restructured meshes.
Technicians then convert this data to sterolithography (STL) files for export to 3D printers, or add Nurbs surfaces and create IGES files for further editing in MCAD systems. Making reverse engineering even more difficult, these "dumb" solids, so-called because they represent only the pure geometry, force users to recreate part features from scratch to revise mechanical parts going inside stylish enclosures.
Fortunately, new technology including automated 3D scanning systems and reverse-engineering software largely eliminates these aggravations. An example is the LPX-600 laser scanner from Roland Corp., based in Japan and California. The system simplifies eight of the total eleven reverse-engineering steps, generating more consistent results than traditional methods and saving hours of manual work in creating a watertight STL surface.
Users can export STL files from this system to widely used rapid prototyping machines for 3D part printing manufactured by companies such as Roland, 3D Systems, Stratasys, Z-Corp., and Solidscape. The scanner works well with a range of applications that have so far included blisterpackage design, face models for anaplastologists, and handsculpted characters for feature animation.
HEART MODELS FOR SURGEONS
A recent application comes from the Chamberlain Group, Great Barrington, Mass., which specializes in custom models for the medical industry. Chamberlain used a Roland desktop 3D laser scanner to digitize an anatomically correct sculpture of a human heart. The company exported the scanned model as a Nurbs file into a CAD system, edited the model, and exported it as an STL file to a 3D printer from Z-Corp., Burlington, Mass. The machine printed the digitized model to different scales for making molds and patterns for silicone castings. These resulted in lifelike hearts, with the consistency and response of living tissue, which surgeons can use to practice new procedures.
PARTS FOR JET ENGINES
Going a step further, RapidForm XO Redesign software from Inus Technology Inc. in Korea lets users interact directly with scan data. It automates the conversion of scanned STL files into fully featured, parametric solid models, a process that once took days or even weeks. For example, Lufthansa Technik AG in Germany maintains, repairs, and overhauls commercial aircraft engines and components.
Technicians there scan existing parts with a 3D Alliance scanner and use the software to create accurate parametric CAD models. The company uses the models to fabricate replacement parts within strict tolerances and to improve designs to boost performance. Also, the firm ensures components get manufactured based on design intent by redesigning parts from scanned data.
For a recent job, the company scanned a compressor component of a jet engine. With only a partial scan the software helped create a CAD model in just a few hours. The company optimized the part design using real-time deviation tracking and then sent the file to Unigraphics NX for manufacturing.