Rapid prototyping with laser cutting (1995)

The potential of Rapid Prototyping is enormous, yet existing RP systems do not address the needs of many designers and are only being used for only a small portion of the design process. Because of high costs, slow run times and severe size limitations Rapid Prototyping has not yet become practical for the early design stages, or for producing large scale models. Laser Cutting: In recent years laser cutting has become widely accepted in many fields, including architectural modeling, film special effects and graphic design. The process is extremely useful for cutting or scribing complex patterns from flat sheet material, yet many people dismiss laser cutting as solely 2D process, inapplicable for true 3D modeling. Recently, however, creative new techniques in laser cutting and advanced in 3D CAD software have allowed laser cutting to break the 3D barrier. These techniques offer exciting potential for producing truly rapid and cost-effective study models, mockups and large scale prototypes. This presentation will focus on how laser cutting can be used as a Rapid Prototyping tool, highlighting project examples and benchmark comparisons with other RP systems. The techniques for producing 3D laser cut models fall into the following three categories: Slicing/Layering: This is a variation of the LOM (laminated object modeling) process. 3D CAD files are sliced into multiple layers corresponding to the material thickness to be cut. These slices are then separated and laid out in flat sheets with registration holes and layer numbers added. The slices are laser cut from a wide range of possible materials with alignment pins providing registration. The steppe surface of the model can then be sanded or filled using a variety of techniques. Because the laser can cut relatively thick sheets (from paper thickness to over 1”), the process is practical for large scale models. Recent applications of this process have included automotive design models, a 25 ft. long aircraft model and a 36 ft. long sculpture of a lion, built for a theatrical set. “Egg-Crate” Modeling: With this process, 3D CAD files are sliced in two directions at evenly spaced intervals. These slices are then laser cut with notches at the intersection points. The interlocking parts can be quickly assembled to form armatures for traditional clay modeling or voids can be filled with spray urethane foam. This process is extremely cost effective and quick for producing large scale mockups and exhibits. In a recent project, a 1/2 scale exhibit model of a concept car was laser cut and finished in less than 1 week. Unfolding: A third technique is to take 3D, faceted CAD files and “unfold ” them into flat patterns. The laser can then cut outlines and score fold line out of flexible material, such as cardboard. These parts are then folded and glued to produce very inexpensive, yet detailed study models. This process is currently being used in the automotive industry to produce early design studies of complex interior and exterior body panels. Conclusions: These laser cutting techniques do not replace existing Rapid Prototyping systems, but instead open up many new areas where RP has previously been impractical or impossible. Several companies have found that laser cutting can be a complementary addition to their existing rapid prototyping equipment. Raychem Corporation (Menlo Park, CA) for example has added two laser systems to an industrial design lab that already includes two SLA machines and a range of other CNC equipment. 3D laser cutting is also being tested at Te Art Center College of Design (Pasadena, CA) on several automotive design projects.