Even though additive rapid prototyping receives most of the news buzz in the industry, don’t overlook subtractive rapid prototyping. Recent developments in subtractive RP can help you eliminate even more steps and costs in your development process; in some cases eliminating the need for additive processes.
Subtractive RP is really an advance in CNC machining. Noted Brad Cleveland, President and CEO of Proto Labs, Inc., “Manual programming of the tool path, which was holding back subtractive RP from greater use by engineers, has been replaced with automatic tool-path generation software. Today, you can produce your part as quickly and inexpensively with subtractive as you can with any additive process.” Now, depending on the vendor you choose, you can obtain quotes in minutes and a part within two days.
Tool-path generation programs have progressed to allow subtractive RP to handle complex geometries that are nearly on par with additive geometries.
“Additive RP is a wonderful process,” added Cleveland, “but if we had had automatic tool path generation software twenty years ago, we would not have needed to invent all of the additive processes to get around the need for tool path generation software.”
In most cases, all that is required is to upload the geometry from your 3D CAD file, select a material, and you will receive your sample shortly.
“The benefit of subtractive,” continued Cleveland, “is that you don’t need to settle for the reduced mechanical properties that you can get with additive processes. With additive, you trade off everything: surface finish, material choice, material properties, and any validation of the manufacturing process. If you want parts that are real and not injection molded wannabes, parts that you can use for testing because they are made of the same material that you want, subtractive RP delivers this, and just as quickly.”
Even though additive vendors are developing metal materials for their processes, the metals turn out parts that are less dense and that still require surface finishing. Subtractive RP closely mimics the surface finishes and tolerances of injection-molded parts, enabling you to test the design for function.
Another development in subtractive RP is the geometry it can now support. The tool path software can handle more complex shapes, often on par with additive processes. Additive is still the choice for certain geometries, such as a sphere within a sphere or parts that interlock in unusual ways. But, as Cleveland pointed out, you don’t really want to prototype a part that you can’t manufacture.
In addition, some companies are working to develop subtractive equipment that you can use close to the office, like additive has done.
“Subtractive RP is the application of a standard process with breakthrough software,” said Cleveland. “Additive RP is the application of standard software to a breakthrough process. There is a place for both.”