3D printers can be used to create models or products directly from digital designs.
A rapid prototype model is usually a plastic or metal part created from a computer drawing, which allows a customer to review a product in development. In the late 20th century, computer software was developed that allowed designers to create three-dimensional (3D) drawings. The parallel development of teams that could create physical structures from these drawings led to the rapid business of modeling.
Designing a part with 3D software begins with a concept drawing of the desired part. A designer can take that drawing and create a software-based 3D model that allows a part to be viewed from different angles or orientations. This software can also virtually disassemble the part to show the customer how the assembly can be done in an industrial plant. Software design often includes the ability to “test” the part under different stress or impact conditions to estimate part failures or design defects.
Rapid development of prototype models became a reality with the introduction of 3D printers. Several different technologies evolved in the late 20th century, but they were all tied to computer-aided design (CAD) programs that created software models. All 3D printers use a technique of building successive layers of plastics or metals in sequence to create a physical sample of the part.
One type of printer used a fine powder inside a printer cabinet. The computer software transformed the drawing into thousands of extremely thin layers, like cutting the image extremely thin. The printer sprayed a chemical binder onto the powder as a bottom layer. The powder was then mixed into this layer and the flat pan lowered slightly. The next layer of binder and powder was added, and so on, until a 3D part was made. Depending on the complexity of the part, the printer may need to run for days to complete a sample.
Another type of rapid prototype model printer used a meltable plastic. A nozzle placed small dots of the molten material on the printer’s tray in successive layers to form a part. These parts were often used straight from the machine, because the plastic layers formed a solid plastic prototype. This was an improvement over some powder printers, which created parts that could be handled but weren’t strong enough to test or use.
A process called metal sintering can also create a rapid prototype model. A metal such as aluminum or copper with a relatively low melting point can be used in a 3D printer in a similar way to molten plastic. The finished metal part typically required no further processing and could be used directly from the machine for further testing or development.
Many 21st century products were designed entirely in CAD software, turning the virtual image into a rapid prototype model, without the need for a physical sample. This has become common for large industrial machines, aircraft, and large vehicles such as ships. Many parts were too large to create separate prototypes or would have delayed the development of the final product.
Engineers developed software tests that could simulate actual test conditions, eliminating the need to test prototypes. The first commercial aircraft were designed this way in the late 20th century. A commercial jet aircraft was built entirely on a computer, going from a design directly to a plane capable of flight without intermediate prototypes.