Rapid prototyping

Rapid prototyping is the speedy creation of a three-dimensional (3-D) model of a product or part. It is also known as rapid mechanical prototyping. It may be created as a model of a digitally created item, or used in the testing process before the item is manufactured. Most rapid prototypes are made using computer aided design (CAD) and 3-D printers, also known as additive layer manufacturing technology. Some prototypes are made using direct metal laser sintering (DMLS). Rapid prototyping is used in a wide range of fields, including manufacturing and medicine.

Prototyping is usually a part of the ideation process, when ideas and solutions are discussed and shared. Ideation helps a group filter many ideas and narrow them down to the best. The prototype allows users to experience the product or part and can generate feedback. Prototypes may be low-fidelity—such as sketches, which are often part of the early stages of development—or high-fidelity—such as realistic illustrations or 3-D models, which usually are developed later in the process.

Background

Rapid prototyping developed during the late twentieth century with the creation of CAD and 3-D printers. Many prototypes are designed with CAD and realized using 3-D printers.

The roots of CAD lie in the World War II (1939–1945) focus on computing. Patrick Hanratty and Ivan Sutherland are regarded as the fathers of CAD. Hanratty developed the Program for Numerical Tooling Operations (PRONTO) for General Electric in 1957. Sutherland included the first graphical user interface in his doctorate thesis at the Massachusetts Institute of Technology (MIT) in 1962. Commercial CAD programs were used in many industries, including automotive, by the early 1980s. Programs for personal computers (PCs) were soon developed, and by the 1990s, PCs could calculate 3-D designs.

3-D printing is based on topography and photosculpture. Topography is a detailed map of land that indicates surface features, including mountains, valleys, and rivers. During the late nineteenth century, J.E. Blanther patented a method to make 3-D maps on wax plates. Photosculpture is an art form developed in 1859 by artist François Willème. He placed his subjects on a platform, around which he placed twenty-four cameras spaced fifteen degrees apart. Prints of the twenty-four photos captured by these cameras were traced onto wood, and the shapes cut out. These pieces were laboriously combined to create a 3-D portrait of the subject.

Hideo Kodama and Charles Hull are regarded as the founders of rapid prototyping. Kodama described a method of making solid items by building up layers hardened with a polymer in 1981. He made a model of a house containing twenty-seven layers of 0.078 inches (2 millimeters) thick resin. He did not file a patent on his process. In 1984, working independently, Hull invented a system he called stereolithography apparatus (SLA), which built objects in a way similar to Kodama's method. The first object he printed, a cup, took months to produce. Hull received a patent in 1987 and founded a company, 3D Systems. Other people were also working on similar and related ideas.

3-D printing of prototypes began in Germany in 1989. German car manufacturer BMW commissioned Electro Optical System (EOS) to help it with projects it was developing. The BMW object printing progressed from a powder resin to metals.

As interest in 3-D printing grew, attention turned to making the process less expensive. Adrian Bowyer at the University of Bath, United Kingdom, founded the RepRap project in 2005 to create an affordable 3-D printer that could print its own parts. RepRap developed fused filament fabrication (FFF), an open source method of rapid prototyping. Within a few years, several companies, including 3D Systems, were offering less expensive printers as well. By 2024, some 3-D desktop printers cost under $400.

3-D printers create an object by building tiny slices, layer by layer, based on a CAD. This is a high-tech version of building a brick wall, or a pyramid, by first establishing the bottom layer, then adding each layer one at a time. The production of solid items directly from a computer model is called solid freeform fabrication (SFF).

Overview

Widely available CAD software and inexpensive 3-D printers have provided individuals and corporations with similar opportunities for rapid prototyping. Individuals have designed cell phone cases and prosthetic limbs in CAD and quickly printed out prototypes. A manufacturer can easily design a product, such as an easy-grip fork, and rapidly produce a prototype of the item for consumer testing and review. Advances in 3-D printing allow users to produce models of many materials—including color models and transparent models—that closely mimic the final product.

Rapid prototyping allows producers to refine items. A product or part may fail during testing, despite careful attention to detail during the engineering process. Extensive consumer research may still result in an item that does not appeal to customers. The design team may want to change a product's shape or size in CAD. These decisions can be made before a great deal of time and expenses are devoted to production.

Rapid prototyping allows groups to continue seeking solutions if the prototype creation process is not too time-consuming, such as when using a 3-D printer. Models can help individuals better understand an item or how it works, and see how it might be improved. Rapid prototyping allows working groups to more easily compare models and choose the best features of each. A prototype can help sell an idea or feature—for example, a company can quickly produce a working model to show to clients when seeking financing.

Rapid prototyping has become important in the field of medicine. Cardiologists, for example, have many imaging tools such as computed tomography (CT) and 3-D transthoracic (TTE) scans with which to view congenital and structural heart diseases, but 3-D images are difficult to understand when viewed in 2-D on a computer screen. Doctors are increasingly relying on rapid prototyping to produce models to get a more complete picture of their patients' heart conditions. The heart model helps the doctor determine the extent of the condition and a course of action. It also helps the doctor better explain the condition to the patient.

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