Prototype construction can be divided into two main design fields, mechanical and electrical. Mechanical prototyping usually starts with the generation of 3D computer models enabling the designer to check the fit of parts. Material selection for the prototype is next, and is dictated by the type of prototype needed. Conventionally, parts are fabricated by hand, by machines and through molding. This progression of fabrication usually follows the progression of prototype type, i.e. a looks-like prototype is usually constructed by hand, and so on. Hand fabrication involves using foam, wood, and other easily manipulated materials.
Often an inventor or prototyper can make representative plastic parts from wood or other formable material, and then cast a silicon mold around it. The master is then stripped out of the sold mold and castable polyurethane is poured in, producing a plastic part. The technique can be used with many molding kits available on the market today. A works-like prototype may involve the machining of metals and plastics and the use of commercial parts. A works-like looks-like prototype is usually made through a combination of machining and rapid prototyping such as 3D printing (more on this later). Pre-production mechanical prototypes use pre-programmed milling and assembly operations as well as large cavity molds.
Electrical prototyping is also dependent on prototype type. The most basic and easiest form of electrical prototyping consists of using low cost pre-designed electronic kits or development boards to perform some predefined function such as wireless communication or sound generation. With no engineering skills and sometimes a soldering iron for assembly, electronics can easily be added to make works-like prototypes quickly and efficiently.
If a works-like-looks-like prototype is desired, the process begins with the generation of a schematic, showing all the electrical components and connections needed in the design. This schematic is then used to create either a breadboard or a printed circuit board (PCB). A breadboard would be used in the earlier stage prototypes to verify that the circuit works as expected. There are two types of breadboards; solderless and perf. A solderless breadboard consists of a board with holes that components and wires can be pressed into to create circuits without soldering. Perf breadboards consist of a thin piece of fiberglass with holes drilled every 0.1 inch to hold components and allow wires to be connected. Each electrical connection is soldered by hand to complete the circuit.
Depending on the complexity of the design, the engineer may wish to do this as a first pass to verify that the circuit works. If the time involved in assembling a breadboard is too much, a printed circuit board is created from the schematic. A printed circuit board consists of alternating thin layers of fiberglass and etched copper to create the electrical connections between components that are soldered to the board. Printed circuit boards are created using printed circuit board layout programs on a personal computer (PC).
Associated Costs of Prototyping
Cost factors in prototyping are regulated largely by complexity; however, the relative scale of costs does correlate to the type of prototype as well. A looks-like prototype of the invention will almost always cost less than a works-like prototype and so on; therefore, it is highly important to establish which type of prototype the inventor will need to accomplish his or her goals prior to committing to a type of prototype. The bulk of costs associated with prototype creation are usually found in engineering time for the development of works-like and works-like looks-like prototypes.
Mechanical Prototyping Tip
One cost saving methodology for mechanical prototypes is the use of rapid prototyping machines such as a 3D printer. 3D printing is a slightly different process from stereolithography (SLA) and selective laser sintering (SLS) processes in that it does not use heat or infrared light to cure layers of material; rather it uses a regular inkjet head to bind a plaster powder together. The plaster powder is then infiltrated with a high strength epoxy to give it rigidity. By using plaster powder as a base, components can be created for far less cost than other modeling techniques. Part costs range between $130 each to $400 each, and multiple parts can usually be produced for less through quantity discounts.
Once a master is made, duplicates can be formed at home by making a soft mold and casting parts using a molding kit. Molding kits (such as the one by www.DesignNotes.com) typically cost less than $100 and can make multiple parts.
Electrical Prototyping Tip
Don't be intimidated by electronics! Obtain an electronic kit or development board and create your own prototype. Electronic kits and development boards typically cost less than $50.00. Low-cost kits and development boards of all types can be found on Internet electronic retailer websites such as www.DesignNotes.com.
What to Do?
When pursuing a prototype, the inventor should first consider the type they will need to meet their immediate needs. If the inventor is pursuing licensing only, rarely should an investment be made in a pre-production prototype, since the manufacturer will most likely use their own resources anyway. In most cases, a works-like-looks-like prototype is the most advanced type that the inventor will need to create. If the inventor is interested in manufacturing the device personally, a prudent step would be to have a reputable engineering firm evaluate the idea to recommend a proper course of action involving design stages and prototype types.
Most reputable engineering and product design firms will recommend producing a works-like prototype first for more complicated ideas so that the idea can be "fleshed" out prior to investing in a works-like looks-like prototype. As always, the inventor should research firms prior to sending any proprietary information and make sure that a mutual non-disclosure agreement has been signed.
IMET Corporation provides in-house prototyping, development, short run production, full design documentation, and project management solutions to inventors and industry. Thomas Krol will be speaking at the INPEX® Inventors University™, Wednesday, June 6, 2007 from 10:00 to 11:00 AM.
