In the process of manufacturing, the term injection molding prototype can refer to two distinct things. An injection molding prototype can be a custom injection molding part. The term can also refer to the original part used to create an injection mold from which duplicate parts may be cast. In either case, a prototype is usually either a singular part or a part from an early series of developed products.
The first usage of the term refers to products of the injection molding process. These parts are usually one of a kind and created for a specific purpose. The injection molding prototypes produced in this manner do not require mass production, and the production numbers are limited.
While the first usage of injection molding prototype is fairly straightforward, the second requires a bit of explanation. The prototype used to create injection molds has been employed since the early history of injection molding. Similar to the lost wax method of casting, injection molding prototype casting utilizes the original prototype to shape and form the injection mold. Machines force molten plastics into a mold made in the exact negative of the original injection molding prototype. By creating molds in this way, an exact duplicate of the original part can be made.
This process is often accomplished by the same techniques used to create lost wax casting molds. The injection mold maker uses vulcanized rubber to make an exact negative mold of the injection molding prototype. The mold maker uses this negative to create injection molding dies for long production runs. The worker may also use the original mold for projects that do not require mass production.
The injection molding prototype may be made from wood, metal, ceramic, or other materials. The only standard for prototype product choice is that the material must be able to withstand the heat of the mold making process. This wide variance in materials makes it possible to create prototypes in a reasonably low-cost manner.
In some cases, the injection molding prototype of an exact part might be too detailed for proper casting of injection molded parts. In these circumstances, details such as threading or cut-aways may be omitted from the injection mold and later tooled into the individual work pieces. While the tooled components will not have the same strength as purely injection molded pieces, this step can eliminate trouble areas in the casting process.