| Prototype Injection Molding, Thermoplastic | | | | components using solid freeform fabrication. They |
| Injection Molding, and information on Injection | | | | are used in a wide range of applications, |
| Molds. | | | | everything from medical to fine art. Rapid |
| Approximately 30% of all plastic products in the | | | | Prototyping machine works by taking virtual |
| world are produced by an injection molding | | | | models from software and then converting it into |
| process. Within this another 30% are produced | | | | extremely thin, horizontal cross-sections and then |
| using a custom injection molding technology. There | | | | goes onto create each of the cross-section in |
| are basically six steps involved in the normal | | | | physical space in a cyclic manner until the model is |
| injection molding process. The first step is the | | | | completed. Rapid Prototyping is a WYSIWYG |
| clamping of the mould, the clamping unit makes | | | | process in which the virtual model bears identical |
| for one of the three units of the molding machine. | | | | resemblance to the finished physical model. |
| The other two being the injection unit and the | | | | Additional fabrications allows the machine to lay |
| mold, once the clamping unit holds on to the mold, | | | | down layers of sheet, liquid or powder material |
| the molten plastic is injected into the mold by the | | | | and build up a series of cross-sections These |
| injection unit. The plastic is fed in the form of tiny | | | | layers are finally automatically fused together to |
| pellets onto a hopper. These are then allowed into | | | | render the final product. The main advantage of |
| a cylinder where they are heated into a molten | | | | rapid prototyping is the ability to create any shape |
| state and injected into the mold. The steps that | | | | no matter how complex the geometry is. The |
| follow are referred to as dwelling phase. It | | | | commonly used data interface between the |
| basically involves making sure all the cavities in the | | | | machine and the software is the STL format. It |
| mold are fully filled. The mold is then allowed to | | | | works by approximating the geometry of a part |
| cool with the clamping intact. Finally the mold is | | | | using triangular facets, smaller the facets higher |
| opened and the component is ejected out. The | | | | will be the surface quality. The word rapid |
| biggest advantage of plastic injection molding is | | | | is used relative top conventional methods which |
| the cost factor of the produced parts, especially | | | | take days to construct a model depending upon |
| when you need large number of parts. The | | | | its complexity. Rapid prototyping can create the |
| disadvantage is the cost of manufacturing the | | | | model within a few hours, though it is highly |
| molds; a simple injection mold can cost you $3000 | | | | dependent of the type of machines and the size |
| while the bigger complex ones can run into | | | | of the model. There have been several new |
| several hundreds of thousands. | | | | technologies available for rapid prototyping |
| | | | | including Fused Deposition Modeling, Selective laser |
| Rapid Prototyping: Rapid Prototyping is the | | | | sintering, 3D printing, and Electron Beam Melting. |
| process of automated manufacturing of physical | | | | |