History of Rapid Prototyping
Rapid prototyping is quite a recent invention. The first machine of rapid prototyping hit the markets in the late 1980s. The early rapid prototyping process derived its name from the activities and the purpose for which the earlier machines were utilized.
Rapid prototyping refers to physical objects that are automatically constructed with the aid of additive manufacturing technology.
Rapid prototyping in its earlier days was applied to production of models and prototype parts. But nowadays with the advancement in technology, rapid prototyping is used widely for many applications that include manufacturing production-quality parts. The manufacturing of these quality parts however are very small in numbers. Apart from industrial applications, rapid prototyping is also used in sculpting. The application of rapid prototyping in sculpting is to generate fine arts exhibitions.
Rapid prototyping as mentioned earlier, involves the use of additive manufacturing technology which actually takes the virtual designs from computer aided design (CAD) or animation modeling software (AMS).
These designs are further transformed into thin, virtual, horizontal cross sections and then the process of creating successive layers continues till the model in complete. On completion of the model, one may find that the virtual model is almost same as the physical model. Over here a process called WYSIWYG (What You See Is What You Get) takes place wherein the final product is same as the image created. Once the layers which correspond to the virtual cross section from CAD are formed, they are either joined or fused automatically to yield the final shape. Additive fabrication has the benefit of creating any shape or geometric feature.
Working of Rapid Prototyping Machines
CAD software and the rapid prototyping machine are connected with a data interface that is called as the STL file format.
This STL file format enables the approximation of a shape of a part or the entire assembly using triangular facets. Smaller the facet, higher is the quality surface. One should consider the meaning of the word rapid as ‘relative’, as the construction process of a model with the contemporary methods can take up a long time which can be several hours to several days. It actually depends upon the complexity and size of the model. The method used over here also plays an important role. Sometimes the type of machine being used also influences the time taken for the creation of a new model though the additive systems are applied. Even here the size and the number of models to be created play an equally important role.
There are some other techniques that are used in the construction of parts. The technique used in solid free-form fabrication involves the use of two materials in the construction of parts. One of it is the building material of that part and the other is the support material. The use of support material is to provide support to the projecting features during construction.
In case of manufacturing polymer products in higher quantities, a process called traditional injection molding is more feasible in terms of cost, but when it comes to manufacturing parts in smaller volumes, the application of additive fabrication is recommended more and is cost effective.
Some of the prototyping technologies used in various rapid prototyping machines are as follows:
Selective Laser Sintering (SLS):
This technology involves the use of high power laser for the fusion of tiny particles of plastic, metal etc, into a mass that represents a desired 3D object, through the help of a SLS machine. This is an additive manufacturing technique. Materials used in this technique are metal powders and thermoplastics.
Fused Deposition Modeling (FDM):
This additive manufacturing technology was invented in the late 1980s by S. Scott Crump and is used for applications like modeling, prototyping and production. This technology involves the use of eutectic metals and thermoplastics.
Stereo lithography (SLA):
This also is an additive manufacturing technology and is used for production of models, patterns etc through the Stereo lithography machine. Photo-polymer is the principle material used in this technique.
Laminated object manufacturing (LOM):
Paper material is the base material used in this technology. In this method layers of adhesive-coated plastic, paper or metal laminates are fused together and cut into shape with the aid of a knife or a laser cutter.
This too is an additive manufacturing technology and involves the use of various materials. In this technology successive layers of material create a 3D object. 3D printing technology actually is said to be more affordable, easy to use and speedy than the additive manufacturing technologies. Though production applications are actually dominated by the additive manufacturing technologies, 3D has a great potential to prove useful in the production applications.
Rapid prototyping, is now entering into rapid manufacturing which is more advanced as compared to rapid prototyping machines as it can be used for large products. This is an additive fabrication technique, that would be applied to the manufacturing of solid objects. This process involves the sequential delivery of energy, material (material sometimes may not be used) to the specified points in space, in order to produce a particular part. Rapid manufacturing is an advanced form of this technology.