rapid prototyping

  1. Rapid Prototyping (RP) can be defined as a group of techniques used to quickly fabricate a scale model of a part or assembly using three-dimensional computer aided design (CAD) data. OR Rapid prototyping is the fabrication of parts from CAD data sources. There is a multitude of experimental RP methodologies either in development or used by small groups of individuals. This section will focus on RP techniques that are currently commercially available, including Stereo lithography (SLA), Selective Laser Sintering (SLS), Laminated Object Manufacturing (LOM), Fused Deposition Modeling (FDM), Solid Ground Curing (SGC), and Ink Jet printing techniques. *
  2. The reasons of Rapid Prototyping are  To increase effective communication.  To decrease development time.  To decrease costly mistakes.  To minimize sustaining engineering changes.  To extend product lifetime by adding necessary features and eliminating redundant features early in the design. *
  3. The basic methodology for all current rapid prototyping techniques can be summarized as follows: 1.A CAD model is constructed, then converted to STL format. The resolution can be set to minimize stair stepping. 2.The RP machine processes the .STL file by creating sliced layers of the model. 3.The first layer of the physical model is created. The model is then lowered by the thickness of the next layer, and the process is repeated until completion of the model. 4.The model and any supports are removed. The surface of the model is then finished and cleaned. *
  4. • Stereo lithography • 3-Dimensional Printing • Fused Deposition Modeling • Laminated Object Manufacturing • Selective Laser Sintering *
  5. A stereolithography machine uses a computer controlled laser to cure a photo-sensitive resin, layer by layer, to create the 3D part. *
  6. In this method roller is to distribute and compress the powder evenly in the fabrication chamber. The multi-channel jetting head then creates a layer of liquid adhesive in the geometry of the part in the bed of powder. A layer of the part geometry is created when the powder that containing liquid adhesive bonds and hardens. When a layer is completed, the fabrication piston will move down in increments. These increments are specified to determine the layer thickness. Additional layers are formed to create the entire part geometry. Once the part is completed, the fabrication piston is raised to expose the part. With the part exposed, the access powder can be brushed away. *
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  8. In this process, a strand of filament is unwound from the coil and fed into an extrusion nozzle. The plastic is melted and controlled by the nozzle. The nozzle is able to move in the X and Y directions and is mounted to a stage system. Layers are formed by very small beads of plastic being deposited from the nozzle in the shape of the part geometry. The plastic beads begin harden immediately after being extruded from the nozzle in addition to bonding with the layer beneath *
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  10. The LOM process produces prototypes by utilizing layer building concepts. During the LOM process, a laser is used to cut individual layers of paper to form a prototype. *
  11. SLS process produces parts directly from 3D CAD model; layer by layer similar to SLA but rather than liquid resin powder is used. *
  12.  Rapid Prototyping can provide with concept proof that would be required for attracting funds.  The Prototype gives the user a fair idea about the final look of the product.  Rapid prototyping can enhance the early visibility.  It is easier to find the design flaws in the early developmental stages.  Active participation among the users and producer is encouraged by rapid prototyping.  As the development costs are reduced, Rapid prototyping proves to be cost effective.  The user can get a higher output. *
  13.  Some people are of the opinion that rapid prototyping is not effective because, in actual, it fails in replication of the real product or system.  disadvantage of rapid prototyping is that it may not be suitable for large sized applications.  The user may have very high expectations about the prototype’s performance and the designer is unable to deliver these.  The system could be left unfinished due to various reasons or the system may be implemented before it is completely ready. *
  14.  Design  CAD model Verification  Visualizing object  Proof of concept  Engineering, Analysis and planning  Form and fit models  Flow analysis  Stress distribution  Mock-up  Diagnostic and surgical operation planning  Design and fabrication of custom prosthesis and  implant *