As continuation to the previous post....

Fused Deposition Modeling:

    The set up in this process consists of an extrusion nozzle which follows a tool path that is defined by the CAD file. This nozzle is heated which melts the material (mainly thermoplastics or wax) and is movable with the help of motors to form layers that are extracted from STL file. The nozzle can turn the flow on and off.  

     The materials are deposited in layers as fine as 0.04 mm (0.0016") thick, and the part is built from the bottom up – one layer at a time. FDM works on an "additive" principle by laying down material in layers.

Picture depicting FDM process

Solid Ground Curing (SGC):

       In this process a plate is charged selectively and coated with black powder which results in photographic mask of clear and opaque areas for a single slice of the part. This layer is placed over photopolymer and exposed to a UV lamp which hardens the polymer selectively. The unhardened polymer is removed from the surface and affine layer of wax is deposited and hardened which acts as support. After completion of the process the wax is melted and removed.

    This process has many advantages as the process is non time consuming and post curing is eliminated.

    The step wise procedure can be found here:

http://www.efunda.com/processes/rapid_prototyping/sgc.cfm

The setup for SGC process

Laser Engineered Net Shaping (LENS):

      This process fabricates the model directly from the CAD model using metal powder injecting into a molten pool created by a focused, high powered laser beam. Simultaneously the substrate on which the deposition is occurring is scanned under the beam/powder interaction zone to fabricate the desired cross sectional geometry. Consecutive layers are sequentially deposited, thereby producing a three-dimensional metal component.

 

 

Rapid Prototyping

         In this post a brief introduction of Rapid Prototyping  process is given.

           Rapid prototyping is the process of creating a prototype of the model with the help of 3-D CAD model in less lead time using various techniques.

This technique prominently depends on .STL file formats that can be created using 3-D design software tools. STL stands for STereoLithography. It is also known as Standard Tessellation Language. 

RP technique mainly involves the following steps:

1.Creation of solid CAD model of required part.

2.The above CAD file is converted to .STL file.

3.Then the file is sliced with the closely spaced planes (.SLI file is generated).

4.Part fabricaton.

5.Post processing.

 Various techniques available are:

     Stereo-lithography (SL)  

     Laminated Object Manufacturing (LOM)

     Selective Laser Sintering (SLS)

     Fused Deposition Modeling (FDM) 

     Solid Ground Curing (SGC)   

     3D Printing  (3DP)

     Laser Engineered Net Shaping (LENS)

Stereo-lithography (SL):

     In this Stereo lithography  process a liquid ultraviolet curable photo polymer resin and an ultraviolet laser, to build parts' layers one at a time, are used. For each layer that is sliced, the laser beam traces a cross-section of the part pattern on the surface of the liquid resin. Exposure to the ultraviolet laser light the resin cures and solidifies and  the pattern traced on the resin is joined to the adjacent layer.

     After the pattern has been traced, a resin-filled blade sweeps across the cross section of the part, re-coating it with fresh material. On this new liquid surface, the subsequent layer pattern is traced, joining the previous layer. A complete model is formed by this process. After being built, parts are immersed in a chemical bath in order to be cleaned of excess resin and are subsequently cured in an ultraviolet oven.

The process can be best explained by the video:

http://www.acucast.com/video.htm  

picture shows the setup producing the model

 Laminated Object Manufacturing:

       In this process  layers of adhesive coated paper, plastic or metal laminates are successively sticked together and brought  to shape with laser cutter. The arrangement is such that the platform adjusts itself to receive the next layer.

 

1 Foil supply. 2 Heated roller. 3 Laser beam. 4. Scanning prism. 5 Laser unit. 6 Layers. 7 Moving platform. 8 Waste.

Selective Laser Sintering:

      In this process the small particles of powder material say plastic, glass or ceramic are fused to a desired prototype component using high power laser. The laser selectively fuses powdered material by scanning cross-sections generated from a 3-D digital description of the part on the surface of a powder bed. After each cross-section is scanned, the powder bed is lowered by one layer thickness, a new layer of material is applied on top, and the process is repeated until the part is completed.

SLS system