Shape Deposition Manufacturing

Sara Lechleitner 

Michelle Pitkethley

Matt Dennerline

 

How does SDM work? 

How is design information transmitted to the manufacturing process?

What materials does SDM use? 

What are the size and shape limitations on the parts?

How much do parts cost?

How quickly can parts be manufactured?

Advantages

Disadvantages

 

How does SDM work? 

    SDM is a solid freeform fabrication process which means it is built from start to finish rather than by removing excess materials from a given object.  It does this by layering support material and the desired finished material. 

    These graphics show the blue support material and the yellow final products. 

  • Support material is laid down as a base for the final material.  

  • Final material is laid on top of the support material.

  • CNC mills the part to the desired shape.

  • Surface is washed clean and prepared for the next layer of support and final material.

  • This process is repeated until the final layer is reached

  • Support material is removed. 

 

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How is design information transmitted to the manufacturing process?

    Part information is drawn in a 3D CAD model.  Then, the part is broken into thin two dimensional layers that are sent to the SDM machine.  This tells the machine where to place the support or part material and when a new layer is necessary.  

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What materials does SDM use? 

    SDM can be used with any castable material especially plastics, metals, resins, polymers and ceramics.  When using ceramics, a mold is made of the support material and then the desired material is cast inside of it.  

  1. Mold  is made from mold material (wax) and support material.

  2. Support material is removed leaving the wax mold.

  3. The desired ceramic material is cast inside.

  4. The mold is removed.

  5. Any excess material is removed.

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What are the size and shape limitations on the parts?

    Almost any shape can be manufactured because SDM allows complicated convex and asymmetrical parts to be supported during the fabrication process.  The size of the part is limited only by the size of the machine. 

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How much do parts cost?

    Since this an experimental process, the cost of parts changes constantly based on size, shape, material, availability, and advances in technology.

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How quickly can parts be manufactured?

    Because of the dramatic differences in the way individual parts are made, manufacturing time can vary greatly.  The number of layers needed, the amount of support material, the number of embedded objects, and the availability of the machine are all contributing factors.  

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Advantages

An advantage of SDM is the ability to embed objects into the part as it is being manufactured.  This could include electronic equipment that needs precise placement in the object.  It is also possible to use different materials within the same part.  This process is illustrated in the figure to the right.  
    SDM is also extremely precise; accurate within 5 microns.  There is a lot of flexibility with the shape being made and the materials being used.    

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Disadvantages

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All figures are courtesy of the Robotics Institute at Carnegie Mellon University
Additional information was found at the Rapid Prototyping Laboratory of Stanford University