Stereolitographie (STL)

The solidification of liquid polymer through Polymerization is named Stereo lithography. The Firm “3D Systems” has named this process Stereo lithography, on the other hand, the Firm “EOS” calls it Stereography. Both ideas are registered trademarks of their respective companies.

Principally, Stereo lithography equipment requires only one container,  which acts as build space and supply stock at the same time. When the liquid polymer is exposed  to a laser, it solidifies. When the laser is controlled, it is possible to draw a shape which corresponds to the layer information of the CAD design.  The rapid prototype is built upon a platform.  After the solidification of one layer, the platform is shifted downward, according to a defined layer thickness, and the next layer is solidified.

This process demands the simultaneous construction of a support construction to hold the piece during the build process. There are unreachable areas that are not hardened and thus the overlaid layers do not offer support for transitions.

The technology requires that the finished piece be washed in a solvent  and then treated in a UV oven.  The final solidification of the polymer binding occurs there, based upon the stability of the supports.

Picture: Illustration of the Stereo Lithography Process.

Application:

Advantages Disadvantages
  • Able to manufacture parts that are tedious or cannot be manufactured with conventional processes
  • Fast manufacture from casting drafts with better accuracy
  • Continuous work over 24hr without permanent monitoring
  • Photo-polymer provides characteristics that confine the application of the parts
  • Necessity of support constructions
  • High cost for reworking
  • Polymer leftovers must be disposed of by a professional
  • The durability  of the part is limited when exposed to sun light