Stereo lithography, which is also called Stereolithography, SLA Rapid Prototyping, or short for SLA, is an important method of rapid prototype technology.
Photosensitive resin, filled in the resin tank, will quickly cure under the UV laser beam irradiation. At the beginning of this SLA prototyping process, under computer numerical control, the focused laser beam begins to scan along the liquid surface. The resin being scanned is cured so as to get a cross-sectional plastic sheet. The worktable then is lowered for a new layer and endlessly all cured layers are firmly bonded for the final molding.
The advantages of SLA rapid prototyping are as follows:
Stable. Once the system starts to work, the entire process of SLA prototype is fully automated and does not require special attention until the end of the process.
High dimensional accuracy. Stereo lithography ensures you that the accuracy is within 0.1mm for every workpiece.
Good surface quality. The top surface of the workpiece is very smooth, the side is good as well.
High system resolution. This stereolithography advantage makes complex structure easy.
The selective laser sintering process is to spread a layer of powdered material onto the upper surface of the shaped part using a powder stick and heat it to a temperature below the sintering point of the powder. The control system controls the laser beam according to the layer The cross-sectional profile is scanned on the powder, the temperature of the powder is raised to the melting point, sintered, and bonded to the molded part below. When a section of sintering is completed, the table down the thickness of a layer, laying roll and covered with a layer of uniform dense powder, a new section of the sintering, until the completion of the entire model.
The prominent uniqueness of SLS process is manufactruing metal products or parts directly compared to other rapid manufacturing processes ,as well as some advantages below:
1)Variety of materials available In principle, any material that its viscosity reduces when being heated can be used in SLS process.
2)Simple Complex-structured Cavity mold ,masterpattern,parts and tools can be complete by SLS prototyping method.
3)Hign accuracy Usually the tolerance of SLS parts can be reached within ±（0.05--2.5）mm as per the material,grain size,the geometrical shape and complexity of the workpiece. It can meet the masterpattern accuracy within ±1% when the material grain size is below 0.1mm.
4)No need of structural support Like the LOM process, the SLS process does not require a support structure, and the voids that appear during the stacking process can be supported directly by the unsintered powder.
5)High material utilization No need of support structure and no scrap material and most powder material is cheap , so the material utilization of SLS is very high.
6)Short production cycle It’s just several or dozens of hours from CAD design to workpiece complete and can be revised during the whole digitized process,making SLS quite suitable for new product development.
7)Wide application Masterpattern design test ,mould,investment casting,direct shell production casting and mold core etc.