WHAT IS STEREOLITHOGRAPHY
SLA or Stereolithography is a new and advanced manufacturing method based on 3D CAD, computer controlled layers scanning and rapid layer separating and accumulating principles. SLA is a process whereby a laser converts a liquid photopolymer into a solid plastic layer by layer. It is one of the major branches of recent rapidly manufacturing technology.
WHY USE SLA FOR RAPID PROTOTYPING
SLA is mostly used for rapid prototyping for part which have a complex shape and which are not achievable using traditionnal CNC process. SLA process for rapid prototyping is mostly used for accurate part requirement.
PROCESS OF SLA FOR RAPID PROTOTYPING
As the SLA machine is controld by computer, it needs to be fed with proper file. As the process is making part by designing layer by layer part, the object ins 3D CAD file has to be cut into slice first so the laser beam know in which coordinate it should go.
Stereolithography is an additive manufacturing process which employs a vat of liquid ultraviolet curable photopolymer “resin” and an ultraviolet laser to build parts’ layers one at a time.
For each layer, the laser beam traces a cross-section of the part pattern on the surface of the liquid resin. Exposure to the ultraviolet laser light cures and solidifies the pattern traced on the resin and joins it to the layer below.
After the pattern has been traced, the SLA’s elevator platform descends by a distance equal to the thickness of a single layer, typically 0.05 mm to 0.15 mm (0.002″ to 0.006″).
Stereolithography requires the use of supporting structures which serve to attach the part to the elevator platform, prevent deflection due to gravity and hold the cross sections in place so that they resist lateral pressure from the re-coater blade.
Layer after layer, the object is built and in the end quite often a slight polishing is necessary to get a smooth surface.
ADAVANTAGES OF SLA FOR RAPID PROTOTYPING
- Everything is made by machine
- Can perform some complex part that CNC can not make
- Resolution ± 0.05mm
- Accuracy 0.1mm.
LIMITATIONS OF SLA FOR RAPID PROTOTYPING
- Doesn’t use the same material that will be used during manufacturing.
- Platform size usually limited in dimension 600x600x400mm so big parts can not be achieved
MATERIALS USED FOR SLA PROTOTYPING
Material: An epoxy based UV curing resin is used. A variety of ABS type resins are available, such as EP60(transparent),EP70(white),DSM Somos 14120,11122,GP Plus, Next.
Materials: EP06, Somos 14120, others on request
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