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Rapid Prototyping & Manufacturing Technologiescontrol in ensuring the reaction conditions. For example, the chamber of SLA ismaintained at 28°C ± 1°C.Resins used in SLA process are mixture of photo-initiator, linkers, oligomers andmonomer mixture in liquid state, photonic energy source will trigger the chainreaction of polymerization. Two parameters penetration depth (Dp) and criticalexposure (Ec), which are vary from different resins, are as the primary input to theSLA machine for controlling the power and time of laser emission. The followingillustrate the underlying principle of the two important parameters;Penetration Depth (Dp) and Critical Exposure(Ec)When a beam of light hit the resin surface, it will cure a region of resin in theshape of a bullet. The intensity of the beam determined the extent of reaction andthe size of the bullet.The threshold exposure, Ec, is the energy required for the photopolymer changesfrom the liquid to the gel phase. In the process, D p and E c is primary characters ofthe resin provided by manufacturer. The SLA machine determine P L and V s on thefry by the relation that the draw speed of the laser V s proportional to (P L /E C )exp(-C d /D p ).C pD pE maxE cCritical depth, given by the functionC d =D p ln(E max /E c )The depth of penetration which thepower of laser decay to approx. E max /3The power of laser at resin surfaceCritical Exposure, a primary resincharacter, unit in mJ/cm 2Page 8IC Professional Training