Research on Relationship between Depth of Fusion and Process Parameters in Low-Temperature Laser Sintering Process
Model of low-temperature laser sintering, in which part warpage during process is prevented by anchoring of parts instead of high-temperature preheating, is discussed. Low-temperature laser sintering process allows powder bed temperature to be lower than those in normal laser sintering process which suppresses parts warpage by preheating powder bed above its recrystallization temperature. When we introduce a new process or material, many experimental examinations are required to decide adequate building conditions. To reduce this process, theoretical process modeling and simulations are carried out. In stereolithography, relationship between laser irradiance and cure depth is known as “working curve,” and used for fundamental equation for this technology. On the other hand, many theoretical models for laser sintering have been introduced, and most of them are thermal models dealing with heat transfer in powder bed. Contrarily, there are few reports concerning measurement and calculation of fusion depth though fusion depth can be obtained easily by experiment and working curve is a useful to determination of building parameters. In this study, working curve which represents relationship between part thickness obtained by monolayer scan and incident energy was investigated. As a result of normalizing the power by the minimum power that can melt the surface of the powder bed, all the plots lay on the same single line. This line, namely master curve, is unique for each powder and useful to finding various parameters.