Analysis of preheating temperature field characteristics in selective laser sintering

Abstract

Selective laser sintering technology has broad application prospects in the manufacture of small batch parts with complex structure. In the sintering process, the preheating efficiency and temperature of powder layer determine the processing quality. A method of preheating powder by lamp radiation and tropical heat conduction is proposed in this paper. The thermal radiation model is established, and the angle coefficient is introduced to describe the proportion of radiation energy on the surface of powder layer. Based on the geometric characteristics of the powder cylinder, the heat conduction process is simplified to one-dimensional heat conduction along the radial direction, and the heat conduction model is established. The coupled temperature field under two actions is obtained by combining the heat radiation model with the heat conduction model. The uniformity coefficient [Formula: see text]/[Formula: see text] of the temperature field is defined to represent the uniformity of the preheating temperature field of the powder layer. By comparing the uniformity coefficient [Formula: see text], a more uniform temperature field can be obtained when the height coefficient is 1.8 under combined action. The validity of the model is verified by a comparative experiment with processed water atomized iron powder. Constructing uniform temperature field can effectively reduce the deformation of parts and improve the forming quality.

Laser sintering of polyether sulfone/carbon black composite powders using near-infrared laser

“…Moreover, they can be operated at a relatively low power of 20 W. However, the laser absorption rate of polymer materials for near-infrared lasers is considerably lower than that for the CO 2 laser, 8,9 thereby limiting the application of near-infrared lasers in LS. Moreover, powders typically should be heated during LS processing; 10,11 therefore, both the complexity and cost of the equipment increases owing to powder heating and thermal insulation functions, which adversely affect the feasibility of miniaturizing LS equipment.…”