Fig. 1. Schematic diagram of slicing of the overhanging structure

Fig. 2. Model and scanning strategy of the overhanging sample. (a) Model; (b) scanning strategy

Fig. 3. Principle of lower surface process area division and the division results of different models. (a) Principle of lower surface process area division; (b) influence of different downward comparison layer numbers T on the lower surface process area of the sample with the same inclination angle; (c) adaptive control of the lower surface process area for the variable angle samples

Fig. 4. Low angle molding sample model, thickness test points and lower surface process differentiation area. (a) Forming model; (b) thickness test points; (c) inner and lower surface process area of the sample under different downward comparison layer numbers T

Fig. 5. Morphology and grouping of overhanging samples formed by different processes. (a) Morphology of overhanging samples formed under different processes; (b) typical morphology of over-melted samples; (c) typical morphology of melting-suitable samples; (d) typical morphology of under-melted samples

Fig. 6. Overhanging single layer printing splash diagram and the influence of scraper on overhanging structures. (a) Overhanging single-layer print splash diagram; (b) diagram of the action of scrapers on overhanging structures

Fig. 7. Interlayer lap joints of overhanging samples formed by different processes. (a) Over-melting process; (b) suitable melting process; (c) under-melting progress

Fig. 8. Effective overhanging length of formed sample under the different downward comparison layer numbers (T)

Fig. 9. Warping mechanism of the sample and the influence mechanism of the different downward comparison layer numbers. (a) Warped sample; (b) warping mechanism; (c) laser action mechanism when T=0; (d) laser action mechanism when T≥40

Fig. 10. Topography of the upper and lower surfaces of the low-angle samples. (a) Lower surface of the contour is not opened; (b) upper surface of the contour is not opened; (c) lower surface of the contour is opened; (d) upper surface of the contour is opened

Fig. 11. Schematic diagram of interlayer scanning

Fig. 12. Forming thickness of the samples with different sizes. (a) Forming thickness of the samples with different thicknesses; (b) forming thickness of the samples with different widths

Fig. 13. Annular impeller model and the formed sample. (a) 15° inclination area of the impeller; (b) 45° inclination area of the impeller; (c) top view of the formed impeller; (d) side view of the formed impeller; (e) upper surface morphology of the formed impeller blade

Fig. 14. Limitations of the lower surface process area division. (a) Proportion of the lower surface area of the thick sample; (b) the proportion of the lower surface area of the thin sample; (c) concave model