**7. Contour path**

algorithm is not versatile also, while it is particularly useful for components with large number

**Figure 13.** Example of decomposition–regrouping method for multidirection slicing. (a) Volume decomposition; (b)

Another important step in AM is the development of an elaborate path planning strategy. Path planning for powder-based AM processes that have fine, statistically distributed particles is somewhat independent of geometric complexity. However, path planning for AM processes that have coarse and large-sized deposits is influenced by geometric complexity. Also, the property of the deposited shape will be influenced by the deposition path trajectory. In the following sections, methods are described to generate different types of deposition paths.

The raster scanning path technique, as shown in **Figure 14a**, is based on planar ray casting along one direction. In this strategy, 2D regions are filled by a set of scan lines with finite width [11]. It is commonly employed in commercial AM systems due to its simple implementation

Derived from the raster strategy, zigzag tool-path generation is the most popular method used in commercial AM systems. While it fills geometries line by line along one direction like the

Sub-volume regrouping; (c) Slicing in multiple directions [3].

and suitability for almost any arbitrary boundary.

**4. 2D path planning**

**5. Raster path**

**6. Zigzag path**

of holes.

12 New Trends in 3D Printing

Contour path generation as shown in **Figure 14c**, which is another typical method, can address the above geometrical quality issue effectively by following the geometrical trend of the boundary contours [14, 15]. Various contour map patterns were investigated by Li et al. [16] to develop optimal tool-path patterns for sculptured parts with a single island and no seriously non-convex shape.

**Figure 14.** Raster path pattern. (a) Raster path; (b) Zigzag path; (c) Contour path [15]; (d) Spiral path [17]; (e) Hybrid path [18].
