Scanning speed is one of the critical process parameter in laser engineered net shaping. For 304 stainless steel, Chai R, et al. studied, smooth laser cladding surfaces with modest track widths/heights are produced at scan speeds ranging from 4 to 16 mm/s. If the scan speed is too slow, the material is exposed to the laser for a longer period of time, generating more heat and expanding the heat affected zone. The metal will not melt if the scan speed is too fast. Depending on the properties of the powder material being used, the scan speed should be chosen to be within or near the specified scan speed range. As shown in Fig. 3(b), scanning speed has also a negative effect on the surface roughness.
(b)
Deposition Pattern
Xinlin W. et al. were investigated the effect of scanning parameter (reciprocating and unidirectional deposition way) and z-increment on overhang structure and accuracy in 3-axis LENS process. In unidirectional deposition, the deposited overhang had uneven surfaces and voids on the left side (end side of the path). The surface of the overhang through the round-trip deposition path was flat and symmetrical compared to the unidirectional path. The z-increment had a significant effect on the angular accuracy of the deposited overhang. By optimizing the z-increment, the discrepancy between the designed overhang tilt angle and his experimental overhang tilt angle was greatly reduced. The optimal z increment value depends on various process parameters (laser power, scan speed, and powder feed rate).
Layer Thickness
Ronda N. et al. studied on M300 maraging steel parts the effect of layer thickness on the microstructure, metallurgical quality and mechanical properties . Microscopic observation of the structure of the samples unconcealed a fine cellular structure. It had been noted that a decrease within the layer thickness leads to a decrease within the cell size and at the same time lowers the porosity of the fabric. A rise within the layer thickness causes a little however noticeable deterioration of the fabric properties between the 0.5 and 0.75 metric linear unit layer thicknesses. While producing ceramic components, cracking is the main challenge. Crack range of made-up specimens decreases clearly with the rise of layer thickness, and crack direction step by step changes from horizontal direction to transverse direction. Once the layer thickness is zero.8mm and on top of, close to crack-free structures are often obtained. Total energy consumption for every ceramic specimen deceases clearly with increasing of layer thickness, that is helpful to reduce the strain and therefore scale back the cracking behavior. Porosity increased as layer thickness increased.