The purpose of this paper is to investigate the influencing rule of the standoff distance variations between the nozzle outlet and the powder deposition point on forming dimensional accuracy.
The thin‐wall parts were built with three different standoff distances: 1 mm more than the powder focus length, equal to the powder focus length and 1 mm less than the powder focus length. Based on the experimental results, the steady standoff distance can be acquired and the difference between the building height and the ideal height of thin‐wall parts can be compensated automatically in several layers by theoretical calculation.
The experimental results show that the top surface unevenness of thin‐wall parts can be compensated automatically on the consequent successive layers when the standoff distance is less than the powder focal length from the nozzle outlet to the powder focal point, and the poorer results are obtained when the standoff distance is equal to or more than the powder focal length in the deposition of stainless steel 316L under open‐loop control.
The shape of parts affects the self‐regulation effect in practical applications, so the self‐regulation effect is useful when the single contour of parts is continuous straight faces and the surface of parts is perpendicular to the build platform, and will be useless for parts with holes.
According to the requirements under different process conditions in practical applications, one should first find out the relationship between the standoff distance and the building height of single‐trace cladding layer, and then use regression algorithm to obtain the stable standoff distance by simple theoretical calculation. The uniform building height, layer thickness and smooth surface can be obtained at the stable standoff distance under open‐loop control.
Zhu, G., Li, D., Zhang, A., Pi, G. and Tang, Y. (2011), "The influence of standoff variations on the forming accuracy in laser direct metal deposition", Rapid Prototyping Journal, Vol. 17 No. 2, pp. 98-106. https://doi.org/10.1108/13552541111113844Download as .RIS
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