Modeling and application of droplet oscillation momentum for elucidating the development of surface roughness in wire-arc additive manufacturing

Abstract

ABSTRACTIn feedback control systems of wire-arc additive manufacturing (WAAM), timely adjustments before the occurrence of deviations (feedforward control) would reduce excessive requirements on the sensitivity and accuracy of characteristic parameters of control systems. However, the search for characteristic parameters suitable for feedforward control is extremely rare in the WAAM field. Herein, based on ‘mass-spring' theory, a model of droplet oscillation momentum (DOM) is developed to describe the dynamic behavior of a pendant droplet and its influencing mechanism on surface roughness. The model combines the contribution of wire movement to droplet displacement with experimental correction of the spring/damping coefficients. The results show that the predictions of the model are in good agreement with the experimental values, and DOM is quadratically correlated with the surface roughness. Therefore, the model can be expected as a characteristic parameter to elucidate the development of surface-forming quality of WAAM-fabricated components.

Keywords

• Wire-arc additive manufacturing
• droplet oscillation momentum
• control strategy
• molten pool fluctuation
• surface-forming quality