Empirical formulation for bead shape prediction in direct energy deposition

Abstract

In the metal deposition process, the bead shape plays a critical role in determining the precision and mechanical properties of the final product. Therefore, prior to additive manufacturing, it is essential to determine an optimal bead shape. In this study, the representation of bead shape using an empirical formulation in direct energy deposition, a metal additive manufacturing process, was investigated. Experiments were conducted by depositing SUS316 powder on an AISI D2 substrate and systematically varying major process parameters such as laser power and powder feed rate to observe the resulting changes in bead shapes. The findings revealed that the bead shape changed linearly in response to variations in these process parameters. Through detailed analysis, the effects and interactions of process parameters on the bead shape were predicted, and an empirical formulation based on changes in the cross section of real beads was derived. Remarkably, using only information related to process conditions, the bead shape and area were accurately predicted. Comparison of the cross-sectional values of the actual bead shape and the empirical formulation showed a maximum difference of 0.0287 mm2 and a minimum difference of 0.0002 mm2 in all experiments. These results provide valuable insights for establishing basic data that can be used to create an empirical formulation for bead cross-sectional shape and single bead volume in the metal additive manufacturing process.

Keywords

• bead shape prediction
• bead volume
• direct energy deposition
• empirical formulation
• sus316