Investigation on the Cause-Effect Relationships between the Process Parameters and the Resulting Geometric Properties for Wire-Based Coaxial Laser Metal Deposition

Abstract

Coaxial Laser Metal Deposition with wire (LMD-w) is a valuable complement to the already established Additive Manufacturing processes in production because it allows a direction-independent process with high deposition rates and high deposition accuracy. However, there is a lack of knowledge regarding the adjustment of the process parameters during process development to build defect-free parts. Therefore, in this work, a process development for coaxial LMD-w was conducted using an aluminum wire AlMg4,5MnZr and a stainless steel wire AISI 316L. At first, the boundaries for parameter combinations that led to a defect-free process were identified. The proportion between the process parameters energy per unit length and speed ratio proved crucial for a defect-free process. Then, the influence of the process parameters on the height and width of single beads for both materials was analyzed using a regression analysis. It was shown that linear models are suitable for describing the correlation between the process parameters and the dimensions of the beads. Lastly, a material-independent formula is presented to calculate the height increment per layer needed for an additive process. For future studies, the results of this work will be an aid for process development with different materials.

The effects of laser wire directed energy deposition processing parameters on the properties of 309L stainless steel

“…Visual inspection of test conditions 1 showed evidence of wire dripping, as well as deformation at the edges of the sample, as shown in Figure 1. The dripping defects was because of high heat input [3,4]. A change in test conditions from test conditions 1 to test conditions 2, showed an improvement eliminated the dripping defects, due to an increase in dimensions.…”

“…The deposition improved slightly with this parameter window, although the test cube that was deposited at 350 mm/min showed dripping defects due to high heat input of 154 J/mm. Test cubes that were fabricated at 550 mm/min and 650 mm/min travel speed had wire dripping defects forming due to excessive travel speed [3] (see Figure 3). A further increase in the dimensions of the test cubes greatly improved the surface finish, however, there was incomplete melted wire on the test cubes.…”

“…This process is repeated until the required 3 dimensional part is built [1,2]. Coaxial wire-directed energy deposition (DED) machines are a recent development that feed wire orthogonal to the substrate, enabling uniform processing from any direction of motion [3,4]. Advanced manufacturing studies in the literature primarily focus on austenitic stainless steels such as the 316L and 304L grades [5].…”

“…It has been reported that the bead height is directly proportional to wire speed and speed ratios, and it is not affected by laser power or energy. The bead width on the other hand is directly proportional to the laser power and energy per unit length and inversely proportional to the travel speed and slightly affected by wire speed [3]. The most common process defects that may result from incorrect processing parameters are dripping and stubbing.…”

“…The most common process defects that may result from incorrect processing parameters are dripping and stubbing. These defects are due to excessive high laser power, insufficient wire speed and laser power, and excessively high travel speed [3,4]. The effect of processing parameters on cladding of carbon steel with 309L welding wire using the laser wire DED has been investigated by Bozeman et al [4].…”