IMPROVING THE EFFICIENCY OF WAAM-BASED HYBRID MANUFACTURING THROUGH SELECTIVE IN-SITU MACHINING BASED ON HEIGHT ERROR PREDICTION

Document Type

Conference Proceeding

Publication Date

8-20-2024

Department

Department of Materials Science and Engineering; Department of Mechanical Engineering-Engineering Mechanics

Abstract

Hybrid manufacturing processes combine additive and subtractive methods that offer a promising avenue for achieving intricate geometries and enhanced printed properties. Parts produced using additive manufacturing technologies typically have inferior surface finish and dimensional accuracies compared to subtractive machining processes. A key advantage of hybrid manufacturing is the allowance of a single platform to produce a printed part that contains improved surface finish and tolerances of selective features compared to traditional printing. Therefore, critical to the success of hybrid processes is maintaining precise control over the part's dimensional accuracy, particularly the in-situ layer height. Currently, the Wire Arc Additive Manufacturing (WAAM) process begins by determination of weld bead geometry. This is achieved by printing lines of test beads consisting of the desired levels of prominent print parameters that include welding voltage, torch travel speed, and wire feed speed. The test beads are then measured, these measurement values are then used to set the bead geometry used to establish the layer height and step over values used in the part program. Currently, in-situ machining is conducted in hybrid systems to provide a flat surface for subsequent layers. However, the machining heights established during programming are currently arbitrarily based on nominal layer heights. Printing using constant voltage, torch speed and wire feed speed do not produce consistent bead geometry, causing varying layer heights. Because of varying layer heights, this non-adaptive method of in-situ machining results in inefficient and repetitive tool changes that limit the efficiency of hybrid manufacturing processes. The research presented in this paper aims to investigate a method to adaptively determine the in-situ machining height through in-process temperature measurement. This study was conducted by printing sample parts and collecting detailed height measurements of WAAM parts to assess the deviation from the actual printed part height to the nominal part model height. These measurements were then correlated with temperature data collected throughout the manufacturing process to derive a relationship between temperature measurements and the physical layer height. The relationship was then used to determine the proper machining height for in-situ machining. The results of this study were conducted on a robotic WAAM-based and milling hybrid system. The results of this study offer critical insights into the in-process timing of when to switch between printing and machining to enable more robust and precise manufacturing strategies. Hence, this research contributes to the overall ongoing advancement of hybrid manufacturing techniques and their broader adoption in industrial applications.

Publication Title

Proceedings of ASME 2024 19th International Manufacturing Science and Engineering Conference, MSEC 2024

ISBN

[9780791888100]

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