Quantification of geometrical errors and thermal effects during wire EDM of thin wall structures—A numerical study

• Published in: Journal of manufacturing processes 2024-04, Vol.115, p.256-274
• Main Authors: P., Aswin, Mote, Rakesh G.
• Format: Article
• Language: English
• Subjects: Precision removal; Thermo-mechanical coupled model; Thin wall machining; Wall deflection; Wire EDM
• ISSN: 1526-6125
• DOI: 10.1016/j.jmapro.2024.02.009

Machining thin-walled structures with a high aspect ratio using Wire EDM can lead to geometrical errors, primarily of two types; overcut error due to kerf formation and thermal deformation of the entire wall section. To understand the driving mechanisms behind these errors three distinct numerical models were developed. Initially, a model based on a moving heat source was created, employing the apparent heat capacity approach to predict kerf width and the associated overcut error. These insights were then utilized to formulate a transient temperature distribution model with a redesigned geometry, considering time-dependent evolution of the kerf and corresponding changes in the material properties of the sub-domains. Finally, a thermo-mechanical coupled model was developed to predict geometrical errors caused by the deflection of the wall, considering the varying stiffness of the part. A series of experiments were conducted to gain insight into the effect of the designed wall thickness on wall deflection. For the selected design profile and machine parameters, the model predicts a 62.4% reduction in thickness and a corresponding over-cut error of 188μm. Similarly, the model predicts wall deformation in the range of 6μm to 312μm for various wall thickness levels and these findings were validated with experimental observations.