Dimensional Variations in DLBMM of Aerospace Alloys

Abstract

Micro-channels are extensively used in various engineering applications including micro-channel heat exchangers, micro-channel coolers, micro-channel heat pipes and micro-channel pulsating heat devices widely used in several important and diverse fields such as aerospace, automotive, cooling of gas turbine blades, cryogenic systems, bioengineering and many more. All such fields required different sized micro-channels according to the cooling requirements and installation space constraints. Variation or oversizing/undersizing to the designed channel geometries imparts significant disturbance to fluid flow. Different sized micro-channels of rectangular cross section were fabricated in nickel alloy (Inconel 718), titanium alloy (Ti-6Al-4V), and aluminium alloy (AA 2024) through Nd:YAG pulsed laser beam micro-milling (LBMM). The variations (in %) in actual geometrical characteristics from the designed geometries were calculated and observed for various sizes of micro-channels. Laser parametric influences on geometrical characteristics such as channel’s top width, bottom width, depth and degree of taperness are categorically evaluated for each size of micro-channel. Finally, the effect of micro-channel size on each geometrical variation is evaluated by making a comparison plots of each geometry, each size and each employed laser parameter. The results reveal that the effects of individual laser parameter on each micro-channel size and each geometrical characteristic are different for different sizes and response predictors (geometrical characteristics).