Abstract:
Inconel-718 is a nickel-based super alloy with exceptional mechanical properties; including
high yield, creep-rupture, and high tensile strength at temperatures up to 977 K. Along with its
frequent uses in high temperature fasteners and bolts, and high-speed aircrafts’ parts such as
spacers, wheels, buckets, and engines, Inconel-718 have also its applications in automotive,
submarine and biomedical industries. Although this nickel-based alloy is an ideal material for
high temperature and high corrosive environment, it is difficult to handle while machining it.
To improve the machinability of the alloy as compared to the conventional micro milling, an
experimental setup has been designed using laser-based ultrasonic assisted low speed micro
milling (LLUMM). This study focuses on low-speed ultrasonic milling of laser-cut constantdepth slots which are created on a workpiece of Inconel-718 using Laser Marking Machine.
Effects of cutting parameters including cutting speed, feed rate, depth of cut, amplitude of tool
vibration and tool coating surface roughness, tool wear and burr formation are investigated,
using each factor at four different levels. Cutting tool’s diameter is kept fixed at 0.5mm with
uncoated and coated materials, including TiAlN, TiSiN, and nACo. A Design of Experiment
technique, namely Taguchi L16 array, is used to create experiments. Experimental data is
statistically analysed to identify the best and worst set of parameters for achieving the desired
results. Optimization of individual response variables is carried out using signal to noise ratios,
with the help of Minitab-21, while multi-objective optimization uses Weighted Grey Relational
Grades (W-GRG) in which Grey Relational Analysis is coupled with Principal Component
Analysis (GRA-PCA). It has been revealed by validation experiments that LLUMM produces
better results as compared to traditional micro milling.
