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Indexed by:Journal Papers
Date of Publication:2024-04-26
Journal:International Journal of Advanced Manufacturing Technology
ISSN No.:0268-3768
Key Words:Aluminum alloy LF 21; Micro-milling; Multi-objective optimization; Genetic algorithm
Abstract:Micro thin-walled structure of aluminum alloy LF 21 has a strong ability to reflect electromagnetic waves and is widely used
in waveguide radar antenna. Micro-milling technology is a potentially effective technique for machining micro thin-walled
structure of LF 21. However, LF 21 has the characteristics of low strength and hardness and high plasticity and is prone to
plastic flow under cutting force, resulting in extrusion, accumulation, and other defects and easy to produce burrs. Then the
surface roughness and surface residual stress are difficult to guarantee. To ensure the machining quality of micro-milling
thin-walled LF 21, a 3D simulation model of micro-milling LF 21 process is established based on Abaqus to output residual
stress. The validity of the residual stress output is verified by experimental results. Four-factor and three-level orthogonal
simulation experiments are conducted, and a prediction model of residual stress is established based on the simulation results.
Based on the response surface method (RSM), four-factor and five-level center composite design (CCD) experiments are
conducted to establish a surface roughness prediction model and a top burr size prediction model. The validity of the built
prediction models is verified by experiments. Multi-objective optimization (the minimum surface roughness, the minimum
top burr size, and the maximum surface compressive residual stress) is transformed into single-objective optimization by
using the analytic hierarchy process (AHP)-entropy weight method. Genetic algorithm (GA) is used to solve the above opti
mization problem, and the optimal machining parameters of micro-milling LF 21 are achieved. The optimal micro-milling
parameters are as follows: the spindle speed n is 62,000 r/min, the axial depth of cut ap is 70 μm, the radial depth of cut ae
is 65 μm, and the feed per tooth fz is 0.95 μm/z.
