Analysis of force patterns and tool life in milling operations

The paper describes the practical effects of the operating parameters in the milling operation. Experiments have been conducted to measure cutting force and tool life under dry conditions. Based on the experimental results, three mathematical models have been developed: Force, TLife and Force/TLife. Further analyses have been conducted on the cutting force patterns: seasonal pattern and nonlinear trend. A process optimisation that is based on the minimum production cost has been applied to relate Force model, TLife model and machinability criteria, such as power consumption, cutting parameters and surface roughness.Nomenclature C_w cost of workpiece ($) - C_s set-up cost ($) - C_m machining cost ($) - C_o overhead cost ($) - C_r tool replacement cost ($) - C_t tool cost ($) - D diameter of the cutter (inch) - d depth of cut per pass (inch) - d₀ required depth (inch) - e_t random error attth sample - F cutting force (N) - f feedrate (ipm) - L length of workpiece (inch) - N spindle speed (r.p.m.) - n number of teeth - P power of the motor (h.p.) - R surface roughness (µm) - R_e real part of a complex function - T tool life (min) - t sample number - t_m machining time (s) - t₀ overhead time (s) - t_r tool replacement time (s) - t_s set-up time (s) - U_i unit cost of itemi ($/unit)v - v cutting speed (i.p.m.)