Force and preheating temperature regulation for γ-TiAl surface defect suppression

Laser-assisted machining (LAM) enhances the machinability of γ-TiAl alloy. However, large temperature gradient with insufficient softening leads to undesirable poor surface uniformity across the entire zone. Thus, precise temperature control is essential for the modulation of machinability and surface integrity. This study addresses this challenge by proposing a novel temperature regulation strategy that explicitly integrates milling force feedback to modulate thermal softening effects. It establishes a synergistic relationship between force and temperature control. Two preheating strategies were implemented to comprehensively investigate preheating temperature uniformity and their effects, which are linear heating with a large spot (CLAM) and scanning heating with a small spot (GLAM), respectively. Furthermore, the constitutive model parameters and laser absorptivity of γ-TiAl were identified. Experimental results demonstrate that LAM reduces milling forces by over 50 %, with the GLAM yielding an additional 15 % reduction with improved stability. Critically, the proposed strategy ensures a wide-width zone preheated to a homogeneous and optimized thermal state, maintaining nearly uniform thermo-mechanical loads within cutting zone. It enhances surface consistency by suppressing surface defects and edge failure. Meanwhile, the force and temperature prediction have acceptable accuracy with the maximum error of 15.3 % and 5.39 %. As a result, it provides a quick and efficient method for solving the parameter matching and temperature control issues to achieve better machinability, exhibiting broader applicability for extension to various difficult-to-cut materials.