Interrupting the hereditary effect: helical path vector-orthogonal additive method for enhanced subtractive machining performance and accuracy of thin-walled rotational parts

In the manufacturing of complex thin-walled rotary parts via Laser Directed Energy Deposition ( LDED ), the “hereditary effect” induced by surface asperities and inhomogeneities in microstructure and mechanical properties represents a critical bottleneck restricting the precision and performance of subsequent subtractive machining. To address this, this study proposes a helical vector-orthogonal additive manufacturing method, which achieves uniform powder and energy input per unit area, thereby regulating the deposition state at the source. Comparative experiments utilizing 316 L stainless steel powder against the conventional reciprocating path process indicate that this strategy significantly improves macroscopic surface morphology and promotes the formation of a refined, homogeneous cellular grain structure. Consequently, the average microhardness increased by over 60%, with significantly enhanced uniformity (standard deviation <6 HV ). The peak-to-valley cutting force in the X-direction decreased from 515.335 N to below 220 N , and the dominant vibration frequency shifted to the high-frequency, low-energy region of 30 kHz . Ultimately, the maximum cross-sectional roundness error decreased from 0.100 mm to ≤0.035 mm , and cylindricity decreased from 0.102 mm to ≤0.051 mm . Dimensional and concentricity deviations were effectively controlled, and surface roughness improved from 4.80/5.00 μm to 3.11/2.26 μm (outer/inner walls). This study confirms that synchronously regulating macro- and micro-structures via additive path optimization can suppress cutting vibrations and force fluctuations, interrupting the adverse hereditary chain and establishing a solid process foundation for the high-performance, high-precision integrated manufacturing of complex thin-walled parts.