Hybrid processes of additive and subtractive manufacturing offer designers the potential to develop complex, lightweight parts by additive manufacturing coupled with superior surface quality and tolerance by subsequent machining. The thin-walled additive structures tend to deflect while machining due to static and dynamic effects. With the design for additive manufacturing, additional stiffening structures can be included to reduce vibrations. This work investigates the design of additively manufactured stiffening structures for vibration reduction in the milling of thin-walled parts. A vibration analysis of a probe geometry is simulatively performed to identify significant design parameters. From the outer dimensions, the height of a stiffening structure shows the highest influence, followed by the length. With larger stiffening structures, the mass rises, so a tradeoff between deformation reduction and additional material is necessary. Over the parameters length, width, and height, the deformation can be reduced by a factor of 800 while a mass increase of 4.82 %. Stiffening structures shall be positioned against the excitation direction of the milling force. Over the parameters quantity, position, and distance, a deformation reduction of 185 for a mass increase of 7.11 % can be realized. The paper concludes with design guidelines for additively manufactured stiffening structures.

Additively manufactured components require machining of functional surfaces to meet geometric requirements. Due to low stiffness and non-nominal as-built geometry, they are susceptible to milling-induced shape deviations. This paper presents a hybrid process simulation for predicting shape errors in compliant metallic laser powder bed fusion components. The method combines real-geometry-based technological NC simulation, quasi-static force prediction, finite element-based structural response simulation, and surface reconstruction between roughing and finishing to enable multistage operation. The approach is validated for linear and non-linear toolpaths with varying immersion angles and compliance conditions. The results show reproduced force profiles, while magnitude deviations highlight the relevance of deformation-dependent engagement feedback in high-compliance regions. An analytical back-calculation based on the effective engagement cross-section reveals that accounting for deflection-induced engagement reduction reduces force deviations. During roughing, maximum shape errors for linear and non-linear toolpaths are overestimated by 4–5 %, and critical high-error regions are identified. The reconstructed intermediate geometry after roughing is essential for finishing, since neglecting geometry feedback underestimates finishing forces. With geometry feedback, the maximum finishing shape error is predicted as 0.090 mm, while the measured value is 0.086 mm. The simulation captures dominant quasi-static shape-error regimes and supports process-chain-oriented prediction in additive-subtractive manufacturing.