PSI - Issue 81

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ScienceDirect

Procedia Structural Integrity 81 (2026) 447–454

© 2026 The Authors. Copy from the contract: Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of DMDP 2025 organizers Keywords: curved axis, manufacturing technology, machining accuracy, center holes, tooling, machining error . Introduction The advancement of mechanical engineering is driven by the implementation of knowledge-intensive technologies, modern machine tools, cutting instruments and technological equipment. Machining parts with external cylindrical surfaces whose geometric axes intersect at a specific angle – known as curved axes – presents distinct challenges. It is important to make a proper definition of the process, thus provide essential means for process control and its optimization (Paulo Davim J.(2008, 2016)). A urrekoetxeaet al.(2022) studied the effects of clamping on machining, and different clamping devices were developed to avoid deformations. Jian-Hua et al. (2016) designed a clamping system in which stresses can be released during machining. This is an adaptive double-sphere system that is adjusted to produce stress-free clamping, thus avoiding induced location errors. Wang et al. (2016) used a low-melting-point alloy to clamp and support thin-walled parts. Meshreki et al. (2008) introduced a new concept to optimize clamping capability by designing a model predicting the dynamics of complex thin-walled aerospace structures under Abstract This paper examines and substantiates the technological challenges associated with machining curved axes, characterized by the absence of coaxial center holes. The complexity stems from the fact that the vertex of the angle formed by the intersecting geometric axes of the part lies within its body, while the part geometry and fixture design create an imbalance in the fixture-part subsystem that continuously varies throughout the machining process. Three locating schemes for turning and grinding operations using three center holes are technologically proposed: utilizing a parallel-offset, angular and axial centers; two perpendicularly offset and one axial centers; and two centers positioned in the part's plane of symmetry along with an axial center. Analytical calculations and experimental investigations for all three locating methods demonstrate that the most accurate approach is locating with parallel-offset, angular and axial centers. The precision of the resulting angle between geometric axes for this locating variant can be achieved within 5 13   − . Locating the axis using two perpendicularly offset and one axial center enables precision of 25   , while locating with two centers in the plane of symmetry and one axial center yields 22   . Development and investigation of technological approaches for ensuring reliable locating, operational allowances, parameter control and tooling reliability will eliminate the identified shortcomings in curved axis manufacturing technology. VIII International Conference “In - service Damage of Materials: Diagnostics and Prediction“ (DMDP 2025) Machining technology for curved axes: uncertainty in locating and accuracy challenges Igor Stoiko*, Oleg Lyashuk, Igor Tkachenko, Dmytro Mironov, Andriy Gupka, Oleg Lakh, Igor Okipnyi Ternopil Ivan Puluj National Technical University, 46001 Ternopil, Ukraine

* Corresponding author. Tel.: +380967517889. E-mail address: lyashuk_o@tntu.edu.ua

2452-3216 © 2026 The Authors. Copy from the contract: Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of DMDP 2025 organizers 10.1016/j.prostr.2026.03.077