eng Science and Education Publishing American Journal of Mechanical Engineering 2328-4110 2025-10-21 13 1 11 20 10.12691/ajme-13-1-3 AJME20251313 article Heping Peng hbjhun_hppenn@163.com 1 Zhuoqun Peng 2 Qianpeng Han 2 School of Intelligent Manufacturing, Jianghan University, Wuhan 430056, China Wuhan Urban Railway Branch, China Railway Electrification Engineering Group Co., Ltd. Wuhan 430074, China Most of the existing concurrent tolerancing methods can only be used to solve optimal tolerance allocation problems under the conditions of given manufacturing processes and economical process tolerance ranges, which are difficult to get the global optimization solutions of process and design tolerances, as well as the most economical processing routes. With the aim to address these shortcomings, an optimization mathematical model was developed in this paper, in which we consider the selection of alternative manufacturing processes by introducing a manufacturing process selection coefficient into the existing concurrent tolerancing model. The recommended model simultaneously allocates the design and process tolerances with alternative machining process selection by minimizing the total cost including the production cost and the expected quality loss, and taking the product function requirements, the economic machining tolerance range for each alternative process operation, and alternative manufacturing process selection as constraints. In order to accurately solve this discrete integrated optimization model, the MATLAB R2016b is adopted as a nonlinear programming technique to achieve the optimization solution of concurrent tolerancing allocation and manufacturing process selection. The numerical example of a gear assembly proves that the proposed model can not only select manufacturing processes but also realize concurrent optimization allocation of tolerances. https://pubs.sciepub.com/ajme/13/1/3/ajme-13-1-3.pdf Concurrent Tolerancing Quality loss function Alternative manufacturing processes Optimization Process tolerance