Abstract: Spare parts inventory management is a very important work in equipment support engineering, and the classical METRIC theory is proposed for repairable spare parts with high price and low demand rate, and such spare parts usually adopt (S-1,S) inventory strategy. However, for non-repairable spare parts with moderate price, high consumption and important role in equipment operation, the inventory strategy of continuous inspection (S-1,S) is no longer applicable, and this kind of spare parts is more suitable to adopt (r,Q) inventory strategy. On the other hand, under the carbon tax policy, the spare parts support unit has to adjust the ordering strategy to achieve emission and cost reduction. Therefore, under the two-echelon support chain consisting of multiple grassroots stations and one base station, we conduct joint optimization on the ordering strategy of each station, and analysis the impact of carbon tax policy on the ordering decision of support chain.
In this paper, it is assumed that the demand for spare parts is subject to Poisson distribution; the grassroots station i implements (r_i,Q_i) inventory strategy and the lead-time is L_i; the base station implements (T₀,Q₀) inventory strategy and the lead-time is L₀. With such assumptions, the spare parts ordering models of grassroots-level and stations are firstly constructed respectively. Then, the joint order model is obtained by combining the separate models together, and the model takes grassroots station reorder point r_i, order quantity Q_i and base station replenishments times m_i as decision variables, takes spare parts satisfaction rate as constraint, and takes expected cost as target. Finally, the model is solved by the policy-iteration algorithm, and the influence of carbon tax on support chain decision is studied in the numerical analysis.
The numerical analysis results show that the results of the influence of the lower limit of spare parts satisfaction rate to the decision of the support chain are consistent with the actual situation, thus the correctness and feasibility of the model are verified. When the carbon tax is relatively high, the grassroots stations tend to order fewer spare parts in the larger reorder points, while the base station tend to order fewer spare parts at an earlier time to make up for the increase of the support chain cost caused by the high tax value. Although the carbon tax policy increases the support chain cost, while a reasonable tax can be achieved significant emission reduction effect and is conducive to the reduction of environmental cost.

Key words: support chain, consumable spare parts, joint ordering, spare parts satisfaction rate, carbon tax