## 3 Modeling
### Model for Order Reorganization Level  
After being processed by the order splitting level, the demand plan is divided into multiple sub-order tasks, which are then passed to the order reorganization level for further processing. The order reorganization level optimizes the production sequence, process flow, and resource scheduling of each sub-task to ensure efficient task completion while preventing excessive equipment usage, frequent process changes, and material waste. Additionally, by optimizing task prioritization and scheduling, the reorganization level ensures that all sub-tasks are completed on time, reducing extra costs caused by delays. This enhances production efficiency, lowers costs, and guarantees on-time delivery. Therefore, the main objectives of the order reorganization level are twofold: minimizing production costs and minimizing order delivery delays. 1. Production costs. In the process of constructing a mathematical model with the goal of minimizing the production cost of orders after restructuring, it is necessary to comprehensively consider the changes and impacts of material costs, labor costs, and equipment costs during the order restructuring process. The mathematical expression is as follows: \[C\_mat=\sum_{i\in I}\sum_{m\in\mathcal{M}}\left(pr_{m}\cdot q_{i}\cdot B_{m,i} +v_{m}\cdot q_{i}\cdot\eta_{m}\right)\] (23) \[C\_lab=\sum_{i\in I}\sum_{p\in P}\sum_{j\in J}\sum_{r\in R_{p}}\eta_{\text{ lab}}\cdot\frac{\tau_{ip}^{(r)}}{\eta_{k}}\cdot x_{ijp}\] (24) \[C\_mac=\sum_{i\in I}\sum_{p\in P}\sum_{j\in J}\sum_{k\in K}c_{\text{run}} \cdot T_{ipjk}\cdot x_{ijp}+\sum_{i\in I}\sum_{j\in P}\sum_{k\in K}c_{\text{ switch}}\cdot Sw_{ijp}+\sum_{i\in I}\sum_{p\in P}\sum_{j\in J}\sum_{k\in K}c_{dep} \cdot T_{ipjk}\cdot x_{ijp}\] (25) where \(C\_mat\), \(C\_lab\), and \(C\_mac\) represent material costs, labor costs, and equipment costs, respectively. 2. Delivery delays. In the order reorganization model, incorporating delayed delivery time as one of the optimization objectives is significant as it systematically balances production resource allocation and order prioritization, effectively reducing order delivery delays. This, in turn, enhances customer satisfaction and strengthens the company's reputation. Since an order demand plan consists of multiple orders, and each order includes multiple product specifications, the delivery delay time of each order is determined by the latest delivery time among its product specifications. The total delivery delay time is the sum of the delivery delays of all orders. Therefore, the total delivery delay time of an order demand plan can be obtained using Equation (26). \[T_{\text{delay}}=\sum_{i\in I}\underset{i\in I}{max}(0,\underset{i\in I,p\in P }{max}(Tg_{ip})-Tde_{i})|\] (26)  
After completing the construction of the production cost and delivery delay models, the objective function of the mathematical model for the order reorganization level can be expressed as Equations (27) and (28). \[min\ C_{produce}=C_{mat}+C_{lab}+C_{mac} \tag{27}\] \[min\ T_{delay}=\sum_{i\in I}\underset{i\in I}{max}(0,\underset{i\in I,p \in P}{max}(Tg_{ip})-Tde_{i})| \tag{28}\]Meanwhile, throughout the order reorganization process, this study also establishes constraints from multiple dimensions, including materials, processes, equipment, and work efficiency.