###### Abstract  
Increasing productivity and efficiency in factories with make-to-order (MTO) production systems have attracted growing interest of academia and industry. In MTO companies, efficient order release and schedule are essential for succeeding in today's marketplace. However, dynamic demand of customers and constrained resources make it difficult to achieve, as well as limiting the profits. Thus, to overcome the problem of order releasing and multi-item scheduling considering the capacity constrained resources investigated, a heuristic approach is proposed based on the drum-buffer-rope (DBR) method. The proposed heuristic is tested on different types of problems based on due date tightness and demand of products. The performance of the proposed heuristic is compared with other famous heuristic methods in literature. End results indicate that the proposed heuristic based on the DBR method outperforms against the other competitors, and it gives more significant results when optimal buffer size is adopted. drum buffer rope; order releasing; multi-item scheduling; capacity constrained resource; heuristic algorithm +
Footnote †: journal:  
0000-0001-999-2000-0000-0000-0000-0000-0000-0000-0000-0000-00000-0000-00000-0000-00000-0000-00000-00000-00000-00000-00000-00000-00000-00000-000  
In MTO companies, the planning to produce the final product begins when the customer order is received by the company. One of the disadvantages of the MTO companies is that the lead time to fulfill the orders can exceed the due date of orders, and it may result in penalty costs for companies. Order acceptance and scheduling problems have been investigated in literature by many researchers with different optimizing objectives, including minimization of tardiness or minimizing tardiness related penalties [4; 5]. Different heuristics and meta-heuristic methods have been developed for order selection and scheduling problem in literature [3; 6; 7; 8]. However, most of the companies are used to sequence the customer orders at a planning level based on the earliest due date (EDD) or first in first out (FIFO) rules, etc. to simplify the process. Moreover, these heuristics have also been employed to optimize the multi-level planning and scheduling problems [9; 10; 11; 12]. Once the scheduling of orders is completed at the planning level, the customer orders are then scheduled according to the material-based grouping or order release-based rules. In real environments, the customer orders are received randomly and demand is uncertain. The accurate demand and the production order release to produce different parts for final products are critical to determine for each planning horizon. Moreover, production order release from the planning level to the scheduling level is critical to give timely order release information. In most of the companies, there is no proper control mechanism that can determine the production order release of the mix model products [13]. Therefore, rescheduling frequently occurs during the production, which can increase the production lead time and cannot give required production in the required time [13; 14]. In addition to these problems, in most of the production lines, some resources hit a bottleneck due to insufficient planning. The resources in a bottleneck can limit the production rate, which are known as capacity constrained resources (CCR). Companies try to fully utilize CCR resources to give continuous production with improved production rate or throughput. Therefore, semi-finished parts are stored near CCR in buffer so that CCR resources cannot become idle in case of any failure. Consequently, the CCR can continuously process to make product models by taking already completed parts of the mix of products from buffer. In MTO, the CCR can be a resource which can use semi-finished standard parts of the product models to make customized product models. Moreover, the production of final product models is carried out on a series of machines like a flow shop.