Research On The Processing Problem Of Rush Orders Based On The Theory Of Constraint

For manufacturing enterprises, in the field of production planning and control,how to combine and optimize the normal order and the rush order under themake-to-order (MTO) production style is a significant decision-making problem.The rush order is a double-edged sword under the condition of limited productioncapacity. On the one hand, it can bring high profit to enterprise, but on the otherhand it will interfere with the production of the normal order. This paper takes theadvantages of the tool of theory of constraint (TOC) DBR (Drum-Buffer-Rope)，which has the superiority of identifying and eliminating the dynamic bottlenecks inproduction systems, to study the rush order processing problem. The topic of thispaper has its practical and theoretical value.Based on the similar studies about rush order processing problem and theapplication of TOC, this paper summarized the theory of MTO, common processingmethods of rush orders and DBR method, studied two decision-making problems:the first is how to insert the rush orders into normal orders; the second is how tocontrol the material input in the production process. For the former, this paperelaborated the necessity and basic principles of order inserting, focus on the study oforder evaluation based on grey correlation analysis method, the method considering8factors of rush orders, and determine the priority of each rush orders in accordancewith the grey relational grade, ultimately form the rush order sequence. Then, a rushorder inserting method which based on profit preference is presented, and theoptimal order inserting scheme is determined. For the latter, in consideration ofDBR method has the advantages of dynamic identification and elimination ofbottleneck resource, to solve the production control problem through using it. Firstof all, select the DC-WIP dynamic input strategy to guide the material input in theproduction process of optimal scheme; then identify the bottleneck procedure inproduction system, and set its material input rate to coordinate with other workingprocedures; at the same time, set the buffer time at bottleneck and assembly workingprocedures, establish mathematical model to calculate the time buffer capacity.Finally, combined with the actual case of vehicle manufacturing enterprises,this paper established a production system simulation model based on DBR method,presented a material input solution which considered the time buffer, then compare and analysis the different effects of existing scheme and the solution this paper havepresented through three indicators: The order completion time, The utilization rateof equipment, The amount of WIP. The simulation and evaluation results show that:the rush order evaluation method which based on grey correlation analysis methodand the rush order inserting method which based on profit preference model arefeasible, they can determine the optimal rush order inserting scheme scientificallyand reasonably; the production material input control solutions which consideringthe time buffer is better than the existing scheme of enterprise on technique andeconomy.