Modeling And Simulation Of The Bottleneck-Driven Integrated Workload Control Method For Order Release And Shop Scheduling

Workload control is an effective production planning and control technology to deal with MTO production environment by controlling the order release of pre-pool,which maintains the WIP at a relatively stable level,thus shortens the production cycle and reduces the tardiness of orders.In the MTO production environment,there is no pure job shop,but general flow shop.However,the traditional workload control method research and application is more focus on the job shop rather than general flow shop with bottleneck,limites to order release,and neglects the setup time constraints.Therefore,based on the analysis of the current research on workload control method,this paper studies the production environment of the general flow shop with bottleneck and the setup time of orders,and proposes a method of bottleneck-driven order release and shop scheduling integrated workload control by combining the DBR mechanism with workload control method and develops the model and simulation of Lvalve enterprise production system.Modeling and simulation of the bottleneck-driven integrated workload control method for order release and shop scheduling proposed in this paper as follows: Firstly,according to the characteristics of general flow shop with bottlenecks,DBR mechanism is introduced to construct a periodical and continuous mixed release method of LUMC COR-DBR,periodical release method same as LUMC COR,but the trigger condition for continuous release is that when the bottleneck workload is lower than the workload trigger,the bottlenecks machine pulls the first step to the pre-pool to release.Secondly,for orders in pre-pool,there are two types according to whether or not they pass through the bottlenecks machine: drum chain and non-drum chain.For the non-drum chain order,the planned operation start time is calculated according to the traditional method.For the drum chain order,considers the setup time of the order on the bottlenecks machine and the setup time of the order before the bottlenecks,and proposes an IPST order sorting rule.Finally,in order to save setup time and based on the LUMC COR-DBR method,heuristic rules for order release in pre-pool and scheduling rules based on buffer state for shop bottlenecks machine front orders are designed.Based on the bottleneck-driven integrated workload control method of order release and shop scheduling,the integrated workload control method is simulated by FlexSim software with the actual case of L-valve enterprise.The experimental results show that when the workload norms and the workload norms ratio are at any level,the IPST order ordering rule proposed in this paper is better than the PST order ordering rule;when the workload norms is greater than or equal to 15 and the workload norms ratio is greater than or equal to 1(or workload norms is greater than or equal to 25 and the workload norms ratio is equal to 0.5),the SOBS which saves setup time is better than the BS and FCFS rule.When the difference in processing time between different orders on the bottlenecks machine is small,the workload control method considering setup time saving in the integration of order release and shop scheduling is superior to the workload control method considering setup time saving only in the order release or only in the shop scheduling.