Simulation Study On Control Performance Of Assembly Workshop Based On Load-based Card System

For the customized assembled products in the multi-varieties and small-batch production mode,its production management is highly complex.In terms of the external environment,the market demand for customized assembled products is unstable,and different orders have obvious differences in product structure,process resource demand,and product delivery time.In terms of the internal environment,the production load in the workshop is highly unbalanced due to the uncertain factors in the production process,resulting in the unbalanced distribution of production load in time and space.Secondly,the assembly constraint relationship between the related parts of products makes it difficult to coordinate the production of the parts.The assembly process cannot begin until all the necessary materials have been processed.Therefore,the method of production management and control of customized assembled products needs higher environmental adaptability.The traditional methods of production management and control,such as MRP or OPT,show considerable limitations due to their slow response to market demand changes and do not allow the existence of drift bottlenecks.As a kind of simple and effective production control system,the card control system is flexible to produce on demands according to the information in the feedback loop.Because of its practicability and ease of implementation,it has been successfully applied in the past production practices.Traditional card control systems,such as Kanban system and CONWIP system,are mainly aimed at the manufacturing environment where the product structure is relatively fixed and the production process is relatively stable.The LB-POLCA((i.e.Load-based paired-cell overlapping loops of cards with authorization)and the Cobacabana(i.e.Control of balance by card-based navigation)are two new types of load-based card control systems,which are more suitable for the production environment of multi-varieties and small-batch,and have the capacity of load balancing in the workshop.They have certain potential for workshop production control of customized assembled products.However,previous research on these two types of systems often focused on the traditional job-shop,neglecting the assembly associations between materials.In view of this,under different assembly relevance levels,the workshop performance of these two types of systems is simulated under the combination of control parameters in this thesis.Firstly,the key control parameters of system was analyzed.Secondly,a generalized simulation model was established based on the platform of simulation software e M-Plant,and a large number of experiments were conducted to reveal the changes of system performance under different assembly relevance level and different combinations of system control parameters.Then,six purpose-oriented handling strategies were proposed,which were combined with the system operation mechanism of LB-POLCA and Cobacabana respectively.The influence of each handling strategy on system performance is simulated under different assembly assembly relevance.Finally,the system performance of LB-POLCA and Cobacabana is to be compared.In this thesis,the applicability of LB-POLCA systems and Cobacabana systems under complex assembly constraints environment is evaluated by using computer simulation technology,which revels the influence of the difficulty of schedule coordination caused by the increase of assembly relevance levels on the performance of such card control systems.Under different assembly relevance levels,the correlation law of different purpose-oriented WIP handling strategies on the performance of card control systems is obtained.The research results of this thesis have enriched the theory of card control technology and provide some reference for the application of card control system in the production of customized assembled products.