Research On U-shaped Mixed-model Assembly Line Balancing Problem Base On Lean Production

Since the financial crisis of 2008,the economic recovery has been slow,and make manufacturer face more and more unprecedented challenges.With the raw material prices and labor costs continue to rise in recent years,it aggravates the enterprise burden.In addition,the fierce competition between domestic and foreign enterprises and the demand are increasingly personalized and diversified,which brings great impact to enterprises planning,organization and on-time delivery.Facing the pressure of cost,competition and management,a management technology is urgently need to change the current predicament.Practice has proved that lean production is one of the most efficient production methods.U-shaped layout is used by lean production,its exit and entry are in the same side,and the space for the U-shaped line is compact.The job assignment for the U-shaped line is more flexible.It can be adjusted the takt time base on the customer demand,so it has better flexibility.So it is widely used in mixed-model manufacturing of multiple varieties in small batches.However,many uncertain factors in actual production affect the improvement of U-shaped mixed-model assembly line balancing.Therefore,the research of uncertain U-shaped mixed-model assembly line balancing based on lean theory is more practical and instructive for enterprises.The research object for this paper is U-shaped mixed-model assembly line base on lean theory.First,this paper will start lean production and assembly line balancing basic theory,and analyze Urban shadow constraint model and improve and pefect it by adding the position of the coding,at the same time,analyze the final optimization objective of the U-shaped mixed-model assembly line balancing base on the characteristics of the lean theory.Then research the U-shaped mixed-model assembly line balancing base on the certain and uncertain operating time,and the practical case of S company is actted as the application analysis to verify the effectiveness of the model.When set up the multi-objective optimization model for the certain U-shaped mixed-model assembly line balancing problem with fully considering the rule as learning effect,strengthening constraint,the task priority relationship constraint and takt time constraint,etc.Take Jackson and other standard problems as examples to solve the U-shaped mixed-model assembly line balancing problem base on certain operating time by the Matlab code of the traditional genetic algorithm,and the running results show that the model is effective.However,in the actual manufacturing process of enterprises,there are many uncertain factors such as customer demand,product demand ratio,operating time,machine failure,etc.,which affect the normal operation of the production line at any moment.Therefore,the research of uncertain U-shaped mixed-model assembly line balancing is closer to the actual production of enterprises.Due to the complexity of uncertain factors affecting the normal operation of production line,it is difficult and unrealistic to comprehensive research all the factors.However,the analysis of uncertain factors reveals that most of them directly or indirectly affect the working time.Therefore,this paper only studies the uncertainty of operating time.An U-shaped mixed-model assembly line balancing optimization model with uncertain operation time is set up and solved by improved genetic algorithm.The improvement of the genetic algorithm was mainly completed by the two-layer random coding principle and improving the fitness by difference coefficient.The running results based on the Kilbridge problem showed that the model and the improved genetic algorithm were also effective.Finally the water alarm line of S company is acted as an application sample to research,and the mixed-model assembly line balancing rate are more than 90% after running the Matlab code of the improved genetic algorithm,which is better than 75% balancing rate for the current,and the improved effect is obvious.The results show that U-shaped mixed-model assembly line balancing problem model and the improved genetic algorithm has the realistic operability,and it is of great realistic significance to the enterprise.