Research On Freezer Door Production Line Sequencing Problem

With the increasing of global market competition and the development of personalized customer requirements, manufacturing enterprises have to ensure that products of high quality and production of low cost, and guarantee to satisfy the personalized needs of customers in the shortest possible time. So, the production pattern of enterprise transform from the traditional mass production mode to multiple varieties and small batch production mode, the assembly line of traditional single varieties gradually replaced by the mixed flow assembly line of multiple varieties. Among them, the reasonable production sequencing of mixed flow assembly line is one of the effective ways to improve the efficiency of mixed flow assembly line, and it has the vital significance for the enterprise in market competition.This paper applies an freezer door production line of a freezer company as an object, studies with the foaming mould constraints of mixed flow production line sequencing problems. This production line consists of two parts, with pre-assembly line and foaming line. Among them, the pre-assembly line complete the assembly of the parts of a door, the foaming line complete the filling of door body heat preservation and heat insulation layer. Due to the constraints of mold type and mold number of foaming line, in the case of mixed flow production, sequencing of production in the pre-assembly line and sequencing of mould in the foaming line directly affect the matching rate of product model and foaming mould model in the process of production, which affect the number of empty foaming mould and the number of average work-in-process inventory. Therefore, this paper optimize the sequencing of mixed flow line production of pre-assembly line and foaming line, in order to reduce the number of empty foaming mould and the number of average work-in-process, so as to achieve the purpose of increasing production and reducing cost.First of all, the sequencing of production in the pre-assembly line is studied. Production sequencing is to ensure that the purpose of the balanced production, shorten the delivery time, reduce the work-in-process inventory, and improve enterprise competitiveness. Pre-assembly line, therefore, the introduction of the three objective functions are:keep average consumption rate of all parts, minimize the Minimal Production Set (MPS) cycle time and maximize the process similarity. Through the establishment of the three objective function can be made with the pre-assembly line to achieve balanced production and shortest production on time.Next to the study of mould in the foaming line sequencing. For foaming line, the minimum quantity of empty foaming mold and minimum of average work-in-process inventory quantity is studied. With a view to make foaming line with pre-assembly line to achieve the optimal matching degree, thus improve enterprise’s production and improve the utilization rate of resources.Then, according to the characteristics of the pre-assembly line and foaming line, this paper choose improved genetic algorithm for solving the mathematic model of two stages. For premature phenomenon such as existing genetic algorithm, combined genetic algorithm and tabu search algorithm, join tabu table judging in cross section, and join tabu search for data processing in the variation part. Especially in light of the characteristics of foaming line, design the inventory calculation algorithm to calculate the number of empty mold foaming mould and work-in-process inventory quantity.Finally, the practical problems in the door production line of this air-conditioner company as case analysis, respectively use basic genetic algorithm and improved genetic algorithm to solve sorting scheme of two stages. The final results show that the improved genetic algorithm is better than that of the basic genetic algorithm, and proved in this paper, the feasibility of the research method, effectively improves the production efficiency of the enterprise, and avoid the waste of resources.