Study On Semi-Finished Product Inventory Distribution In The Postponement Of Iron And Steel Enterprises

In China,most steel enterprises adopt production processes with blast furnaces and converters as the main production facilities,which are typical process oriented production enterprises with strong production continuity,unidirectional production processes,and a multitude of process steps.With advancements in steel production technology and the growth of the steel market,more iron and steel enterprises have adopted Postponement to ensure production stability while reducing total costs and shortening lead times to meet customer order demands.The Postponement in iron and steel enterprises involves the continuous production process,utilizing semi-finished product inventory to postpone the formation of final products until precise customer demands are obtained.Among these elements,the distribution of semi-finished product inventory is a critical factor in implementing Postponement in iron and steel enterprises.Balancing the service level to meet customer requirements and reducing total costs through the control of semi-finished product inventory distribution is a key challenge in Postponement.This dissertation focuses on the study of semi-finished product inventory in the Postponement of iron and steel enterprises.It analyzes the characteristics of the steel production process and the requirements of Postponement.The dissertation consolidates the three stages of steel production(smelting,rolling,and finishing)into two stages in the Postponement process.The first stage encompasses iron-making,steel-making,and rough rolling,serving as the generalized production process in the steel Postponement.The second stage includes finishing rolling,finished product and deep processing,and deep processing,representing the specialized production process in Postponement tailored to customer order requirements.The dissertation considers both internal and external factors influencing steel production,constructing mixed-integer programming models for optimizing semi-finished product inventory distribution in the two-stage production process for a single cycle.Additionally,it extends the models to multiple-cycle scenarios.Particle swarm optimization algorithms are applied to solve the proposed models,and the effectiveness of the models is validated by using real enterprise data.The study reveals that improving customer service levels and increasing delay penalty coefficients both encourage semi-finished product inventory distribution points to move closer to the endpoint of their respective processes,but specialized production processes are more significantly affected by semi-finished product inventory.The capacity of semi-finished product inventory points in the dissertation specialized production process directly influences the consumption of semi-finished product inventory in the generalized production process.External factors such as the automotive industry supply index,building materials industry supply index,construction machinery industry supply index,and comprehensive steel prices can promote the movement of semi-finished product inventory distribution points toward the endpoint of their respective processes by influencing internal factors.This dissertation enriches the research on the optimization of semi-finished product inventory distribution in the Postponement of iron and steel enterprises,providing modeling methods and research insights that can be applied.The optimization models constructed in this study effectively analyze the distribution patterns of semi-finished product inventory and offer managerial recommendations for the production and operation management of iron and steel enterprises.The innovations of this dissertation are as follows:(1)The proposal of the viewpoint "dividing Postponement of steel production into two stages of generalization and specialization" was proposed..Based on the characteristics of process steel production and the requirements of Postponement,combined with the distribution and function of semi-finished products inventory,and using system analysis methods,the traditional three-stage process of steel production,including smelting,rolling,and finished products,is re-divided into two stages of general and specialized processes suitable for Postponement of steel production.This process not only meets the requirements of steel production technology and Postponement,but also simplifies the stage division of semi-finished product inventory,which can better study the distribution of semi-finished product inventory in Postponement of steel production.(2)The construction of the "Basic Optimization Model for Semi-finished Product Inventory Distribution in Postponement of Iron and Steel Enterprises" is constructed.Unlike previous studies on Postponement inventory that only considered a single decoupling point in inventory control,this dissertation solved the inventory point and storage capacity of semi-finished products corresponding to the two stages of generalization and specialization in Postponement of steel production,aiming at minimizing the total cost under a certain customer service level,and constructed the "Basic Optimization Model for Semi-finished Product Inventory Distribution in Postponement of Iron and Steel Enterprises".And achieved joint optimization of the distribution of two types of semi-finished product inventory by limiting the total inventory of semi-finished products through constraint conditions.Aiming at the mixed integer programming model,particle swarm optimization(PSO)is used to solve it,and an example is analyzed with enterprise data,which verifies the effectiveness of the model and algorithm,and identified the impact of model parameter changes and constraints on the distribution of semi-finished product inventory.(3)The proposal of a method to integrate external factors affecting steel production into the semi-finished product inventory distribution optimization model in a quantitative way was proposed,and the "Optimization Model for Semi-finished Product Inventory Distribution Considering Internal and External Factors" is constructed.In the past,only external factors that affect production were considered as uncertain factors in inventory control for Postponement.This dissertation proposes a method of determining the main external influencing factors of steel production through data mining,using correlation analysis and multiple regression analysis to quantify the relationship between external and internal factors,and constructs an "optimization model of inventory distribution of semi-finished products in Postponement of steel production considering internal and external factors".Particle swarm optimization(PSO)is used to solve the model,and an example is analyzed to determine the influence of main external factors on the inventory distribution of semi-finished products.(4)The proposal of a method to transform the multi-period model of semi-finished products inventory distribution in Postponement of iron and steel into a two-period model was proposed.According to the current situation of multi-cycle steel production,according to the analysis of the generation,consumption and transfer of semi-finished products inventory in multi-cycle and multi-stage Postponement,this dissertation puts forward a method to transform the semi-finished products inventory distribution problem of multi-cycle steel production into the semi-finished products inventory distribution problem of two-cycle steel production,which solves the problem that the semi-finished products inventory of multi-cycle steel production is influenced by cycle transformation,and constructs the "semi-finished products inventory distribution optimization model based on multi-cycle production" based on the single-cycle optimization model.Particle swarm optimization(PSO)is used to solve the problem,and the distribution law of multi-cycle semi-finished products inventory is discovered through example analysis.There are 35 figures,23 tables,and references to 152 sources.