Research on the application of lean MES system in

Research on the application of lean MES system in enterprise management

manufacturing execution system (MES) is developed on the basis of enterprise resource planning (ERP). It is located between the upper planning management system and the lower industrial control system. It is divided into 11 functional modules, such as production scheduling management, human resource management and production quality management. It can optimize the management of the whole production process from order release to product completion through information transmission. When real-time events occur in the factory, it can respond and report them in time, and analyze and process them with current accurate data

however, under the trend of enterprise lean, the problems exposed by the existing MES system are becoming more and more obvious. For example, when using "push production" in production scheduling, it is easy to produce differences between planning and actual production, and it is also easy to cause the pressure of WIP in the workshop, which increases the production cost of the enterprise; Ignoring the important role of people in site management; Backward quality management means, etc. These aspects are exactly the advantages of lean production. Therefore, this paper considers the combination of lean production and MES system, puts forward the concept of lean MES, and studies its functional architecture

I. functions and defects of the existing MES system

the American advanced manufacturing Research Institute (AMR) proposed a three-tier enterprise integration model in the 1990s, which positions the MES system at the executive level between the enterprise planning level and the control level. On the one hand, MES system recognizes and decomposes the planning information (such as production information, process reports, etc.) obtained from the upper layer in the system, and then transmits the information to the bottom controller to operate the equipment and guide the personnel to carry out production; On the other hand, feedback is obtained from the bottom controller, and the collected real-time production data, equipment status, product processing information, etc. are stored in the system. After statistical analysis and processing, they are returned to the upper planning layer, so as to ensure the smoothness of the information between the planning layer and the control layer

mes system can be roughly divided into two types: traditional MES (t-mes) and integrated MES (I-MES). The former has strong industry-specific characteristics; The latter is modular, reconfigurable and extensible

the existing MES system mainly has deficiencies in the following functional modules:

(1) production scheduling management module. The production scheduling of MES system is a typical push production scheduling. However, due to the uncertainty of production, the actual production situation is often very different from the plan. Therefore, this scheduling method will cause a large number of WIP backlog and the waiting for materials and downtime of some processes

(2) human resource management module. In MES system, people are regarded as the extension of equipment, and the operator can only passively accept the command of the system and cannot actively communicate with the system, which limits the exertion of workers' subjective initiative. In addition, there is a lack of necessary incentives for operating workers

(3) process level production planning module. MES system decomposes the workshop level production plan obtained from the upper ERP system into process level detailed production sequence plan, which is arranged to each work place. However, there are often large differences in production conditions and workers' levels, which will cause fluctuations in production, making it difficult for the actual production situation to coincide with the plan. Therefore, this module needs to be further refined

(4) resource allocation and status management module. In the MES system, the meaning of resource allocation and status management is: "manage the resource status and allocation information, including machine tools, auxiliary tools, materials, workers and other production capacity entities, as well as the documents and detailed historical data of resources that must be available at the beginning of processing, as well as the reservation and scheduling of resources to meet the requirements of production planning." The premise of these is that the system's allocation of resources is reasonable and effective, so corresponding methods need to be used to assist

(5) production process management module. MES system collects real-time production information from the site through various instruments and equipment to monitor the production process and achieve the effect of automatically correcting errors in production. However, this kind of monitoring by instruments is only a passive monitoring - waiting for errors to occur, then catching errors, and then taking measures to remedy them. The control of the production process must be changed from passive to active, and nip in the bud

II. Functional architecture of lean MES

lean MES is based on I-MES. Its functions include traditional production scheduling management, human resource management, process level production planning, resource allocation and status management, product tracking and product data management, production process management, production quality management, production equipment management, field data collection, document management, production performance analysis, etc. At the same time, lean MES emphasizes the idea of lean, which makes up for the shortcomings of the existing MES system

(I) lean MES function module. Based on the above description of MES system defects, lean MES needs to expand and improve the existing MES system in five aspects: production scheduling management, human resource management, process level production planning, resource allocation and status management, and production process management. The improved lean MES system should have the following functional modules:

(1) push-pull scheduling module. In terms of production scheduling, the method of "push planning and pull production" should be adopted, that is, when formulating the scheduling plan, various resources should be allocated according to the "push", and the time of product input and production of each process should be specified; In actual production, the "pull" method is adopted. When a process completes the task, a completion information is sent to the system. After receiving the information, the system sends a demand instruction to its previous process through electronic kanban. In this way, the flow production is realized through the pull between processes. Here, the scheduling plan is only a reference rather than an instruction. The real instruction is "electronic Kanban". After a certain time, the system must update the scheduling plan once to adapt to the actual production situation at that time

(2) human resource management module based on people. In terms of human resource management, in addition to providing workers' basic information and real-time work status information, real-time communication technology should also be used to realize the information communication between the production site and vehicle control; Add the function of post evaluation, use the real-time recorded IAI for statistical analysis, and display it through the electronic Kanban in the workshop, so as to improve the enthusiasm of employees to a certain extent, and provide data basis for year-end evaluation. In addition, in order to improve production efficiency and reduce workshop operating costs, enterprises must cultivate versatile workers who are competent for a variety of jobs. Therefore, MES system should establish a training plan suitable for each employee, conduct regular assessment, and record the types of work mastered by workers as the basis for human resource allocation during production scheduling

(3) step level production planning module. Introduce the work standardization method of lean production. First, realize the standardization of operation through action analysis technology, specify the operating conditions, contents and steps of various processing in detail, and refine them to specific actions. Then use stopwatch method or scheduled time standard method (PTS) to determine the standardization time, and enter the above information into the MES system database. Finally, when the MES system decomposes the process level production plan, it automatically takes these information from the database and adds it to the process card, so as to better guide workers to carry out efficient production operations

(4) customized resource allocation and state management module. Using the positioning management method of lean production, before the resource allocation of MES system, the placement position and status of various items (such as equipment, raw materials, knives, fixtures, etc.) must be determined according to the action economy principle and process requirements, so as to ensure that the operators can get the required items quickly, accurately and with less effort. Then the information of these items and their corresponding location information are stored in the MES system. When the system allocates resources, it comprehensively considers factors such as cost and time according to the information recorded above. Complete the configuration of equipment, personnel, materials, auxiliary tools, etc. Once the system has completed the resource allocation, it is necessary to carry out the site location management in strict accordance with the predetermined location method. In this way, we can ensure that the use of industrial alliance in the field of synthetic Litao aluminum new material diesel engine of MES system resource management can be rationally and accurately reflected on the operation site

(5) visual production process management module. In this regard, an experienced manager has greater advantages than instrumentation. Because using people to manage, we can not only find and solve the errors that have occurred in the production process, but also have a sharper ability to predict the errors that are happening or will happen. Therefore, first of all, we need to introduce the "visual management" method of lean production into the MES system to visualize the on-site problems, and then configure a certain number of on-site managers at the production site to cooperate with the MES system to complete the production process management. In order to achieve this goal, lean MES system needs to realize a wireless network interface in function, so that field managers can interact with the system in real time through terminals (such as handheld computers)

(6) other modules. Lean MES system. The equipment management, document management, production performance management, quality management, product tracking/Product data management and field data acquisition modules are basically the same as the current MES system, and will not be repeated

(II) information model of lean MES system. Based on the above functional model, build a lean MES information model. Lean MES system has 2 inputs and 9 outputs. The specific information transfer description of each module is as follows:

"field data acquisition" module is connected with the bottom control system. It collects various production information from the bottom control system manually or automatically, and transfers it to the corresponding module for processing

"customized resource allocation and state management", "equipment management" and "document management" four modules statistically analyze the information about human resources, production resources, equipment, production records and so on collected from the site, and then integrate the human resources information (including the natural conditions of workers, skills mastered, working state, fatigue degree, opinions and suggestions, etc.) Production resource information (including the basic information, storage location, available status, etc. of various equipment and accessories), equipment information (including equipment model, location, processing accuracy, reliability, etc.), document information (including production process, process card, operation standard, etc.) are transferred to the "step production plan" module to provide data basis for the decomposition of the plan. At the same time, these information will be output to the system users in the form of charts

"visual production process management", "product tracking/Product data management", "Lean quality management" and "production performance analysis" record and analyze the production process information, product information, quality information, production statistics and other information collected from the site, and transmit the analysis results to the push-pull scheduling module in real time. This includes delayed pauses in the production process