The MES manufacturing execution system is mainly used to solve the problem of disconnection between the production plan and the production process in the overall optimization. This problem has not only directly affected the production efficiency of the enterprise, but also has restricted the internal information integration of modern enterprises and the supply chain optimization between enterprises. The bottleneck.
The MESA International Federation defines MES as follows: MES can optimize the management of the entire production process from production order to product completion through the transmission of information. When real-time events occur in the plant, the MES can react to these events in a timely manner, report them, and constrain and process them with current accurate data.
At present, the development of MES key technologies has reached a fairly mature level. To develop an MES is not a problem in terms of production technology. The difficulty is how to set system function specifications and how to successfully use MES to play its functions. . The difficulties encountered can be roughly divided into the following items:
(1) The factory itself has not yet had a complete system, the mobility of personnel is large, and the organizational changes are also large. The specifications set by the former, after the completion of the production, the responsible personnel are changed, and the specifications are also changed.
(2) MES has just started in China, and there are still few successful examples in the manufacturing industry. There is also a lack of professional implementation companies. There is no correct concept and understanding, and there is not enough confidence and determination.
(3) The nature of the factory is mostly small and diverse, the order-based production type, the production site is confusing, there are often exceptions, and it is difficult to cooperate in the operation.
(4) In order to achieve real-time and accurate monitoring and management functions, on-site operators must fully cooperate. Generally speaking, the operators are busy with production, and it is difficult to require them to input data. In general, MIS or ERP systems are mostly on-line batch jobs, rather than Real-time jobs, which are more flexible in execution.
(5) The first-line manager of the MES site (such as the team leader) may have difficulty understanding the meaning of MES import correctly, but the transparency has made the power deprived.
(6) The average person is accustomed to using a pen to record, and is less accustomed to Paperless electronic work.
(7) Because MES emphasizes that real-time data collection, supervision and control are more difficult than general data processing applications, it is technically difficult to have professional computer system technology experience. For the user, this system includes software and hardware for real-time on-site operation, and maintenance is also more difficult.
The application of MES should fully consider the specific situation of the enterprise in order to seek the most suitable information solution.
The production methods of enterprises can be mainly divided into order production, inventory production or a combination of the two. In terms of production type, it can be divided into mass production and single-piece small batch production. In terms of product type and production process organization, the industry type of the enterprise can be divided into process production industry and discrete manufacturing industry.
Typical process production industries include pharmaceuticals, petrochemicals, electricity, steel manufacturing, energy, and cement. These enterprises mainly adopt inventory-based, batch-based, and continuous production methods. Typical discrete manufacturing industries include machinery manufacturing, electronics, aerospace manufacturing, and automotive manufacturing. These enterprises are produced both in order and in stock; both in batch production and in small batch production.
The MES system covers both the process production industry and the discrete manufacturing industry, both in terms of functional models and information models and related technologies. However, there are big differences between the process production industry and the discrete manufacturing industry in terms of process flow and production organization. Therefore, in the specific implementation of MES, it should be treated differently according to industry characteristics.
Industry demand difference
The process production industry mainly increases the value of raw materials by mixing or separating, pulverizing, heating and other physical or chemical methods. Usually, they are produced in batch or continuous mode. Discrete industries are mainly products that add value by changing and assembling the physical shape of raw materials. In terms of MES requirements, application environment and many other aspects, there are big differences between the two.
product structure
The product structure of a discrete manufacturing company can be described by the concept of a “tree”—the final product must consist of a fixed number of parts or components that are very clear and fixed. The product structure of process companies is quite different. They are often not very fixed—the quantitative relationship between superior materials and subordinate materials, which may vary with temperature, pressure, humidity, season, personnel skill level, and process conditions.
In the process production industry MES, the concept of formula is generally used to describe this dynamic product structure relationship. Secondly, in each process of the process production industry, the output is not only the product or the intermediate product, but also may be subdivided into the main product, the by-product, the co-product, the reflow and the waste. When describing the formulation of this product structure, MES should also have requirements for batch and expiration date.
Process flow
Order-oriented discrete manufacturing, characterized by multiple varieties and small batches. Therefore, the arrangement of the production equipment is not arranged by product but by process. For example, discrete manufacturing often arranges the position of the machine according to processes such as turning, grinding, planing, and milling. Because each product’s process may be different, and there are more than one machine that can perform the same process. Therefore, discrete manufacturing needs to schedule the materials being processed. And the intermediate goods need to be handled.
The characteristics of the process production industry enterprises are fixed varieties, large batches, high investment in production equipment, and arranged according to products. In general, enterprise equipment in the process manufacturing industry is dedicated and difficult to use for other purposes. When planning the MES system, it is necessary to take into account the characteristics of the production equipment layout in different industries and make a good configuration.
The raw materials of discrete industrial enterprises are mainly solid, and the products are also solid shapes. Therefore, the storage is mostly an indoor warehouse or an outdoor open warehouse. The raw materials and products of the process production industry are usually liquid, gas, powder and so on. Therefore, storage is typically stored using cans, bins, cabinets, buckets, etc., and the majority of the storage can be metered with sensors that can be converted to electrical signals. The MES system can obtain the necessary information from these sensors.
Level of automation
Discrete manufacturing companies rely on discrete processes, and the quality and productivity of their products depend to a large extent on the skill level of workers. Discrete manufacturing enterprise automation is mainly at the unit level, such as CNC machine tools, flexible manufacturing systems. Therefore, discrete manufacturing enterprises are generally staff-intensive enterprises with relatively low levels of automation.
In the process production industry, most of them adopt large-scale production methods, and the production process technology is mature. PCS (process control system) is widely used, and the automation equipment for controlling production process conditions is relatively mature. Therefore, most of the production processes in the process production industry are automated, and the personnel in the production workshop are mainly management, monitoring and equipment maintenance.
Production planning management
Discrete manufacturing companies that are mainly engaged in single-piece, small-volume production. Because the process of products often changes, they need to have good planning capabilities. For companies that organize production by order, it is difficult to predict when an order will arrive. Therefore, planning for procurement and production workshops requires a good production planning system, especially for computers to participate in the planning system. As long as it is applied properly, the benefits of investing in a production planning system can be quite high in discrete manufacturing.
Process companies, mainly in mass production. Only at full capacity, companies can reduce costs and be competitive in the market. Therefore, in the production planning of the process production industry enterprises, the annual plan is more important, which determines the material requirements of the enterprise.
device
The products of the process production industry are relatively fixed, and once produced, it may be unchanged for more than ten years; the products of machinery manufacturing and other industries have a relatively small life expectancy. Reflected in the equipment, the equipment of the process enterprise is a fixed production line, the equipment investment is relatively large, and the process flow is fixed. There are certain restrictions on its production capacity, and equipment maintenance on the production line is particularly important and cannot be trouble-free. This is not the case with discrete processing industries, where a single device can be stopped for maintenance without affecting overall system production.
Batch number management and tracking
In the production process of the process production industry, various co-products, by-products, waste products, reflows, etc. will be produced, and the management of materials needs to have strict batch numbers. For example, pharmaceutical manufacturing processes in the pharmaceutical industry require very strict batch records and tracking, from raw materials, suppliers, intermediates, and products sold to users. In the event of a problem, the company must use the batch number to find out who the raw materials, which department, and when it was produced, until the problem is identified. Discrete manufacturing generally does not emphasize this requirement, although many discrete manufacturing companies are gradually improving batch tracking management.
MES application characteristics
The above differences between process manufacturing companies and discrete manufacturing companies have led to differences in MES applications for discrete manufacturing and process industries.
Different requirements for MRPII/ERP
The MES is at the planning execution level of the enterprise, accepts planning instructions from the MRPII/ERP layer, and feeds back information to the MRPII/ERP. Therefore, regardless of the process manufacturing industry or the discrete manufacturing industry, MES must establish close information integration with MRPII/ERP.
At present, most MRPII/ERP systems on the market are developed in discrete manufacturing and are suitable for discrete manufacturing. ERP products for the process production industry are still rare. Some of the terminology used in the MRPII/ERP system, the management concepts provided are inconsistent with the conceptual habits of the process enterprise. Therefore, there is a difference between process enterprises and discrete manufacturing, and ERP of process enterprises needs to be treated exclusively.
The different requirements of MRPII/ERP in process manufacturing industry and discrete industry are mainly reflected in:
The requirements for the production model are different – the process production industry reflects the production model with the recipe as the core, while the discrete industry reflects the production model with the product BOM as the core.
In terms of production planning methods, the concept of process enterprises to produce according to market demand has gradually deepened. However, under normal circumstances, especially for products with large market demand, it is “promotional promotion” – through mass production, reducing costs and improving competitiveness. Therefore, as the basis for the production plan of the process enterprise, it is mainly the market forecast. On the one hand, discrete enterprises can produce according to orders, on the other hand, they can also be used as the basis for production planning based on market forecasts. The MRPII/ERP system of the discrete enterprise issues the operation plan instruction to the MES mainly in the form of “Job Order or Work Order”, and the operation plan of the process enterprise is mainly issued in the form of instruction plan.
In terms of cost accounting, the cost of computing products of discrete enterprises is calculated from the low-level to the higher-level layers according to the processing and assembly process described by the product BOM. This method of calculating costs according to the actual process of cost generation is called a layer-by-layer accumulation method, or cost roll-up, which reflects the actual process of product value addition. The cost accounting method of the process enterprise generally adopts the parallel carry-over method. Among its cost components, the largest proportion of the production cost is the raw materials. Generally, raw materials account for 70% to 80% of the cost of products, and the proportion of labor costs is small, accounting for about 2% to 5%. Others are sharing costs. Job scheduling
The scheduling of production operations in discrete enterprises requires scheduling of operation plans at the process level and equipment level based on priorities, work center capabilities, equipment capabilities, and balanced production. This scheduling is based on limited capability scheduling and accurately calculates the start time, completion time, preparation time, queuing time, and travel time of the process by considering interleaving, overlapping, and parallel operations in production. Through a good work sequence, production efficiency can be significantly improved.
The products of the process enterprise are organized in a streamlined production line and continuous production mode. There are only continuous process flows, and there is no strict process route corresponding to discrete enterprises. Therefore, in terms of job scheduling, it is not necessary or accurate to the process level, but is scheduled in units of the entire production line. From the role and implementation of the work plan, it is relatively simpler than the discrete enterprise.
data collection
The data collection function of MES can realize the collection and finishing of various data on the production site, which is the basis for material tracking, production planning, product history maintenance and other production management.
The data collection of discrete enterprises is mainly based on manual reporting, and can be combined with semi-automatic information collection technologies such as barcode collection to collect information such as working hours, equipment, materials and quality. This kind of data collection method has a large time interval and is easily affected by human factors. Special attention should be paid to ensuring the accuracy of data.
The process production industry has a high degree of automation, and the equipment control level uses DCS and PLC in large quantities. In terms of detection drive, various smart meters and digital sensors have been widely used; process control is widely used as an automatic control system based on minicomputers. The traditional division of labor, electricity, and instrumentation is no longer obvious. The application of computer technology has penetrated into various fields. These automated devices automatically and accurately record a variety of production site information. For MES, the focus is on making data interfaces with these automation devices when the system is built.
Release of work instructions
In the MES of the discrete industry, the method of dispatching the operation plan scheduling result to the operator is generally notified by means of a written form such as a work order or a construction order, or an electronic kanban method is adopted to enable the operator to grasp the production task of the relevant process in time. The content of the operation plan, including the start, completion time, and production data of the process.
In the MES of the process production industry, not only the operation instructions and PDI (Panel Data Interface) data, but also the operation instructions are converted into operation instructions of various units and equipments and control parameters of various basic automation equipments (for example PID control parameters – Proportional Integral Derivative, proportional integral derivative control, and issued to the corresponding PCS system (Production Control System, production control system).
Recoil processing
The production of the process production industry has been completed and reported, and backflushing is widely used. Generally, the finishing report point is set at the end of the process flow, and the backflushing process is performed on the previous process flow, such as manual working time recoil, equipment working time recoil, material backflushing, thereby tracking the work in process and cost.
In the case of completion reporting in discrete manufacturing, it is generally reported for each process, or a kickback point is set in a key process, and the previous process is backflushed.
When configuring the corresponding modules, the MES system should pay attention to these differences to meet the needs of the enterprise.
Equipment management
The arrangement of production equipment in discrete industries is not arranged according to the product but according to the process. There are usually more than one machine that can perform the same machining process. The failure of a single device will not have a serious impact on the process of the entire product. It is generally necessary to focus on managing critical and bottleneck equipment.
In the production line of the process production industry, equipment maintenance on the production line is particularly important. Each piece of equipment is a critical piece of equipment and cannot fail. The failure of one piece of equipment can lead to the termination of the entire process.
Warehouse material management
In the discrete industry, there is also a corresponding warehouse for the semi-finished product warehouse, and each process is separately selected according to the production operation plan and the supporting list.
In the process production industry, for the continuous production mode, there is generally no intermediate semi-finished warehouse, and the location of the recipe raw materials is generally set next to the process. Recipe picking is not based on the process, but is based on the production plan and is placed in the process location.
Quality Control
Whether in discrete industries or process manufacturing, quality inspection and management are important, but there are differences in the way MES performs quality inspection and management. In the discrete industry, for single-piece small batch production, it is generally necessary to check the processing quality of each part and each process; for mass production, the first inspection, sampling inspection, and SPC analysis are generally used.
In the process production industry, sampling inspection on each process of production batch number products is generally adopted.
Of course, in different production methods and production types in each industry (for example, single-piece small batch or large-scale mass production in discrete industries, in different process production industries such as pharmaceutical, chemical, steel, etc.), there are still some differences in the application of MES. A comprehensive analysis is required based on their respective characteristics.
The manufacturing execution system MES is designed to enable the master to the management level and down to the production unit (shop, shift) to fully grasp the job site information and effectively control the production process. Overall, it increases the productivity of the entire company, shortens the lead time of manufacturing, and provides the backbone of rapid response to changes in the supply chain system.
MES aims to provide real-time, useful and accurate information required for production. The human-machine interface is friendly, and the system is based on a distributed architecture. The operation is stable and efficient, enabling managers to make appropriate judgments and decisions for production conditions and make manufacturing cycle time. Significantly reduce and provide flexible production and adapt to the changing environment of customer needs, thereby improving manufacturing quality, shortening financial turnaround time and improving customer service quality.
Before the implementation of MES, the company’s ERP system communicated with the production site through human interaction, so that the production site was like a black box operation, and it was impossible to grasp the real-time correct information. After the introduction of the MES, in addition to providing automation of the on-site information flow, it plays the role of the link. It is not difficult to see that the interaction between MRP (Manufacturing Resource Planning) or ERP (Enterprise Resource Planning) systems, one is the upper planning system (Planning), and the other is the lower actual execution system (Execution).
For example, if the production department takes the order, when MRP calculates that the order is started at 9:00 am this morning, and it will be completed at 2:00 pm tomorrow, the workshop is ready to start production, how to do the MES system?
When the MRP calculates the manufacturing order, it is completed at a certain time. MES can use barcode recognition technology to carry out the product flow and quality in production. (Quality does not meet the requirements: MES can accurately know which process is wrong, how is the problem, and which one is out Wrong), how to store the safety stock of the warehouse, etc., and notify the department heads and inform your customers in a timely (real-time) manner. It can also be published in real time on the factory’s electronic signage, so that all employees know that I should pay attention to those problems, how many finished products (or semi-finished products) that have not been done, and so on. The so-called MES is actually able to understand the real-time dynamics of the factory and the black box operations of the production, so that their factories can truly reach the modern digital workshop.
Equipment management
The arrangement of production equipment in discrete industries is not arranged according to the product but according to the process. There are usually more than one machine that can perform the same machining process. The failure of a single device will not have a serious impact on the process of the entire product. It is generally necessary to focus on managing critical and bottleneck equipment.
In the production line of the process production industry, equipment maintenance on the production line is particularly heavy.
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