Small-batch, non-standardized product enterprises (hereinafter referred to as small-batch enterprises) can only organize production according to orders. However, user demands are diverse and ever-changing, often with tight deadlines, and the enterprises lack inventory to supply. Due to the uncertainty of products and the variability of processes, it is difficult to form product structure databases and process route databases in MES design, and business processing flows are difficult to determine. Even if product structure databases, process route databases, and business processing flows are designed, they lack sufficient industry and enterprise characteristics, resulting in insufficient applicability, adaptability, and scalability during actual operation. This leads to poor user benefits, a short system lifespan, and hinders the effective implementation of enterprise informatization in these enterprises. These small-batch enterprises have extremely low levels of information structure in their information processing, and their informatization work remains in an "information silo" state for a long time. The informatization environment is difficult to standardize and regulate, and information sharing is also poor. In production management, this manifests as low timeliness and effectiveness in the execution of engineering plans, production plans, and construction operation plans; low efficiency and high repetition in process design; poor consistency and rationality in work and material estimation; incomplete quality analysis and responsibility identification information during quality inspection; inability to provide timely feedback on quality information; and inability to provide timely guidance for construction operations, etc. Through the analysis of the production management business of small-batch enterprises and the experience of MES software development and application, this paper proposes several basic methods for the design of information systems for such enterprises. These include a product feature library describing product characteristics, a reference process library recording typical product processes, and a business process design method that combines strictness and leniency. I. Using a product feature library to replace a product structure library No matter what type of machinery manufacturing enterprise, the engineering plan starts from the customer order and continues until the project settlement, forming the basic information that runs through the entire production management process. How to compile an engineering plan that meets certain standardization requirements and how to make the most of the information from previous production management during the compilation of the engineering plan have become the primary issues for the informatization of small-batch enterprises. 1. Formation and use of product feature library When faced with a customer order, regardless of whether the technical data such as drawings and process requirements are complete, three situations will occur when compiling an engineering plan in a small-batch enterprise: (1) Products that have been produced. This product has been produced in this factory. It can be accurately determined by the drawing number, or by the product name and related product characteristics; there are also cases where the drawing number or name is inconsistent, but it can be determined by analyzing the product characteristics and process requirements. Experienced planners know whether the factory has the process data and tooling for the product, and thus determine whether it is a recurring or non-recurring product, thereby judging the difficulty of organizing production. (2) Similar products. By analyzing the product characteristics and process requirements, it can be determined that the product is similar to a certain product that the factory has produced before, and the existing process data and tooling can be used after adjustment. (3) New products, that is, products that the company produces for the first time. New products with high difficulty in process design and tooling manufacturing and complex production technology and processes must be treated specially. In the information-based production management system, product and process information accumulated in daily work can be collected and refined to form a product feature database (referred to as product feature database). When compiling an engineering plan, by inputting certain product feature information, if the same or similar product and process information can be extracted from the product feature database or the current engineering plan database, the engineering plan and reference process of the new project can be formed directly or after adjustment. 2. Data Structure of the Product Feature Library The data structure of the product feature library is basically the same as that of the engineering plan library. Following the conceptual model of a relational database, the basic data structure of the product feature library is: Product Feature (Project Number, Project Category, Product Name, Drawing Number, Material, Reference Project). Where: ① Project Number: Serves as the key for the product feature. ② Project Category: Determines the management attributes of the project construction. ③ Product Name: May also have aliases; its superior category is the product category. ④ Drawing Number: The unique drawing number for this product; it can serve as an auxiliary key for this product feature. ⑤ Material: Determines the overall or main material requirements of the product; for ease of production statistics, multiple levels of material categories may be defined. ⑥ Reference Project: The process feature information of a project extracted from the current process library or the reference process library. These features may be identical, similar, or nearly identical. The drawing number is usually used as the basic key, including the number of parts, material and spare parts requirements, and basic procedures. For products without drawings or those produced frequently, the project number formed in the engineering plan may be used as an auxiliary key to establish a connection with the reference project. II. Replacing the Process Route Library with a Reference Process Library 1. Formation and Use of the Reference Process Library After the project plan is issued, if a reference project has been provided, the relevant process is extracted based on the reference project number. Simultaneously, regardless of whether a reference project was provided during project planning, the responsible process engineer can extract reference processes from the existing process library or the reference process library using the project's characteristics to form the process information for the current project. In this process design, the final responsibility for process design lies with the process engineer; the information stored in the information system is only for reference and sharing. The reference process library is also formed by the responsible process engineer copying and transferring existing project and process information according to production needs. When using the reference process library or the existing process library for process design of new projects, there are issues related to rounding up and manual adjustments. This is because there is a certain proportional relationship between the quantity of the new project and the quantity of the reference project, but the relationship may not be an integer multiple. In this case, the automatic calculation of the component quantity, estimated working hours, and estimated weight can only be rounded up, that is, rounded to the nearest integer multiple. For such automatic proportional calculations, the process engineer needs to make final adjustments based on the actual situation to ensure the rationality of the component quantity, working hours, and weight. 2. The structure of the reference process library: Generally, the current process library and the reference process library have the same data structure, both using product drawing number and part drawing number as keys, and the project number and part number of the referenced project as auxiliary keys. Although there are significant differences in the production characteristics and management habits of different enterprises, their process library data structure is basically a set of tables as follows: ① Component breakdown (project number, part number, part drawing number, quantity, unit of measurement, specifications, technical performance, material, process requirements, supplier); ② Specialized processes (specialized category, project number, part number, operation (operation number, operation name, estimated working hours, processing instructions, completion time)); ③ Material and spare parts requirements details (project number, part number, material, specifications, technical performance, weight, required time). Specialized categories are typically divided into machining, pattern making, casting, forging, structure, heat treatment, and assembly. In the reference process library, the key is the combination of project number and part number, with the project number being the key link to the product feature library. Auxiliary keys are product drawing number and part drawing number. The supplier determines the basic order of the flow of various components and process operations from outside the enterprise to within the enterprise. The operations in machining processes and the components in structural processes are sub-data items within the basic processes, representing a "one-to-many" relationship data structure. For the same component, the semi-finished product process can only choose one of three types: casting, forging, and structural design, while machining, semi-finished product processing, and heat treatment may all be required. The basic idea behind the design of product feature libraries and reference process libraries is to utilize similar or related information to achieve user-friendly and standardized operation, thereby maximizing information standardization and practicality. By collecting and storing existing production management information, continuously accumulating information with similarities, and fully utilizing information from current or historical products through selection, copying, referencing, and adjustment, the goal of improving production management can be achieved. III. A Business Process Design Method Combining Strictness and Flexibility For products with tight deadlines and poor process requirements and construction management standards, strictly organizing production according to the order of engineering plan, process design, production plan, construction operation plan, quality inspection and warehousing, and material/spare part or semi-finished product requisition may delay normal production due to untimely or incorrect information entry at any stage. Therefore, a management control method combining strictness and flexibility should be adopted, maintaining necessary rigor while providing sufficient flexibility. Based on the principle that information is a tool for production management and that production management systems should not restrict production, flexibility and practicality must be the primary considerations in the business process design of production management information systems for small-batch enterprises. During production planning, construction operations, and quality inspection, the engineering plan and current processes are the binding information that construction operations must strictly adhere to; construction operations without the engineering plan and relevant process information are not permitted. However, the preparation and issuance of production plans may not be timely or consistent with the current capacity of the production workshop, potentially requiring temporary manual instructions to organize workshop operations. Similarly, quality inspection of semi-finished or finished products does not necessarily require a construction operation plan; as long as the product is within the engineering plan, quality inspection and warehousing can be carried out according to process requirements. With the warehousing of finished products and delivery to customers, engineering management enters the engineering settlement stage. Engineering settlement signifies that part or all of the products in the project have passed product qualification inspection and been warehoused, obtaining a product certification from the customer, thus allowing the preparation of an engineering settlement statement. When all products in a project have been settled according to the quantity required by the engineering plan, it marks the end of the project's production phase within the enterprise. Based on project settlement and customer payment status, partial or full financial settlement of a project can be performed, thus completing a customer order. The relationships between various stages in the entire production management business process can be categorized into strict control relationships and reference/hint relationships based on their potential closeness. In MES design and operation, switching between these two relationships can be achieved by setting up a switch function. The basic idea of ​​this design method is not to insist on absolute strictness of control, but to allow appropriate settings based on the actual needs and possible conditions of the enterprise, providing users with suitable choices for the business process. Of course, this production business process control method may result in some incomplete statistical analysis data, but its sufficient flexibility ensures usability, meets the production management requirements of such enterprises, and significantly enhances the applicability, adaptability, and scalability of the information system.