Due to the wide range of batch production, it is usually divided into three types: “mass production”, “medium production” and “small batch”. Small batch production refers to the production of special products that produce a single product that is basically in small batch demand. There is a wide variety of single-piece production operations, each producing only one, with a low degree of repeatability. Single-piece small batch production is a typical order-type production (MTO), which has similar characteristics to single-piece production and is customarily called “single-piece small batch production”. Therefore, in a certain sense, the statement of “single piece small batch production” is more in line with the actual situation of the enterprise. It is composed of custom-made products (such as custom-made garments and turbines for hydropower generation), which are produced in single-piece and small-volume production units. For single-piece small batch production, because the order arrival is random, the product is often a one-time demand, and the overall planning of the production tasks in the planning period cannot be made in advance, and linear programming cannot be applied to optimize the variety and output combination. However, a small batch production still requires a production plan. The production plan outlines the guidance of the company’s production and operation activities and order acceptance decisions during the plan year. Generally speaking, when the outline is prepared, some orders have been confirmed. The company can also predict the tasks of the plan year according to the situation and market conditions in the past years, and then optimize according to the constraints of resources. The production plan of a single small batch production enterprise can only be instructive, and the product production plan is made on an order basis. Therefore, for a single small batch production enterprise, it is very important to accept the order decision. Single-piece small batch production methods and a large number of large-scale production methods are typical production methods. The large-scale mass production has the advantages of low cost, high efficiency and high quality, making it difficult to compete with general medium-volume production. The single-piece small batch production has firmly established itself in the market with the innovation and uniqueness of its products. There are three main reasons for this:

1. The various mechanical equipment used in a large number of large-scale production is special equipment, and the special equipment is manufactured in a single-piece small batch production mode.

2. With the rapid advancement of technology and increasing competition, the product life cycle is getting shorter and shorter, and a large number of new products have become the key to winning competitive advantage. Even if a new product is to be mass-produced, in the research and trial production stage, its structure, performance, and specifications must be improved. It can only improve the production efficiency of a single-piece small-volume product.

3. Most of the products manufactured in small batches are production materials, such as large ships, power station boilers, chemical refining equipment, and assembly line equipment of automobile factories. They are the means for new production activities.

Because the basic characteristics of a single piece of small batch production bring a series of problems in terms of design, process, production organization and production management. There are four disadvantages:

1. The product manufacturing cycle is long, the capital turnover is slow, and the user orders are long in advance;

2. Use more people, low production efficiency and low labor productivity;

3. High cost;

4. Product quality is not easy to guarantee.

The single-piece small batch production operation type has the advantage of “changing invariably” but its low efficiency is its fundamental defect. How to improve the efficiency of single-piece small batch production operation has become a concern of today’s production operation management theory and industry. There are two ways to improve the efficiency of production operations: reducing part changes and improving the flexibility of the production operation system. There are three ways to reduce the change of parts: (1) to promote product serialization and standardization and generalization of parts, and to implement product serialization to reduce the number of products, and the various needs of users can be satisfied through the product series. If the size of the foot is a continuous amount, it is impossible for the shoe factory to produce an unlimited number of shoes of different sizes, but a shoe of a size series can be produced, and the customer can select the appropriate shoe according to his own requirements to meet the requirements of use. Standardization and generalization of components can directly reduce changes in parts, so that mass production can be organized to reduce costs, improve quality, and shorten customer ordering cycles. (2) Implementing composition technology, group technology cannot directly reduce parts changes. A method of organizing small batch production using part similarity. Many different parts have similarities in terms of design attributes and manufacturing attributes. By merging similar parts into part families, the same or similar methods can be used to reduce rework, save time, improve efficiency, improve work quality and product quality; (3) implement change reduction method (VRP), VRP is one A new kind of manufacturing engineering ideas and methods for market diversified needs. VRP starts from the analysis of the root cause of product “variability”, in line with the idea of ??”changing invariable”, changing the variety of products into parts and crafts, and creatively dividing the product cost into “functional cost”. “change cost”