The mold has the characteristics of complex structural profile, high precision requirements, high hardness of the materials used, and short manufacturing cycle. Mold manufacturing is a complex production process with tight production cycles and high technical requirements. Each mold is a new project with different structural features. Therefore, the technical level of machining is highly demanded. The traditional machining technology and equipment have certain limitations, the process level is low, the precision is not enough, and the production cycle is long, which directly affects the production efficiency and quality of the mold manufacturing. The diversified development of CNC machining technology, including CNC milling, CNC EDM, CNC EDM, CNC turning, CNC grinding and other in-depth research of CNC machining methods, can provide a wealth of mold manufacturing Production means. Among them, CNC milling machines and machining centers are the most widely used. The application of the number of wire-cutting processes and CNC EDM in the NC machining of molds is also very common. It can be said that CNC machining technology is the core application in mold manufacturing technology.

1. Features of CNC machining
(1) Mold manufacturing is a single piece production, each sub-mold has different structural characteristics, and there is almost no chance of re-opening in the manufacturing process, so there are high requirements in terms of digital programming and machine control. . When processing more complex molds, it is often necessary to use third-party mechanical software for automatic programming and then revision by the mold manufacturing process personnel.

(2) The design and development of the mold does not appear as the final product, but serves the research and development of the new product project. Therefore, the development quantity and development time are not fixed, and the manufacturing randomness is strong. Therefore, the mold design and manufacturing personnel should Strong adaptability and need to have a wealth of practical experience. At the same time, for the complex processing of the mold cavity surface, the process requires sufficient precision to process the cavity surface, and it is best to avoid the mold fit and manual polishing work.

(3) The manufacturing precision of mold processing is high. In order to ensure the precision of the formed product, the error of the mold processing must be effectively controlled at any time, otherwise the error on the mold will be amplified on the product. Mold tolerances range from 1/5 to 1/10 of the formed product, and the precision requirements at the mating point are higher. Only when sufficient precision is achieved can it be guaranteed not to overflow.

(4) Special machining is included in the mold manufacturing. Generally speaking, the internal structure of the mold is relatively complicated, and it is impossible to machine into place for sharp corners, ribs and the like. In addition, some special requirements require EDM, and EDM requires electrodes. A discharge gap needs to be set during electrode processing. The mold electrode is usually made of pure copper or graphite. Graphite has the characteristics of easy processing, fast electrical processing and low price. However, in numerical control processing, graphite dust is extremely damaging to the machine tool, and there must be a special dust suction device or immersion in liquid. For processing in the middle, a dedicated CNC graphite machining center is required.

2, CNC machining technology in the mold manufacturing applications
Based on the research on CNC machining of molds, the requirements for machining technology in mold manufacturing are high, and CNC machining as a modern machining method can meet the special requirements of mold manufacturing, especially digital control technology and precision of CNC machine tools. Has improved. In the NC manufacturing of molds, the application of CNC machining can improve the machining accuracy, shorten the manufacturing cycle, and reduce the manufacturing cost. At the same time, due to the wide application of CNC machining, it can reduce the excessive dependence on mold benching experience. Therefore, the application of CNC machining in the mold has brought revolutionary changes to the mold manufacturing. At present, advanced mold manufacturing enterprises mainly manufacture molds based on CNC machining, and arrange the mold manufacturing process with CNC machining as the core.

2.1 CNC turning processing
In general, CNC turning machining is mostly used for shaft standard parts in mold manufacturing, such as various rod parts, including tops, guide columns, etc., and can also be used in the manufacture of rotary molds, such as bottles and basins. Injection molds for the class, forgings for shafts and disc parts, punches for stamping dies, etc. Due to the limitation of the machining plane, CNC lathes can only be used for machining parts of the mold.

2.2 CNC milling processing
Since the external structure of the mold is mostly a flat structure, and at the same time, it is mostly a concave-convex surface and a curved surface. Therefore, the numerical control milling machine has many applications, and the numerically controlled milling machine can process a mold with a complicated contour or a curved surface. For example, electrodes for electric discharge machining, injection molds, die-casting molds, etc., can also be CNC milling. With the continuous development of CNC machining technology, large-scale milling centers are currently used in mold manufacturing.

2.3 CNC EDM
CNC EDM is mostly used for rapid prototyping, its processing precision is high, and the programming difficulty is relatively low. The numerical control spark amount is higher than the micro complex shape, special material mold, plastic insert cavity and insert, Machining of molds with shaped grooves. Wire cutting is mainly applied to various straight wall mold processing, such as concave and convex molds in stamping molds, inserts, sliders in injection molds, electrodes for electric discharge machining, and the like.

3 Conclusion
Today, CNC machining technology has been widely used in various production areas of mold manufacturing, especially in the home appliances, light industry, automotive, medical equipment, handicrafts, children’s toys and other industries have been more fully applied, and the current advanced CNC Processing technology has begun to manufacture molds for wind power, hydropower, nuclear power, rail transportation and aerospace. In short, the mold has the characteristics of complex structure, complex profile, high precision requirements, high hardness of the materials used, and short manufacturing cycle. The application of CNC machining molds can greatly improve the machining accuracy, reduce manual operations, improve machining efficiency, and shorten the mold manufacturing cycle. At the same time, the numerical control machining of the mold has a certain typicality, which has higher requirements than the numerical control processing of ordinary products.