1. Mold Material Selection
The selection of mold material is crucial to the performance and service life of the mold. Commonly used mold materials include steel and aluminum alloys, with steel being the most widely used. For different types of injection molds, the appropriate steel should be selected based on the batch size of the plastic products, the characteristics of the plastic, and the working conditions of the mold. For example, for injection molds with large batch sizes and high precision requirements, high-quality pre-hardened steels such as P20 and 718 can be selected, as these steels have good machinability and polishing properties. For hot runner molds subjected to high temperatures and pressures, hot work die steels such as H13 can be selected, which have good thermal stability and wear resistance.
2. Machining Process
The machining processes for mold manufacturing mainly include machining, electrical discharge machining (EDM), and wire cutting. Machining is the most commonly used method, using processes such as turning, milling, drilling, and grinding to perform rough and finish machining on mold parts to achieve the required dimensional accuracy and surface roughness. For complex shapes that are difficult to machine, such as mold cavities and cores, electrical discharge machining (EDM) can be used. EDM utilizes the principle of electrical discharge corrosion, generating high temperatures through pulsed discharge between the tool electrode and the workpiece, causing localized melting or vaporization of the workpiece material, thereby removing the material. Wire EDM is mainly used for machining various irregular holes, narrow grooves, and complex contours in molds. It uses a moving thin metal wire (electrode wire) as the tool electrode, performing machining through electrical discharge corrosion.
3. Mold Assembly and Debugging
Mold assembly is the process of assembling the machined parts according to design requirements to form a complete mold. During assembly, the fitting accuracy between parts must be strictly controlled, such as the fit clearance between guide pillars and guide sleeves, and the assembly clearance between the core and cavity, to ensure smooth mold opening and closing movements and that the positional accuracy between components meets requirements. After assembly, the mold needs to be debugged by trial molding on an injection molding machine to check the mold's molding performance and the quality of the plastic products. During the trial molding process, based on the problems that arise, such as flash, material shortage, and deformation of the plastic products, the mold is adjusted and optimized accordingly until qualified plastic products are produced.