The structure design and parameter selection of the mold must consider factors such as rigidity, guiding, unloading mechanism, positioning method, and gap size. The consumables on the mold should be easily replaced. For plastic molds and die-casting molds, it is also necessary to consider a reasonable casting system, molten plastic or metal flow state, and the position and orientation of the entering cavity. In order to increase productivity and reduce runner casting loss, a multi-cavity mold can be used to simultaneously complete multiple identical or different articles in one mold. High-efficiency, high-precision, high-life molds should be used in mass production.
The stamping die should adopt a multi-station progressive die, and the carbide insert can be used to improve the life. In small batch production and new product trial production, simple molds with simple structure, fast manufacturing and low cost should be used, such as combined die, sheet die, urethane rubber die, low melting alloy die, zinc alloy die, superplastic alloy die, and the like. Molds have begun to use computer-aided design (CAD) to optimize molds through a computer-centric system. This is the development direction of mold design.
According to the structural characteristics, the mold manufacturing is divided into a flat punching die and a cavity die having a space. The punching die utilizes the precise fit of the punch and the die, and some even have no clearance fit. Other forging dies such as cold extrusion dies, die casting dies, powder metallurgy dies, plastic dies, rubber dies, etc. are all cavity molds for forming three-dimensional shaped workpieces. The cavity mold has dimensional requirements in three directions of length, width and height, and the shape is complicated and manufacturing is difficult. Mold production is generally one-piece, small batch production, manufacturing requirements are strict and precise, and more sophisticated processing equipment and measuring devices are used.
The plane blanking die can be formed by electric spark machining, and the precision can be further improved by forming grinding and coordinate grinding. Forming grinding can be carried out using an optical projection curve grinder, or a surface grinder with a microfilming and sanding mechanism, or a precision surface grinding machine with a special shaped grinding tool. Coordinate grinding machines can be used for precise positioning of the mold to ensure precise aperture and hole spacing. It is also possible to grind any curved shape of the punch and the die with a computer numerically controlled (CNC) continuous track coordinate grinding machine. The cavity mold is mostly processed by copy milling, EDM and electrolytic machining. The combination of copy milling and numerical control and the addition of a three-way translational head device in EDM can improve the machining quality of the cavity. Increasing gas-filled electrolysis in electrolytic processing can increase production efficiency.