Mold design and manufacturing are closely related to plastic processing. The success or failure of plastic processing largely depends on the effectiveness of the mold design and the quality of mold manufacturing, while plastic mold design is based on correct plastic product design.
The structural elements to consider in plastic mold design include:
① Parting surface: This is the contact surface between the cavity and core when the mold is closed. The selection of its position and form is influenced by factors such as product shape and appearance, wall thickness, molding method, post-processing technology, mold type and structure, demolding method, and molding machine structure.
② Structural components: These include sliders, angled ejector pins, and straight ejector blocks in complex molds. The design of structural components is crucial, affecting mold life, processing cycle, cost, and product quality. Therefore, designing the core structure of complex molds requires high comprehensive capabilities from the designer, aiming for simpler, more durable, and more economical design solutions.
③ Mold precision: This includes anti-jamming, precise positioning, guide pillars, and locating pins. The positioning system affects the appearance quality of the product, mold quality, and lifespan. Different positioning methods are selected according to the mold structure. Positioning accuracy control mainly relies on processing, while internal mold positioning mainly depends on the designer's careful consideration to design a more reasonable and easily adjustable positioning method.
④ Gating system: This is the feed channel from the injection molding machine nozzle to the mold cavity, including the main runner, sub-runners, gate, and cold slug well. In particular, the gate position should be selected to facilitate the molten plastic filling the cavity in a good flow state, and the solidified runners and gate cold slugs attached to the product should be easily ejected and removed from the mold during mold opening (except for hot runner molds).
⑤ Plastic shrinkage rate and various factors affecting product dimensional accuracy, such as mold manufacturing and assembly errors, and mold wear. In addition, when designing compression molds and injection molds, the process and structural parameters of the molding machine should also be considered. Computer-aided design technology is widely used in plastic mold design.
