In the manufacturing industry, injection molds and die-casting molds are two key tools essential for producing plastic and metal parts. Although they may appear similar, significant differences exist in their structure, working principles, operational conditions, materials, applications, and pros and cons.
Injection molds consist of two main parts: the moving mold and the fixed mold. They also incorporate seven systems, including the injection system, forming system, side core-pulling system, ejection system, temperature control system, exhaust system, and guiding positioning system.
Die-casting molds primarily consist of fixed and moving molds and require complex systems and structures for smooth operation and part ejection. Common components include forming cavities, injection systems, overflow exhaust systems, guiding parts, ejection mechanisms, heating and cooling systems, and side core-pulling mechanisms.
In die-casting mold design, three-plate molds are rare, whereas they are common in plastic molds. Die-casting molds cannot rely on ejectors for venting, necessitating exhaust and slag discharge features along the parting line.
The working principle of injection molds involves the injection machine providing power to bring the moving plate to the fixed plate for mold closure. Molten plastic is injected under pressure through a nozzle into the cavity, where it cools and solidifies before being ejected.
In die-casting, the process is similar but involves injecting molten metal under high pressure into the cavity after applying a release agent. Once cooled, the mold opens, and the product is removed, forming the basis of the die-casting cycle, a critical efficiency metric.
Injection molds typically operate at temperatures between 80-160°C and pressures of 50-90 MPa, with materials like SKD11 or DC11 tool steels chosen for their properties.
Die-casting molds face harsher conditions, operating at temperatures of 230-280°C and pressures of 70-100 MPa. For example, molten aluminum enters at 670-710°C, necessitating materials like H13 or H11 tool steels, which offer enhanced thermal resistance and durability.
Injection molds are widely used for producing various plastic products (e.g., PP, PE, PVC) across industries like appliances, automotive, electronics, and toys. Their high efficiency, low cost, and accuracy make them vital in plastic production.
Conversely, die-casting molds are primarily for producing high-strength, complex metal parts, particularly in high-volume, high-precision applications such as automotive engine components and decorative items.
Both types of molds have unique advantages and drawbacks based on their usage and processing characteristics. Injection molds offer higher precision, typically within ±0.01 mm for dimensional accuracy. In contrast, die-casting molds generally have a precision requirement of ±0.02 mm. The cost of injection molds is lower due to material choice, whereas die-casting molds, using high-performance steels and facing harsher conditions, are more expensive and have longer production cycles.
Overall, both injection molding and die-casting are powerful methods for large-scale industrial production, applied in different contexts and for various products. Understanding their differences aids in selecting the appropriate mold type to meet diverse production needs, with ongoing advancements offering further potential for development and improvement in the future.