In the modern plastic molding industry, hot runner mould technology stands out due to its significant contributions to enhancing production efficiency, reducing scrap rates, and lowering costs. A hot runner mould is a specialized injection mold designed to keep molten plastic in a heated state throughout its conveyance, allowing for continuous injection molding. This technology's core lies in its intricate internal structure, which includes the hot runner plate, nozzles, heating elements, temperature control systems, and gates.

Hot Runner Plate

The hot runner plate serves as the heart of the hot runner mould, responsible for distributing molten plastic from the injection machine’s nozzle to each mold cavity. When designing the hot runner plate, material selection is crucial. Typically, high-temperature resistant and corrosion-resistant alloy steel is used to ensure durability and stability over long-term use. Additionally, the flow channel design should minimize pressure loss during plastic flow, ensuring uniform distribution to every cavity and preventing product defects caused by poor channel layout.

Nozzles

Nozzles are positioned between the hot runner plate and the mold cavities, controlling the entry of molten plastic into the cavities. The design must ensure a good seal to prevent leakage. Moreover, nozzles should be easily replaceable to accommodate different product requirements. Internally, nozzles often feature heating wires or heating rings to maintain an appropriate temperature, preventing premature solidification of the plastic.

Heating Elements

Heating elements are essential for maintaining the operational conditions of a hot runner mould. Common types include heating rods, heating rings, and heating tapes, which are installed around the hot runner plate or nozzles. They convert electrical energy into heat, keeping the plastic in a molten state throughout the conveying process. Selecting the right heating elements and their arrangement is critical for achieving uniform heating, avoiding issues like localized overheating or cooling.