For plastic products weighing less than 1 gram, selecting the right hot nozzle is critical, as it directly determines the success of the molding process. Such parts typically fall under the category of precision injection molding (e.g., electronic connectors, medical devices, micro-gears, etc.).
Priority should be given to valve-gated systems for the following reasons:
- They achieve excellent gate aesthetics, making them almost the only choice for externally visible surfaces with high cosmetic requirements.
- The valve pin mechanism prevents drooling and stringing, ensuring a clean, flat gate surface.
- One of their greatest advantages is the precise control over packing time. Once the valve pin closes, the cavity is sealed, allowing optimal packing effectiveness. This significantly reduces part shrinkage and internal voids, which is crucial for dimensionally precise micro-components.
- For multi-cavity molds producing ultra-small parts, Sequential Valve Gating (SVG) serves as the ultimate solution for ensuring uniform filling and balance. It eliminates weld lines, maintains consistent pressure across all cavities, and guarantees highly consistent weight and dimensions—even for parts as light as 0.5 grams.
Disadvantages of valve-gated systems:
- High cost and system complexity, requiring additional valve control systems and mold space.
- Not all hot runner manufacturers can produce robust solutions for very small shot weights or glass-filled (GF) materials.
We recommend hot runner systems from Husky, Maenner, and Günther for such demanding applications.