What is Hot runner systems?

Hot runner systems are a key technology in the plastic injection molding process, as they allow the molten plastic to be kept at a constant temperature inside the mold until it is injected into the cavity. Unlike cold runner systems, where the material solidifies in the channels and must be removed as waste or recycled, the hot runner keeps the flow active, improving process efficiency and significantly reducing material waste.

These systems are composed of heated nozzles, manifolds, and temperature controllers that are integrated into the mold and work in sync to ensure a continuous supply of molten plastic. Thanks to their design, hot runner systems enable direct injection into the cavity without leaving runners, reducing cycle times and eliminating post-processing steps such as trimming or separation.

One of the main advantages of hot runner systems is the optimization of material usage. Since they do not generate excess or leftover plastic, the consumption of raw material is reduced—particularly valuable when using technical or high-cost plastics. This not only results in economic savings but also lowers environmental impact, aligning with increasingly important sustainability and energy-efficiency goals in the market.

Another important benefit is the improvement in part quality. The thermal control provided by these systems maintains a stable and uniform material temperature, resulting in better melt flow and fusion. As a result, parts have improved surface finish, reduced internal stress, and a lower likelihood of defects such as bubbles, flow lines, or visible marks.

Hot runner systems also offer great flexibility in mold design, as they allow for multiple injection points and a more balanced distribution of material in complex or multi-cavity molds. This is particularly useful in applications that demand high dimensional precision, such as technical parts in the automotive, medical, electronics, or industrial sectors.

At Plásticos Lezo, we integrate hot runner systems in many of the projects we develop—especially those that require high productivity, consistent quality, and efficient resource use. We work with leading suppliers of hot runner components and adapt each mold design to ensure compatibility with the final product requirements.

Our technical team evaluates from the early stages of the project whether the use of a hot runner is viable and cost-effective, taking into account factors such as production volume, material type, part design, and cycle times. When implemented properly, this technology brings significant improvements in injection molding competitiveness.

We also offer maintenance and technical support for hot runner systems, as their proper operation depends on thermal balance, component cleanliness, and accurate controller calibration. Managing these factors well ensures process stability and extends the lifespan of the mold and its components.

In short, hot runner systems represent an advanced and efficient solution for manufacturing high-quality plastic parts. Their implementation helps reduce costs, improve finishes, minimize waste, and increase productivity, making them a strategic ally for any industry looking to optimize its injection molding process and meet today’s standards of quality and sustainability.