Breaking the limits: How 3D printing redefines hot runner design

Energy and material savings are top priorities for injection moulders across the globe. In the face of escalating raw material and energy costs, manufacturers are under growing pressure to reduce overheads while maintaining their competitive edge. One of the most effective strategies for achieving these objectives lies in optimising tooling with hot runner systems, as HASCO explains. 

Hot runner technology has long been known for its ability to significantly reduce cycle times compared to traditional cold runner systems. In conventional cold runner moulding, the sprue and runner system are typically thicker than the actual moulded part. As a result, the cooling time is dictated by the cold runner and not the part itself. 

Hot runners eliminate this issue by maintaining the material in a molten state, meaning only the part needs to be cooled. This speeds up production cycles while reducing material waste, as there is no excess sprue to be reground or discarded.

Despite these benefits, hot runner systems have historically faced resistance in certain applications. Two common barriers are difficulties with colour changes and the need for compact mould designs that fit into smaller injection moulding machines. In traditional hot runner systems, colour changes can be slow and inefficient, as residual material remains within the manifold and nozzles, leading to colour streaking or contamination. Many hot runner systems also require large manifolds and wide pitch layouts, which limit their use in high-cavity or space-constrained moulds.

These challenges have recently been addressed thanks to advances in additive manufacturing. By leveraging 3D printing technologies, hot runner suppliers can now create more compact, efficient and customisable systems that overcome the historical limitations of traditional designs. 

HASCO was the first to introduce a solution that significantly improves both colour change performance and space efficiency. Its approach uses additive-manufactured components to reduce the pitch and overall manifold thickness, enabling moulders to fit hot runner systems into smaller machines without compromising performance. The new design offers complete freedom in cavity layout and quantity, enabling a highly tailored solution that meets the specific needs of each application.

Additive manufacturing is also making waves in valve gate systems. One persistent issue with traditional valve gates is the formation of stagnated material behind the valve pins, which can lead to quality issues and prolonged colour changes. HASCO has addressed this by developing an innovative insert manufactured using 3D printing that eliminates dead spots and improves material flow. The result is a cleaner, more efficient moulding process with fewer defects and faster changeovers.

These technological advancements are helping to shift the perception of hot runner systems. What was once seen as a niche or high-end solution is now being recognised as a mainstream method for improving manufacturing efficiency and sustainability. With improved justification models, easier integration and clear cost-saving benefits, more and more moulders are adopting hot runners as a standard practice rather than an exception.

In conclusion, hot runner technology — particularly in its latest form, enhanced by additive manufacturing — is redefining what’s possible in injection moulding. It offers a compelling response to the twin challenges of rising costs and environmental responsibility, positioning itself as a key enabler of sustainable and cost-effective production for the modern moulder.