What is a hot runner system?
A hot runner system comprises heated components utilised inside plastic injection moulds to transport molten plastic from an injection moulding machine’s barrel into the mould cavities.
Many factors influence the size of hot runner melt channels, including resin type, injection speed, fill rate, and the moulded object. A temperature controller heats the injection mould’s hot runner system and the resin inside the machine barrel to processing temperature before injecting the wax into the mould.
The resin flows via the inlet, down into the manifold, and finally through injection points into the final mould cavity, making the last item. Today’s moulds can have anything from one to 192 nozzles, depending on the plastic parts.
Parts Of Hot Runners
Locating Ring – A locating ring aligns the injection mould with the moulding machine’s platen. It ensures that the mould is adequately aligned with the device.
Inlet – When the resin is injected into the mould, this is the entry port through which the resin enters from the injection machine’s nozzle. Depending on the resin type and hot runner design, the inlet component may be heated to optimise the moulding process.
Manifold – The manifold allows the resin to flow into various nozzles and injection locations (gates). Manifolds are commonly utilised when several cavities are injected or when more than one nozzle/gate is required per portion. Manifolds are available in various materials, designs, and shapes and are frequently optimised by utilising CAE analysis to improve the moulding process.
Nozzles – Nozzles are components that allow the resin to be injected into a cavity via a gate. Nozzles are typically inserted into the mould plate with or without a manifold, depending on the design. A wide range of nozzle designs using diverse materials is available to obtain the processing characteristics of various resins that best fit the application.
Heater Technology – The foundation of all hot runner systems is heater technology. Various possibilities, each with advantages and disadvantages. Heaters using heater bands/plates, paste-in/flex heaters, or brazed-in heaters are the most prevalent hot runner technology.