Hot Runners Saving energy in multi-cavity moulds

Editor: Eric Culp

Even those who run high-performance moulding systems want to cut their electric bills. Hot runner supplier HRS Flow says it worked with a moulder to lower the shop's energy costs for a food packaging product.

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The more the cavities are involved, the more evidence of benefits, HRS Flow says.
The more the cavities are involved, the more evidence of benefits, HRS Flow says.
(Source: HRS Flow)

Market demands for systems with increasing performance and greater energy savings are becoming increasingly common. However, this concept should not only be limited to energy savings, i.e., low consumption, but should also include waste reduction during the start-up and colour-change phases. The more the cavities are involved, the more evidence of benefits.

Creating heating solutions with simulations

For this specific case, the HRS Flow Multitech division proposed a solution with MT29-75 nozzles. The part was a yogurt cap (2 gm, 1.6 mm thickness ) moulded in HDPE. Considering these are systems running at very short cycle times, special attention was given to the thermo-fluid dynamics aspect of the whole system. The hot runners include innovative systems that balance the melt flow in the runner in the most optimal way, the company said.

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Following FEM analysis, the system has been thermally optimised by means of properly shaped heaters. For this purpose, the supplier's R&D department created a series of transitory simulations to replicate the exact production environment. The injection nozzle comprises a series of technological solutions combined with high-performance materials for a range of features – such as high wear-resistance sintered tips – that make the component a strong point of the system. The hot-half platens are shaped in order to ensure good stability, and wherever possible, the concept of platen support has been used.

The features created not only a high-performance system, but one that’s easy to use despite the large number of cavities, the moulder was quoted as saying.

Filling cavities at restart proves key

The start-up stage deserves special attention. After 15 minutes of stand-by, all 64 cavities are filled completely, thus reducing waste during the restart. This saves energy without having to increase the temperature of the hot runner. Thanks to the attention paid during the design stage and the involvement of the technical staff, the customer's target was met.