Reducing energy consumption How hot runner design and technology can positively impact sustainability goals

Source: Mold Masters Reading Time: 6 min

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Mold-Masters is committed to aiding its customers in achieving their sustainability objectives through a multifaceted approach. The focus is on four key areas: the use of Hot Runners over Cold Runners and Product Lightweighting helps in reducing plastic consumption.

According to the company, the Mold-Masters Master-Series hot runner system consumes less energy than competitive systems.
According to the company, the Mold-Masters Master-Series hot runner system consumes less energy than competitive systems.
(Source: Mold-Masters)

Reducing energy consumption — either directly through energy savings or indirectly through increased productivity — offers one of the most significant approaches to improving a company's sustainability efforts and can deliver immediate results. The production of injection moulded plastic parts involves a large amount of equipment, such as the injection moulding machine, mould and auxiliary equipment, which require a lot of energy to operate. The sustainability performance of the hot half of the mould can be significantly improved by incorporating Mold-Masters energy efficient hot runner products.

A system-based approach to reducing energy consumption

Hot runners are more than just heated nozzles. Poor hot runner design, materials and construction can quickly wipe out any energy savings from a single component. Mold-Masters understands this and uses a wide range of technologies, special materials and sound design practices that work together as a system to minimise energy consumption.

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In a comparison of hot runner systems, the Mold-Masters Master-Series hot runner was found to consume less energy than competitive systems. The materials used and the overall hot runner design were found to be key factors. Hot runner systems that are not strategically designed and manufactured to prevent heat dissipation will consume significantly more energy. This is the trade-off when purchasing a low cost system versus a premium high performance hot runner system from Mold-Masters. It's inevitable that there will be differences in performance and quality depending on the application. The final purchase decision lies with the customer, but what's clear is that the decision to invest up front in an optimised Mold-Masters hot runner system can pay for itself while contributing to sustainability goals.

In this area, Mold-Masters has an extensive and proven history of introducing unique hot runner design innovations and technologies that improve sustainability by reducing energy consumption. These include Brazed Heater Technology, I-Flow manifold technology, Eco Disk and more.

Brazed Heater Technology

Mold-Masters’ Brazed Heater Technology consists of proprietary heaters manufactured by Mold-Masters that are embedded in the steel of the heated part. Embedding the heaters increases the efficiency of the heater by directing the heat into the part rather than releasing it to the environment. As a result, Master-Series nozzles use less energy to inject resin than competitive nozzles (based on internal laboratory tests). Brazed heaters are so reliable that they are available with a ten-year warranty. This means that they not only reduce energy consumption, but also reduce nozzle heater consumables and extend component life. Fewer heater failures also prevent costly unplanned downtime, resulting in increased productivity.

There is also a secondary benefit because the brazed heaters are inserted into customised heater channels that optimise thermal profiles for processing. This eliminates cold spots because they don't shift like conventional heater coils. The result is improved part quality and reduced scrap.

In 18 months we have had to replace 243 conventional heaters and only eight Mold Masters nozzles based on a similar number of drops! In 24 months we spent 6,110 dollars on conventional heaters in spare parts alone, more if you include labour and downtime. Mold Masters cost us nothing and kept us in production.

European closure moulder


I-Flow manifold technology

I-Flow manifolds incorporate Mold-Masters patented melt flow geometry, flow path options and runner shapes that promote smooth resin flow. This gives our designers extensive flexibility to optimise hot runner performance. I-Flow is also known for providing best-in-class melt management, resulting in industry-leading mold-fill balance, fast colour change performance and lower pressure drop.

I-Flow's curved channels minimise sharp corners and dead spots, facilitating fast colour changes. In fact, in certain applications, colour changes can be completed up to four times faster with an I-Flow manifold than with a conventional unbalanced hot runner. This significantly reduces material waste in the colour change process, which also minimises wasted energy, labour and time. For example, one customer reported that a PET bottle application that traditionally took six hours and 288 kg of resin was reduced to 1.5 hours and only 21 kg of resin using an Axiom hot runner system with I-Flow.

The curved channels of the I-Flow also create less flow restriction and therefore less pressure drop. In other words, less pressure is lost on its way from the machine to the part. This helps to minimise the amount of energy required by the injection machine to inject resin through the hot runner system, while also creating the potential to run the mould on a smaller injection machine that requires less power to operate.

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Heat plays a critical role in the processing of plastics in a hot runner system. Thermal management is essential to ensure the system is optimised for production, affecting both production quality and energy efficiency. I-Flow manifolds are typically thinner than conventional manifolds. This reduced mass makes heating more efficient.

Eco Disc

The Eco Disk is a ceramic contact pad that minimises heat transfer losses to the mould plates. This improves the thermal balance of the entire hot runner system and reduces energy consumption compared to a hot runner system using conventional steel pressure discs. This is an optional component on Master Series hot runners, but Eco Disk can be retrofitted at any time.

Recent Innovations

As a company, Mold-Masters is never satisfied with the status quo and is always looking for new ways to drive improvements. These improvements can be applicable to a wide range of applications or they can be application specific. The latest innovation is specific to the Sprint systems, a hot runner optimised for high speed moulding of caps and closures. The new Apex gate seal has been developed to further optimise the performance of the Sprint system. One benefit of this new gate design is that it improves colour change performance by up to 65 percent. What would normally take 310 shots to change colour can now be achieved in just 110 shots. This not only saves a significant amount of energy in the process, but also minimises the amount of plastic waste sent to landfill.


Electrification of the mould and injection cell is another way to further reduce energy consumption. Valve-gated hot runner systems (where valve pins are opened and closed) are traditionally driven by pneumatic or hydraulic actuator systems, and automated mould functions (such as spin stacks, core pulls, index plates, ejector plates, etc.) are typically operated hydraulically. For comparison, a hydraulic system always needs power to move and hold position, whereas an electric servomotor only needs power to move. Electrifying these processes by incorporating electric servomotors for different movements can further reduce energy consumption compared to hydraulic actuation. Mold-Masters offers two options for electric actuation control: the E-Drive electric synchro plate and the SeVG+ (Servo Electric Valve Gate). For motion control of automated mould functions, the M-Ax controller is offered.

Outside the mould itself, there are further opportunities for electrification. The Mold-Masters E-Multi auxiliary injection unit, which converts single-shot machines to multi-shot capability, is also all-electric. Incorporating an all-electric E-Multi helps to reduce the energy consumption of the system and the entire moulding cell.

Proper maintenance is critical

Regardless of the brand of hot runner or equipment used in the production cell, it is always important to carry out ongoing maintenance to ensure it is always running at peak performance for optimum productivity. Lack of maintenance can lead to part quality issues or component failures, resulting in cavity shutdowns and reduced production rates. Regular cleaning and inspection of equipment can help to overcome these problems. After a certain point of prolonged production, it is always ideal to carry out a refurbishment service to return the mould to 'like new' condition, as this involves a thorough cleaning and replacement of all wearing parts. Refurbishments also provide an excellent opportunity to upgrade internal components to the latest designs, which can help to further improve performance and energy efficiency.