How much more efficient can injection moulding machines get?
27 May 2019
Tex Plastics are currently testing environmentally efficient injection moulding machines which could reduce energy consumption by almost 70%.
What impacts on the energy efficiency of injection moulding machines?
An injection moulding machine has seven main functions that use energy: plastification, barrel heating, platen movement, injection, clamping pressure, ejection, and barrel retraction. All seven can be made more energy efficient. Efficiency, typically measured in kilowatt-hours per kilogram of material (kWh/kg), is different for each moulded part, depending on melt temperature, part weight, cycle time, machine size, and machine efficiency. For thin-walled parts with short cycles, specific energy consumption of 0.3 kWh/kg is very efficient; for a thicker part moulded more slowly, 0.6 kWh/kg could be efficient.
“The debate within the injection moulding industry continues to be discussed about the merits of both types of machines and which will come out on top. My view is, the electric version having seen the first electric machine some years ago, my first reaction was as it is now, this is the way forward for injection moulding especially when you consider the energy consumption. New all-electric injection moulding machines only use about 30% of the power required by a conventional hydraulic machine with a fixed volume pump – or even a variable volume pump.”
Justin Davies, Managing Director Tex Plastics
Hydraulic injection moulding machines
Hydraulic machines have a hydraulic motor with the costs lower than an electric one. With the hydraulic motor, higher energy can be reached, therefore also higher injection pressures compared to an electric motor. The main disadvantage of a hydraulic injection moulding machine is the high consumption of electric energy. The hydraulic motor is connected to an electric power unit, it works at maximum power in every phase of the moulding process, this means having high costs of electric energy.
All-electric injection moulding machines
Thanks to the precision of the electric devices, the all-electric machines allow production efficiency, greater repeatability, a reduced noise and shorter injection times due to dynamic servo-motors with breath-taking acceleration performance. This in turn means a better quality of the products produced. Traditional hydraulic injection moulding machines are less efficient than electric machines because they consume energy even while idle. Electric injecting moulding machines only use energy when in action, meaning the motor output is only equal to that of the load requirements.