Seeking the energy-saving benefits of electrics and the power of hydraulics, molders are increasingly turning to hydraulic-electric hybrid injection molding machines. However, these machines often fall somewhat short of energy-efficiency goals.
The reason is that, while the typical hybrid machine has an electric screw drive, three of the four axes are hydraulic – meaning that nearly all of those hoses, valves and pumps associated with a hydraulic system are still part of the machine. Along the way, energy is lost as it is in all hydraulic systems.
A simple comparison of comparable tonnage machines, a typical hybrid and an all-electric, shows the major differences:
Typical Hybrid 550
85 Power Factor
95 Power Factor
Motor/Drive creates harmonics
Hydraulic HP does not decrease to keep same injection rate and clamp speed
HP decreases when not needed
A New Kind of Hydraulic-Electric Hybrid
Unlike the typical hybrid, a new electric-based hybrid injection molding machine for the first time delivers electric efficiency along with hydraulic force.
The new system uses a hydraulic accumulator to provide the force that would otherwise require an all-hydraulic machine. The rest of the machine is electric-driven, maximizing the energy savings.
In other words, molders using the new hybrid configuration, available on Milacron POWERPAK®™ machines, get all the benefits of an electric machine, but with injection rates up to 300+ cubic inches per second (compared to all-electric machines, which top out around 100).
These rates are necessary especially for applications with thin-walled parts with high length over thickness (L/T) ratios, in which the material must fill the entire part before setting in the thinnest areas.