All Electric vs Hybrids

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

 All-Electric 550

Hydraulic Clamp
 4 Pulleys

Hydraulic injection

Hydraulic eject

2 Rollerscrews

1 rack/pinion

1-2 Motors
 5 motors
85 Power Factor
 95 Power Factor
Motor/Drive creates harmonics
Low 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.