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» What are the reasons for cycle savings?
What are the reasons for cycle savings?
- Overlapping of operations (ie: clamp and extruder; clamp and injection - pre-injection; eject on fly) is a built-in design capability. This can reduce cycle times over 0.5 seconds.
- Since Electric IMM machines have no oil, the ability to quickly ramp up to full speed is easily obtainable in comparison to hydraulic systems, which rely on the electric motor, pumps and valves to ramp up. For example, it is common for a hydraulic system to use +10% of the screw stroke to reach full injection speed while the electric machine can typically achieve this in under 0.05 seconds.
- Hydraulic systems are frequently prone to shock in their systems which can cause mechanical failures. Software delays are programmed into the machine to reduce these shocks, which can then add up into longer response and cycle times.
- Since the motors are connected directly to the mechanisms of the machines, when the motor is commanded to change speed instantly, the mechanism changes. In comparison, when oil flow is cut off, the mechanical action has inertia, which cannot be stopped without using an “oil braking” system on the opposite side of the hydraulic cylinder piston. Without this, in order to reduce the amount of overshoot caused by the mechanical inertia, the software is tuned so that the velocities are ramped down farther away from the stopping set point. Using the electric machine means that the machine requires less distance to stop and so higher velocity can be held until the last possible moment, resulting in shorter cycles.