Advantage of Injection molding machines with Accumulators
Does Injection molding machines with Accumulators in Injection or clamping side have any advantage over conventional machine?
On some machines the accumulators are just added to compensate for a small pump.
If it is a question of getting lower energy use, I think that you should ask the machine suppliers for documentation for the savings (in production) achieved with their accumulators. If you have a project on hand, they can base their calculations on that. If it is a question about obtaining higher injection speed you really do not have a choice…
suppliers that make these kinds of machnes are Klockner, Krauss, Engel, some Japaneese suppliers and othersits al depending of what your in to.
The oil requirement during injection cycle varies significantly (zero during cooling). Conventional machines would have a constant volume pump (less expensive) and if the pump is sized for the highest oil requirement (fast injection), during lower oil need, the pump will dump to the tank the excess oil, creating a lot of heat = loss of energy = loss of $$.Accumulators allow sizing the pump to a medium oil need and when it drops below it, the pump will fill-up the accumulators and when it goes above it, the accumulator will provide that stored oil. Some "conventional machines" have more pumps, with diferent volums for diferent times in the cycle. That also adds cost in hardware and complicates the controls.
Modern systems have variable displacement pumps which accommodate to the oil need during cycle and like Peter says, even such system may require accumulators for a very fast injection speed.
Peter is also right in saying to have the supplier justify one way or the other for your specific application . I know Husky does that.