Electric molding machines continue to increase in popularity as energy costs continue to rise and injection molding finds new applications.
The benefits include:
· Reduced energy consumption compared to hydraulic machines
· Zero defect production capabilities
· Low maintenance and housekeeping requirements
· Clean and safe – suitable for clean room environments
· Low noise level allowing for a more comfortable working environment
· Faster start-up due to no oil preheating requirement
· Sensitive mould protection - extending mold life
Electric machines provide the greatest benefit to a molder in markets that have high volume, fast cycling requirements needing high positional machine accuracy and repeatability.
Such markets include packaging, medical and micro-moulding applications.
The machines are not suited to parts that require long hold times or long cooling times which can be problematic for electric servo motors although Niigata machine manufacturer claim to have overcome these issues.
There is also a limit on machine size. Most machine manufacturers don’t make a machine beyond 600 ton clamp size.
What ’s more, they can be too smart for there own good. With so many safety switches and process parameter setting options they can be a great source of frustration.
It takes time to get used to them and understand how they can be used to your advantage. Proper training from the machine manufacturer is critical to getting the most out of them.
To get the most out of these machines a good quality mold must be used. The mold must be designed and built right so that all cavities fill at the same rate and the parts eject evenly. Mold cooling must also be right.
Most importantly, the machine should not have to work harder than is needed so the mold should not be over clamped. That means keeping the injection pressure as low as possible while still making good parts.
If you are buying an all-electric molding machine to save energy and reduce your energy bill then be aware that energy can be saved on existing hydraulic machinery without any investment cost. Just by reducing the opening stroke of a machine will save you energy.
What’s more, changing other process parameter settings can save thousands of dollars a year. Click here to read a case study.
In short, if you are thinking about purchasing an all-electric machine get an energy cost consumption comparison test done between your existing hydraulic machine and an electric machine by molding the same plastic part. Not all plastic parts are suited to electric machines.
In addition, some all electric moulding machines require water cooling of the servo motors so this must also be taken into consideration with any cost comparison test.