A partnership between energy management specialists, NRG, and Parker SSD, part of the Automation Division of Parker Hannifin, looks set to help injection moulding companies cut the power consumption of moulding machines by more than half without affecting machine performance.
With technical and product support from Parker SSD, NRG has developed an novel system for managing the energy used by motors that control the various hydraulic functions in injection moulding machines. This system is based on a combination of analyses of individual machine characteristics, with the ability to implement predictive and precise control of motors and associated devices using a specially developed SyncroSpeed system, which incorporates the latest Parker drive technology.
“Energy consumption is one of the biggest costs for injection moulding companies, with speed and pressure requirements often fluctuating considerably throughout each machine cycle,” says Rob Parkes, business development manager at NRG. “For example, high pressures during tonnage build-up, hold on injection and cooling phases, while lower, yet still variable pressures are needed for all other phases of the moulding cycle. These frequent changes in power demand during each machine cycle are especially noticeable in jobs with cycle times in excess of 30 seconds, or where thicker wall sections require extended hold and cool sequences”.
In most injection moulding machines the control mechanisms, although accurate, are generally unsophisticated. As a result, the systems on each machine that consume most power are often set to deliver maximum pressure or flow regardless of the actual process requirements at any moment in time.
“The most common power units are ac induction motors coupled with fixed delivery hydraulic vane pumps; these offer low capital cost and reliability but are only capable of delivering fixed outputs with normal machine control systems, irrespective of the operating conditions,” Rob Parkes adds.
The SyncroSpeed system offers maximum energy savings while retaining the full performance of the injection moulding machine. In essence, it provides infinitely variable control of all motor functions, regulating control of speed and thus flow, pressure and volume to match instantaneous demand at the source point of the prime motor rather than elsewhere in the system. SyncroSpeed can be retrofitted to existing injection moulding machines and, once installed and set up, is effectively transparent to machine operation.
The 650V drives, which have been developed specifically for use with open loop ac motors, are quick and simple to configure and test on-site, and incorporate a wide range of features, including filters, 150% overload protection, analogue, digital and motor thermistor inputs and a six-button, password protected operator keypad with backlit LCD.