Energy-saving drive cuts injection moulding costs

A British firm has developed a variable speed drive and control system that, it claims, could cut the power consumption of injection moulding machines by 30-70%. Payback periods as short as nine months are possible for larger machines, says Newcastle-based Powermiser.

Most injection moulding machines waste large amounts of energy during the moulding cycle because their motors run continuously at full power, creating surplus energy that is dissipated through the hydraulics. The Powermiser system adjusts the speed of the motors so that they deliver only as much power as is needed at each stage of the cycle.

Powermiser has been developing the system for 2½ years, initially relying on private funding. More recently a venture capital organisation has acquired a third of the company.

Dr Roy Booth, Powermiser`s managing director, believes his is the first dedicated energy control system for injection moulding machines. Although there are other systems built using off-the-shelf components, these can be tripped by the severe, short-term overloads experienced by the motors during the moulding process.

"We`ve beefed up the power electronics for peak overloads," he says. "We`ve also thrown away a lot of the bells and whistles," he adds, with the result that his system is "a fraction of the price" of rival systems.

Booth says that there are about 32,000 injection moulding machines in use in the UK and about 10,000 of these would be suitable for retrofitting with the Powemiser system. In addition, Booth is talking to several moulding machine suppliers about building his technology into their machines.

The system can be retrofitted to an existing machine in a matter of hours. Its control element determines what the machine is doing, works out the most efficient configuration for the hydraulic system, calculates the optimum motor speed, and sends this information to the variable speed drive, and adjusts the hydraulic valves.

Booth is hopeful that the Powermiser system will qualify for support under the Government`s Enhanced Capital Allowances scheme designed to encourage the installation of energy-saving equipment.