2012-02-27 - An ABB industrial drive has reduced the 24/7 energy consumption of a plastic injection molding machine by 70 percent for a Danish manufacturer of fishing net floats. "We were amazed by the size of the savings and the short 70-day payback period on our investment," said the customer.
By ABB Communications
The ABB ACS800 industrial drive is installed on a hydraulic plastic injection molding machine owned by Neptun Plast, a Danish manufacturer of plastic products based in Vordingborg, about 100 km south of the capital, Copenhagen.
The machine operates around the clock and produces trawl floats of various strengths and sizes, including ultra-robust deep-sea floats that can be used at depths of up to three kilometers, where the pressure on the floats is intense.
Local system integrator Normann & Kock proposed the drive solution to Neptun Plast. They calculated that using an ACS800 variable speed drive to speed-control the machine’s hydraulic system would reduce electricity consumption by 40-50 percent – a huge and impressive saving verified by test installations on similar machines at another Danish plastics company.
However, once installed on Neptun Plast’s injection molding machine, the forecast energy savings proved to be significantly underestimated.
"It may seem difficult to believe that a drive could reduce energy consumption by 70 percent," says Niels Martin Lundsgaard, Neptun Plast’s technical director. "The actual saving was marginally less – 68.5 percent – but that is a huge reduction that we are more than happy to accept. The payback time for our investment was just 70 days."
Eliminating wasteful energy consumption
The drive’s biggest energy saving is in the cooling process for large trawl floats. The cycle time for making a large float is 500 seconds, only 25 of which are for the injection process. The remaining 475 seconds are for cooling. Prior to the ABB solution, the injection pumps ran unnecessarily at full speed during cooling. Now, the drive automatically switches the pumps off, thus eliminating almost eight minutes of costly energy consumption from the production cycle.
The machine in question is an old but well-maintained injection press driven by a hydraulic driving system. Although hydraulic presses are not the most energy efficient on the market, they are the most widely used worldwide. The fact that ABB can reduce the energy consumption of these machines by as much as 70 percent is good news for plastics manufacturers all over the world.
An additional benefit for plastics manufacturers in Denmark and many other countries is that they can sell their emission reductions on the local CO2 trading exchange. "These are settled in cash and are an additional benefit on top of the huge energy savings we are already making," says Lundsgaard.
The ABB 30 kW ACS800-01 drive has reduced the energy consumption of the hydraulic plastic injection molding machine by 68.5 percent (left). N.M. Lundsgaard, managing director of Neptun Plast, with racks of trawl floats in the background.