Three of three massive aluminium extrusion presses, at Alcoa in Hannover, now depend on variable speed drives from Control Techniques and, as well as dramatically increasing production time availability, increasing throughput by 10% and decreasing maintenance costs, the installations have cut energy consumption by a huge 40%, saving thousands of kilowatt hours of energy every year!
These two biggest extrusion lines, both using the indirect extrusion process accept billets of aluminium alloy at around 265mm and 412mm diameter and lengths between 400 and 1350mm, pre-heated to between 300 and 550 C. These billets are then extruded through two high pressure extruding presses at 56 MN and 33 MN respectively. Both extruders are hydraulically-powered, with the oil pressure being generated by pumps controlled by Control Techniques AC drives.
The big press line was upgraded in 1998, a big project requiring the installation of 12 off 132 kW Unidrives (for 12 pumps), to produce the required maximum pressure of 315 Bar. In January this year, the 33 MN line was similarly upgraded with variable speed drives, this time the drives chosen were six 160 kW Unidrive SPM modular drives, producing an oil pressure of 250 Bar.
The operation runs around the clock, 365 days a year and so the latest installation was carried out with the line in full operation.
In both cases, the savings are considerable, explains Herr Stefan Heine, who has responsibility for technical operations and purchasing at the Alcoa plant.
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