Press Release
KEEPING UP THE PRESSURE AT GERMAN ALUMINIUM PLANT
Alcoa Germany depends on Control Techniques modular drives
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
265-mm and 412-mm diameter and lengths between 400 and 1350-mm,
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.
“The original hydraulic plant was designed to give the required
thrust with additional oil being sent through a by-pass – so
effectively the pumps were running at full speed all the time. Now
Control Techniques variable speed drives integrate with the
hydraulic controller using Profibus and give exactly the required
power at every stage of the operation. Not only does this save some
40% of the power, but also gives better control, giving improved
quality of extrusions. But this is just part of the story. Because
the plant (the valves, pumps, pipes and seals) is less stressed,
equipment is less susceptible to breakdown and I believe that our
throughout has increased by around 10% because of reduced downtime.
The oil lasts longer too – a not inconsiderable saving when you
consider that the machine incorporates some 15,000 litres of oil
and 6,000 litres passes through the system during each extrusion
(this is then cleaned and returned).”
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