A leading American producer of specialty aluminum products worked with a trusted integrator and WEG to upgrade equipment at two mills in South Carolina. Producing flat-rolled aluminum products distributed for use in various consumer and commercial applications, these two mills pressed aluminum down from one thickness to another. The first mill, known as I-Mill, feeds spooled aluminum coil into the second mill: K-Mill. In 2015, the aluminum producer decided that the DC motors operating in the K-Mill were too old and required too much maintenance. They called their integrator to discuss acquisition and installation of a new drive system, including new AC motors, and that integrator brought WEG in to review the application.
After a thorough engineering evaluation and with all parties in agreement of the actions to be taken, WEG supplied for the K-Mill two main mill stand motors rated 1500HP at 400 RPM, two payoff / rewind motors rated 1100HP at 500 RPM, and a side trimmer motor rated 155HP at 1800 RPM. The main mill stand WEG motors are coupled shaft-to-shaft in tandem, with a shifted-base-frequency design – meaning that the payoff, rewind, and mill stand motors could be moved to any spot within the mill. This shifted-base-frequency electrical design allowed the development of a common frame - meaning that unforeseen failure of any machine would not result in a complete shutdown, which costs a significant amount of money! Instead, the mill would be able to move any of the mill stand motors to any location within the mill. The mill would then be able to run at a reduced capacity until the failed motor could be serviced or repaired. This unorthodox but extremely innovative design also allowed the aluminum producer to avoid purchasing and storing spare motors.
During the K-Mill project in 2016, it was realized that production was being limited by I-Mill’s capacity, so the decision was made to upgrade the I-Mill to remove that production limitation and the intensive maintenance requirements of the DC motors. WEG supplied for I-Mill one main mill stand motor rated 3000HP at 540 RPM, two payoff / rewind motors rated 800HP at 400 RPM, and a special isolation transformer. The transformer is an outdoor oil-filled unit rated 2750kVA with 13,800V primary and 690V secondary with proper K-factor to support the line-side harmonics of the drives. The outdoor oil-filled unit was selected to reduce the size of and air-conditioning requirements of the drive control room, which removed significant operational costs. WEG technicians were on-site for the installation and commissioning of the equipment, and quickly addressed the problems and issues that arose to ensure the project schedule was maintained.
The upgrades to the I-Mill were completed in February of 2018 and the project manager from the integration company has confirmed that the aluminum producer is very happy with the performance of the motors in both mills. WEG was committed to this project and worked over a three-year period to support the mill upgrades from start to finish, helping the manufacturer to achieve their goals of reduced maintenance and downtime, increased production capacity, and lower costs of operation.