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Leader in DC drives with Mentor II, and AC drives with Unidrive, Commander SE and M'ax, Control Techniques is now an international landmark in industrial automation, due to its complex automation systems, the power of its drives, its widespread Drive Centre network and its staff.

By Maurizio Zarantonello

Control Techniques met an important challenge for one the most important industries in the Middle East, Gulf Aluminium Rolling Mill Co. This consisted of designing and installing innovative automation in order to improve product reliability, performance and quality on the three rolling mills in the Bahrain rolling division in the Persian Gulf. These mills roll aluminium sheet to a thickness of a few microns.
Everything was engineered in various phases by Control Techniques's network of Drive Centres. The English Drive Centre from Telford completed the first phase in 1997, which was designed to improve reliability and performance by replacing old control panels with automation engineered with DC drive Mentor II and an Allen Bradley PLC.
The second phase, in collaboration with Telford Drive Centre and Vicenza Drive Centre, focused on the quality of the rolled product.
The Creazzo team from Vicenza's Drive Centre has acquired considerable experience in cold-rolling of metals and in particular aluminium.
The second phase was planned along two guidelines: engineering an automatic thickness control system based on a PLC and a production control and supervision system in order to guarantee constant production quality.

Thickness control
The new thickness control system immediately resulted in an increase in system productivity, reducing pauses needed for continuous operations and significantly improving rolling quality.
Basically, productivity increased by more than 30% and the quality of rolled material improved with a reduction in thickness error ranging between an average of 5% and 1%, in addition to a substantial and positive decrease in waste material and customer complaints.

The supervision system
The customer's second requirement was to have a supervision and control system that guaranteed the following:

• process supervision with a display of the most important measurements and thickness error trends
• production control, with tracking of the three different rolling mills using a work program that could be used by the programming office and able to guarantee production repeatability and therefore constant quality
• production reports for each process phase, with a record of significant historical data and error tracing
• statistical analysis of error tracing and definition of its quality through the distribution curve and typical parameters such as CP (Process Capability) and CPK (Process Capability Index)

The supervision system was designed using modern industrial panel-mounted PCs, with a 15" TFT liquid crystal screen, industrial membrane keyboard with trackballs and 100 Mb Ethernet network. Two industrial PCs were installed on each rolling mill, whereas the office was equipped with a traditional PC, with a 17" CRT monitor.
One of the PCs equipping each machine provides the operator's interface (HMI), whereas the other is designed to continuously display thickness error tracing, so replacing obsolete paper folders. All the PCs are connected to each other and to the PC in the office. This PC fully displays real-time data on each rolling mill, and a complete work order programming system allows you to schedule the work of the entire rolling department from a single work program.
A historical file collects all the data on produced coils and analyses them. The software was developed using a product distributed by Automa, which with Super-Flash offers a "No Royalty" development package that is able to meet countless requirements, from simple HMI systems to numerous workstations, and in this case, an operating system like Windows NT Workstation.
Automa and Control Techniques have formed a strong partnership: this software house proves to be a special partner for Control Techniques, with its focus on customer demands and online professional support.

Work program
The work program simultaneously manages the production program of the three rolling mills, with a dynamic display of the production status. On the work program page, you can enter the production recipes, each consisting of six possible passes on the three rolling mills: you can therefore program coil machining through several phases on different machines.
You can also choose the parameters of each pass using a file of standard rolling recipes. The historical production file shows the list of all rolled coils.
Each rolled coil is attributed a general report, a layout and a thickness error statistical analysis.