Adapting existing #rollingmills to present day market requirements has become imperative for present day #aluminium producers. Modernization of old rolling mills has made Aluminum rolled product plants more profitable and competitive in both domestic and export market. Automation helps in increasing uptime and productivity, reduces mill breakdowns by over 35% and product rejection rate by over 40%. Latest generation rolling mills with lower power demand and higher productivity can produce at a low cost with the help of newer technologies.

1. TRANSFORMING INFORMATION
ENHANCING PERFORMANCE
Industry Value Proposition:
Modernization of old rolling mills

2. Adapting existing rolling mills to present day market requirements has
become imperative for present day aluminium producers.
Modernization of old rolling mills has made Aluminum rolled product
plants more profitable and competitive in both domestic and export
market. Automation helps in increasing uptime and productivity,
reduces mill breakdowns by over 35% and product rejection rate by
over 40%. Latest generation rolling mills with lower power demand and
higher productivity can produce at a low cost with the help of newer
technologies.

3. Background
One of India’s major aluminum producers, operating for over last six
decades, upgraded their cold mills in 2005 with the then state of the
art automation and till date, they have been enjoying the leading
status in producing high value – sophisticated rolled products for
domestic and export markets.
The sheet rolling plant had two cold strip rolling mills e.g. one
intermediate and one thin gauge finishing, which were in operation
over two decades.

4. Challenge

5. In early 2000, the Company decided to completely modernize the
controls of these two mills to become more quality competitive on both
the domestic and export market and realize their vision of becoming the
industry leader. The management felt that the mill electrics had become
obsolete and was not delivering the desired results leading to high
downtime, inconsistent product quality, and fluctuation of operating
cost, customer dissatisfaction, and loss in market share.
The Company approached different electrical & automation giants
through the original mill builders, who had good working relationship with
them and finally chose a “mill upgrader” to retrofit as well as modernize
both mills with new control systems and automation solutions. Key
objectives for the project included improving product quality to meet
international standards, reducing the cost of production through
improved productivity, increasing the consistency of quality through
automation and reducing waste, customer rejection and rework.
Improving productivity required optimizing rolling speed, reducing coil
turnaround and roll changeover time, and increasing yield per pass.

6. The upgrade required a complete and clear understanding of mill
operations and desired future enhancements to plan the appropriate
migration path. While the task was relatively simple for the
intermediate mill, it posed a major challenge for the finishing mill,
since most of the technical data for the mill had been destroyed in a
recent major mill fire and the mill was under shutdown at that time to
make it ready after the fire.
To acquire the information the mill upgrader had to interview plant
engineers and the original mill builder, to acquire more details about
its old electrics and control system.

7. The interviews revealed that frequent breakdown of old electrics and
controls were resulting in long periods of downtime. The breakdowns were
associated with lengthy startup procedures due to multiple operating
stations employing an outdated hard-wired relay-logic system , which
needed regular maintenance. With limited documentation and
diagnostics, troubleshooting was extremely difficult. Moreover, obsolete
spare parts were scarce and expensive to procure.
To minimize downtime and huge daily loss due to the mill shutdown,
caused by the fire, the Company required that a solution comprising
hardware, software integration, startup, and commissioning is
implemented within 110 days.

8. Solution

9. Like others, the Company also used a variety of branded
equipment/components in their mills. The mill upgrader’s solutions,
therefore, were designed to be integrated in exactly this type of
environment.
They proposed a control system that would precisely interface with
the OEM’s equipment. The system is designed around OEM’s
Distributed Power System (DPS) drives and provided a specially
engineered PLC system with very special type of chosen I/Os. This
modular system delivers power to the motor and signals to the
customer’s existing sub-systems, including OEM’s Automatic Gauge
Control (AGC) and Automatic Flatness Control (AFC) systems.

10. The Power Module Interface provides digital regulation for the main
mill, coiler, and pay off. It communicates with the Universal Drive
controller on the main PLC rack through a fiber optic network,
which is capable of interfacing with different brands of power
modules. The ‘Panel View’ .provided the human machine interface
(HMI) for process monitoring. An Ethernet (TCP/IP) network
interfaces with the auto shape controller.
The system is connected to the mill management system. Data can
be shared with mill operators to control recipes for optimum rolling.

11. Results

12. The entire project was completed ten days before time, significantly
reducing losses accrued due to shut down. The Company was able to
start operating both the mills at desired rolling speeds within just 30 days
of commissioning of each mill.
The Electrical supplier was able to resurrect and completely modernize
the aging mills. Integration between the distributed power system and
controls such as AGC and shape control had been seamless. Digital
regulation has meant improved mill performance and simplified startup.
PLC-based logic and sequencing, complete documentation, and
detailed diagnostics through Sigma and Panel View made maintenance
much easier.

13. The upgrade had increased productivity and improved product
quality, while reducing waste and downtime. The upgrade
increased the reliability of the intermediate mill by 12% and of the
finishing mill by 22%. The breakdown hours for the intermediate mill
reduced by 37% and that for the finishing mill by 39%. The rejection
rate due to quality issues was reduced by 41%, while recovery of
the highest contribution product improved by 33% compared to
what it was before the upgrade. Intermediate mill roll change time
was also reduced by 50%, increasing uptime and productivity.

14. In the words of Company’s spokesman “The automation solution has
made us more competitive in the export market,” and “The project
helped us to improve operational efficiencies and product quality. It
has resulted in increased production and an excellent return on
investment.”
(The author is a Chartered Mechanical Engineer with over 38 years of working
experience in downstream sectors of leading Aluminium Industries in India and abroad.
Executed Greenfield projects both in India and abroad to set up new Aluminium
downstream facilities and also led various brownfield developments at different
Aluminium manufacturing locations in India.)
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