The Steel industry is facing tough challenges in meeting profitability goals. By making caster operations more visible, we can have significant contribution in revenue by segregating the quality levels & billing them according to appropriate pricing strategy. At the other end, growing demands of production can be met by process optimization and reduction of wastages caused by surface defects, cracks and other defects.

1. Continuous Casting: Get more from your Caster
Axcend Automation & Software Solutions
S
teel, being the most important Engineering raw material, is the key for the growth
of Manufacturing Industry. A strong steel sector propels industry growth, which in
turn drives economy’s growth. Such is the might of this metal which is facing turbulent
times in its growth trajectory.
While Steel is the base of all industries, Continuous Casting is emerging as the preferred
choice in steel making. The basic concept in continuous casting is the use of an open
ended mold to cast an indefinite length of the desired cross sectional shape.
Continuous casting transforms molten metal into solid on a continuous basis and
includes a variety of important commercial processes. These processes are the most
efficient way to solidify large volumes of metal into simple shapes for subsequent
processing. Most basic metals are mass-produced using a continuous casting process.
The molten metal solidifies against the mold walls while it is simultaneously withdrawn
from the bottom of the mold at aratewhich maintains the solid / liquid interface at a
constant position with time. The process works best when it operates such that all the
parameters remain steady.In case of Continuous casting, the capital cost is higher, but
the operating cost is lesser, when compared to other casting processes. It is the most
cost-efficient and energy-efficient method to mass-produce semifinished metal products
with consistent quality in a variety of sizes and shapes. Continuous Casting, along with
other benefits, provides benefits such as considerably lower pollution, improved labour
productivity and improved quality, as compared to the conventional methods.
The main challenges facing the steel industry
today are under-utilization of capacity, high
raw material costs, high energy costs and price
volatility. There’s an adage which says “Even
the best can be bettered.” It perfectly applies
to Continuous casting. Industry leaders always
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“Realizing 300MT – Challenges Ahead”

2. work on this concept of “there is a better way” and don’t settle for less. One of the
thought processes is how to get more from the investments on continuous casters
by optimization of the operations. This thought process is vital in the current tough
market conditions. Evolution of manufacturing processes through perfect application
of technology provides the
right platform to optimized manufacturing operations. Steel manufacturers consistently
focus on to attend high quality of the yield and reduce scrap. This article contains the
overview of all the processes involved to get more from your caster.
Challenges
In the continuous casting process of steel making, the challenges are manifold. As the
plant operates on 24/7 basis, it demands enormous manual efforts to continuously
monitor and ensure desired quality of steel output. Continuous monitoring of the mold
signals is important to detect common issues that occur during the casting process.
Taking appropriate actions such as reducing cast speed, controlling water spray,
cascading, secondary processing, up/down grading through manual inspection at the
right time becomes important to achieve intended quality.
Presently, Quality inspection of samples takes place after the production which leaves
no opportunity for corrective action. Defect at specific points leads to lower grading
of entire length of bloom/billet. Blooms graded to lower quality levels need to be sold
at lower cost, thus adversely impacting the profitability. In fact, severe defects force
categorization to scrap grade. Minimizing these scrap levels is a key plant objective.
Solution Approach
Considering above challenges, here is a real time probabilistic system that helps in
grading by identifying and segregating different quality levels, while casting. It also
enables optimization of production by reducing wastage. It helps in identifying the
defects and taking corrective actions to achieve better quality of steel. Defects can
be analyzed and specific affected area of bloom made visible. Operators can use this
information and decide the quality levels for each slab/bloom/billet. Best processes are
defined from the knowhow of the steel casting process and any deviation while casting
is recorded and analyzed to identify the quality levels achieved. It also enables users
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3. to define a framework wherein standard practices are set and necessary corrective
actions can be built incrementally.
Input: Grading Rules & Actual Process Signal
Grading rules provide standard set points for categorizing quality. Application Software
defines rules for quality, which can be customized for the different customers and
grades. Process signals like liquid metal temperature (especially the superheat value),
level of liquid steel in the mold, quality of electromagnetic stirring, casting speed,
tundish weight, tundish temperature, spray cooling and other real time signals are
logged from field instruments and control system. These act as inputs for the grading
system.
Output: Grading & Assign Quality Levels
Application software receives the input data, which is weighed against the predefined
rules. Based on these results, system will identify the quality level of the slab/bloom/
billet. The system identifies a specific length in a slab/bloom/billet as poor or best
quality, thus providing an opportunity for the operators to take corrective actions like
surface treatment for the specific length. Hence, cast product can be upgraded to
better quality which commands higher price. The algorithms developed based on the
rich tacit knowledge gained over the years helps in defining the quality (both surface
quality and internal composition) of steel. It is observed that the results produced by
this kind of analysis could be fine-tuned to get 70-80% accuracy.
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4. Implementation
The above diagram gives an overview of the implementation of online grading and tracking
application at different layers. The required information is gathered by integrating PLC
and SCADA.PLC monitors and controls all the casting machine operations, and SCADA
serves as visualization application for operators.
to monitor and control. All critical operations of the casting process are controlled by
operators. Data acquisition system is put in place to collect key process signals from
PLC, SCADA and then logged into database at regular intervals. Application software
fetches the process data from the database and required analysis is carried out based
on algorithms and set of defined rules to identify the quality level of cast products.
For a given heat/sequence, it is assumed that chemical composition of the steel grade
remains same. However, based on event generation the quality level of each bloom
produced can be segregated as 1st Best, 2nd best, and 3rd best and so on.
Spray Cooling is also one of the key processes which would have direct impact on
quality levels. In order to maintain right cooling based on chemical composition and
its grade, water volumes to be sprayed for each zone are decided and are sent back to
SCADA to spray. This is done to reduce the deviations.
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5. In water flow levels and to ensure optimal cooling based on specific grade of steel.
Hence, it helps in achieving better quality of a product. Based on production, process
& quality parameters we can:
•
Monitor and track production & inventory system.
•
Define better pricing strategy based on quality levels achieved during
production.
Data Integration layer from production control systems to enterprise layer gives a
realistic view of production details, process and inventory. This would help in doing a
better planning and control of production on an enterprise level.
Solution Benefits
•
Optimized process flow and plant utilization through real time application.
•
Optimized schedule to obtain maximum output from the tonnage cast.
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6. •
Customer specific configurations for casting, quality, strand cutting etc.
•
Advanced spray cooling system to avoid sudden changes in the strand thermal
history resulting in more consistently better quality of steel and reduce incidents
of surface defects and cracks.
•
Informed decision making through improved real time visibility.
•
Increased price realization by improving quality grade& higher profitability by
reducing scrap.
The Steel industry is facing tough challenges in meeting profitability goals. By making
caster operations more visible, we can have significant contribution in revenue by
segregating the quality levels & billing them according to appropriate pricing strategy.
At the other end, growing demands of production can be met by process optimization
and reduction of wastages caused by surface defects, cracks and other defects.
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7th India Steel Summit
“Realizing 300MT – Challenges Ahead”