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Manufacturer of cold rolled steel

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					     ‫‪Manufacturer of cold rolled steel‬‬

                                      ‫قال رسول اهلل :‬   ‫‪‬‬

        ‫(خيركم من تعلم العلم وعلمه ) صدق رسول اهلل‬      ‫‪‬‬

‫الساده الزمالء اليكم نبذات مختصره عن صناعة الصلب‬        ‫‪‬‬
                  ‫المدرفل على البارد بمراحله المختلفه‬
                           ‫اعداد م / محمد حسن توفيق‬     ‫‪‬‬

‫االشراف / مجموعه من الخبراء الهنود بشركة 6 أكتوبر‬       ‫‪‬‬
                       ‫للصناعات المعدنيه ( سوميكو )‬
  Cold Rolling Process for CRCA Sheets
HR Slitter
· The Pull through HR slitting line cuts the rough edges of the HR coils, slitting it
into narrower widths

Pickling
· Removes ferrous scales from the surface of the HR Coils
· The pickling line uses three acid tanks and three rinse tanks
· A hot air blower at the end dries off the excess water on the strip

6-Hi Hitachi, 6-Hi Flat & 20-Hi Rolling Mills
· The pickled HR coil is cold rolled to the required thickness
· The 6-Hi mill has automatic gauge control, pass schedule storage and auto
intermediate slow down
· The mills give flat strip shape, minimized edge drops and thinner gauges

Annealing
· Process of heating, soaking and controlled cooling of coil in a non-oxidizing
atmosphere
· Annealing atmosphere contains Hydrogen and Nitrogen
· Cooling done with air and then water followed by natural cooling
  Cold Rolling Process for CRCA Sheets
Skin Passing
· Skin Passing removes stretcher strain or Lines.
· It provides desired finishes such as Matt, Bright on the strip surface
· Imparts flatness to the strip

CR Slitters
· Used to customize the width of the strips to cater to the diversified needs of the
customers
· They have an independent tension unit thus enabling tension variance

Cut to Length
· Cut to Length machine cuts the Cold Rolled steel into sheets as per customer
requirements
· The length can vary from 400mm to 3500mm
COLD ROLLED - CLOSE ANNEALED
     (CRCA) SHEETS & COILS
 Production Process Flow Diagram
  COLD ROLLED - CLOSE ANNEALED
      (CRCA) SHEETS & COILS

DIVERSE APPLICATIONS
  • Automobiles

  • Electrical Panels

  • Furniture

  • White goods

  • Transformers

  • Oil Barrels & Drums

  • General Engineering
                                PICKLING
• Pickling line is basically meant for removal of rust on the surface of HR coils supplied
by the vendor. For this, strips are dipped in acid tanks which removes the rust (oxidized
surface) on HR coils.
• Acid used for pickling is HCL. Pickling is done in three stages. In these three stages
acid concentration is different for pickling – Ist stage 3.5%, IInd stage 7% and IIIrd stage
11%.
• After acid wash strip is rinsed in hot water tanks. Then it is dried in drier. Then it is
passed through oil tank (only for Galvanized sheets). After pickling material is ready for
rolling.
• From PPC planning sheets are issued for shift planning. All planning sheets are issued
in hard copy form. Pickling deptt makes its own program for shifts and scheduling of
material by their own convenience.
• Before pickling raw material inspection is being done by quality control deptt. Chemical
composition of HR coils is tested through spectroscope which gives percentage of Fe, C,
Sn etc.
• A number is given to the coil after inspection and before pickling which is maintained
before finishing & quality control inspection. Raw material HR coils are of 7mm, 6mm,
4mm in thickness which is to be reduced in thickness in rolling mill upto required
thickness as per customer specifications.
                           Loading into       Loading into
 HR Coils - Slitting
                           pickling line        Uncoiler




           Acid Tank III       Acid Tank II    Acid Tank I
           (HCL - 11%)         (HCL - 7%)     (HCL - 3.5%)




       Rinsing Tanks              Drier          Oil Tank




Ready        To Stock
 for                            Unloading         Coiler
Rolling
                                      Rolling
• Rolling is basically done to reduce thickness of strips by imparting tension and
pressure on the incoming strips in a rolling mill.
                            Initial                        Final
                          Thickness                      Thickness
                              t1                             t2




                            %age reduction = (t1 – t2) / t1 * 100
• This percentage is decided by the system or experience as per customer specification.
• If the final thickness is not achieved by single pass then more then one passes is
designed to achieve the required thickness. In 6 Hi Flat and 6 Hi Hitachi, pass schedules
are decided automatically by the system. But in 20 Hi pass schedules are designed
manually by operator as per his experience.
• Mostly CRCA material is rolled in 6 Hi Hitachi mill. Galvanized material is rolled in 6 Hi
Flat and 20 Hi mill. Planning for 6 Hi Hitachi is given by PPC (CRCA sheets planning
deptt. NCRM) and for 6 Hi Flat and 20 Hi mill is given by PPC (Galvanized line by
planning deptt. old CRM).
    Backup Roll


Intermediate Roll

       Work Roll



       t1           t2
                         6 Hi Hitachi Mill
• This mill is an advanced mill for high production rate and maximum width which can be
rolled in this mill is 1700 mm. Speed which can be maintained here is 1200 meter per
minute.
• 90% of the material rolled here is material for CRCA sheets. Planning sheets are
issued by PPC (CRCA Sheets NCRM). According to planning sheets, deptt head of 6 Hi
decide their own scheduling. They decide priorities according to planning sheets issued
by PPC, material availability and convenience of rolling.
• Production reports are generated in hard copy form and delivered to PPC for their
reference, PPC deptt then feed this data in the system and this helps PPC to decide
further planning. PPC issues planning sheets once in a day for three shifts according to
this planning production deptt plans their own scheduling. After deciding which material
is to be rolled in 6 Hi, supervisor feeds the data in the system to plan schedule.
• Here pass schedules are decided by the system after feeding parameters like
thickness, width and weight of the coil and system decides percentage reduction in
every pass.
• After the complete information designed by the system, operator starts machine rolling
according to the information like entry side tension, exit side tension, load, coolant, entry
thickness, exit thickness etc. Operator may change the setting if he thinks that it is more
advisable by his own experience.
          ETR




                                                                                 DTR


• Here after rolling some of mechanical properties of strip changes depending upon the
percentage reduction of the material.
• For all the machine parameters there is a software supplied by the manufacturer which
gives online information of machine parameters like pump on, pump off, coolant on,
coolant off etc. He can operate these parameters by the system. Alarms are also
indicated by the system. These controls gives good support for early warning and
remedy before break down.
• After rolling grain structure also changes due to rolling pressure and tension created
during rolling. Grain size is elongated in the direction of rolling that’s why physical
properties like hardness, tensile strength also changes.
                                                    Increased hardness & brittleness
                                                          Elongated grain size

       Before Rolling               After Rolling
            6 Hi Hitachi Mill Benefits


• Software supplied by the manufacturer provides man machine interface

• Fully flat shape of CRCA sheets through shiftable Inter Mediate Roll (IMR)
shifting

• Reduced edge drop through shiftable IMR and bender force

• Better grain structure due to higher reduction

• Thickness close to nominal through Auto Gauge Control (AGC)

• Uniform properties of the total coil length through elongation control during skin
pass

• High productivity through higher speed of 1200 metres per minute and auto
slowdown
    Backup Roll


Intermediate Roll

       Work Roll



       t1           t2
                     6 Hi Flat (FPE) Mill
• This mill is same as 6 Hi Hitachi. Basic difference is maximum width rolled in this mill
which is 1200 mm. line speed is 1000 meter per minute so production rate is slow as
compared to 6 Hi Hitachi. Mostly Galvanized material is rolled here.
• Planning sheets are delivered here from PPC (galvanized sheets in old CRM). PPC
issues planning sheet according to the OA and stock in hand. According to this planning
sheet 6 Hi mill plans its own scheduling keeping in mind material available for rolling,
gauge of strips, machine capacity and condition of rolls etc.
• After deciding which material should be loaded on line operator has to decide pass
schedule of rolling which is done automatically by the system, according to the
parameter, thickness, width and weight of the coil.
• Here in this mill percentage reduction is achieved by applying pressure (load) on the
work rolls. Tension in the coil has less important roll in 6 Hi flat. Pressure is applied
through backup rolls and intermediate rolls.
• Coolant is basically used to cool the rolls warmed up due to heat generated by the roll.
Heat is generated due to high pressure developed by the work rolls to impart reduction
of thickness in strip. Here we can roll upto 0.10 mm of thickness.
• Here also mechanical properties of strip is changed and grain structure is deformed
after rolling. After this rolling material is send to galvanized line where annealing is done
online before galvanizing.
        ETR




                                                                          DTR




• Here coil is loaded through loading uncoiler. By this uncoiler strip is pass through into
the mill for the first pass. After first slight pass coil is loaded into ETR from where actual
rolling starts for the second pass then it go to DTR.
                             20 Hi Rolling
• Here at 20 Hi mill thickness upto 0.13 mm can be rolled. Here reduction in thickness of
the strip is done mainly by applying tension on the strip, pressure has less important role
in 20 Hi rolling. Here after getting planning sheets from PPC schedule is done according
to this work centers priorities. Pass schedules are decided by experience of the operator
manually not by the system.
• This process is somewhat complicated process that’s why it is not in much use for fine
gauge because adjustments are not so easy here. Operator here decides number of
passes and percentage reduction given to the strip in each pass to achieve final
thickness.
• Initially & final thickness is measured by electronic gauge installed at the entry and exit
of the mill. By this measurement we can control the system more effectively and more
control over output gauge and number of passes.
• After rolled in 20 Hi mill material is ready for the galvanizing line where material is
annealed and galvanized for specific customers. Here mostly material involved is for
galvanized line. Planning deptt responsible for this work station is PPC (Galvanizing in
old CRM). For 6 Hi flat rolling and 20 Hi mill there are two CRS line where rolled material
slits into required width for Galvanizing line. 20 Hi specifications
•Maximum width – 1250 mm
•Maximum speed – 400 meter per minute.
          Electrolytic Cleaning Line

• After rolling for CRCA sheets in 6 Hi Hitachi mill strips contains some coolant on its
surface. After rolling strips has gone through some changes in mechanical properties
and grain structure of the material so it needs annealing to improve these properties
according to customer requirement.
• If this material after rolling goes directly to annealing then the coolant and other
impurities on the surface creates reaction and strip is headed up to annealing
temperature in furnace. For this specific purpose we go through electrolytic cleaning of
the strip in ECL. Surface finish is also improved in this process.
• Strip is pass through electrolyte and then in caustic soda solution where its surface is
cleaned then it passed through dryers and output clean material is ready for annealing.
• This line is in NCRM where it is directly assigned to annealing division which is also in
NCRM near ECL line. Most of the material of CRCA is rolled in NCRM for easy workflow.
All the Galvanized material is processed in old plant.
                               Annealing
• As discussed earlier rolling impacts changes in physical properties and grain structure
of the material, so to improve these properties we anneal the material in annealing
furnace.
• Here coils are stacked in furnace and then temperature raised to 575-650°C (annealing
temperature). After attaining the temperature material is soaked for a particular time
(soaking time) depending upon the parameter mentioned there then it cools to room
temperature.
• Here planning and annealing cycle is decided by the system automatically. Here
system only requires some parameters like grade of the material, thickness, width and
weight of the coil. By these parameters system design the annealing cycle (annealing
temperature, soaking time, cooling time and environment).
• After annealing grain structure is refined and hardness is reduced according to the
customer requirement. Here annealing lot is decided keeping in view the thickness and
width of the strip, coil weight, material grade etc.
• Here planning sheets are issued according to the customers specification, physical
properties and grain structure required by the customer. For different grades annealing
cycle is different so it needs more attention to keep track of the schedule at each
annealing work station.
• At NCRM Division, we boast of a semi automated Hydrogen Annealing equipment.
Annealing is a process of heating, soaking and controlled cooling of coil in a non-
oxidizing atmosphere. Metallurgically, the annealing process relieves the stresses
developed by Cold Rolling and renders the strip soft and restores its ductility and
formability.

•Hydrogen annealing furnaces use 100% hydrogen atmosphere, resulting in bright
surface of the material.

•The semi automated feature of the furnace, help us maintain accuracy in operation
enabling us to give consistent quality.
                  Annealing Cycle
   575 - 640° C       soaking
                                          cooling
Temperature




                     Soaking Time


                          Time




                        • Here heating is done through convection process.




                         Annealing pot
                          Skin Pass Mill

• After annealing material is in required form as per customer specifications grain size is
improved after annealing and material is soft. Then it is passed through skin pass mill.
• Here surface finish is improved and slight increase in hardness on surface of the strip
is achieved by very less (7%) reduction in SPM. Gauge is also checked here by Quality
control because this is the final stage of the process before slitting to required size.
• Here quality control deptt is active to check the QA parameters. Coil number is also
changed after strip come of SPM. All the parameters of quality assurance is checked
over here like gauge, surface condition, defeats, physical parameters, uniformity etc.
• Here all the quality assurance parameters are compared with the specification
delivered by the customer. Once all these parameters are matched with customer
specification material / coil is ready for the finish line.
                  Galvanizing Process
• Hot dip galvanizing is the process of applying a zinc coating to fabricated iron or steel
material by immersing the material in a bath consisting primarily of molten zinc. The
simplicity of the galvanizing process is a distinct advantage over other methods of
providing corrosion protection. The automotive industry depends heavily on this process
for the production of many components used in car manufacturing.

• Galvanizing can be found in almost every major application and industry where iron or
mild steel is used. The utilities, chemical process, pulp and paper, automotive, and
transportation industries, to name just a few, have historically made extensive use of
galvanizing for corrosion control. The electrochemical protection provided to steel by zinc
coatings is a vital element in the effectiveness of galvanized coatings in protecting steel
from corrosion. All pre-galvanized products rely on the cathodic protection provided by
zinc to prevent corrosion of exposed steel at cut edges.

• While the potential difference between metals is the prime driving force providing the
corrosion current, it is not a reliable guide to the rate and type of corrosion occurring at a
particular point. The severity of galvanic corrosion also depends on the ratio of the areas
of metals in contact, the duration of wetness (galvanic corrosion can only occur in the
presence of a conductive solution) and the conductivity of the electrolyte. The presence
of oxide films on the surface of one or both of the metals can greatly inhibit galvanic
corrosion.
 GALVANISED SHEETS & COILS
Production Process Flow Diagram
    GALVANISED SHEETS & COILS
DIVERSE APPLICATIONS

  • Roofing/Cladding

  • Doors/Windows

  • Structural Engineering

  • Automobiles

  • Air Conditioning/Ducting

  • Insulation

  • Partition Profiles

  • Furniture

  • Appliances


  • Trunks/Barrels/Drums/Buckets
                       Galvanizing Line
•   Galvanizing is basically a process of zinc coating on the surface of the strip to impart
    surface finish and prevention from rusting. There are three galvanizing plant where
    two types of galvanizing sheets are processed as per customer requirement.
     1. GP (Galvanizing plain)
     2. GC (Galvanizing corrugated)
•   Two types of material are made in galvanizing line, soft and hard. Hard material has
    only one use that is corrugated sheets for roofing and side fencing. Hard material is
    heated upto 450-550°C and soft material upto 550-650°C in furnace.
•   In galvanizing line I & III both hard and soft material can be processed (Non-ox line)
    in galvanizing line II only hard material is processed (flux line). Final inspection is
    done in galvanizing line before exit side coiler. After galvanizing material is sent to
    CRS and CTL for finishing.
•   For galvanizing line planning is done by GL PPC in GL III. Planning sheets are
    issued from PPC and scheduling is done at this work station according to material
    availability, customer priorities, types of material.
•   Stock is taken in every shift which is recording in log book. Production report is
    prepared and sent to PPC for further planning.
                Galvanizing Line I & III
The type of continuous hot-dip coating processing line in use involves a series of steps.
These may include the following sequential sections:

• An entry-end welder to join the trailing edge of one coil to the leading edge of the
succeeding coil to allow the process to be truly continuous

• An alkaline cleaning section to remove the rolling oils, dirt, and iron fines (surface
contaminants from the cold reduction process) that are on the sheet surface

• An annealing furnace that is used to heat the steel to high temperatures to impart the
desired mechanical properties (strength and formability) to the steel sheet

• A bath of molten metal that contains the metal being applied to the steel surface

• A cooling section to cool the strip and solidify the coating as it emerges from the bath
                Galvanizing Line I & III

• A temper mill to impart the desired surface finish to the coated steel

• A tension leveler to flatten the strip to meet the end use requirements

• A treatment section to apply a clear, water-base treatment to the coating to prevent
storage stains that can form on the coating surface when moisture is present
(condensation and/or water infiltration originating from improper shipping or storage)

• An oiling section used most often to apply a rust-inhibitive oil; at times, used to apply a
forming oil

• A recoiler to rewind the finished coil of steel
                Galvanizing Line I & III
• The incoming steel is most often “full-hard” sheet coming directly from the cold
reduction mill. The cold reduction mill is used to decrease the thickness of the strip to
the desired thickness.

• This cold process makes the steel very hard with limited formability. For heavier sheet
thicknesses, the product may be entered into the coating line directly after hot rolling and
pickling.

• In either case, the sheet is uncoiled, welded to the tail end of the coil ahead of it in the
processing line. Then, it is cleaned in a process that typically uses an alkaline liquid
combined with brushing.

• From the cleaning section, the strip passes into the heating (annealing) furnace to
soften the full-hard strip and impart the desired strength and formability to the steel.

• In the annealing furnace, the strip is maintained under a reducing gas atmosphere to
remove any vestiges of oxides on the steel surface. The gas atmosphere is composed of
hydrogen and nitrogen.
               Galvanizing Line I & III

•This oxide-reduction step, iron oxide being converted to iron by reaction with the
hydrogen, is very important to obtain complete wetting** of the steel surface during the
short time that it is immersed into the coating bath.

•The exit end of the furnace is connected directly to the molten coating bath metal to
prevent the heated steel strip from re-oxidizing (in the air) prior to reacting with the
molten coating metal. In the coating bath, the strip passes around a submerged roll and
then exits the bath in a vertical direction. At the exit point, a set of air knives (high
pressure air) wipe off excess molten metal leaving behind a closely controlled thickness
of molten metal.


** Wetting is the reaction between the steel surface and the molten coating metal. This
reaction is very important to obtain complete coverage by the coating and good
adhesion between the coating and steel when the customer forms the sheet.
               Galvanizing Line I & III
• The coating is then cooled to allow the metal to freeze on the steel surface. Freezing of
the coating, or solidification, has to be accomplished before the strip contacts another
roll to avoid transferring the coating onto the roll. Thus, coating-process lines usually
have a high tower above the coating bath, perhaps as high as 200 feet on some of the
newer lines.

• After cooling to close to room temperature, the strip feeds into the exit end equipment -
temper mill, tension leveler, chemical treatment section, oiler, and then is recoiled on an
exit-end mandrel.

• The continuous strip is sheared at the weld that was made at the entry end of the line
to remove the weld as well as to maintain coil-to-coil identity.

• Not all hot-dip coating lines have all of the above processing steps. For example, some
do not include the aqueous cleaning stage, relying instead on “flame” cleaning in the
entry end of the annealing furnace. Others might not have a temper mill; temper rolling is
not necessary, and perhaps not desired, for some applications of hot-dip coated
products.
                     Galvanizing Line II
• In Galvanizing Line II hot-dip process is used which involves a significantly different
approach. In this process, called the flux-coating process, the steel is annealed ahead of
the coating line in a separate operation, either batch annealing or continuous annealing.
Thus, the coating line does not have the large continuous annealing furnace that was
used in galvanizing line I & III. In the flux-coating process, the steel is cleaned to remove
oils, dirt, etc., and then pickled to remove the thin oxide coating that is present on the
steel surface. After rinsing, the steel is then passed into an aqueous flux solution to
apply a flux residue onto all areas of the steel surface.

• When the flux-covered strip enters the coating bath, the chemical action of the flux
behaves similar to the performance of fluxes used for soldering; that is, the flux reactions
help to obtain rapid “wetting” of the molten coating to the steel surface. Recall that this
wetting reaction is required to obtain (1) complete coverage of the molten coating, and
(2) a good bond between the coating and the steel.

• The remainder of the flux-coating process is essentially the same as that used in the
process described above for the lines that have in-line annealing furnaces.

• Flux-coating galvanizing line II process refer to it as the “cold” process in contrast with
the term “hot” process used to define the lines that have in-line annealing furnaces in
galvanizing line I & III.
                         Quality Control
• At the CR Division, quality is given the utmost significance. From the very stage of
material receipt to the time of product delivery to the customer, the product undergoes
strict quality tests.


• CR Division is an ISO certified Company and acquired QS 9000 certification. To
provide unhindered customer services the Company has planed to implement the SAP
R/3 ERP System, which will improve the Division's relationship and communication with
its customers and clients.


• Quality assurance has been engrained from the initial plant design/layout stage and is
continuous. From the selection of the right input to the establishment of a quality system,
the adherence to systems and procedures is ensured.


• Test Certificate for the Final Product :
Test certificates are provided for all the supplies along with the despatches made by
them. However if any extra information is required, it can be provided as per the
requirement and the format of the Test Certificate as issued by the Company can be
amended accordingly.
                         Quality Control
• In order to ensure the delivery of right quality, CR Division has the following equipment
for checking quality.


                   Product Inspection Equipment at CR Division

           Inspection Equipment                            Inspection Details
                             Spectrometer                         Chemical Analysis

                Metallurgical Microscope                    Study of Microstructure

                                                  Tensile Strength, Yield Strength,
              Universal Testing Machine
                                                        Elongation and Bend Test
                        Roughness Tester                                    Ra Value
                 Vickers Hardness Tester                    Hardness Measurement
               Rockwell Hardness Tester                     Hardness Measurement
               Erichsen Testing Machine                                 ECV Testing

				
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