52ndRMOC

Rolling Mill Operating Committee MeetingBokaro Steel City

Better everyday

Elimination of Biting problem in Blooming Mill

Better EverydayA. Aerial View of JSW Salem Unit

JSW SALEM VISIONTo become the preferred supplier of special steel long products for domestic

and global end users

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Plant located at Pottaneri, MecheriFrom Salem : 40 KMs towards Metturdam 2 of 17

Better EverydayA.JSW Steel Ltd, Salem Works Tamilnadu

JSW Salem , part of USD 12 Billion JSW Group, is India’s largest integrated special steel plant located in

Salem Tamilnadu with installed capacity of 1 Million Tonnes Per Annum (MTPA)Salem, Tamilnadu with installed capacity of 1 Million Tonnes Per Annum (MTPA).

MANAGEMENT SYSTEMS

ISO ISO OHSAS IATF AS 9100ISO 9001

ISO 14001

OHSAS 18001

IATF 16949

AS 9100 Rev.D

ISO - International Organization for Standardization / Technical Specifications

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OHSAS - Occupational Health and Safety Assessment Series

AS 9100D - International standard for manufacturers of Aerospace product

IATF - International Automotive Task Force 3 of 19

Better Everyday

Bill t /Bl 250

Product Profile based on shape and sizeBillets /Blooms- 250,

280x370mm,340x400 mm square.Rounds – 180 mm to 310 mm

As Cast

Coils - 5.5 to 32 mmRound Bars- 20.5 to 60 mmFlats- 60 x 7 to 101 x 38 mm Hexagon -20.5 and 32.5 mm

Rolled

Bar And Rod Mill

Product

Round Blooms-60 to 200 mm ɸ *RCS - 55 to 240 mm SquareBlooming

Mill

* Round cornered squares (RCS)

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Better EverydayJSW Steels Limited, Salem

Process Flow ChartIRON COMPLEX STEEL MELT SHOP

PCI*

Hot

Iron ore

CoalCoke

pple

r

Coke Oven plant Hot Metal

Iron ore fines Sinter

Wag

on T

ip

Sinter Plant

Blast Furnace Energy Optimizing Furnace

Ladle Refining Furnace

Continuous Casting Machine

-Bars-Coils

Annealing

ROLLING MILLS

Billets

Bar and Rod Mill

-RR *-RCS*

g-Flats

Blooms

CUSTOMERS

Blooming MillFinal Inspection and Dispatch * -Rolled Round(RR)

-Round Cornered Square(RCS)-Pulverized Coal Injection(PCI) 5 of 19

Better EverydayBLOOMING MILL - ROLLING PROCESS

Reheating  Descaler Roughing  Finishing  Hot Saw Cooling furnace Descaler Mill Mill Hot Saw Bed

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Better EverydayBlooming Mill – Process Flow DiagramReceiving blooms from START gSteel Melt Shop •250 mm x 250 mm RCS•340 mm x 400 mm RCS

•310 mm RND

Cutting in Hot Saws Bundling

START

Charging of blooms in to Reheating

FurnaceRolling in

Continuous Mill Quality inspectionFurnace

Despatch

Heating of blooms (~1240°C) Front end cutting

•RND – 60 mm to 200 mm

•RCS – 55 mm to 300 mm

END

Descaling Rough rolling in Reversible Mill

Project taken RCS ROUND7 of 18

Better EverydayProcess of Blooming Mill – Hot Rolling

• The Cast blooms from Steel Melting Shop is Reheated in BF gas fired Reheating Furnace

• Then the bar is descaled and Rough Rolled in Reversible Mill (Stand #1)g ( )

• The uneven front end of the rough rolled bar is removed by Gas cutting

• Then the bar is transferred to Finishing mill, which is an 8 stand continuous mill (Stand #2V to Stand #9H)

• The bar is rolled to customer required shape and dimensions in the finishing millq p g

• Hot bars of temperature about 900 °C rolled in series of 4 Vertical and 4 Horizontal stands. Entry and Exit guides are used in each stand to guide the bar work roll groove.

• The work rolls are made of SG iron and used to for a defined life (based on rolling quantity). Then the work rolls are machined in Lathes to remove the roughness formed on the surface during usage

• After finishing rolling, the bars are cut into customer required size, cooled and sent for inspection8 of 18

Better EverydayProblem and Goal

Problem Statement:• When the rough rolled bars are fed into the first stand of continuous mill (Stand #2V), the bars are not

entering into the work roll groove due to slippage. This is called Biting problem. This happens frequentlyentering into the work roll groove due to slippage. This is called Biting problem. This happens frequently when stand #2V is changed.

• Biting problem in Stand #2V causes delay of 303 minutes/month in average.

• This leads to production loss of more than 200 MT/Month.

Goals/Objective(s):R d i d l d t biti bl f 303 i t / th t 50 i t / th• Reducing delays due to biting problem from 303 minutes/month to

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Action Plan

Counter measures are:Counter measures are:

• Increasing the First bloom HV Mill entry temperature

• Introducing Metal coating on Stand #2 Work Rolls

M dif i bl f t d tti• Modifying bloom front end cutting

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Better EverydayImplementation of Actions based on DOE

S.NO What ? How?

1 Increasing the First bloom HV Mill t t tBy changing the minimum required t t f fi t bl t 930 °Centry temperature temperature for first blooms to 930 °C

2 Introducing Metal coating on Stand #2 Work RollsBy procuring metal coating device and coating on the machined rolls in roll shop.

3 Modifying bloom front end cutting Training the gas cutters and introducing new procedure for front end cuttingy g g new procedure for front end cutting

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Better EverydayImplementation of Actions

Arc Spraying on Work Rollp y g

Metal Coated Work Roll12 of 18

Better EverydayImplementation of action

Finishing MillMill

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Better EverydaySide Effect Verification

Action : Introducing Metal coating on Stand #2 Work RollsEffect: Roughness in rolled productTest: Visual InspectionTest: Visual Inspection

Result:Result: Since no roughness found on the rolled bars during trial implementation,

this action can be implemented14 of 18

Better EverydayImplementation of Actions

Front End Taper CuttingFront End Taper Cutting

Inference: New cutting shape in front end of the bar is introducedInference: New cutting shape in front end of the bar is introduced

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Better Everyday

Project Results

350Reduction in Biting Delay

303

250

300h

150

200

nute

s/m

onth

3050

100

Min

30

0

50

Before AfterAchieved Target Linear (Achieved)c e ed a get ea ( c e ed)

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Better Everyday

Conclusion

• Delays due to biting problem in continuous mill is reduced from 303 minutes / month to 30 minutes/month in average

• Total time saved – 273 Minutes/month

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Better Everyday

THANK YOU

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