a case study on throughput improvement in a steel melting shop

A Case Study on throughput improvement in a Steel Melting

Shop

Presentation Contents 

Tata Steel Overview01.

Tata Steel Value Chain02.Case Study : Simulation 03.a) Business Challengeb) Approach & Objectivec) Simulation & Analysisd) Insights & Outcome e) Ways ahead

Presentation Contents 

Tata Steel Overview01.

Tata Steel Value Chain02.Case Study : Simulation 03.a) Business Challengeb) Approach & Objectivec) Simulation & Analysisd) Insights & Outcome e) Ways ahead

Tata Steel Overview (1/3)

Employee base comprises of over 74000 people in ~ 50 counties

Industrial harmony of over 88 years

First integrated steel plant to receive DGP & DEMING Prize (outside Japan)

India’s 1st steel company to receive “Green Co‐Platinum Rating” by CII‐GreenBusiness Centre

A Fortune 500 company & world’s second most geographically diversified steel producer

Sustainable and highly cost efficient operations in India

Flat Produ

cts

Long

 Produ

cts

Selling by pieces

• Fastners• Tyre bead wire• Construction electrodes

• Springs• Doors

• Large construction projects

• Individual houses

ProductsKey Customers Application Unique offering Focused segment

Hot Rolled (HR) Strips

Cold Rolled (CR) Sheets

Galvanized CR Sheets

Reinforcement bars for construction

Wire Rods

•Auto, •Commercial,•General Engineering 

•Auto,• Steel Roofing•General Engineering

•Auto, •General EngineeringDistribution

•General Engg Direct

Customer Products  & BrandsTata Steel Overview (2/3) :

50% LPG cylinders in India are made from Tata Steel HR coil

Nearly all the 1p, 2p, 5p and 10pcoins in the UK are made fromsteel made at Port Talbotplant

75% of Singapore’s scrap isconsumed and recycled byNatSteel

Almost every model inautomotive has some steel fromTata Steel

50% of UK car makers fulfil their steelrequirements from Tata Steel UK

Nearly every Gillette bladeworldwide contains Tata SteelChrome

Every 4th stainless steelutensil in India is made fromTata Steel chrome ore

4 Million Households servedby Tata Steel retail brands (TataTiscon, Shaktee, Durashine)

Interesting Steel FactsTata Steel Overview (3/3):

Presentation Contents 

Tata Steel Overview01.

Tata Steel Value Chain02.Case Study : Simulation 03.a) Business Challengeb) Approach & Objectivec) Simulation & Analysisd) Insights & Outcome e) Ways ahead

RAWMATERIALS 

IRONMAKING

STEELMANUFACTURING

DOWNSTREAMPROCESSING

MARKETING& SALES

CUSTOMERS

Tata Steel Value Chain

Torpedo Station Desulphurization LD Converter Slab Caster Slabs

Removing  sulphur  by 

injecting CaC2 and Mg

Removing C,Mn,P & Si 

Vertical & Bow casting

Hotmetal premixing & and  ladle filling

Steel Making Process Overview

Presentation Contents 

Tata Steel Overview01.

Tata Steel Value Chain02.Case Study : Simulation 03.a) Business Challengeb) Approach & Objectivec) Simulation & Analysisd) Insights & Outcome e) Way ahead

Background: Steel Melting Shop team observed potential to improve vessel charging rate by improvising 

upon existing business rules for handling Cranes and other logistics systems. Existing business rules for handling cranes induce crane idleness mainly while transferring 

hot metal to charging vessels  and while unloading empty buckets on transfer car in pit(s) thereby resulting into loss of charging/heats.

There was a need felt to carry out a study to check and validate whether modifying business rules for handling cranes and other systems help in improving throughput.

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3.(a) Business Challenge 

Torpedo Station

Desulphurization LD Converter Slab Caster Slabs

Removing  sulphur  by 

injecting CaC2 and Mg

Removing C,Mn,P & Si 

Vertical & Bow casting

Hotmetal premixing & and  

ladle filling

Problem Solving Approach : (Simulation)

Identification of problem

Problem Worth Simulating?? Defining Objective Data Collection 

& ModellingValidation, 

Modification, Report 

3.(b) Approach & Objective   

Objective :  

Simulation study to optimize internal logistics of Steel Making unit with the objective to increase throughput. 

3.(c) Simulation Modelling & Scenario Analysis :n Study

3 Scenario were modelled in the Simulation with modified logic of Crane operatingphilosophy :

(1) Using both charging bay crane for Vessel Charging (Existing)(2) Using Crane2 mainly for Vessel Charging, Using Crane 1 while doing parallel charging.(3) Scenario 2 + provision for parking empty bucket at 9m floor.

While creating scenarios ,the objective was to reduce waiting time for Vessels and creatinglogic which offer least interference to charging crane with other crane.

90 Experiments were designed for each scenario by varying DS and Vessel processing time toobserve Heats produced per day ,Crane utilization , waiting time of Vessels .

Simulation Snapshot

Simulation Model Snapshot

L 3.(d) Insights & outcome (1/3) :

Scenario 2‐Scenario 1

Scenario 3‐Scenario 1

Scenario3‐Scenario2

Mean 1 4 3

Median 1 4 3

Statistical Centrality  Measures: • We observe that Heats gain per day is more and Vessel Waiting Time is lesser in Scenario 3 with respect to Scenario 2 and Scenario 1.  

‐2

0

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1 4 7 101316192225283134374043464952555861646770737679828588

Comparison: Heat Gain Per Day

Case2‐Case1 Case 3‐Case 1 Case3‐Case2

‐3.00

‐2.00

‐1.00

0.00

1.00

2.00

3.00

1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 65 69 73 77 81 85 89

Vessel waiting time comparison 

Case2‐Case1 Case3‐Case1 Case3‐Case2

0102030405060708090

Exp 01

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Exp 89

ChargingBayCr 1Utilization(%)

Case 1 Case 2 Case 3

L 3.(d) Insights & outcome (2/3) :

• We observe that Charging Bay Crane 2 Utilization is around 80% in Scenario 3 which is slightly undesirable. For this we recommended to have a robust preventive maintenance plan along with use of crane 1 more frequently in case of liquid charging. 

0

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100

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Exp 89

ChargingBayCr 2 Utilization

Scenario1 Scenario2 Case 3

L 3.(d) Insights & outcome(3/3) :

Result: The statistical analysis of simulation outcome suggests that Scenario 3 has a significant

advantage ofminimum 2 heats/day over Scenario 2 and Scenario 1. It was observed that in Scenario 3 ,Crane utilization and waiting time of Vessels also

improves significantly. Scenario 2 is slightly better than Scenario 1. Scenario analysis suggest it’s always better to use 2nd charging bay crane only for

charging vessels rather than using both the cranes for charging. Provision for parking empty bucket at 9m floor will improve throughput significantly.

L 3.(e) Ways Ahead :

1. Requirement from Business : Incorporating Scrap charging compulsory into the model and analyzing the effect. 

2. Finding the best parameters for arriving at the global optima of the system. 

3. Using Optimization to find the best combinations of the different input parameters at various levels of production flow . 

Thanks

Q & A

Backup

Why Simulation is required?

The system operates in very complex environment. Most of the crane handling related decision making are manual and taken

by different persons for different cranes . Handling various cranes in coherence to optimize the overall process is

tedious task. Moreover, there are many variability/randomness in the system (e.g. process

time of Vessels/DS, downtime etc.) The customer wanted some simple thumb rule to operate cranes so as to

involve least human dependent decision making in various cases and thereby optimizing overall process.

In this purview, there was a need to carry out a simulation study.

System understanding (1/3)

Crane1 Crane2 Crane3

Charging Bay

Torpedo Bay

Torpedo Bay Crane

Steel Melting Shop Schematic

V1 V2 V3

DS1 DS2 DS3

System understanding (2/3)

Crane1 Crane2 Crane3

Steel Melting Shop Schematic

System understanding (3/3)

Steel Melting Shop Schematic

Crane1 Crane2 Crane3

Torpedo Bay Crane

Data Collection

Major Assumptions1.Vessels availability = 87.5% of simulation time2.The system scope is from hot metal unloading from torpedoes into buckets to Vessel taping. (Activities prior to hot metal unloading from torpedoes and post taping are out of scope of this study)3.In simulation, trigger goes to scrap crane 5 mins before charging gets completed in a vessel, to be ready with the scrap for charging.4.Simulation is run for a period of 10 days post warm up period.5.Transfer cars are always available (no downtime).