Operation Study and Analysis of Steel Rolling Mill Submitted To Prof. G. Anand Operations Management II Course I.I.M. Kozhikode
On 18th March 2013
By Bharat Subramony Bharat Wadhwa Gunveer Singh Ranjan Sharma Rohit Singla Utkarsh Rastogi Pratap C Pati
PGP/16/012 PGP/16/013 PGP/16/019 PGP/16/040 PGP/16/043 PGP/16/056 FPM/06/001
Table of Contents About Indrayani Steels and Alloys Private Limited ................................... .......................................................... .......................... ... 3 Origin of ISAPL ......................................................... ................................................................................. ................................................ ...................................... ..............4 Operations of ISAPL ............................................. ..................................................................... ............................................... .......................................... ...................6 Melting ............................................. ..................................................................... ............................................... .............................................. ...................................... ...............7 Purging Process.............................................................. ...................................................................................... ................................................ .............................. ......7 Casting Process............................... Process....................................................... ................................................ ................................................ ...................................... ..............8 Re-heating Process ............................................. ..................................................................... ............................................... .......................................... ...................8 Quenching Process Process ............................................. ..................................................................... ............................................... .......................................... ...................9 Self-tempering Self-tempering Process .............................................. ...................................................................... ............................................... .................................. ...........9 ISAPL Products ............................................. ..................................................................... ............................................... ............................................... .......................... 11 Process Analysis of ISAPL products ................................ ........................................................ ................................................ ............................ .... 13 Variable Control Chart ............................................................. .................................................................................... ........................................ .................14 Attribute Control Chart ............................................................ ................................................................................... ........................................ .................16 Inventory model and control.................................. control......................................................... .............................................. ........................................ .................23 Maintenance Operations ........................................... ................................................................... ............................................... .................................... .............27 Conclusion ............................................... ....................................................................... ............................................... .............................................. ................................ ......... 28 Limitations............................................... ....................................................................... ............................................... .............................................. ................................ ......... 28 Appendix .............................................. ...................................................................... ............................................... .............................................. .................................... .............29
Table of Contents About Indrayani Steels and Alloys Private Limited ................................... .......................................................... .......................... ... 3 Origin of ISAPL ......................................................... ................................................................................. ................................................ ...................................... ..............4 Operations of ISAPL ............................................. ..................................................................... ............................................... .......................................... ...................6 Melting ............................................. ..................................................................... ............................................... .............................................. ...................................... ...............7 Purging Process.............................................................. ...................................................................................... ................................................ .............................. ......7 Casting Process............................... Process....................................................... ................................................ ................................................ ...................................... ..............8 Re-heating Process ............................................. ..................................................................... ............................................... .......................................... ...................8 Quenching Process Process ............................................. ..................................................................... ............................................... .......................................... ...................9 Self-tempering Self-tempering Process .............................................. ...................................................................... ............................................... .................................. ...........9 ISAPL Products ............................................. ..................................................................... ............................................... ............................................... .......................... 11 Process Analysis of ISAPL products ................................ ........................................................ ................................................ ............................ .... 13 Variable Control Chart ............................................................. .................................................................................... ........................................ .................14 Attribute Control Chart ............................................................ ................................................................................... ........................................ .................16 Inventory model and control.................................. control......................................................... .............................................. ........................................ .................23 Maintenance Operations ........................................... ................................................................... ............................................... .................................... .............27 Conclusion ............................................... ....................................................................... ............................................... .............................................. ................................ ......... 28 Limitations............................................... ....................................................................... ............................................... .............................................. ................................ ......... 28 Appendix .............................................. ...................................................................... ............................................... .............................................. .................................... .............29
Declaration
We hereby solemnly declare that, the project titled “Operations Study and Analysis of Steel Rolling Mill”, under Prof. G. Anand, for the course on Operations Management is an original work. The information included in this project report, is true to the best of our knowledge and these facts have been used for pure academic purposes. The information shared by the organization cannot be duplicated for any other purpose, other than sanctioned for. The details mentioned with respect to the aforementioned organization, whether true or fictitious, cannot be held as proof of document for an y legal course of actions against the organization.
About Indrayani Steels and Alloys Private Limited
Indrayani Steel is known to appreciate the constant requirement to evolve – not just in terms of products, even in terms of organizational functionality, to stay ahead with changing market situations. They strive to ensure that their core products conform to the highest quality standards, and our equipment, systems and processes are technologically kept updated. They constantly invigorate their technological competency, through various quality programs and safety initiatives. They hold their customers are at the center of their existence, and assure of unparalleled quality, timely delivery and an enduring business relati onship.
In the current situation of a highly competitive market with cutthroat competition and numerous macro-economic adversities and fluctuating steel industry policies, they have reengineered themselves to meet the challenges through constant innovation and technological enhancements. They boast of a tightly knit family, of all emplo yees whose sole aim is customer satisfaction, immediate response and prompt delivery promise and keeping up to date with market needs.
Origin of ISAPL
ISAPL was incorporated in 2002 and set up its operations in March 2003. We began our manufacturing operations as melting unit in Pune, producing secondary steel products. They later on diversified into production of primary steel making i.e. sponge iron. By continuously expanding their production capacity over the years and setting up multiple plants over several places in Maharashtra, and integrating vertical operations to fully exploit production economies, they have exponentially advanced to rolling.
Mission Statement of ISAPL
We at ISAPL aspire to become the preferred suppliers of innovative, cost-effective and practical construction solutions across diverse markets. Our vision for the future is clear with a consistent set of values we strive to uphold.
We at ISAPL are:
Foster innovation and development, driven by customer requirements and supported by implementation of excellent operational strategies. Work towards employee advancement and personal development by appropriate inward investment and identification of their relevant training needs. Commit to maintaining a high-level of customer service within the dynamic and challenging industry. Strive to set globally recognized standards keeping in view the future generations needs.
Operations of ISAPL
The process of Thermo-Mechanical Treatment (TMT) is comprised of quick and rapid quenching of hot bars at well-designated temperature with controlled pressure and travel ratio through jacket of coolant (generally water-bath), after processing through the finishing stand of rollers, The entire process is automated and completely controlled by a computerized software program, which strives to maintain the accuracy on the final output, eliminating possible human errors to obtain the required mechanical properties. Such case hardened bars give high-yield and ultimate tensile strength. Due to the internal soft core, it helps to maintain higher elongation percentage, and bend and re-bend property that play a vital role in all normal and earthquake zones.
Raw Material Processing
Raw materials such as Sponge Iron/DRI, Billets and B-Boms, used in pre-described properties are generally graded both physically and chemically. The resulting chemical structure that we obtain is then analyzed from all perspectives using in-house equipment called spectrometer and C & S apparatus. If the required specifications are not met, then the base materials must go through a process control procedure, else they are stored in the yard.
Figure 1: Raw Material Yard
Melting
The sample of raw material is introduced to the furnace for melting in an induction furnace. The furnace comprises of a refractory container, which is competent of holding the molten bath, which in turn is surrounded by water-cooled helicoidal coil connected to alternating current. Once the melting gets over, the furnace is tilted to devoid it of the slag, impurities that affect the surface of molten metal. To refine this metal, micro-alloying element-based additives are added, and if necessary, de-surfacing and de-phosphorising are done to extract all gases trapped inside the molten metal. Figure 2 Steel melting shop
Purging Process
The molten metal tapped to the ladle undergoes a Gas Purging process to maintain the consistency of thermal homogeneity, and relieve it of non-metallic inclusions, beyond limit.
Casting Process
Post purging process, the molten material is taken from ladle to turn-dish and turndish to mold’s in a continuous flow type of casting set-up. The liquid steel is then poured into die, and the withdrawn steel is replenished at an equal rate, which in turn depends on the cross-section area of the die-case and the grade and quality of the steel, which is to be produced.
Figure 3 Reheating Re-heating Process
The solidified piece of steel now undergoes a re-heating process, where ingots are reheated up to its crystallization temperature. Producer Gas, which is achieved by gasification of coal or biomass in the Gasifier, is used for this purpose. Re-heating using Producer Gas has been found to be eco-friendly and ensures a u niform distribution of temperature of billets. The billets are pushed into re-heating furnace at temperatures controlled at 1150°C to 1180°C.
Figure 4 Rolling process Rolling Process
The billets after reaching the specified rolling temperature, are exited out from furnace and first passed through the assembly of roughing mills, where gradual size reduction of billets initiates. The size of the billet is reduced in the Intermediate and Finishing Mills, till their desired size is obtained. The reduction of the size of the billet is a trade off between the length of the bar and its diameter achieved. This process of gradually reducing the billet size is of extreme importance in order to ensure that the grain structure of bars is fine. Quenching Process
Here another round of testing is performed, and if passed, the produced bars are fed to a quenching box, sprayed with water inside, at a very high speed. Rapid and controlled water quenching is done to bring down the surface temperature of the bars from 950°C to 300°C. Self-tempering Process
It is seen that the quenching process only reduces the temperature of the outer portion of the bar (case), while the inner part (core) continues to remain hot. Therefore it is passed on to the cooling bed, where the bar whose core i s still hot, is allowed to radiate and vent heat
outside, and in due process tempering it. Due to this self-tempering, the core of the bar gains sufficiently more strength and corrosion resistance properties.
Cutting, Bending and Dispatching
The bars after cooling down are straightened out a nd cut into desired lengths by means of cold shearing machine. These cut-bars are again inspected for meeting the specifications of chemical and physical properties, and then stored in the yard for finished goods. Thereafter, on customer orders, bars are cut and shaped to desired sizes and after complete conformation to the customer requirements; they are dispatched to exact site schedules.
ISAPL Products
TRISHUL 500 TMT Reinforcement Bars are graded Fe 415/500, manufactured under BIS certification mark as per IS: 1786 – a globally recognized standard. This gives it a hi gh advantage in comparison to M.S. or C.T.D. bars. Its optimizat ion and regularity features satisfy metallurgic requirements, while the adequacy of microstructure offers the maximum qualitative levels of the end product. Carbon level i s controlled much lower to BIS specification, which allows excellent ductility, high bend-ability and superior weld-ability. Table 1 : Product Details SIZE
TYPE
STANDARD LENGTH
8,10,12,16,20,25,32
Bundle / Straight
11/12 meters
SPECIFIC WEIGHTS (BIS STANDARD) SIZE
8mm
10mm
12mm
16mm
20mm
25mm
32mm
GM/M
395
617
888
1580
2470
3850
6310
CHEMICAL COMPOSITION IS:1786
TRISHUL
CARBON
0.30 Max
0.18-0.24
SULPHUR
0.06
0.050 Max
PHOSPHOROUS
0.06
0.045 Max
SULPHUR + PHOSPHOROUS
0.11
0.095 Max
CARBON
--
0.60-0.70
Table 2: Mechanical Properties
ELEMENT
TRISHUL 500
ADVANTAGES OF TRISHUL 500
TMT BAR
TMT BARS
AS PER ISI
2
0.2% Proof Stress 500N/mm
550N/mm2
Durability & longevity of concrete structures suited for high-rise, dams,
Ultimate Tensile
2
550N/mm
620-700 N/mm 2
bridges & industrial constructions. Best suited in calamity-prone areas. Necessary safety factor in a concrete structure is achieved through higher
Elongation
12 %
20% Min elongation. Must for earthquake prone areas.
Bend-ability
Average
Excellent
-Easy and fast work-ability saves
Re-bend-ability
5D to 7D
3D to 5D time, cost due to higher bend-ability. Easy weld-ability with no loss of strength at joint. No pre-heating &
Weld-ability
Low
Very High post-heating required during welding. Retains significant strength even at
Fire Resistance
Upto 4000C
Upto 500 0C
higher temperature. Safe in fire hazards up to 500 0C.
Rust & Corrosion
Very High
Suited in humid and coastal
Resistance
environments.
Not Suitable Resistance
Process Analysis of ISAPL products
We now attempt to study the process control and capabilit y of the ISAPL process. Variable Control charts and Attribute control charts can achieve this. Since the attribute of measure here is the number of defectives, i.e. mis-rolls, we make use of p-chart, owing to the variable sample size. The samples are collected, based on their sizes and 30 samples on 20th February 2013, and the result of this is the process capability measured by C pk.
) ( The specification limits are as mentioned as per the IS standards, for production.
Size 8mm 10mm 12mm 16mm 20mm 25mm 32mm
Specified weight gm/m 395 617 888 1578 2470 3850 6310
Tolerance Allowed ±7 ±7 ±5 ±5 ±3 ±3 ±3
Tolerance limit gm/m 367 - 423 574 - 660 844 - 932 1499 - 1657 2396 - 2544 3735 - 3966 6121 - 6499
Table 3 : Specification Limits
C pk – 16mm = 1.4203 C pk – 8mm = 2.3049 C pk – 20mm = 0.7994 C pk – 10mm = 1.3977 C pk – 25mm = 1.4571 C pk – 12mm = 1.1945 C pk – 32mm = 1.1112 We can observe that most processes are capable or within the limits, except for the 20mm production process. A better control on the specification limits and the process variation needs to be established.
Variable Control Chart
Conventional variable control charts have been based on certain measurable parameters, which can be distictly identified and made the basis for comparison. The samples are periodically taken in span of 30 minutes over a day’s production. These samples are for Third week of February, 2013’s production, for all sizes as obtained from the company. The variable control chart can be plot based on the weight per meter of the rolled bars, which is direct measure of the cross-section of the TMT bars, and that can be related to the proof stress and the yield strength. The X-axis is the samples, which are not numbered for any reason, while Y axis is either the variable X or std deviation, as the case may be. Sample
1 389 388 385 388 386 387.2 4 385.1666667 387.7631667 382.5701667
1 2 3 4 5 Sample Range Mean UCLx LCLx
2 388 390 386 385 385 386.8 5 UCLr LCLr R-bar
3 382 387 385 387 384 385 5 9.513 0 4.5
4 387 385 386 382 384 384.8 5
5 381 382 380 380 383 381.2 3 A2 D3 D4
6 384 386 389 386 385 386 5 0.577 0 2.114
Table 4: Xbar-chart and Rbar-chart tabulation for 8mm bars 390
10 9
388
8 386
7
384 382 380
Sample
6
Range
Mean
5
UCLr
UCLx
4
LCLr
LCLx
3
R-bar
2 378
1
376
0 1
2
3
4
5
6
Graph 1 (8 mm Xbar-chart)
1
2
3
4
5
6
Graph 2 (8 mm Rbar-chart)
Since the 8mm production in the fifth sample has gone out of the control limit range, we suggest that production be immediately stopped for the following days for 10mm, and maintenance be performed on the rollers, and line. The 8mm production is therefore out of control, although the process is perfectly capable of meeting the specification limits of IS standards. Sample 1 2 3 4 5 Sample Range Mean UCLx LCLx
1 592 599 595 592 590 593.6 9 595.3 601.8393333 588.7606667
2 593 596 588 601 609 597.4 21 LCLr UCLr R-bar
3 588 595 584 600 589 591.2 16 0 23.95866667 11.33333333
4 600 595 599 600 591 597 9
5 596 592 594 595 597 594.8 5 A2 D3 D4
6 596 603 595 598 597 597.8 8 0.577 0 2.114
Table 5: Xbar-chart and Rbar-chart tabulation for 10mm bar 605
30 25
600
20 595
Range
Sample Mean
15
LCLr
UCLx
590
LCLx
585
UCLr R-bar
10 5
580
0 1
2
3
4
5
6
Graph 3 (10 mm Xbar-chart)
1
2
3
4
5
6
Graph 4 (10 mm Rbar-chart)
The 10mm bars process is well within control, as can be seen from the Xbar chart and Rbar chart. The process capability is also verified from the Cpk calculations. Now we shal l proceed to similar process checks for other sizes.
Sample
1 880 851 872 866 873 868.4 29 869.7666667 880.345 859.1883333
1 2 3 4 5 Sample Range Mean UCLx LCLx
2 864 868 874 877 869 870.4 13 UCLr LCLr R-bar
3 880 857 872 866 873 869.6 23
4 868 876 877 868 869 871.6 9
5 875 868 864 865 874 869.2 11 A2 D3 D4
6 861 885 871 870 860 869.4 25 0.577 0 2.114
Table 6: Xbar-chart and Rbar-chart tabulation for 12mm bar 885
45
880
40 35
875
30
870
Sample Mean
865
UCLx
860
LCLx 855
UCLr 25
LCLr
20
R-bar
15
Range
10
850
5
845
0 1
2
3
4
5
6
1
Graph 5 (12 mm Xbar-chart)
2
3
4
5
6
Graph 6 (12 mm Rbar-chart)
The 12 mm production process is within control.
Sample 1 2 3 4 5 Sample Range Mean UCLx LCLx
1 1563 1542 1555 1540 1545 1549 23 1552.9333 1566.3966 1539.47
2 1547 1543 1538 1535 1527 1538 20 UCLr LCLr R-bar
3 1568 1550 1560 1555 1549 1556.4 19 49.32666 0 23.333333
4 1546 1538 1560 1563 1545 1550.4 25
5 1555 1560 1561 1574 1582 1566.4 27 A2 D3 D4
Table 7: Xbar-chart and Rbar-chart tabulation for 16mm bar
6 1567 1544 1559 1570 1547 1557.4 26 0.577 0 2.114
1570
60
1565 50
1560 1555
40
1550
Sample
1545
Mean
1540
UCLx
1535
LCLx
1530
Range UCLr
30
LCLr 20
R-bar
10
1525 1520
0 1
2
3
4
5
6
Graph 7 (16 mm Xbar-chart)
1
2
3
4
5
6
Graph 8 (16 mm Rbar-chart)
Since the 16mm production in the first and fifth sample has gone out of the control limit range, we suggest that production be immediatel y stopped for the following days for 16mm, and maintenance be performed on the rollers, and line. The 16mm production is therefore out of control, although the process is perfectly capable of meeting the specification limits of IS standards
Sample 1 2 3 4 5 Sample Range Mean UCLx LCLx
1 2 3 4 5 2410 2420 2470 2445 2448 2418 2430 2460 2428 2450 2415 2427 2455 2441 2475 2404 2438 2450 2444 2465 2413 2440 2460 2443 2445 2412 2431 2459 2440.2 2456.6 14 20 20 17 30 2440 UCLr 48.622 A2 2453.271 LCLr 0 D3 2426.729 R-bar 23 D4 Table 8: Xbar-chart and Rbar-chart tabulation for 20mm bar
6 2435 2428 2439 2465 2439 2441.2 37 0.577 0 2.114
The process is clearly out of control in three samples out of six, which is a poor proportion, and hence the variablity of the process must be ascertained and controlled. This can be s een from the following graphs. The process is also not capable with IS standards, in this sample.
2470
60
2460 50 2450 2440
40 Sample
2430
Mean
2420
Range UCLr
30
UCLx
2410
LCLx
LCLr 20
R-bar
2400 10 2390 2380
0 1
2
3
4
5
6
1
Graph 9 (20 mm Xbar-chart)
2
3
4
5
6
Graph 10 (20 mm Rbar-chart)
Sample 1 2 3 4 5 1 3845 3810 3855 3855 3801 2 3819 3819 3828 3809 3818 3 3840 3853 3853 3840 3855 4 3807 3855 3819 3830 3840 5 3826 3795 3813 3845 3841 Sample 3827.4 3826.4 3833.6 3835.8 3831 Range 38 60 42 46 54 Mean 3826.466667 UCLr 100.7673333 A2 UCLx 3853.970333 LCLr 0 D3 LCLx 3798.963 R-bar 47.66666667 D4 Table 9: Xbar-chart and Rbar-chart tabulation for 20mm bar 3860
120
3850 100 3840 3830
80 Sample
3820
Mean
3810
Range UCLr
60
UCLx
3800
LCLx
LCLr 40
R-bar
3790 20 3780 3770
0 1
2
3
4
5
6
Graph 11 (25 mm Xbar-chart)
1
2
3
4
5
6
Graph 12 (25 mm Rbar-chart)
6 3830 3797 3784 3802 3810 3804.6 46 0.577 0 2.114
As we can see in the Xbar and the Rbar chart, the process is in control. The process is also capable of meeting the specification limits.
Sample 1 2 3 4 5 Sample Range Mean UCLx LCLx
1 6337 6273 6222 6215 6189 6247.2 148 6262.466667 6311.800167 6213.133167
2 6165 6279 6293 6178 6210 6225 128 UCLr LCLr R-bar
3 6298 6245 6225 6290 6246 6260.8 73 180.747 0 85.5
4 6267 6280 6295 6271 6275 6277.6 28
5 6292 6257 6296 6303 6270 6283.6 46 A2 D3 D4
6 6251 6330 6307 6240 6275 6280.6 90 0.577 0 2.114
Table 10: Xbar-chart and Rbar-chart tabulation for 32mm bar 6320
200 180
6300
160
6280
140
6260
Sample
120
Range
6240
Mean
100
UCLr
UCLx
80
LCLr
LCLx
60
R-bar
6220 6200
40
6180
20
6160
0 1
2
3
4
5
6
Graph 13 (32 mm Xbar-chart)
1
2
3
4
5
6
Graph 14 (32 mm Rbar-chart)
This process is also in control, and hence safe operation. But a major concern would be the sudden variation in the range within the sample of bars
Attribute Control Chart
Conventional attribute control charts have been based on either number of defects or the number of defectives. In this case, the monthly data for the total production output can be computed based on the data made available by the company executives. Based on the number of misrolls, which were reported to the supervisor, and thereby recorded in monthly report of production, the following p-charts were constructed, which can be seen as below.
1.4 1.2 1 0.8
8mm UCL
0.6
LCL 0.4 0.2 0 June
July
August
September October November December
Graph 15 (8 mm p-chart) and Graph 16 (10 mm p-chart) 1.2
1
0.8 10mm 0.6
UCL LCL
0.4
0.2
0 June
July
August September October November December
0.9 0.8 0.7 0.6 0.5
12mm
0.4
UCL
0.3
LCL
0.2 0.1 0 June
July
August
September
October
November December
Graph 17 (12 mm p-chart) and Graph 18 (16 mm p-chart) 1 0.9 0.8 0.7 0.6
16mm
0.5
UCL
0.4
LCL
0.3 0.2 0.1 0 June
July
August
September
October
November December
Graph 19 (20 mm p-chart) 1.2 1 0.8 20mm 0.6
UCL LCL
0.4 0.2 0 June
July
August
September
October
November December
Graph 20 (25 mm p-chart) 0.9 0.8 0.7 0.6 0.5
25mm UCL
0.4
LCL 0.3 0.2 0.1 0 June
July
August September October November December
Graph 21 (32 mm p-chart) 1 0.9 0.8 0.7 0.6 32mm 0.5
UCL
0.4
LCL
0.3 0.2 0.1 0 June
July
August September October November December
It had been noticed that the defects rate suddenly shot up in a particular week, in the month of November, and therefore, the plant was shut down for maintenance, re -calibration, following which the plant was restarted and production was as per routine. The defect rates were held close to the range of 0.6 to 0.8% of the total production output.
Inventory model and control
While the conventional inventory models cannot be directly applied, to this situation, where daily orders are placed and dispatched; yet a fair estimate can be generated based on the graphical trends. It has been observed that an implicit reorder point of 200 MT of TMT bars had been maintained over the period of 7 months, we followed. But in the wake of new year, the re-order point was upgraded to 400MT for certain size of TMT bars, which are seen from the following graphs. Inventory modeling is also performed on the basis of orders for the month of February 2013.
Graph 22 – Tracking stock level of 8mm We can observe from the above graph that, the i nitial re-order point was 200MT, which was then upgraded to 400MT, in order to reduce production cost, and adequate levels to meet sudden demand surges observed in construction companies in Pune region. The production schedule was such that, production took place once every 10 days, and fixed quantity. This company thus follows a Q-model, i.e. fixed order quantity model of inventory model, where replenishment occurs once the reorder point is reached.
The following graph shows the stock-order levels and inventory levels for all 10mm size of TMT bars, where in the re-order point has been maintained at 100MT, and continues to be so, as it is not quite the value driver for the company. 600 500 400 10mm Stock
300
10mm Order 10mm Production
200 100 0 1
3
5
7
9
11
13
15
17
19
21
23
25
27
Graph 23 – Tracking stock level of 10mm The value of 12mm TMT bars, was down graded following sudden drop in order quantities received, and the re-order level dropped from 400MT to 100MT. 700
600
500
400
12mm Stock 12mm Order
300
12mm Production
200
100
0 1
3
5
7
9
11
13
15
17
19
21
23
25
27
Graph 23 – Tracking stock level of 12mm
Graph 24 – Tracking stock level of 16mm 800 700 600 500 16mm Stock 400
16mm Order
300
16mm Production
200 100 0 1
3
5
7
9
11
13
15
17
19
21
23
25
27
The 16mm variety of TMT bar has shown a stable demand, and has had a stable production schedule. Due to this, the company suspected, its 16mm bars is attractive in market, and therefore pushed to 400MT of inventory, and thereby push its sales, by enticing customers with instant delivery promises. 700 600 500 400
20mm Stock 20mm Order
300
20mm Production 200 100 0 1
3
5
7
9
11
13
15
17
19
21
23
25
27
Graph 25 – Tracking stock level of 20mm The 20mm is a very mobile TMT bar, which receives many, orders, and it can be seen that due to lack an efficient forecasting mechanism or software, the company built its inventory
twice in a month, in spite of small orders. This shows the urgent need for a forecasting model. 900 800 700 600 500
25mm Stock
400
25mm Order 25mm Production
300 200 100 0 1
3
5
7
9
11
13
15
17
19
21
23
25
27
Graph 26 – Tracking stock level of 25mm 25mm TMT bars are produced once a month, and in quantity of 400MT re-order at 400MT. Graph 26 – Tracking stock level of 32mm 400 350 300 250 200
32mm Stock
150
32mm Order
100
32mm Production
50 0 -50
1
3
5
7
9
11
13
15
17
19
21
23
25
27
-100
The 32 mm TMT bar is actually, the most value-generating product, but since the orders are very haphazard, it is usually made to order, by flexible scheduling of the operations. The maximum
Maintenance Operations
Indrayani Steel undertakes daily maintenance operations such as lubrication of bearing, and checking of nylon pads used in couplings for rollers. The roll-passes have always one set of stand-by tandem in case the grooves undergo wear due to rubbing, causing surface erosion on the TMT bars being produced. This is also avoided in process by spraying water over the grooves between two passes. Every month, the plant shuts down, for total maintenance program, where in the furnace is checked for its lining, the rollers are checked, bearings are changed, the conveyors are checked for strength, the shearing machine is ground and sharpened, the quality machines are re-calibrated. Maintenance operations for the quenching machine and steel-melting furnace are outsourced to third party. All other ass emblies are checked using in-house personnel. Every two months, the plant is shutdown for complete overhaul of all equipment and re-assembly. The brick lining for the furnace are replaced, and fuel lines for the furnace are also checked. Spare-parts are ordered in excess of the requirement to accommodate for emergency situations such as sudden breakdown. This is a very good practice, and we appreciate their spirit to keep it up. About 75% of the workforce is permanent basi s, and 25% account for temporary labor force. This has a direct implication on the turn-around time taken for maintenance activities, according to the orders placed and scheduling.
Conclusion
Throughout this project, we seemed to realize the relevance of control charts and other tools for assessing the performance of the process and the capabilit y. The monitoring of the stock levels, enabled us to understand the importance of safety stock, and re-order point and why the company chose to change its safety stock levels, with changing demand and in some cases to change customer perception about the company, in terms of service levels. With some insights of the different types of maintenance programs adopted by industry majors, we could see and assimilate the importance of total productive maintenance and preventive maintenance activities as adopted in Indrayani Steels. The added advantage of studying this company is it gave us a good view of direct impli cations of preventive maintenance programs, and methods of identifying potential maintenance-requiring sites.
Limitations
Our analysis and understanding the operations of Indrayani Steels and Alloys Pvt Ltd, were largely based on the date as made available to us, some of which, could not be confirmed. Secondly, as the company maintained a daily order processing and dispatching service, and the orders were simply placed over phone, thus involving no directly observable order cost, we were not in a position to compute the best possible economic order quantity, for the customers.
Appendix
Size mm June July August September October November 8 1115 1536 1927 1917 1188 1922 10 776 890 935 1242 500 648 12 1342 1165 1092 1295 1246 830 16 1742 1294 1337 1265 1509 1385 20 1233 631 1098 638 950 580 25 729 693 281 716 618 547 32 308 277 310 167 506 337 Table 3 (Title): All column figures except column no.1 are in MT
December 1372 581 1205 1496 1193 375 500
Table 4: Stock position and Order details 8mm 10mm 12mm Stock Order Production Stock Order Production Stock Order Production 483 162 653 442 41 0 126 36 0 625 28 0 316 126 0 41 85 0 575 50 0 316 0 0 41 0 0 575 0 0 266 269 47 0 271 36 515 60 0 391 85 207 229 42 0 433 82 0 326 65 0 209 20 0 408 25 0 228 98 0 201 8 0 393 15 0 123 105 0 186 15 0 666 85 358 312 78 267 171 15 0 586 80 0 618 0 306 171 0 0 586 0 0 528 90 0 457 25 311 559 27 0 435 93 0 420 37 0 559 0 0 274 161 0 350 70 0 484 75 0 186 88 0 302 48 0 437 47 0 400 60 274 278 24 0 382 55 0 649 45 294 238 40 0 302 80 0 928 0 279 238 0 0 302 0 0 788 140 0 208 30 0 192 110 0 678 110 0 118 90 0 132 60 0 488 190 0 480 25 387 102 30 0 347 141 0 468 12 0 292 60 250 431 188 272 357 111 0 214 78 0 601 120 290 332 25 0 172 42 0 905 0 304 332 0 0 172 0 0 840 65 0 140 192 0 57 115 0 825 15 0 110 30 0 369 40 352 807 18 0 469 36 395 283 86 0
Table 4: Continuation 16mm Stock
Order
20mm Production
376
Stock
Order
25mm Production
Stock
193
Order
32mm
Production
Stock
628
Order
Production
-28
351
25
0
168
25
0
598
30
0
-40
12
0
319
32
0
136
32
0
578
20
0
-45
5
0
319
0
0
136
0
0
578
0
0
47.2
0
92.2
263
56
0
80
56
0
569
9
0
46
1.2
0
218
45
0
35
45
0
549
20
0
43
3
0
571
8
361
27
8
0
524
25
0
43
0
0
517
54
0
346
54
373
509
15
0
43
0
0
462
55
0
291
55
0
499
10
0
43
0
0
437
25
0
266
25
0
494
5
0
43
0
0
437
0
0
266
0
0
494
0
0
43
0
0
417
20
0
246
20
0
489
5
0
43
0
0
318
99
0
522
99
375
441
48
0
43
0
0
296
22
0
500
22
0
404
37
0
360
43
360
270
26
0
474
26
0
828
0
424
268
92
0
230
40
0
434
40
0
806
22
0
258
10
0
224
6
0
428
6
0
776
30
0
258
0
0
224
0
0
428
0
0
776
0
0
258
0
0
612
19
407
409
19
0
756
20
0
248
10
0
592
20
0
620
20
231
731
25
0
236
12
0
582
10
0
610
10
0
706
25
0
228
8
0
562
20
0
590
20
0
676
30
0
223
5
0
511
51
0
539
51
0
642
34
0
201
22
0
455
56
0
517
22
0
627
15
0
171
30
0
455
0
0
517
0
0
627
0
0
171
0
0
745
135
425
395
122
0
587
40
0
136
35
0
685
60
0
298
97
0
557
30
0
81
55
0
621
64
0
223
75
0
547
10
0
77
4
0
Table 5: Sample Monthly Production Report (Month)
Size
Pieces
Pieces
Mis-rolls
in ton
In tonnes
Input
Misroll
%
Prodn
Coal
Coal/tonne
Electricity
Units
in Hours
Prod
Units
perTn
Time Run
/hr
8mm
11532
138
1.183%
1115
180.9
144.37
147160
131.98
109
11.50
10mm
8569
69
0.799%
776
116.8
138.22
88600
114.18
62
13.63
12mm
13628
75
0.547%
1342
191.6
135.22
134240
100.03
95
14.92
16mm
6700
57
0.844%
1742
177.7
98.78
107120
61.49
89
20.21
20mm
5677
30
0.526%
1233
145.2
114.96
76680
62.19
72
17.54
25mm
3363
21
0.621%
729
91
121.33
43680
59.92
47
15.96
32mm
1475
8
0.539%
308
41
129.75
18720
60.78
20
15.80
