CHAPTER 4CHAPTER 4CHAPTER 4CHAPTER 4

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Chapter 4

Glass Bangle Manufacturing Units: CDS-Earning

Tradeoffs

Chapter Summary

In this chapter we deal with glass bangle manufacturing (GBM) units in Firozabad,

near Agra. Glass bangles are products made out of block glass of different shades of

colors or directly from batch material. GBM units are labor-intensive in nature.

There are mainly three jobs which involve workers’ exposure to high heat stresses in

GBM units – these are gob making, parison making and spiral making. These jobs

are assessed to be more severe than others as per our initial survey of GBM units.

The investigations carried out in chapter 3 resulted in two important outcomes – (1)

NSGA-II turns out to be a superior technique to HMH to solve CET problems

addressed in this work, and (2) ‘Factor Rating’ is a simpler and faster approach than

ANN approach to evaluate RoOHH. Therefore, we employ Factor rating-NSGA II

approach to solve CET problem of GBM units. The results of CET analysis further

prove the wider applicability of Factor rating-NSGA II approach used in this work.

4.0 Introduction

It is a customary for ladies to wear glass bangles in many countries including India

from their childhood for ornamental decoration and also as a symbol of sanctity.

Firozabad is an important industrial town for GBM units in India, which is located

near the city of Agra in Uttar Pradesh. It is also called the glass capital of India as the

glass industries located in Firozabad account for nearly 70% of the total glass

production in the small-scale sector in India. There is a large agglomeration of small-

scale units in this town, which are engaged in the manufacture of hollow wares,

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decorative items, glass beads, bulbs, headlight covers and a number of other glass

products. However, the single most important product from the cluster that has

brought this city into the world map is a glass bangle. They are produced in a variety

of designs, colors and sizes, and the local workers have perfected the production

process with the art being transferred from one generation to the other over the past

100 years. The glass industry here contributes significantly to local economy by

providing livelihood to over 0.75 million people.

Glass is obtained by the fusion of several inorganic substances at high temperatures.

Silica (SiO2), in the form of sand is the main constituent of glass. Sodium oxide in the

form of Sodium carbonate or soda ash (Na2CO3) is added to reduce the fusion

temperature of silica to lower temperatures, while other chemicals such as limestone

and dolomite (for Calcium oxide (CaO) and Magnesium oxide (MgO) respectively)

are used as fluxes. Varying the chemical composition of the input material can

produce varieties of glasses with distinct chemical and physical properties. Most

commercial glasses have broadly similar composition as given in Table 4.1.

Table 4.1 Composition of a general commercial glass

Constituent Percentage (%)

Silica (SiO2) 70-74

Sodium Oxide (NaO2) 12-16

Calcium Oxide (CaO) 5-11

Magnesium Oxide (MgO) 1-3

Aluminium Oxide (Al2O3) 1-3

Apart from the above-mentioned compounds, various chemicals are added to impart

desired colors to the glass bangles. The manufacturing process (Figure 4.1) of glass

bangles requires high skilled workers in many operations. The main operations are

described briefly as follows. Glass bangle manufacturing starts with batch making

(Figure 4.2 and Figure 4.3). This process involves conveying, weighing, mixing, and

feeding of raw materials into the melting furnace. This can be a manual operation or

mechanical one using hoppers of various sizes. The feeding of raw materials is done

manually in majority of the units in Firozabad cluster. The most crucial operation in

the manufacture of the bangles is the melting of the raw materials in the main furnace.

The temperature required for the melt is 1300 °C - 1400 °C (2372 °F - 2552 °F). The

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process is carried out in a large circular coal-fired closed melting furnace, which

contains 8-12 pots, each with a capacity of about 40 kg. This furnace is sealed and

kept running overnight for about 10-12 hours (Figure 4.4 and Figure 4.5). This is the

most energy intensive operation in glass industry. The molten glass free of bubbles is

continuously tapped from the end of the tank or the pots for shaping or subsequent

operations.

The molten glass is drawn from the pot of the furnace with the help of the iron pipe

and formed into gob to gather required quantity of glass for formation into parison on

iron plates (Figure 4.6 and Figure 4.7). The parison of different colors are joined

together and reheated in an auxiliary furnace to obtain required designs (Figure 4.8

and Figure 4.9). The reheated parison is then transferred to Belan furnace from which

the glass is further drawn into spiral/coil of bangles on the spindle rotated at uniform

rate of revaluation synchronizing with the manually at the other end of the furnace

(Figure 4.10 and Figure 4.11). The formation of spiral/coil on the spindle from the

softened glass parison requires a highly specialized skill and that is why, these

workers are the highest paid staff in the GBM units. The diameter of the bangle spiral

mainly depends upon the diameter of the spindle used in the formation of spirals and

the thickness is controlled by exerting the requisite amount on the softened glass

parison by spiral maker (tarwala) having highly skilled job. Spiral are then taken out

from the spindle (Figure 4.12) and cut with the help of a pencil cutter to separate out

the single pieces of bangles from spiral (Figure 4.13). The disjoined bangles are

counted (Figure 4.14) and then sent for joining of ends (Figure 4.15 and Figure 4.16).

After ends joining, the bundles of bangles are sent for final processing like polishing,

decoration etc. The finished products are neatly packed for dispatching.

Gob makers, parison makers and spiral makers are the three classes of workers in

GBM units who are exposed to high ambient temperature and radiant heat in their

work environment (Rathod et al., 1987). Moreover, the processes involved in the

manufacture of glass bangles are such that the workers have to work continuously

without rest breaks for 11-12 hours a day. The excessive exposure to high temperature

zone contributes to high heat stress of the job in which physical work produces

metabolic heat in the body in proportion to work intensity (Rastogi et al., 1990). The

total heat load of environmental and physical factors imposed on the body causes

undue physiological strain in the exposed workers (Rastogi et al., 1988).

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Figure 4.1 Schematic diagram of glass bangle manufacturing process

Figure 4.2 A GBM worker preparing batch for feeding into melting furnace

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Figure 4.3 Different constituents of bangle glass ready for mixing

Figure 4.4 An idle Pot furnace

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Figure 4.5 Pot furnace in operation

Figure 4.6 Gob maker (gulliwala) in position 1

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Figure 4.7 Gob maker (gulliwala) in position 2

Figure 4.8 Parison maker (sikaiwala) in position 1

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Figure 4.9 Parison maker (sikaiwala) in position 2

Figure 4.10 Spiral maker (tarwala) in position 1

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Figure 4.11 Spiral maker (tarwala) in position 2

Figure 4.12 Bangle spirals being moved to a shed

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Figure 4.13 Bangle cutter (kataiya) cutting the bangle spirals

Figure 4.14 Bangle counter (ginaiya) counting the bangles

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Figure 4.15 Bangle joiners (judaiya) in position 1

Figure 4.16 Bangle joiners (judaiya) in position 2

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4.1 Methodology

To carry out CET analysis in GBM units, we have included 32 glass bangle male

workers, having average health, mean age: 27 years, average height: 161 cm, average

weight: 53 Kg, and average job experience: 6 years, engaged in various operations in

the GBM Unit. None of these workers report a history of chronic health problems.

The workers have been divided into two groups, group-1 is having high risk of heat

stress, and group-2 is having low/no risk of heat stress as shown in Table 4.2. In

group-1, three categories of workers exposed to high temperature zone are selected.

These jobs, being more severe and requiring high skills, are well paid jobs in GBM

units. On the other hand group-2 consists of workers who work in a separate shed.

The area of work of group-2 workers is away from the high temperature zone and

their environmental conditions are normal and quite similar to those found outside the

factory premises. These workers are trained to perform following jobs-combinations:

gob making-bangle cutting, parison making-bangle joining, and spiral making-bangle

counting. It may be noted that each job combination consist of two jobs – one

belonging to group-1 and other belonging to group-2, so that jobs having high risk of

heat stress (referred to as high risk jobs) are combined with jobs having low/no risk of

heat stress (referred to as low risk jobs). Combining a higher risk job with a lower risk

job is the rationale behind deciding each of these job-combinations. Further, the

RoOHH for a job-combination is evaluated based on the composite discomfort score

(CDS) of workers using factor rating (FR) method which is explained in details in

chapter 3.

The following procedural steps are used to develop FR for computing CDS.

(1) We give a new nomenclature to factors (WH, RB and NRB) influencing CDS.

Each factor has two subscripts now, the first one (p) indicates group number of

each job (it may be recalled that all jobs fall in either of two groups as shown

in Table 4.2), and the second subscript (q) shows job number in each group.

Job numbers and group numbers of each job are illustrated below:

Group-1 Group-2 Job Gob

making Parison making

Sprial making

Bangle cutting

Bangle joining

Bangle counting

Job # 1 2 3 1 2 3

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Table 4.2 Two categories of workers considered in GBM units

Group-1: Workers having high risk of heat stress

Gob maker (gulliwala) When the temperature outside the pot furnace drops to tolerable

levels, a worker, known as Gob maker (gulliwala), scoops out a globe

of semisolid glass at the end of a long iron rod and transfers it to an

annealing furnace.

Parison maker (sikaiwala) The melt is given a certain shape by a worker, known as Parison

maker (sikaiwala), who manually manipulating the rod in the

annealing furnace, which is maintained at a temperature of 400 °C -

450 °C (752 °F - 842 °F).

Spiral maker (tarwala) After annealing, the shaped melt is transferred to another furnace, the

Belan furnace, where coils of glass are formed from it. Spiral maker

(tarwala), sits near the Belan furnace and manipulates the annealed

and shaped melt with another long iron rod which is kept inside the

Belan furnace. His task is to draw out a glass filament of requisite

thickness from the melt and transfer it on to the surface of a third,

thicker iron rod kept rotating inside the furnace. Approximate lengths

of these coils of glass are cut manually using abrasive tools for

forming the bangles. This is a highly skilled task.

Group-2: Workers having low/no risk of heat stress

Bangle cutter (kataiya) Spirals are then taken out from the spindle and cut to obtain bangles.

Workers who cut glass spiral to make open bangle is known as Bangle

cutter (kataiya).

Bangle joiner (judaiya) The cut bangles are then send for joining of ends. Worker who joins

the open bangle with the help of burner is called Bangle joiners

(judaiya).

Bangle counter (ginaiya) Worker who counts bangles for making bundles of it is called Bangle

counters (ginaiya).

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We get six factors for each job-combination (gob making-bangle cutting,

parison making-bangle joining, and spiral making-bangle counting) considered

in this chapter, e.g., for gob making-bangle cutting job-combination, the

factors are WH11, RB11, and NRB11 for gob making, and WH21, RB21, and

NRB21 for bangle cutting. The upper and lower bounds of WH, RB and NRB,

along with values in between for each of the four jobs under consideration are

illustrated below.

���� ∈ {2, 3, 4, 5, 6, 7, 8, 9, 10}

���� ∈ 12 − ���� (���� isadependentvariable)

where, q = 1, 2, & 3.

It is apparent that total working time in a job-combination does not exceed 12

hours. The range of RB and NRB are same for each of the six jobs under

consideration as shown below.

���� ∈ �5, 10, 15, 20, 25, 30, 35, 40�

����� ∈ �1, 2, 3, 4, 5, 6�

where p =1, 2, and q =1, 2, 3

(2) For each job-combination, we assign an average weight to each factor, which

indicates its relative importance compared with all other factors for evaluating

CDS (Table 4.3).

Table 4.3 Weights assigned to each factor for three job-combinations

Gob making-Bangle cutting Parison making-Bangle joining

Spiral making-Bangle counting

Factor Weight Factor Weight Factor Weight

WH11 0.43 WH12 0.40 WH13 0.48

RB11 0.12 RB12 0.11 RB13 0.10

NRB11 0.17 NRB12 0.16 NRB13 0.18

WH21 0.15 WH22 0.18 WH23 0.13

RB21 0.08 RB22 0.09 RB23 0.07

NRB21 0.05 NRB22 0.06 NRB23 0.04

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An interview method is adopted to translate perception and opinion of workers

and supervisors into the numeric value of weights. Typically weights sum to

1.0. These weights further verify the perceived severity of each job with spiral

making being the most severe job, bangle counting being the least severe job,

and severity of other jobs falling in between.

(3) In computing CDS, the value of each factor is normalized by dividing it by its

maximum value, yielding ratios ranging between 0.0 and 1.0.

(4) We then multiply the normalized value of each factor with its corresponding

weight, sum them together, and then multiply it by 100 to suitably scale the

values. We term the result so obtained as composite discomfort score (CDS).

We illustrate below the general expression for CDSq.

���� = ��� ����

�����

� × �����− � ����

�����

� ×� ����− � �����

������

� ×

�� �����+ �� ����

�����

� × �����− � ����

�����

� ×� ����− � �����

������

� ×�� ������× 100

where ����,� ����,�� ����,�����, � ����and�� ���� refer to average weights assigned to the respective factors mentioned in the

bracket.

As an example, the expression for CDS3 i.e. spiral making-bangle counting job-

combination is shown below.

���= ��� ��

���

� × 0.48 − � ��

���

� × 0.10 − � � ��

� ���

� × 0.18�

+ �� ��

���

� × 0.13 − � ��

���

� × .07 − � � ��

� ���

� × .04��× 100…(4.1)

It is obvious that WH13 and WH23 contribute positively to CDS, whereas higher values

of RB13, RB23, NRB13, and NRB23 would cause a decrease in CDS. Higher weights to

job#3 of group-1 in comparison to job#3 of group-2 is attributed to the fact that job#3

of group-1 (i.e. spiral making) is more severe than job#3 of group-2 (i.e. bangle

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counting) as mentioned earlier. Composite discomfort scores are verified by

conducting experiments wherein sample workers perform each job-combination

consistently for different values of its factors and are asked to rate the perceived

discomfort level (PDL) for each case as one of the following linguistic values:

negligible, very low, low, moderate, high, very high, and beyond tolerance. We now

illustrate a case of worker’s PDL using CDS. We categorize range of CDS values with

linguistic values of PDL as shown in Table 4.4. It may be noted that CDS-PDL

correlation is domain specific i.e. industry specific. However, it is a matter of chance

that CDS-PDL turns out to be same for BM and GBM units.

Table 4.4 Relation between CDS and PDL for GBM units

CDS (Range a-b)* PDL Abbreviation 1-8 Negligible N 8-16 Very Low VL 16-25 Low L 25-34 Moderate M 34-43 High H 43-51 Very High VH 51 and above Beyond Tolerance BT

*Range a-b indicates � ≤ ��� < �

Case: A worker is doing spiral making, the most severe job, for 10 hours, along with

bangle cutting for 2 hours, in a job-combination approach, with RBs and NRBs as

shown below.

Factor WH13 RB13 NRB13 WH23 RB23 NRB23

Factor Value 10 30 1 2 5 1

Using equation (4.1) we get CDS as 38.56. Sample workers rate PDL as high for this

case.

The following table summarizes per hour earnings of a worker of each category of

jobs under consideration.

Group-1 Group-2

Job Gob making

Parison making

Spiral making

Bangle cutting

Bangle joining

Bangle counting

Job # 1 2 3 1 2 3

Earnings/hours (in INR)

25 25 66.67 20 20.83 16.67

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The resulting expression for earnings/day (ERq/day) is illustrated below for group-1

and group-2 job-combination.

���

Day� = ����� −

����� × ����60

�× ���� + ����� −����� × ����

60�

× ���� … 4.2� Now we mathematically formulate the CET problem for GBM unit under

consideration below.

Min����

Max���/day

Subject to ���� ∈ �2, 3, . . , 10� ���� ∈ 12 − ���� ���� ∈ �5, 10, 15, 20, 25, 30, 35, 40�(� = 1, 2)

���� ∈ �1, 2, 3, 4, 5, 6�(� = 1, 2)

���� = ���,��7 ≤ ���� ≤ 10��,��3 ≤ ���� < 71,������ < 3 �

�ℎ����� = min{6, (���� − 4)}����� = min{3, (���� − 2)}

4.2 Results and Discussion

We make use of NSGA-II, owing to its superiority to HMH, to solve CET. NSGA-II

is coded in MATLAB 7.0 and run on Pentium (R)-based HP Intel (R) computer with

1.73 GHz Processor and 512 MB RAM. Computational experiments are performed to

decide crossover rate, mutation rate and population size on the basis of faster

convergence criteria, and interestingly these remain unchanged i.e. these are 1.0, 0.05

and 50 respectively. Results of example runs of NSGA-II follow to demonstrate its

performance to solve CET problem of a GBM unit.

Evolution of gob making-bangle cutting is depicted using Figure 4.17, Figure 4.18

and Figure 4.19 which respectively show the initial population, intermediate

improvements, and the final population of CET solution points. These figures

illustrate the improvements in the CET profile i.e. front-1 along with other fronts of

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the population. In succeeding iterations, NSGA-II searches for optimal CET profile.

Figure 4.19 depicts the nondominated CET profile of the final generation population,

which is the best obtained CET profile.

A well diversified CET profile evolves for parison making-bangle joining job-

combination. Figure 4.20, Figure 4.21 and Figure 4.22 show the initial population,

intermediate improvement, and final generation population respectively for parison

making-bangle joining job-combination as we move to the final generation

population from initial one, we observe a good convergence of solution points to

higher fronts. More and more solution points accumulate on the best achieved CET

profile which provides more flexibility to the worker and supervisor in choosing a

job-combination strategy.

Spiral making-bangle counting job-combination involves combining the most severe

job with the least severe job. This combination allows a worker to do spiral making

for more number of hours in comparison to combinations involving other two jobs of

group-2, which can be an important requirement in a GBM unit. Figure 4.23, Figure

4.24, and Figure 4.25 represent the NSGA-II fronts for the initial population,

intermediate improvements, and final generation population respectively for spiral

making-bangle counting job-combination. In other words NSGA-II performs well to

solve CET problems under consideration.

We present the nondominated solution points appearing on the CET profile of final

generation population along with best achieved tradeoff points of ER/day and CDS in

tabular form for each of three job-combinations. PDL values are also shown along

with CDS in the last column. In general, workers are considered in a safer zone till

PDL is moderate. Beyond this they fall into higher and higher risk zones as PDL

assumes values high, very high, and extremely high.

Table 4.5 shows the solution points for gob making-bangle cutting job-combination.

Out of 28 CET solution points, 25% points correspond to negligible PDL, 32%

correspond to very low PDL, 14% correspond to low PDL and 19% correspond to

moderate PDL, thereby 90% solutions points fall in safer zone. These figures clearly

depict the advantage of combining gob making job with bangle cutting job. PDL is

moderate till 25th solution point and workers fall into the unsafe zone from 26th

solution point onwards. CET solutions provide a huge flexibility to workers and

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supervisors in terms of choosing the working hours and rest breaks. Similar to a

discussion in BM unit, we present a comparison of two solution points (18th and 19th

both having low PDL and minor differences in terms of CDS and ER/Day) below to

illustrate the flexibility with respect to RB and NRB of gob making job.

SP WH11 RB11 NRB11 WH21 RB21 NRB21 ER/Day CDS

18th 8 40 1 4 25 1 255 19.73

19th 9 5 5 3 30 1 265 20.70

Workers preferring more RB over NRB for gob making job have a choice to opt for

18th solution point, which provides a single rest break of 40 minutes for 8 working

hours. Whereas those favouring NRB over RB can go for 19th solution point, which

offers five rest breaks, each of 5 minutes. Further the safer zone limits the earnings to

INR 277/day (refer to 25th solution point). If at all a worker is interested to earn more,

he or she will have to move to the risky zones. Captivatingly, our proposed system

provides the best possible earnings to a worker even in the risk zones. For example

say in an extreme case, a worker may choose the last solution point i.e. 28th solution

point this would correspond to the highest possible earnings of INR 283/day

against a CDS of 37.83 corresponding to a high PDL.

Table 4.6 depicts nondominated solution points of the final generation CET profile for

parison making-bangle joining job combination. Interestingly, none of the solution

points falls in risky zone out of 32 solution points. In other words, workers may

choose any of 32 solution points depending on their choice. Aged workers may be

asked to restrict themselves to low PDL only. The highest earning is limited to INR

284/day against a CDS of 33.64, and PDL being medium (refer to 32nd solution point).

Table 4.7 demonstrates the nondominated CDS-earnings tradeoff solution points for

spiral making-bangle counting job-combination. It is worthy to mention that herein

we again obtain some very low values of CDS which should make this combination a

preferred job-combination. In other words, spiral making-bangle counting is a useful

combination for workers who are aged and/or having some health issues.

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4.2.1 Comparing JCA with Existing Situation in GBM Unit

For comparison purposes we compute CDS in the existing situation in the GBM unit

at different feasible values of WH, RB and NRB for the jobs that are performed

without any combination. We do so specifically for the parison making job (job#2 of

group-1). Based on the opinion of workers and supervisors, we assign an average

weight to each of the three variables viz. WH12, RB12 and NRB12 which are 0.6, 0.15

and 0.25 respectively. A weight indicates the relative importance of a factor compared

with other two factors for evaluating CDS. Weights sum to 1.0 as mentioned earlier.

We now present a comparison below.

4.2.1.1 Case 1: Parison making job alone

Worker is doing parison making job in the existing system for 12 hours with a single

rest break of 60 minutes. The effective working time is 11 hours.

WH12 RB12 NRB12

12 60 1

CDS is computed as 45.33 using the following formula derived in the similar way as

equation (4.1). Its corresponding PDL is very high (refer Table 4.4).

����� = ��� ����

�����

× 0.6 − � ���

����

× 0.15 − � ����

�����

× 0.25 � × 100

ER12/Day for the above case is INR 272.00, computed using equation (4.2).

4.2.1.2 Case 2: Parison making-bangle joining job-combination

Worker is doing parison making job for 10 hours with a single rest break of 40

minutes and a bangle joining job for 2 hours with a single rest break of 20 minutes in

the proposed system. The effective time is again 11 hours.

WH12 RB12 NRB12 WH22 RB22 NRB22

10 40 1 2 20 1

The above combination, in fact, corresponds to 25th solution point in Table 4.6 with

CDS as 24.43, PDL as low and earning per day as INR 268.

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Figure 4.17 Gob making-bangle cutting: Initial population nondominated CET profile

Figure 4.18 Gob making-bangle cutting: Intermediate improvements in the CET profile along

with other fronts

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Figure 4.19 Gob making-bangle cutting: CET profile and other fronts of final generation

population

Figure 4.20 Parison making-bangle joining: Initial population nondominated CET profile

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Figure 4.21 Parison making-bangle joining: Intermediate improvements in the CET profile along

with other fronts

Figure 4.22 Parison making-bangle joining: CET profile and other fronts of final generation

population

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Figure 4.23 Spiral making-bangle counting: Initial population nondominated CET profile

Figure 4.24 Spiral making-bangle counting: Intermediate improvements in the CET profile along

with other fronts

122

Figure 4.25 Spiral making-bangle counting: CET profile and other fronts of final generation

population

While comparing the results, CDS is much higher in job alone case (45.33 ≫ 24.43)

with slight increase in ER/day of INR 4.00. PDL drops down to low in job-

combination approach from very high in job alone case. Thus job-combination

approach greatly reduces the CDS/PDL and hence the RoOHH.

4.2.2 Validation of Results of FR-NSGA-II for GBM Unit

Although it has been proved that FR-NSGA-II approach works extremely well for

BM unit (section 3.2.1), yet we compare the results of FR-NSGA-II for GBM unit

with experimental results as shown in Table 4.8. It is quite apparent that PDL values

again match. Therefore, it may be concluded that FR-NSGA-II is robust approach and

general enough to be applicable to LIM units.

4.3 Conclusions

In this chapter a glass bangle manufacturing unit, another LIM unit, is thoroughly

investigated to explore possible occupational hazards to workers. Owing to exposure

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Table 4.5 CET solution points: Gob making-bangle cutting job-combination

Solution Points WH11 RB11 NRB11 WH21 RB21 NRB21 ER/Day CDS PDL

1 2 35 1 10 35 3 200 0.77 N

2 2 35 1 10 35 1 224 2.43 N

3 2 40 1 10 25 1 225 2.93 N

4 2 40 1 10 20 1 227 3.93 N

5 3 35 1 9 35 1 229 5.23 N

6 3 40 1 9 25 1 230 5.73 N

7 3 40 1 9 20 1 232 6.73 N

8 4 35 1 8 35 1 234 8.03 VL

9 4 40 1 8 25 1 235 8.53 VL

10 4 40 1 8 20 1 237 9.53 VL

11 5 35 1 7 35 1 239 10.83 VL

12 5 40 1 7 25 1 240 11.33 VL

13 5 40 1 7 20 1 242 12.33 VL

14 6 35 1 6 35 1 244 13.63 VL

15 6 40 1 6 25 1 245 14.13 VL

16 6 5 4 6 30 1 252 15.13 VL

17 6 5 3 6 30 1 254 17.97 L

18 8 40 1 4 25 1 255 19.73 L

19 9 5 5 3 30 1 265 20.70 L

20 10 5 5 2 30 1 270 23.50 L

21 10 5 4 2 30 1 272 26.33 M

22 10 5 3 2 30 1 274 29.17 M

23 10 25 1 2 15 1 275 31.83 M

24 9 5 2 3 15 1 276 32.20 M

25 10 20 1 2 15 1 277 33.33 M

26 10 10 1 2 25 1 278 34.33 H

27 10 5 2 2 15 1 281 35.00 H

28 10 5 1 2 15 1 283 37.83 H

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Table 4.6 CET solution points: Parison making-bangle joining job-combination

Solution Points WH12 RB12 NRB12 WH22 RB22 NRB22 ER/Day CDS PDL

1 2 40 1 10 20 6 200 1.83 N

2 2 40 1 10 35 1 229 3.46 N

3 2 35 1 10 35 1 232 4.83 N

4 3 40 1 9 35 1 234 5.66 N

5 2 40 1 10 20 1 235 6.83 N

6 3 35 1 9 35 1 236 7.03 N

7 4 40 1 8 35 1 238 7.86 N

8 3 40 1 9 20 1 239 9.03 VL

9 4 35 1 8 35 1 240 9.23 VL

10 5 40 1 7 35 1 242 10.06 VL

11 4 40 1 8 20 1 243 11.23 VL

12 5 35 1 7 35 1 244 11.43 VL

13 6 40 1 6 35 1 246 12.26 VL

14 5 40 1 7 20 1 247 13.43 VL

15 6 35 1 6 35 1 248 13.63 VL

16 4 5 2 8 40 1 249 13.69 VL

17 7 40 1 5 35 1 250 14.46 VL

18 6 40 1 6 20 1 251 15.63 VL

19 7 35 1 5 35 1 252 15.83 VL

20 5 5 2 7 40 1 253 15.89 VL

21 6 5 4 6 25 1 258 16.13 L

22 8 40 1 4 20 1 260 20.03 L

23 7 5 2 5 40 1 261 20.29 L

24 8 5 4 4 25 1 266 20.53 L

25 10 40 1 2 20 1 268 24.43 L

26 10 5 4 2 25 1 275 24.93 L

27 10 5 3 2 25 1 277 27.60 M

28 10 5 2 2 25 1 279 30.27 M

29 10 25 1 2 5 1 280 31.93 M

30 10 5 1 2 25 1 281 32.93 M

31 10 15 1 2 10 1 282 33.56 M

32 10 5 2 2 10 1 284 33.64 M

125

Table 4.7 CET solution points: Spiral making-bangle counting job-combination

Solution Points WH13 RB13 NRB13 WH23 RB23 NRB23 ER/Day CDS PDL

1 2 40 1 10 35 1 246 2.81 N

2 2 35 1 10 30 1 253 4.93 N

3 2 30 1 10 35 1 257 5.31 N

4 3 40 1 9 35 1 296 6.31 N

5 3 35 1 9 30 1 303 8.43 VL

6 4 35 2 8 30 1 314 8.93 VL

7 4 40 1 8 35 1 346 9.81 VL

8 5 25 3 7 35 1 357 11.06 VL

9 6 25 4 6 35 1 379 11.56 VL

10 5 40 1 7 35 1 396 13.31 VL

11 6 25 3 6 35 1 407 14.56 VL

12 5 5 3 7 40 1 422 15.18 VL

13 6 10 4 6 35 1 446 15.31 VL

14 6 5 4 6 40 1 467 15.68 VL

15 8 25 4 4 35 1 479 18.56 L

16 9 25 5 3 35 1 501 19.06 L

17 9 25 5 3 25 1 504 20.81 L

18 8 25 3 4 35 1 507 21.56 L

19 9 25 4 3 35 1 529 22.06 L

20 8 10 4 4 35 1 546 22.31 L

21 10 25 5 2 35 1 551 22.56 L

22 8 5 4 4 40 1 567 22.68 L

23 10 25 4 2 35 1 579 25.56 M

24 9 10 4 3 35 1 596 25.81 M

25 9 5 4 3 40 1 617 26.18 M

26 9 5 3 3 40 1 622 29.18 M

27 10 10 4 2 35 1 646 29.31 M

28 10 5 4 2 40 1 667 29.68 M

29 10 5 3 2 40 1 672 32.68 M

30 10 5 3 2 25 1 676 35.31 H

31 10 5 2 2 30 1 681 37.43 H

32 10 5 1 2 15 1 690 43.06 VH

126

Table 4.8 Validation of results of FR-NSGA-II with experimental results for GBM unit

*SP# Job-combination work schedule FR-NSGA-II Results Experimental Results

Gob making-bangle cutting

WH11 RB11 NRB11 WH21 RB21 NRB21 ER/Day CDS PDL ER/Day PDL

1 2 35 1 10 35 3 200 0.77 N 200 N

14 6 35 1 6 35 1 244 13.63 VL 244 VL

28 10 5 1 2 15 1 283 37.83 H 283 H

Parison making-bangle joining

WH12 RB12 NRB12 WH22 RB22 NRB22 ER/Day CDS PDL ER/Day PDL

16 4 5 2 8 40 1 249 13.69 VL 249 VL

23 7 5 2 5 40 1 261 20.29 L 261 L

30 10 5 1 2 25 1 281 32.93 M 281 M

Spiral making-bangle counting

WH13 RB13 NRB13 WH23 RB23 NRB23 ER/Day CDS PDL ER/Day PDL

6 4 35 2 8 30 1 314 8.93 VL 314 VL

17 9 25 5 3 25 1 504 20.81 L 504 L

32 10 5 1 2 15 1 690 43.06 VH 690 VH

*SP# is Solution Point Number in the respective Job-combination Table

127

to high temperature, risk of heat stress is found significant for three jobs. Using JCA

each high risk job is combined with a unique low/no risk job (resulting in three job-

combinations) to reduce RoOHH of workers exposed to heat stress. Results of

previous chapter motivated us to employ the following methods: (1) ‘factor rating’

approach for measurement of RoOHH for each job-combination and (2) NSGA-II to

solve CET problems of GBM unit. Solutions obtained for each job-combination

provide a wider flexibility to a manager to arrange to complete the jobs in GBM units.

In view of these facts, the work presented here forms an important basis to effectively

address the issues pertaining to health management of GBM workers. It is therefore

concluded that ‘integrated factor rating-NSGA-II’ is a generalized approach which

can be employed to solve similar problems of other LIM units.