2012 Southeast Asian Network of Ergonomics Societies Conference (SEANES)

Risk Assessment Craft in Bronze Alloy Melting

Process for the Production of Balinese Gamelan

IGN. Priambadi1, N. Adiputra

2, Ketut Tirtayasa, IGB. Wijaya Kusuma

3

1Faculty of Medicine

2Dept. of Ergonomics

3Dept. of Mechanical Engineering, Faculty of Engineering

University of Udayana, Bali, Indonesia

priambadi.ngurah@yahoo.com, ketut.tirtayasa@gmail.com, nadip2003@yahoo.com, wijaya.kusuma88@yahoo.com

Abstract—Activity especially in Balinesse cultural and religious

activities cannot be separated from the acoustic instrument called

gamelan. It is an existence value of the Balinese Hindu

civilization which has been maintained from generation to

generation. In the development device gamelan instruments has

got functional development rapidly from utilization of the

religious to the cultural activities. The sound harmonization

produced by the gamelan cannot be separated from the

traditionally process starting from the manufacture of bronze

alloy composition, melting, molding, forging through the

establishment of sound as well as the alignment for gamelan

sound in a single device. Bronze alloy composed of two elements

ie metals copper (Cu) and tin (Sn) in which these elements are

fused at a temperature of ± 1083 oC. In the process of alloy

melting bronze, craftsmen use an open stove model so the heat

produced exposure in the workplace. It will give the risk of

craftsmen such as radiation risks, these conditions impact to the

so that they will be quickly fatigue. The of the study research

showed temperatures exposure in the workplace based on the

method of gamelan craftsmen mean radiant temperature (MRT)

was 42.69 ± 0.732 ° C with levels of radiation 563.47 ± 5.175

W/m2, wind speed 0.1 m/s and relative humidity 25%. In the

melting process was carried out craftsmen average pulse rate

were measured before work 81.9 ± 2.47 pulse / min and an

average pulse rate was measured after working before the

breaking was 118.47 ± 4.274 pulse / minute. This condition

describes, the activities who did by craftsmen in the production

process shows a fairly heavy workload.

Keywords-gamelan; smelting furnace;, bronze alloy; the

workload

I. PRELIMERY

The life existence of Balinesse gamelan cannot be separated from religion, especially Hinduism, even though its development the Balinese gamelan has dominance in various types of performances that are not in a religious context. Almost every Banjar Pekraman Peoples of Bali has all the equipment complement of this ceremony. The village of Tihingan Banjarangkan Klungkung District is located 3 km towards the west of the town of Klungkung, a small famous village that know as the centre of gamelan craft and known well all over the world. Craftsman (pande) in processing the

raw materials to be a set of gamelan use more traditional methods that have been heritaged from generation to generation. The process of gamelan starting from the making of bronze alloy consist of copper (Cu) and tin (Sn) with a composition of 80% and 20%, the composition has been commonly used by craftsmen and provide the best quality of gamelan. The alloy bronze is formed through the working of process heat that melted reached boiling point in temperature of ± 1083 º C [1], to reach the boiling point need fire smelters to have higher temperatures, then cast (casting) in the mold after freezing process followed by forging and the last is a alignment process (the establishment of the fundamental tone) with a stingy or grinding.

Daily activities in the process of gamelan is very risky for the gamelan craftsmen, such as during the melting process in the furnace (furnace) at high temperatures where the risk of workers/craftsmen to be quickly fatigue due to workplace exposured by high temperatures. Based on the Ministry of Labor SE-01/MEN/1978, decided the value of noise exposure at work place about 85dBA for 8 hours a day, 40 hours a week, the requirements for ambient temperatures between 21-30 degrees Celsius, 65-95% humidity levels, and requires employers to take specific actions to reduce the air temperature above 30 degrees. DEPNAKERTRANS.

II. HEAT EXPOSURE

Gamelan craftsmen working conditions generally work in hot area, it is caused during the melting process in the furnace bronze alloy. The amount of radiation energy emitted heat from the furnace [2].

Eb = σ.T4 W/m

2 (BTU/h.ft2) (1)

where:

Eb = energy radiated

= 5.669 x 10-8 W/m2.R4

= 0.1714 x 10-8 BTU/h.ft2.K4

2012 Southeast Asian Network of Ergonomics Societies Conference (SEANES)

T = temperature of exposure (K), is measured from the method of mean radiant temperature

According to ISO 15265 [3], the radiation exposure that occurs should be on interventions that work can provide comfort for crafters. Form of intervention can be based on six factors in accordance with ASHRAE Standard comfort 55P [4] above. Mean radiant temperature can be calculated by the equation below:

360

....... 332211 nnTTTTMRT

(2)

where:

T = temperature of the surface of the corresponding point of measurement (° C)

θ = angle of exposure (o)

III. EVALUATION OF WORKLOAD BASED ON THE PULSE

A. Workload

The measurement of workload based on the pulse during working is a method to assess cardiovascular strain using the method of 10 pulse.

B. Fatique

The fatigue of workers is burden accumulation of an acceptable body due to work activities for long time to produce the production. This situation is natural sign to get a break, it is important to avoid the permanent fatigue that can cause the body damage, but most of people would accentuate the effect of fatigue as a factor of decreasing efficiency work. Determinant the two theories of fatigue, namely: (1) based on chemical theory, fatigue is due to reduced energy reserves and increasing metabolic waste that causes loss of muscle efficiency, and (2) based on the neuro theory of nerves, fatigue is a chemical change in muscle cells, which lead to stimulate neuro sensory channeled through to the brain, which is recognized as muscle fatigue [5]. Fatigue can be using measured subjectively a questionnaire rating scale of 30 items issued by the Japan Association of Industrial and Health.

IV. PROBLEM

The process of formation of the bronze alloy as a raw material made by melting the metals copper (Cu) and tin (Sn), where the fusion occurs at a temperature of ± 1083 º C. In reaching that temperature of the fire in melting process has higher temperature than melting temperature. High temperatures in the workplace would be exposed to radiation on the body of crafters because it forms an open fireplace, so that fast craft experience fatigue and decrease the comfort of the craftsmen working environment itself. Radiation exposure that occurs in the workplace area should be minimized, so the craftsman can work comfortably, and environmental conditions can be maintained.

V. METHOD

Assessment of the risk of gamelan craftsmen when melting process is done by performing measurements on the workplace or the subject as follows:

The design of the study using the same subjects [6], where the influence of heat in the workplace on the subject was measured before and after the melting process is carried out before the lunch break;

Workplace temperature measurement when melting process occurs every hour before the break, this is done by the method of MRT (mean radiant temperature);

Perform measurements with the method of pulse 10 beats before and after work, to see artisans working load;

Assessing subjective of the crafters fatigue subjectively before and after working with the filling of the questionnaires.

Assessment of the craftsmen risk made before the lunch break and be repeated three times in the same time but different days.

VI. RESULT AND DISCUSSION

Assessments of the craftsmen in the process of smelting bronze alloys are carried out as follows. Due to hot work environments, where the data are measured according to the following figure:

Figure 1. Exposure to radiation heat

From Fig. 1 shows that the average of radiation exposure occurs high sufficient amounts to 563.466 ± 5.175 W/m2 with a temperature of 42.670 ± 0.732 ° C and tended to increase with time crafters work. At the time of the measurement of relative humidity in the workplace 25% with wind speed 0.1 m / sec. Comfort zone for the country with two seasons tolerate hot temperatures 35 ÷ 40 oC work environment or the level of radiation 510.163 ÷ 544.106 W / m2 [7].

2012 Southeast Asian Network of Ergonomics Societies Conference (SEANES)

Figure 2. The pulse

Fig. 2 is based on the workload of the crafters of the melting process measured by increased pulse rate before and after working an average of 36.5 ± 2.635beats /min it indicates that the workload is quite heavy crafters. Increased resting pulse rate to the allowable working pulse 35 beats / min for males (calculated when sitting) and 30 beats / minute for women [7].

Figure 3. Fatigue score

Based on at Fig. 3 score of fatigue that occurred in prior work where the craftsmen average before work 1.130 ± 0.079 and 1.990 ± 0.2 after work flat.

According [8] the above data show that the average crafter physical exhaustion in performing activities of a bronze alloy melting process.

VII. CONCLUSION AND SUGGESTIONS

A. Conclusion

From the observations that have been done show that the activity of craftsment in the process of smelting bronze alloys have a high sufficient risk to the heat radiation emitted by the smelting furnace. Thermal radiation at the working conditions of craftsment rapidly create physical fatigue this caused quite a heavy workload crafters.

B. Suggestion

Reduce the impact of radiation on the body, at least crafters need to equip themselves with protective clothing, keep the air circulation in the workplace.

REFERENCES

[1] S. Tata and C. Kenji, Teknik Pengecoran Logam, 7th ed. Jakarta: Pradnya Pramita, 1996.

[2] J. P. Holman, Perpindahan Kalor (Heat Transfer), 5th ed. Jakarta: Penerbit Erlangga, 1984.

[3] ISO 15265: 2004: Ergonomics of the Thermal Environment—Risk Assessment Strategy for the Prevention of Stress or Discomfort in Thermal Working Conditions. Geneva: International Organization for Standardization, 2004b.

[4] ASHRAE Standard 55P. Thermal Environmental Conditons for Human Occupancy. 2003.

[5] V. DeKeyser, “Analysis Of Activities, Taks And Work Systems” In: Stellman, J. M., Editor. Encyclopedia Of Occupational Health and Safety, 4th ed., vol. 1. Geneva: International Labour Offuice (ILO), 1998.

[6] T. D. Cook and D. T. Campbell, Quasi Experimentation. Design & Analysis Issues for Field Settings. London: Houghton Mifflin Company, 1979.

[7] E. Grandjean and Kroemer, Fitting the Task to The Human. A textbook of Occupational Ergonomic, 5th ed. Piladelphie: Taylor & Francis, 2000.

[8] N. Adiputra, Metodologi Ergonomi. Program Studi Ergonomi-Fisiologi Kerja, Program Pascasarjana Universitas Udayana, 1998.