DISCOMFORT EXPERIENCED BY STAMPING MACHINE OPERATORS

Transcription

1 DISCOMFORT EXPERIENCED BY STAMPING MACHINE OPERATORS Nor Hayati Saad a, Md Fuad Bahari a and Darius Gnanaraj Solomon a a Faculty of Mechanical Engineering, Universiti Teknologi MARA, UiTM, Shah Alam, Selangor D.E., Malaysia. Abstract Stamping Machines produce vibrations of high amplitude and low frequency due to poor mounting of machinery in Small & Medium Industries. The workers exposed to the vibration due to the stamping process are likely to be exposed to noise at the same time. Relevant information are presented from the literature to show how researchers are carrying out similar works in related areas to find the effect of vibration produced by machinery on the discomfort experienced by human beings. This paper presents the results of our study about the discomfort experienced by Industrial workers working on stamping machines. It is found that Headache and Muscular pain are the two major discomfort experienced by them; many workers get into depression and losing their mood for working efficiently. Keywords: Stamping Machine, Vibration, Health, Safety, and Discomfort 1. Introduction Stamping is a forming process that presses a metal blank with a powerful die into a predetermined desired shape (or pattern). The metal formed must be ductile (malleable) enough to bend into shape without breaking. Deep drawn metal stamping draws the metal shape through progressive passes through the stamping die to produce long narrow final metal stampings [1]. Stamping includes a variety of operations such as punching, blanking, embossing, bending flanging, coining, drawing and hemming. The processes are differed by the shape and contour of a die set applied. Stamping process is generally performed on materials 0.5 mm to 2 mm thick. But this process also can be applied to foils as thin as mm or to plate stock with thickness approaching 25.4 mm. An Industry situated in Shah Alam uses stamping process to make automobile parts for PROTON, air conditioner parts for Matsushita Industrial Corporation and micro-wave oven parts for Samsung Electronics. A general view of the stamping machine and the working environment of a stamping machine operator are reported by Nor Hayati et.al.[2]. When we visited this industry we could feel the floor vibrations during every cycle of stamping operation. The noise due to impact also affected us and we developed head-ache during our stay in this environment. When we discussed with the Production Managers, we realized that the machines were not fitted with anti-vibration mounts and were fitted directly to the machine foundations. A close view revealed that the machines are fitted to the foundation using spacers for raising the level. These spacers cannot absorb shocks or Impact Loads. This experience led us to conduct a survey among stamping machine operators to find the discomfort experienced by them due to vibrations and noise. The following sections describe the details of the literature survey, survey conducted in SMIs and our findings from the survey. 2. Literature Review Whitham and M. J. Griffin [3] showed that for vertical vibration there is a distinct difference in the locations of discomfort on the body at different frequencies and that the locations are not much affected by the vibration level. For horizontal motions, feelings of discomfort predominated in the lower abdomen and buttocks irrespective of vibration frequency or direction. Helmut Seidel and Michael J. Griffin [4] reported that back problems are very common and contribute to discomfort and days off work. Some back disorders are attributed to

2 inappropriate loading of the spine that can be combined with other influential factors such a body posture, whole-body vibration and shock. Bengt-O. Wikström, Anders Kjellberg and Margareta Dallner [5] performed two studies in order to compare different technical methods for assessing the effect of mechanical shocks on discomfort. The studies were carried out in the field with a forest machine and a harbour tractor. These were driven by professional drivers on test tracks consisting of different sections with obstacles producing shocks. The discomfort of each section was rated with magnitude estimation. In many vehicles and working-machines shocks occur, which can be harmful to the driver. Knowledge of how to evaluate these shocks should therefore be of interest for manufacturers of vehicles and also for health service groups in industry. Following a comprehensive review of the subject of man-made ground vibrations, measurements of ground vibration caused by vibratory sheetpile driving in recent soil deposits are reported by Athanasopoulos [6] in terms of particle velocities vs. distance from the source of vibration. The existing criteria for human exposure to vibrations in buildings, according to the results of this study, seem to adequately define the degrees of human discomfort. We see from the information available in literature survey that researchers are carrying out similar work in related areas to find the effect of vibration produced by machinery on the discomfort experienced by human beings. The following sections give details about the questionnaire prepared by us and the results of our findings about the discomfort experienced by Stamping machine operators. 3. Details about the Questionnaire A questionnaire was prepared by us having the following 4 major sections along with relevant questions as shown in Table 1. Survey will be conducted in 40 Small and Medium Industries situated in and around Shah Alam. So far we have completed personal interviews with Managers, Supervisors and workers in 16 Industries. Two Research Assistants help this team in carrying out this survey. 4. Results of the Survey Table 2 shows the results of the Survey conducted among the stamping machine operators and Table 3 gives the output of the survey conducted among the Mangers/Supervisors through personal interviews. We could receive information from 16 Managers/Supervisors and workers from 8 industries. As can be seen from Table 2 that in each industry 3 categories of workers have been interviewed; the first category with less than one year experience, the second category with 1-2 years experience and the third category with more than 3 years experience. This practice was followed to receive information from workers having different lengths of experience. We can see from Table 2 that Headache and Muscular pain are the two major discomfort reported by the workers working on stamping machines. As a result of that many workers get into depression and losing their mood for working efficiently. The information reported in Table 3 which are collected from the Managers and Supervisors confirm the details given by the workers. Many industries use safety shoes, Gloves and Ear plugs for enhancing the safe working environment for the workers. Even though 75% of the companies use anti-vibration mount we are concerned about the remaining 25% of the companies which do not provide anti-vibration mounts. Our future work deals with the effect of providing anti-vibration mounts to stamping machines in such industries.

3 Table 1: Major Sections and Details of the questions in the Questionnaire Major Sections A: General Questions Name of the company Address Number of Production Workers Number of Production Shifts/day Average number of working hours by each worker in a day B: Production Machinery causing Vibration in your industry Type of Industry Major components produced Arrangement of machines and equipment C: Anti-Vibration Mount Type of Stamping Machine Type of Machine Operation Type of production material used Thickness of raw plate material Number of machines fitted with anti-vibration mounts Type of Anti-vibration mounts used Frequency of replacing anti-vibration mounts D: Safety and Health Physical Stress Heart Disease Ulcer High Blood Pressure Headache Sleep disturbance Muscle pain Psychological Stress Behavioural Stress Safety in work place Job dissatisfaction Depression No mood to work Burnout Poor job performance Higher accident rate High number of medical leave per worker per month Aggression Workers wear safety shoes to absorb floor vibration Workers use platforms which absorb floor vibration Worker wear gloves to prevent contact with work piece

4 Table 2. HEALTH & SAFETY IMPACT Information collected from Workers Total No. of Industries that responded to this survey: 8 TYPE OF HEALTH AND SAFETY IMPACT OF OPERATORS Experience (less than 1 Year) [Total: 6] Male = 3 Female = 3 Experience (between 1-2 Years) [Total: 7] Male = 7 Female = 0 Experience (more than 3 Years) [Total: 8] Male = 7 Female = 1 Female Male Female Male Female Male Physical Stress Heart Disease Ulcer 1 15% High Blood Pressure 1 15% Headache 3 100% 1 33% 6 85% 2 30% Sleep Disturbance 2 67% 2 30% Muscular Pain 2 67% 3 100% 5 70% 1 100% 6 85% Psychological Stress Job Dissatisfaction 1 33% 1 15% 1 15% Depression 1 33% 1 15% 3 43% Moodiness 1 33% 1 33% 3 43% 3 43% Burnout 1 33% 1 15% 2 30% 1 15%

5 Table 3. HEALTH & SAFETY IMPACT Information collected from Managers/ Supervisors Total No. of Industries: 16 TYPE OF HEALTH & SAFETY IMPACT 1. Physical Stress Heart Disease Ulcer 1 High Blood Pressure 1 Headache 8 [50%] Sleep Disturbance Muscular Pain 11[69%] 2. Psychological Stress Job Dissatisfaction 1 Depression 3 Moodiness 5 Burnout 3 3. Behavioral Stress Lower Job Performance 5 High Accident Rate 6 High Number of Medical Leave/ 1 Absenteeism Workplace Aggression 1 4.Safety in Work Place Usage of Safety Shoes 14 (87.5%) Usage of Platform to Eliminate Floor 3 Vibration Usage of Gloves 15 (94%) Usage of Goggle 4 Usage of Ear Plug 12 (75%) Usage of Anti Vibration Mount 12 (75%) Natural Rubber Compound Rubber Polyurethane - 7 [58%] - 3 (Rubber Pad) 1 (Air Cushion) 1 (Spring Type Rubber)

6 5. Conclusions 1. Relevant information are presented from the literature to show how researchers are carrying out similar works in related areas to find the effect of vibration produced by machinery on the discomfort experienced by human beings. 2. This paper presents the results of our study about the discomfort experienced by Industrial workers working on stamping machines. 3. It is found that Headache and Muscular pain are the two major discomfort experienced by industrial workers; many of them get into depression and losing their mood for working efficiently. 4. It is found that 25% of the SMIs do not fit anti-vibration mount to the Stamping machines, which affect the safe working environment for Industrial workers. 6. Acknowledgements The authors thank the Bureau of Research and Consultancy, Universiti Teknologi MARA (UiTM) for funding the Research grant for doing this work. We are grateful for the support and cooperation rendered by the management of the industries for conducting this research work. We would like to record our heartfelt gratitude to our Research Assistants En Zamsuri and Khairuddin for their involvement in the fieldwork. 7. References 1. Serope Kalpakijian and Stevan R. Schmid, Manufacturing Engineering and Technology, Prentice Hall International (2001) 4 th edn. 2. Nor Hayati Saad, Md. Fuad Bahari and Darius Solomon, Increasing Comfort of Stamping Machine Operators, Proceedings of the National Occupational Safety and Health Conference, Institute of Occupational Safety and Health Management, Universiti Utara Malaysia, (21-22 April 2003), Penang, Malaysia. pp E.M. Whitham and M.J. Griffin, The effects of vibration frequency and direction on the location of areas of discomfort caused by whole-body vibration, Applied Ergonomics, Volume 9, Issue 4, (December 1978), Pages Helmut Seidel and Michael J. Griffin, Modelling the response of the spinal system to whole-body vibration and repeated shock, Clinical Biomechanics, Volume 16, Supplement 1, (2001), Pages S3-S7 5. Bengt-O. Wikström, Anders Kjellberg and Margareta Dallner, Whole-body vibration: A comparison of different methods for the evaluation of mechanical shocks, International Journal of Industrial Ergonomics, Volume 7, Issue 1, (January 1991), Pages G. A. Athanasopoulos and P. C. Pelekis, Ground vibrations from sheetpile driving in urban environment: measurements, analysis and effects on buildings and occupants, Soil Dynamics and Earthquake Engineering, Volume 19, Issue 5, (July 2000), Pages

7 Details for Participant Directory 1. Mrs. Nor Hayati Saad, Tel: / h/p: , 2. Prof. Madya Dr. Darius Gnanaraj Solomon, Tel: / h/p: , 3. Prof. Madya (Hj.) Md. Fuad Bahari, h/p: ,