UNIVERSITI TEKNIKAL MALAYSIA MELAKA

Transcription

1 UNIVERSITI TEKNIKAL MALAYSIA MELAKA EVALUATING RISK FACTORS IN MANUAL MATERIAL HANDLING TASKS (LIFTING AND LOWERING) This report submitted in accordance with requirement of the Universiti Teknikal Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering (Manufacturing Management) (Hons.) by BAZLI FAIQ BIN ZAINI B FACULTY OF MANUFACTURING ENGINEERING 2015

2 DECLARATION I hereby, declared this report entitled Evaluating Risk Factors in Manual Material Handling Tasks (Lifting and Lowering) is the results of my own research except as cited in the references Signature :... Author s Name : Bazli Faiq Bin Zaini Date : 2 nd July 2015

3 APPROVAL This report is submitted to the Faculty of Manufacturing Engineering of UTeM as a partial fulfillment of the requirements for the degree of Bachelor of Manufacturing Engineering (Manufacturing Management) with Honours. The member of the supervisory committee is as follow.... (Nor Akramin Bin Mohamad)

4 ABSTRAK Pengendalian bahan secara manual seperti mengangkat, menurunkan, menolak, menarik atau memegang memerlukan kekuatan manusia untuk mengendalikannya. Otot atau kekuatan manusia ialah struktur asas dalam pengendalian bahan secara manual. Pengendalian yang salah boleh menyebabkan berlakunya ketidakselesaan otot pada pekerja. Objektif utama kajian ini ialah untuk mendapatkan maklumat tentang faktor risiko yang menyebabkan lesu otot; untuk menganalisis aktiviti otot semasa pengendalian bahan secara manual menggunakan kaedah Rekabentuk Eksperimen dan membina hubungan model antara aktiviti otot dengan peramal iaitu postur badan, jisim beban dan masa pendedahan. Soal selidik digunakan untuk mengumpul maklumat tentang penilaian faktor risiko yang menyumbang kepada ketidakselesaan otot. Data untuk aktiviti otot di RT bisep BR, LT bisep BR, LT Upper Trap, RT Lumbar ES dan LT Lumbar ES dianalisis dengan menggunakan peralatan surface Electromyography (semg) semasa subjek melaksanakan pengendalian secara manual dan akhir sekali hubungan antara aktiviti otot dan parameter (postur, jisim beban, masa pendedahan) akan dimodelkan menggunakan analisis varians (ANOVA). Keputusannya, jisim beban menjadi faktor penting yang menyebabkan terjejasnya aktiviti otot semasa eksperimen dan tiada interaksi yang terlibat. Model hubungan pula membuktikan hanya tiga otot (RT Biceps BR, LT Biceps BR dan LT Upper Trap) yang terlibat dalam pembentukan model linear untuk menunjukkan nilai pekali daripada parameter yang boleh menjejaskan aktiviti otot. Kesimpulannya, jisim beban menjadi faktor utama yang menjejaskan aktiviti otot semasa pengendalian manual dalam eksperimen yang boleh menyebabkan lesu otot dan hubungan model membuktikan terdapat tiga otot yang terlibat dalam pembentukkan model iaitu otot RT Biceps BR, LT Biceps BR dan LT Upper Trap. i

5 ABSTRACT Manual handling activities such as lifting, lowering, pushing, pulling or holding a load are commonly examples of tasks that requiring human strength. Muscle or human strength is a basis for manual material handling (MMH) job and workplace design. Improper ways of manual handling will cause a muscle fatigue and muscle discomfort at the workers. Manual handling activities at work can result in a wide range of musculoskeletal disorders (MSDs). The main objectives of this study were to evaluate risk factors contributing to muscle fatigue; to analyze muscle activity while performing MMH tasks using Design of Experiments methodology and to model relationship between muscle activity with predictor namely body posture, load mass and exposure time. To assess the risk factor contribute to muscle discomfort, related information were gathered from the questionnaire. Data for muscle activity at RT Biceps BR, LT Biceps BR, LT Upper Trap, RT Lumbar ES and LT Lumbar ES were analyzed using surface electromyography (semg) while subject performing manual lifting/lowering task and lastly the relationship between muscle activity and parameter (posture, load mass, exposure time) were modelled using analysis of variance (ANOVA). As a results, load mass become an important factor that affected all muscle activity during the experiments and no interaction involved since all the combination were not significant. From the model relationship, only three muscles (RT Biceps BR, LT Biceps BR and LT Upper Trap) were involved in performing linear model as to show the coefficient value from the parameter that can affected muscle activity. As a conclusion, load mass become a main factor that can contribute to muscle fatigue and model relationship proved that there were three muscles involved were formed at RT Biceps BR, LT Biceps BR and LT Upper Trap muscle. ii

6 DEDICATION Dedicated to my beloved parents, Mr. Zaini Bin Ismail and Mrs. Nor Iazan Binti Mohd Ali. Also, to all panels, my family and friends for all the encouragements. iii

7 ACKNOWLEDGEMENT I am highly indebted to my great supervisor MR. NOR AKRAMIN BIN MOHAMAD for his guidance and constant supervision as well as for providing necessary information regarding the study and also for his support in completing the project. I would also like to express my gratitude towards my parents and friends for their kind co-operation and encouragement which help me in completion of this project. iv

8 TABLE OF CONTENT Abstrak Abstract Dedication Acknowledgement Table of Content List of Tables List of Figures List Abbreviations, Symbols and Nomenclature i ii iii iv v ix xii xiv CHAPTER 1: INTRODUCTION Introduction Background of Study Problem Statement Project Objective Scope and Limitation of Study Organization of Report 6 CHAPTER 2: LITERATURE REVIEW Introduction Manual Material Handling Principle of Manual Material Handling Risk Factor Types of Ergonomic Risk Factor Risk Effect in Manual Material Handling Summary of Previous Research Work Related To Material Handling Technique 19 v

9 CHAPTER 3: METHODOLOGY Introduction Planning and Activities Evaluate the Information on Risk Factor Contributing To Muscle Fatigue and Muscle Discomfort Associated with Manual Material Handling Analysis of Muscle Activity While They Are Performing Manual Material Handling Task Subjects for Experiment (semg Measurement) Design of Experiment for the Surface Electromyography Measurement Surface Electromyography Signalling and Processing Apparatus Working Procedure To Model Relationship between Muscle Activity and Load Mass, Task Frequency, Exposure Time and Rest time Data Collection Data Analysis Descriptive Statistics Analysis of Variance T-test Expected Result 47 CHAPTER 4: RESULTS AND DISCUSSIONS Introduction Evaluation of Risk Factor Contributing To Muscle Fatigue and Muscle Discomfort Associated With Manual Material Handling Tasks Result of Evaluating Risk Factor Based On Manual Material Handling Result of Evaluating Risk Factor Based On Muscle Discomfort Result of Evaluating Risk Assessment Based On Muscle Discomfort (Mean) 55 vi

10 Result of Evaluating Risk Assessment Based On Muscle Discomfort (Standard Deviation) Summary on Evaluating Risk Factors Interpretation of Muscle Activity Data While Performing Manual Material Handling Task First Muscle Activity (RT BICEPS BR) Second Muscle Activity (LT BICEPS BR) Third Muscle Activity (LT UPPER TRAP) Fourth Muscle Activity (RT LUMBAR ES) Fifth Muscle Activity (LT LUMBAR ES) Summary for All Muscle Activity Model Relationship between Muscle Activities with Body Posture, Load Mass and Exposure Time using Analysis Of Variance (ANOVA) Hypothesis Testing for RT Biceps BR Muscle ANOVA for RT Biceps BR Fitted Model for RT Biceps BR Hypothesis Testing for LT Biceps BR Muscle ANOVA for LT Biceps BR Fitted Model for LT Biceps BR Hypothesis Testing for LT Upper Trap Muscle ANOVA for LT Upper Trap Fitted Model for LT Upper Trap Hypothesis Testing for RT Lumbar ES Muscle ANOVA for RT Lumbar ES Fitted Model for RT Lumbar ES Hypothesis Testing for LT Lumbar ES Muscle ANOVA for LT Lumbar ES Fitted Model for LT Lumbar ES Summary of Model Relationship between Muscle Activities With Body Posture, Load Mass and Exposure Time. 101 vii

11 CHAPTER 5: CONCLUSIONS AND RECOMMENDATIONS Introduction Research Findings Evaluating Risk Factors Analyzing Muscle Activities Using Design of Experiments Methodology Model Relationship between Muscle Activities with Parameter (Body Posture, Load Mass and Exposure Time) Limitation of Study Recommendation for Future Study 106 REFERENCES 107 APPENDICES 117 viii

12 LIST OF TABLES 1.1 Organization of Report Criteria on the Manual Material Handling Task Principle of Manual Material Handling Risk Effect on Manual Material Handling Experiment Sample Experimental Factor Material Handling Technique and their Parameter Variable and Data Analysis Used To Analyses Data Questionnaire Development Anthropometric Measurement for Participants The Levels of the Factor Muscle Activity Experiments Analysis Procedure for a 2 k Design General ANOVA for Two-Factorial with n Replication Per Cell Expected Outcome for This Research Risk Assessment by the Workers Risk Factor that Causes Muscle Discomfort Risk Assessment That Exceed Standard Deviation More Than Summary for All Muscle Involves in Experiments One-way ANOVA and Two Sample T-Test for Body Posture One-way ANOVA and Two Sample T-test for Load Mass 77 ix

13 4.7 One-way ANOVA and Two Sample T-test for Exposure Time ANOVA for RT Biceps BR Muscle Estimated Effects and the Coefficient for Muscle Activity RT Biceps BR One-way ANOVA and Two Sample T-Test for Body Posture One-way ANOVA and Two Sample T-test for Load Mass One-way ANOVA and Two Sample T-test for Exposure Time ANOVA for LT Biceps BR Muscle Estimated Effects and the Coefficient for Muscle Activity LT Biceps BR One-way ANOVA and Two Sample T-Test for Body Posture One-way ANOVA and Two Sample T-test for Load Mass One-way ANOVA and Two Sample T-test for Exposure Time ANOVA for LT Upper Trap Muscle Estimated Effects and the Coefficient for Muscle Activity LT Upper Trap One-way ANOVA and Two Sample T-Test for Body Posture One-way ANOVA and Two Sample T-test for Load Mass One-way ANOVA and Two Sample T-test for Exposure Time ANOVA for RT Lumbar ES Muscle Estimated Effects and the Coefficient for Muscle Activity, RT Lumbar ES One-way ANOVA and Two Sample T-Test for Body Posture One-way ANOVA and Two Sample T-test for Load Mass 97 x

14 4.27 One-way ANOVA and Two Sample T-test for Exposure Time ANOVA for LT Lumbar ES Muscle Estimated Effects and the Coefficient for Muscle Activity, LT Lumbar ES Summary Table on The Hypothesis Testing, P-value and Model Relationship Summary of Model Relationship between Muscle Activities with Body Posture, Load Mass and Exposure Time 105 xi

15 LIST OF FIGURES 1.1 MSD Most Common Work-Related Problem Exposure to Physical Risk Proper Technique of Manual Material Handling Improper technique of Manual Material Handling Example of Manual Material Handling Task Ergonomics Risk Factor Working Posture Contact Stress Factor The Process Flow of Study Electromyography Electrode Placements Symmetric Lifting and Lowering Asymmetric Lifting and Lowering Flow Processes for Experimental Procedures Minitab User Interface Process Flow for Model Relationship between Muscles Activities with Factors Involves Common Posture for Load Lifting Most Comfortable Posture for Load Lifting Normal Weight Lifted Weight That Can Be Lifted Time Taken to Lift a Load in a Single Period Normal Time to Lift a Load in a Single Period Rest Time between Each Task Complain on the Sufficient Rest Time RT Biceps BR and LT Biceps BR LT UPPER TRAP Muscle RT LUMBAR ES and LT LUMBAR ES 59 xii

16 4.12 Pareto Chart for the Effect of RT Biceps BR Main Effects Plot (Data Means) for RT Biceps BR Interaction Plot for RT Biceps BR Pareto Chart for the Effect of LT Biceps BR Main Effects Plot (Data Means) for LT Biceps BR Interaction Plot for LT Biceps BR Pareto Chart for the Effect of LT Upper Trap Main Effects Plot (Data Means) for LT Upper Trap Interaction Plot for LT Upper Trap Pareto Chart for the Effect of RT Lumbar ES Main Effects Plot (Data Means) for RT Lumbar ES Interaction Plot for RT Lumbar ES Pareto Chart for the Effect of LT Lumbar ES Main Effects Plot (Data Means) for LT Lumbar ES Interaction Plot for LT Lumbar ES 71 xiii

17 LIST OF ABBREVIATIONS, SYMBOLS AND NOMENCLATURES ANOVA - Analysis of Variance APDF - Amplitude Probability Distribution Function BLS - Bureau of Labour Statistics BMI - Body Mass Index DF - Degree of Freedom ES - Erector Spinae EGM - Electrogoniometer EMG - Electromyography HAV - Hand Arm Vibration ILO - International Labour Organization INC - Inclinometer KG - Kilogram LT - Left LBD - Low Back Disorder MS - Mean Square MLTs - Material Licensing Tracking System MMH - Manual Material Handling MSD - Musculoskeletal Disorder NIOSH - National Institute of Occupational Safety and Health OSHA - Occupational Safety and Health Act PLBDR - Probability of Low Back Disorder Risk xiv

18 PSM 1 - Projek Sarjana Muda 1 PSM 2 - Projek Sarjana Muda 2 RA - Reverse Arrangement RT - Right RMS - Root Mean Square SS - Sums of Square SEMG - Surface Electromyography TRAP - Trapezius WBV - Whole Body Vibration WHO - World Health Organization WMSD - Work-Related Musculoskeletal Disorders xv

19 CHAPTER 1 INTRODUCTION 1.1 Introduction This research centers on problems related to issues on muscle activity while carrying a manual material handling task. Specifically, the purpose of this research is to identify the risk factor, and investigate the muscle activity that affected from the specific manual material handling tasks. This chapter begins with a background study and then discusses and presents the problem statement, objectives and scope involves. Finally, the organization of the whole research is presented. 1.2 Background of Study In contempt of the widely use of robots in industrial jobs such as assembling parts and Material Licensing Tracking System (MLTs), there are still several tasks in industry that require humans to perform it manually. These tasks consist of lifting, holding, carrying, or moving loads in the work area. They often cause musculoskeletal injuries to that worker (Jozef Zurada, 2012; Shengli Niu, 2010;). Although the majority of jobs becomes automated, human strength is still used in many industrial activities. Other researchers also agreed that manual material 1

20 handling (MMH) tasks such as lifting, lowering, pushing, pulling or carrying loads are common tasks that require human strength (Min K.Chung & San H. Kim, 1996). There is a risk of injury if such tasks are not carried out properly and safely and researcher shows an important correlation between manual handling and musculoskeletal injury (Widanarko et al, 2011). Manual lifting exists as a significant problem even with more frequently developed industrial activities and technologies that lead to musculoskeletal injury (Kim et al. 2011). Over one third of reported injuries in the UK resulting in 3 days or more absence are cause by manual handling incidents at work (Health Safety Executive, 2010b). In a bad scenario, the effect of musculoskeletal injuries may result in performance decrement for industrialized countries. World Health Organization came out with the result that musculoskeletal injuries or musculoskeletal disorder (MSDs) are the leading cause of workplace disability in developed countries (WHO, 2003). Representing one-third of work injuries, they have affected some criteria such as: i. Significant economic and social consequences (Punnett and Wegman, 2004) ii. High cost for company due to reduced of quality and productivity (Eklund, 1997) iii. Overburden the health system (Badley et al., 1994) Until this time, there are only a handful of tools that exist for assessing lifting risk. National Institute of Occupational Safety and Health prepare the health and safety community with a lifting index so it can be used easily in industry or factory floor. However, there is still some limitation to apply this application because data quality needed for kinematic or kinetic model inputs are difficult to obtain. (J.D. Matthews et al. 2007). 2

21 1.3 Problem Statement The Department of Occupational Safety and Health Malaysia stated that there are almost 700 occupational musculoskeletal diseases happen in 2014 and make the number increase from the previous year 2013 (SOCSO Annual Report, 2014). Besides that, in the same period there were a report stated that the fatal injuries occurred for every 3.2 cases out of every 100,000 full-time workers (Bureau of Labor Statistic, 2012). Ergonomics problems at the work area and bad organization of work are among of the reasons that contribute to risk factor as mentioned by occupational safety and health problem (Shengli Niu, 2010). Among situation that contribute to the raising magnitude of musculoskeletal disorders (MSDs) suffered by the workers are caused by postural stress from prolonged standing, sitting, and awkward posture. In addition, the psychosocial factors including psychological stress, job stress and job dissatisfaction are the factor that related to ergonomics problem. Most of the ergonomics problems are related to the risk factor affected to the workers (Frymoyer & Mooney, 1986). Work related MSDs may occur even the workers are exposed to an occupational risk factor at the workplace on an occasional basis for only 25% or less as stated by previous exposure-response data. (Punnet, 2000). Risk factor can cause several visual effects such as eye strain, fatigue, MSDs such as low back pain, neck pain, shoulder pain, repetitive motion injuries and tensions (Punnett & Wegman, 2004). According to Bureau of Labor Statistic, there are 387, 820 MSD cases accounted for rate of 33% worker injury and illness in (OSHA 2012). Previous researcher stated that the number of musculoskeletal accidents during lifting is up to 52%, pushing and pulling 13%, holding loads 10%, repetitive movement is about 13% and 12% is for others manual material handling activities. (Abdillah, 2013). Figure 1.1 and 1.2 below shows a problem relates to the MSD most common work-related problem and exposure to physical risk. MSD causes 25% of workers complain of backache and 23% of muscular pain. In term of physical risk exposure, 3

22 65% report a repetitive hand and arm movement as a problem, 45% of working in painful and tiring position and 35% are required to working with excessive heavy loads (Shengli Niu, 2010). MSD most common workrelated problem 23% 25% Backache Muscular pain Figure 1.1: MSD Most Common Work-Related Problem Exposure to Physical Risk 35% 45% 65% Repetitive hand & arm movement Painful & Tiring Position Heavy load Figure 1.2: Exposure to Physical Risk 4

23 1.4 Project Objective The specific objectives of this study are elaborated as follows: 1. To evaluate the information of risk factor contributing to muscle fatigue and muscle discomfort associated with manual material handling tasks. The physiological factors of workers such as working postures are determined and analyzed using ergonomics assessment tools to regulate the effect of identifying occupational risk factors on worker s health. Examples of such activities include working posture, repetitive motion, forceful exertion, contact stress or vibration where the related risk factors are involved. 2. To analyze muscle activities of workers while they are performing manual material handling task by using Design of Experiments (DOE) methodology. The purpose of this activity is to analyze and evaluate the muscle activity recorded using surface electromyography (semg) and muscle discomfort within specific time of manual material handling task. 3. To model relationship between muscle activities with posture, load mass and exposure time. The purpose of this objective to analyze and to identify the factor or factors that affected most muscle activity and to identify which factors that iterated on the effect muscle activity. 5

24 1.5 Scope and Limitation of Study This section is intended to describe the scope and limitations of carried out study. This study will be focusing on the real situation such as human (subject), work load, manual handling tasks, exposure time and rest time. Risk factor that contributed to muscle fatigue and discomfort associated with manual material handling were observed and identified. Muscle activities that are related to the participants will be identified based on the parameter namely body posture, load mass and exposure time from the experiments. These experiments were focused only on three samples from the same population due to the time constraint and limited electromyography equipment. The analysis of muscle activity will be conducted in real experiment situation. Data from muscle activity will be analyzes using computer software and ANOVA method were used to model the relationship between muscle activity and parameters involved. 1.6 Organization of Report The whole of the research is arranged in Table 1.1 below. The research included five chapters which consists introduction, literature reviews, methodology, result and discussion and finally the conclusion. 6