A STUDY ON HAND PRESS GRIP FORCE FOR PUSH

ACTIVITY IN LAY UP PROCESS AT

AEROSPACE INDUSTRY

SITI NURATHIRAH BT MOHD ZULKEFLLE

B051110021

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

2015

B051110021 BAC

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S.) 2015 UTeM

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

A STUDY ON HAND PRESS GRIP FORCE FOR PUSH

ACTIVITY IN LAY UP PROCESS AT

AEROSPACE INDUSTRY

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

SITI NURATHIRAH BT MOHD ZULKEFLLE

B051110021

920928036126

FACULTY OF MANUFACTURING ENGINEERING

2015

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA

TAJUK: A STUDY ON HAND PRESS GRIP FORCE FOR PUSH ACTIVITY IN LAY UP PROCESS AT AEROSPACE INDUSTRY SESI PENGAJIAN: 2014/2015 Semester 2 Saya SITI NURATHIRAH BT MOHD ZULKEFLLE mengaku membenarkan Laporan PSM ini disimpan di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut: 1. Laporan PSM adalah hak milik Universiti Teknikal Malaysia Melaka dan penulis. 2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan

untuk tujuan pengajian sahaja dengan izin penulis. 3. Perpustakaan dibenarkan membuat salinan laporan PSM ini sebagai bahan

pertukaran antara institusi pengajian tinggi. 4. **Sila tandakan ( )

SULIT

TERHAD

TIDAK TERHAD

(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia sebagaimana yang termaktub dalam AKTA RAHSIA RASMI 1972)

(Mengandungi maklumat TERHAD yang telah ditentukan oleh organisasi/badan di mana penyelidikan dijalankan)

Alamat Tetap: LOT 1011 KG PAUH DUA,

BANGGU 16150 KOTA BHARU,

KELANTAN. Tarikh: ________________________

Disahkan oleh:

Cop Rasmi: Tarikh: _______________________

** Jika Laporan PSM ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh laporan PSM ini perlu dikelaskan sebagai SULIT atau TERHAD.

DECLARATION

I hereby, declared this report entitled “A Study On Hand Press Grip Force For Push Activity In Lay Up Process At

Aerospace Industry ” is the results of my own research except as cited in the references.

Signature : ……………………………………….

Author’s Name : SITI NURATHIRAH BT MOHD ZULKEFLLE

Date : …………………………………………

ii

ABSTRACT

Grip strength is the force applied by the hand to push objects and is a specific part of

hand strength. It is generally considered that all aspects of the hand must be

exercised to produce a healthy and strong hand. Repetitive usage of hands will cause

an imbalance between closing and opening (antagonist) muscles, and can lead to

problems such as carpal tunnel syndrome. The purpose of this study is to analyse the

hand press grip force and muscle fatigue at the left and right triceps for push activity

among the workers in the aerospace industry while workers perform their task. By

using observation, interview, questionnaires, Tekscan system and Electromyography

(EMG) tools is used to evaluate hand pressure grip force and muscle fatigue of the

workers. Findings will show the factors that affect the hand pressure grip force and

its relation with muscle fatigue. At the end of this study, the result will be discussed

to achieve the objective and also propose an ergonomic improvement in the

aerospace industry.

i

ABSTRAK

Kekuatan cengkaman adalah daya yang dikenakan oleh tangan untuk menolak objek

dan bahagian tertentu menggunakan kekuatan tangan. Secara umumnya dianggap

bahawa semua aspek tangan, perlu dititik beratkan dan sentiasa melakukan senaman

tangan untuk mendapatkan tangan yang sihat dan kuat. Penggunaan tangan secara

berulang-ulang dalam jangka masa yang panjang akan menyebabkan

ketidakseimbangan antara penutupan dan pembukaan (antagonis) otot, dan boleh

membawa kepada masalah seperti sindrom carpal tunnel. Tujuan kajian ini adalah

untuk menganalisis kekuatan cengkaman tangan dan keletihan otot triceps di kiri dan

kanan untuk aktiviti tolakan di kalangan pekerja dalam industri aeroangkasa ketika

pekerja melaksanakan tugas mereka. Dengan menggunakan pemerhatian, temubual,

soal selidik, sistem Tekscan dan Electromyography (EMG) digunakan untuk menilai

tekanan tangan daya cengkaman dan keletihan otot para pekerja. Penemuan

menunjukkan faktor-faktor yang memberi kesan kepada daya cengkaman tekanan

tangan dan kaitannya dengan keletihan otot. Pada akhir kajian ini, keputusan akan

dibincangkan bagi mencapai objektif dan juga mencadangkan peningkatan

ergonomik dalam industri aeroangkasa.

iii

DEDICATION

This thesis is dedicated to my beloved parents, (Hj Zulkeflle Bin Mohamed

Noor and Hjh Rozani Binti Yajid), family, friends and my loved ones who have

given their support, encouragement and good advice to me. This thesis is also in debt

to Dr. Seri Rahayu Kamat, a mentor who has been a constant source of knowledge

and inspiration.

iv

ACKNOWLEDGEMENT

First and foremost, I thank the almighty god (Allah s.w.t) for being by my side

throughout. I wish to extend my sincere thanks to Dr. Seri Rahayu Binti Kamat as

my supervisor for helping and guiding me throughout the development of the

research. I am grateful to thank my colleagues as many creative thought and valuable

discussion about the research have had a significance influence throughout my

project development. Also not to forget the Faculty of Manufacturing Engineering,

Universiti Teknikal Malaysia Melaka for allowing me to be a part of the network and

thus giving useful knowledge and experiences. In addition, I am especially thanked

to my parents, (Hj Zulkeflle Bin Mohamed Noor and Hjh Rozani Binti Yajid), for

their love, support, encouragement and understanding during my studies.

v

TABLE OF CONTENT

Abstrak i

Abstract ii

Dedication iii

Acknowledgement iv

Table of Content v

List of Tables ix

List of Figures xii

CHAPTER 1: INTRODUCTION 1

1.1 Background 1

1.2 Problem Statement 3

1.3 Objectives 4

1.4 Scope and Limitation of Study 4

1.5 Importance of the study 5

CHAPTER 2: LITERATURE REVIEW 6

2.1 Ergonomics 6

2.2 Ergonomics Risk Factors 7

2.2.1 Awkward Posture 8

2.2.2 Force 8

2.2.3 Repetition 9

2.2.4 Vibration 9

2.2.5 Static Loading 11

2.2.6 Contact Stress 12

2.2.7 Extreme Temperature 12

2.3 Grip Force 13

2.4 Push and Pull Task 16

2.4.1 Factors Affecting Pushing and Pulling Forces 19

2.4.1.1 Friction 19

vi

2.4.1.2 Wheels 19

2.4.1.3 Weight on the Cart 19

2.4.1.4 Handle Height 20

2.5 Musculoskeletal Disorders (MSDs) 21

2.6.1 Symptom of Musculoskeletal Disorders (MSD) 22

2.6 Carpal Tunnel Syndrome (CTS) 23

2.6.1 Symptoms of Carpal Tunnel Syndrome 24

2.7 Muscle Fatigue 25

2.7.1 Types of Muscle 26

2.8 Electromyography (EMG) 27

CHAPTER 3: METHODOLGY 29

3.1 Phase 1 30

3.2 Phase 2 32

3.3 Literature Review 33

3.4 Data Collection 33

3.4.1 Interview 34

3.4.2 Questionnaires 35

3.5 Tekscan System 35

3.6 Electromyography (EMG) 36

3.6.1 sEMG signal acquisition and processing 38

3.6.2 Muscle fatigue analysis method 39

3.6.3 Time-to-fatigue analysis method 39

3.7 Research Plan 40

3.8 Summary 40

CHAPTER 4: RESULT & DISCUSSION 41

4.1 Questionnaire Analysis 42

4.2 Analysis of data in Layup Department 53

4.2.1 Data for Tekscan System 53

4.2.2 Data for Electromyography (EMG) 70

vii

CHAPTER 5: CONCLUSION & SUGGESTION 76

5.2 Conclusion 76

5.2 Suggestion 77

5.2.1 Prevents Ergonomic Hazards at Workplace 77

5.2.2 Using the appropriate manpower for a task that involves 78

heavy equipment

5.2.3 Medical check-up for the workers 78

5.2.4 Hand massage (one in two weeks) 78

5.2.5 Suitable glove that can reduce discomfort 78

5.2.6 Regular exercise hands frequently to improve circulation 79

5.2.7 Reduce the exposure time 79

REFERENCES 80

APPENDICES

ix

LIST OF TABLES

2.1 Borg's CR-1O rating scale 14

2.2 Table for three stages of symptom in CTD 25

3.1 Methods used to achieve objectives 33

3.2 Benefits of using EMG technique 38

4.1 Table for age 44

4.2 Table for working experiences 46

4.3 Table for working condition 47

4.4 Table for body parts 49

4.5 Location of body and percentages of pain. 50

4.6 Table for time being discomfort 51

4.7 Table for level of discomfort 53

4.8 Table for the suggestion that is recommended by CTRM Workers 54

4.9 Data Analysis of Tekscan Test 56

4.10 The distribution of hand pressure grip force while performs the

push task for operator A

66

4.11 The distribution of hand pressure grip force while performs the

push task for operator B

67

4.12 The distribution of hand pressure grip force while performs the

push task for operator C

68

4.13 The distribution of hand pressure grip force while performs the

push task for operator D

69

4.14 The distribution of hand pressure grip force while performs the

push task for operator E

70

4.15 Data for muscle fatigue influence by hand pressure grip force for

10 minutes.

71

ix

LIST OF FIGURES

2.1 Working experience for each worker 10

2.2 Correlation of grip force and working experience 11

2.3 Illustration Of selected risk factor conditions 13

2.4 Definitions of the grip push and contact forces 14

2.5 Grip Dynamometer 15

2.6 Risk factor of Musculoskeletal Disorders in workplace 22

2.7 Stage of MSD symptoms 23

2.8 Examples of skin surface electrodes 28

2.9 Schematic of a fine wire electrode 29

3.1 Project’s Methodology 32

3.2 Tekscan system 37

4.1 Figure for marital status 44

4.2 Figure for the duration of work 45

4.3 Pie Chart for duration of working in current position 47

4.4 Images for body parts 48

4.5 Pie chart for part of body that experience pain 50

4.6 Pie Chart for time that workers feeling discomfort 52

4.7 Graph for analysis of serious CTS and early sign CTS 52

4.8 Location of hand feeling discomfort 53

4.9 Operator pushing the mould panel 55

4.10 Graph of force vs time for operator A left hand 58

4.11 Graph of force vs time for operator A right hand 59

4.12 Graph of force vs time for operator B left hand 60

4.13 Graph of force vs time for operator B right hand 61

4.14 Graph of force vs time for operator C left hand 61

4.15 Graph of force vs time for operator C right hand 62

4.16 Graph of force vs time for operator D left hand 63

4.17 Graph of force vs time for operator D right hand 64

4.18 Graph of force vs time for operator E left hand 64

x

4.19 Graph of force vs time for operator E right hand 65

4.20 Graphs Analysis and Part of the Muscle of EMG 72

4.21 Graph of maximum pressure grip force vs LT LAT. Triceps while

operators perform the work task for 10 minutes.

75

2.22 Graph of maximum pressure grip force vs RT LAT. Triceps while

operators perform the work task for 10 minutes

75

1

CHAPTER 1

INTRODUCTION

1.1 Background

Manual material handling such as lifting heavy products, reaching materials, pushing

or pulling excessive loads and bending forward their back when doing tasks because

those tasks require a large degree of freedom and stable position. Pushing and pulling

activities are one of the activities for manual material handling that can increase the

risks of back pain problem (Kuijer et al., 2007). The pushing and pulling activities

are a continuous activity for a large segment of the workforce, including hospital

workers, manufacturing workers, construction workers, forest workers, etc (Jellad et

al., 2013). Moreover, both of these activities are associated with the awkward

posture.

The theory of the awkward posture can be understand as a discomfort posture

because it is harmful position for human body when a joint is not in its neutral range

of postures and cause muscles are either less or more than resting length. The

muscles around the joint are stretched or compressed when joints are exposed to

postures that involve range of movement near the extreme position. If the exposure

to extreme postures is prolonged, the muscles do not immediately revert to their

resting length (Hayot et al., 2012).

2

In manufacturing workplaces, most of the processes jobs were recommended to be

performed in awkward posture. For example, they need to raise their elbow above

their shoulder, bend their neck forward greater than 30 degrees, bend their wrist

downward with palm facing downward greater than 30 degrees, bend their back

forward greater than 45 degrees, and squatting, etc (T-Krajewski et al., 2009).

Musculoskeletal disorders can be caused by repetitive usage of hand-held tools due

to factors such as awkward hand posture (Bovenzi et al., 1998); static loading of the

muscle during repetitive gripping of the handle (Grant et al., 1993); excessive force

exertions (Lin et al., 2006); the weight of the tool being supported exposure to hand-

arm vibration (Lin et al., 2007) and etc. To determine the optimal diameter for handle

use for the general population an extensive research has been conducted. Tool handle

diameter has been identified as the most significant factors that affect grip force

production (Edgren et al., 2004). Grip production, local contact pressure of a handle

configuration and the perceived acceptability can be affected by factors such as

handle orientation; texture, angle and shape (Sancho-Bru et al., 2003).

The Ergonomics Design and Analysis tool of Computer-Aided Three-Dimensional

Interactive Application (CATIA) software and tekscan software are one of the

ergonomics analysis tool that have been applied to analyse pushing and pulling

activities of workers while performing tasks in awkward posture (Vieira & Kumar

2007, Landau et al., 2008, Sheikhzadeh et al., 2009, Daraiseh et al., 2010, Govindu et

al., 2012).

Besides that, this ergonomics analysis tool also can quantify comfort level of

working posture while workers perform their tasks using Rapid Upper Limb

Assessment (RULA) feature. Several epidemiology studies used this feature because

they wanted to know whether the working posture in comfort or discomfort condition

(Hoy et al., 2005, Shuval & Donchin et al., 2005, Jones & Kumar 2007, Hwang et

al., 2010, Ozturk & Esin 2011, Dockrell et al., 2012, Meksawi et al., 2012).

3

1.2 Problem Statement

In aerospace industry, almost all the jobs are performed in standing position and this

can lead to muscle fatigue. At XYZ Sdn Bhd, the operators at the Layup Station are

doing their task manually. Most of the task involved performing the job tasks such as

pushing and pulling activity, the operators might feel the discomfort and pain in their

arms and wrist. The operators are tending to experienced fatigue while performing

the job at Layup Station that may take to serious injuries known as Musculoskeletal

Disorders (MSDs). (MSDs) are often caused by awkward postures, excessive force

and repetition because of the limited work area, standing for prolonged periods and

heavy equipment. The top management of XYZ Sdn Bhd is worried about the

declined health quality of the operators can affect their productivity and hence

decreases the efficiency of the manufacturing operation.

This study focus on analysing the activity related with push activity that gives

discomfort for workers in layup room by using Tekscan system, electromyography

(EMG) and lastly giving suggestion on proper technique to reduce hand discomfort

and muscle fatigue by using an ergonomic approach to overcome all the problems.

Based on the scenario of the working environment at XYZ company, it is important

to explain and give a better understanding about the (MSDs) and Carpal Tunnel

Syndrome (CTS) in the aerospace industry.

According to the previous research done by Seri Rahayu et al., (2014) most of the

problem related to (MSD) in Lay up department is related with push activities.

Workers have discomfort experience with Carpal Tunnel Syndrome while undertake

the activities. The result show the muscle fatigue when the workers used the

sustained force in a long period of time. Due to muscle fatigue, the muscles will

involve with contraction and this condition lead to discomfort. Therefore in this

research we want to investigate the hand press grip force and muscle fatigue at the

left and right triceps while worker undertaken push activity to show the significant

effect of the Carpal Tunnel Syndrome problem in layup process/department.

4

1.3 Objectives

The objectives of the study are:

i. To investigate and analyse the activity related to push activities that cause

discomfort to workers at Layup department in Aerospace Industry.

ii. To analyse the hand press grip force and muscle fatigue at the left and right

triceps for push activity among the workers in aerospace industry while

workers perform their task.

iii. To give a suggestion on proper technique to reduce hand discomfort and

muscle fatigue using an ergonomic approach for the operators in aerospace

industry.

1.4 Scope and Limitation of Study

This study focused on analysis of hand press grip force for push activities at Lay up

department and only covered the upper limb of the body area. This study is done by

collecting data from Layup department. In this study, the aspects that will be look are

ergonomic requirement, ergonomic principle and ergonomic problem faced by the

workers. Besides, other aspects such as improving the muscle fatigue were also

covered in this study.

5

1.5 Importance of the Study

This study is able to:

i. Provide and analyse of the best ergonomic approach that can be used to

reduce all the pain or health experience that occur because of the effects of

discomfort.

ii. Encourage the implementation of ergonomics approach in aerospace industry.

6

CHAPTER 2

LITERATURE REVIEW

This chapter contain the literature review of the study which related to the objectives

and scope of the study. It will look into Ergonomics, Ergonomic Risk Factor (ERF)

and discusses the hand pressure grip force, muscle fatigue experience and push and

pull activities. It also covers the Musculoskeletal Disorders (MSDs) and Carpal

Tunnel Syndrome (CTS).

2.1 Introduction

Ergonomics is the science of fitting workplace condition and employments interests

to the capabilities of the working population. In other meaning, ergonomic is the

laws of work that define the limits to human capability. Effective and successful

‘fits’ assure high productivity, increased satisfaction among the employee of the

organization and avoidance of illness and injury risk. Despite the fact that the scope

of ergonomics is much wider, the term here refers to assessing those work related

factors that may induce a risk of musculoskeletal disorder and recommendation to

reduce them. Basic examples of ergonomics risk factor are found in the works

involving the repetitive, forceful, or prolonged exertions of the hands; prolong

awkward postures; and frequent or heavy lifting, pushing, pulling, or carrying of

heavy objects. Jobs or working conditions that shows multiple risk factors will have

7

a higher probability of developing a work related musculoskeletal disorder. The level

of risk relies on the frequency, intensity and duration of the exposure to these

conditions and the individual’s capacity to meet the force of job demands that might

be included. (Mat Rebi, 2003).

Ergonomic assessments are required with a specific end goal in order to know how

efficiently the company is implementing ergonomics or precisely where to begin

when first utilizing ergonomics. An ergonomic assessment of workplace can disclose

any unsafe areas, identify ergonomics solutions and help to implement an ergonomic

plan that will improve the overall ergonomics of the organization.

2.2 Ergonomics Risk Factors

Ergonomics Risk Factors cause difficulties in elimination, identification, reduction

and control, thus give the challenge to the management team to handle the problems.

According to Mat Rebi (2003), Ergonomics Risk Factors (ERF) is a circumstances

that exist or created purposefully or unintentionally that could or may help contribute

to results contravene or against the standards or philosophy of ergonomics that could

or may be unsafe to the wellbeing and health of clients or individuals at work or after

work. Before solutions for the issues could be found, awareness and understanding

on the negative factors of Ergonomic Risk Factors are essential and critical for

countermeasure to take.

According to N.Jaffar et al., (2011), the primary Ergonomic Risk Factor are force,

vibration, static loading, awkward posture, contact stress, repetition and extreme

temperature.

8

2.2.1 Awkward Posture

Awkward posture occurs when any joint of your body twists or bends excessively,

outside a comfortable range of movement. On the other hand, awkward posture is

related to an increased risk of injury. It is generally considered that the more a joint

deviates from the natural position, the greater the risk of injury.

Posture refers to the position of different parts of your body. Muscles, ligaments and

tendons must work harder and can be focused on when you are in an awkward

posture. If the position is held long enough for you to feel throbbing painfulness,

then your muscles have been held in one position for a long time. A posture held for

a long time is known as a static posture.

Posture issues can be created by work routines (bending the wrist to assemble a part;

turning and twisting to pick up a box) or workplace measurements (stooping in the

stockpiling of a plane on account of the limited space while taking care of baggage;

extended range to obtain apart from a bin at a high position). Particular postures have

been identify with injury for example, shoulder, wrist, low back and neck. Other

parts of body are tenses not due to work but maintaining posture. (N.Jaffar et al.,

2011)

2.2.2 Force

Force is the physical or mechanical work to accomplish particular movement or

effort. Force can be defined as the measure of physical effort needed to perform

certain work. Case in point lifting or to keep up control of the tools or machine. The

energy may originate from lifting, grasping, pulling or pushing exercises according

to N.Jaffar et al., (2011). The measure of energy relies on upon the sort of action,

weight of an item, type of grasp, body position and the period of the errand. The

9

measure of strength needed by a movement can now be amplified bringing on

significantly more muscular fatigue. It may as well contribute to musculoskeletal

problems when there is insufficient time for relaxation or recovery. In general, higher

force means a higher degree of risk.

2.2.3 Repetition

N.Jaffar et al., (2011) said that repetition can be simply known as performing the

same movements or group of movements excessively. Repetition includes doing a

work that uses the same muscles again and again with minimal opportunity to rest or

recovery. Repeated identical or similar motions performed over a period of time

could cause over-extension and overuse of certain muscle groups, which could lead

to muscle fatigue. As a conclusion, the greater the number of repetitions, the greater

the degree of risk. Still, the relationship between degree of injury risk and repetition

is altered by other risk factors such as posture, force, recovery time and duration.

2.2.4 Vibration

Vibration may be characterized as any movement which a body makes about a

settled point. Vibration has been discovered to be an etiological variable in

workplaces using instruments vibrating in the frequency of 20 to 80 Hz. Vibration

could cause damage of the body organs as an outcome of their being buffeted by high

vibration levels at generally low frequencies and breakdown of body tissues because

of continuous resonance wave or to their assimilation of high power vibration

(N.Jaffar et al., 2011).