Halim Isa

Analysis of Muscle Activity using Surface Electromyography for Muscle Performance in Manual Lifting Task

In industries, manual lifting is commonly practiced even though mechanized material handling equipment are provided. Manual lifting is used to transport or move products and goods to a desired place.Improper lifting techniquescontribute to muscle fatigue and low back pain that can lead to work efficiency and low productivity.The objective of this study were to analyze muscle activity in the left and right Erector Spinae, and left and right Biceps Brachii of five female subjects while performing manual lifting taskwithdifferent load mass, lifting height and twist angle.The muscle activitywere measured and analyzed using surface electromyography (sEMG).This study found that the right Biceps Brachii, right and left Erector Spinae experienced fatigue while performingasymmetric lifting (twist angle = 90°) at lifting height of 75 cm and 140 cm with load mass of 5 kg and 10 kg. Meanwhile, the left Biceps Brachii experienced fatigue when the lifting task was set at lifting height of 75 cm, load mass of 5 kg and twist angle of 90°.The load mass and lifting height has a significant influence to Mean Power Frequency (MPF) for left Biceps Brachii, left and right Erector Spinae. This study concluded that reducing the load mass can increase the muscles performance which can extend the transition-to-fatigue stage in the left and right Biceps Brachii and Erector Spinae.

Ergonomic Design of CNC Milling Machine for Safe Working Posture

In milling operation, Computer Numerical Control (CNC) milling machine has been recognized as one of effective solutions for high productivity, efficiency, and precision. However, the existing CNC milling machine has contributed to ergonomics-related problems such as awkward working posture. The aim of this study is to redesign the existing CNC milling machine by considering working posture of the machinist. This study performed questionnaire survey to determine ergonomics feature requirements from the machinist. The requirements of the machinist are then translated using Quality Function Deployment (QFD) to obtain technical specifications of new design CNC milling machine. The working posture of machinist during operating the existing CNC milling machine and the redesigned CNC milling machine was assessed using Rapid Upper Limb Assessment (RULA). Based on the analysis, the redesigned CNC milling machine has improved the working posture as shown by low score of RULA. This study concluded that by considering the ergonomics feature requirements to the design of CNC milling machine enabled the machinists to perform milling operation in safe working posture. This study suggests that environmental factors should be considered in the future research works.

Dimensional Deviation Affected by Cutting Parameters and Machine Tool Rigidity in Dry Turning of S45C Steel

Performance of machining processes is assessed by dimensional and geometrical accuracy which is mentioned in this paper as dimensional deviation. A part quality does not depend solely on the depth of cut, feed rate and cutting speed. Other variable such as excessive machine tool vibration due to insufficient dynamic rigidity can be deleterious to the desired results. The focus of the present study is to find a correlation between dimensional deviation against cutting parameters and machine tool vibration in dry turning. Hence cutting parameters and vibration-based regression model can be established for predicting the part dimensional deviation. Experiments are conducted using a Computerized Numerical Control (CNC) lathe with carbide insert cutting tool. Vibration data are collected through a data acquisition system, then tested and analyzed through statistical analysis. The analysis revealed that machine tool vibration has significant effect on dimensional deviation where statistical analysis of individual regression coefficients showed p<0.05. The developed regression model has been validated through experimental tests and found to be reliable to predict dimensional deviation.

An Overview of Ergonomics Problems Related to CNC Machining Operations

In the new era of advanced manufacturing technology, machine tool design plays an important role in maximizing productivity and occupational health of industrial workers. However, the machine tool manufacturers face difficulty in designing an ergonomic machine tool that can be suited to Malaysian industrial workers because almost all machine tools were designed according to physical dimensions, capabilities and limitations of European or American populations. This mismatch between machine design and worker abilities may eventually lead to occupational injuries. Therefore, the purpose of this paper is to disseminate information on ergonomics problem, assessment methods, and control measures associated with CNC machining operation. Published articles related to CNC machining operation have been reviewed. Based on published researches, work-related musculoskeletal disorders such as low-back pain, neck and shoulder problem have been identified as common health problems associated with the machine operation. Engineering and administrative controls have been proposed to minimize the health problems.

Prolonged Standing Strain Index (PSSI): A Proposed Method to Quantify Risk Levels of Standing Jobs in Industrial Workplaces

Industrial occupations such as metal stamping workers, electronics parts assembly operators, automotive industry welders, and lathe operators perform their jobs in standing position for a long period of time. Prolonged standing can contribute to discomfort, and muscle fatigue particularly in the back and legs. This study developed prolonged standing strain index (PSSI) to quantify risk levels due to standing jobs and propose recommendations to minimize the risk levels. Risk factors associated with standing jobs such as working posture, muscles activity, standing duration, holding time, whole-body vibration, and indoor air quality were considered as basis to develop the PSSI. All risk factors are assigned with multipliers, and the PSSI is the product of these multipliers. Based on PSSI, recommendations were proposed, however, extensive studies are required to validate their effectiveness.

The Effects of Roller Conveyor on Muscle Activity in Workpiece Loading on CNC Machining Centre: A Preliminary Study

In the recent years, Advance Manufacturing Technology (AMT) has been widely used in manufacturing industry to increase manufacturing process capability. However, Computer Numerical Control (CNC) machine designs have only focused on its operational capability. The harmonious coordination between users and CNC machines is often neglected, which can contribute to hazardous working practices that can affect the health of users. Bending posture while loading the work piece to the machine can cause fatigue and discomfort to the users. Thus, the focus of this preliminary study is to analyse the effect of CNC machine work piece loading on muscle activity levels and to determine the effectiveness of roller conveyor in reducing muscle activity levels. Muscle activity has been analysed using surface electromyography (sEMG) technique. Erector spinae, biceps and trapezius muscles were concurrently measured during the work piece loading. Five male subjects (n=5) participated in the pre-intervention study and two subjects (n=2) in the post-intervention study (roller conveyor implementation) participated to test the effectiveness of the roller conveyor. Result pre-intervention study found that muscle activity level of biceps was the highest followed by trapezius and erector spinae. Based on the post-intervention study involving the roller conveyor, muscle activity of the erector spinae was reduced meanwhile the muscle activity of biceps and trapezius increased for both subjects.

Integration of Failure Mode Effect and Criticality Analysis (FMECA) and Analytical Hierarchy Process (AHP) to Improve the Packaging Process for Automotive Stamping Part

In the business world today, organizations must be able to respond promptly and efficiently to the changing market needs. Therefore, the flaw in the conventional approach such as inefficiency and time consumption can contribute to product failure in the marketplace. This hinders organizations to provide the performance required and should be improved to respond to the current situation. Concurrent engineering should be adopted to overcome the problems associated with the conventional approach. This paper focuses on minimizing the conventional method by implementing concurrent engineering tools and techniques. Thus, the main objective of this paper is to reduce the wastage of time and costs, as well as labor during packaging process, by identifying the failure of the existing process and choosing a new concept for the packaging process using the integration of FMECA and AHP approach. Failures in the current procedure of packaging process were identified by using FMECA analysis, and 4 new concepts were proposed to improve the packaging process. To select the best concept, AHP was used due to the variety aspects to be considered, such as performance, maintenance, time of development, cost of development and potential cause of failure, in the selection of new concepts. The result shows that the proposed new concept for the packaging process can reduce the time, costs, and labor, in addition to the various aspects considered in the selection of a new concept. This paper presents the importance of considering the concurrent engineering tools in the manufacturing industry.

Application of Quality Function Deployment to Design a Liquefied Petroleum Gas Trolley

In Malaysia, the liquefied petroleum gas (LPG) is widely used for domestic purposes. The delivery men who are in charge of delivering the LPG cylinders to the customers are exposed to the ergonomic risk factors associated with excessive force due to the heavy steel cylinders. There are devices used to assist the delivery task, however, the devices are not efficient to be used in non-elevated apartments. Due to this reason, this study aims to design an LPG cylinder trolley. Quality Function Deployment was integrated to design the LPG cylinder trolley, so that it can fulfill the delivery mans requirements, thus, an effective device to assist the delivery task is produced. Based on the findings, it can be concluded that the integration of QFD is an effective solution in designing an effective LPG cylinder trolley.

Investigation of Cutting Parameter and Machine Tool Vibration Effects Using Regression Analysis to Enhance Part Dimensional Accuracy

Dimensional accuracy plays important criteria in producing high quality machined parts. This is a big challenge to manufacturers of precision components to produce good quality parts with minimum manufacturing error. The focus of this paper is to study the influence of the machine tool rigidity and cutting parameters on dimensional accuracy in turning operation. A method was prepared for identifying the factors effecting dimensional accuracy in a turning process. Experimental setup involved computerized numerical control (CNC) lathe machine, with VBMT 160404 carbide insert and mild steel, as cutting tool and workpiece respectively. The statistical analysis was used for analyzing and determining the accuracy of experimental data through Minitab statistical software. The regressions model was developed. The developed regression model could be used to predict the dimensional precision of the parts based on machine tool vibration and machining parameters during turning process. This is the aspect to be seriously considered and be applied in attaining sustainable machine tool development during design and development stage and its usage. This finding provides useful guidelines for manufacturers to produce high quality machined parts at minimum manufacturing cost. It was found that the cutting speed, feed rate, final part length, vibration x and vibration z have significant effects on dimensional accuracy of the machined parts.

Psychophysical Experience and Heart Rate Analysis in Manual Lifting Task of Malaysian Population

Back pain is one of the prevalent injuries that occurs among Malaysian industrial workers. This is due to manual lifting task. Minimal studies have been conducted to determine the effects of manual lifting on psychophysical experience and heart rate of Malaysian population. The objective of this study is to analyze the psychophysical experience and heart rate of Malaysian in manual lifting task. The lifting task was experimented at various lifting heights (55 cm, 75 cm and 140 cm); loads with masses of 5 kg, 10 kg and 13 kg; and twist angles (0°, 45° and 90°). Six male and six female Malaysian students participated as subjects in the experiment. The Likert Scale was used to evaluate the psychophysical experience; meanwhile the heart rate monitor (Polar FT2, Finland) was applied to measure the heart rate. This study discovered that the psychophysical experience recorded the highest rating when performing lifting test at maximum load mass (13 kg), lifting height of 130 cm, and twist angle of 90°. Furthermore, the subjects experienced the highest heart rate after performing lifting test at maximum lifting height (130 cm) and load mass of 13 kg. This study concluded that the load mass, lifting height, and twist angle are proportional to the level of psychophysical experience. Additionally, when the load mass and lifting height were increased, the heart rate was also increased.