REBA evaluation on garage worker: a case study

Garage workers always involve with awkward posture as their task being carried out manually in most small scale vehicle maintenance industries. Therefore it is crucial to identify the problems causing awkward posture because it can result to the development of Musculoskeletal Disorder Symptoms (MSDs), which may gone unnoticed and might cause higher compensation cost later. Postural analysis tool using Rapid Entire Body Assessment (REBA) were applied and conducted on nine workers engaging in maintaining three types of vehicle namely car, Multi-purpose vehicle and bus. The evaluation of working postures in different activities is carried out using worksheet of scoring system. Result shows that most of the tasks involved awkward posture and most at high risk level. There is lack of ergonomic awareness and knowledge which contribute more towards high risk of MSDs problem.Keywords: garage worker; assessment tools; musculoskeletal disorder; REBA; ergonomi

Prevalence and factors contributing to musculoskeletal disorder among garage worker in Malaysia

Maintenance involves task that is performed occasionally with exceptional conditions. This paper focused on Musculoskeletal Disorder (MSDs) among garage worker. The objective is to analyze the prevalence of Musculoskeletal symptoms among garage workers as well as the risk factors that contributed to the symptoms. Method used in this study is standard Nordic questionnaire (SNQ) Malay version for 150 garage workers who performed maintenance work on vehicle. The result of biomechanical evaluation indicated that three risk namely psychological, ergonomic and demographic play important role in contributing to MSDs. Shoulder, neck, wrist/hand, feet, low back and waist were among the body parts that recorded high percentage of developing bellow, pain and discomfort. Data gaps include lack of information regarding the prevalence of MSDs in garage workerKeywords: vehicle maintenance; musculoskeletal disorder; ache, pain, discomfort; prevalenc

Modeling and Simulation of Temperature Generated on Workpiece and Chip Formation in Orthogonal Machining

Experimental investigation in machining operation for the temperature generated on workpiece, chip formation and cutting tool are difficult, time consuming and costly to carry out. Machining simulation using FEM software is an alternative. This paper presents a simulation study of temperature generated on workpiece and chip formation for various combinations of tool geometries (rake angle and clearance angle). Ductile cast iron FCD500 grade was used as material workpiece, and uncoated carbide tools with code number DNMA432 were used as cutting tool. Twelve designs of carbide cutting tools with various combination of rake angle (15, 20, and 30 deg) and clearance angle (5, 7, 8 and 9 deg) were designed. The nose radius of the cutting tool was kept constant at 0.4 mm. Machining parameters of cutting speed, feed rate and dept of cut (DOC) were kept constant at 200 m/min, 0.35 mm/rev and 3 mm respectively. Using a commercial software package Deform-3D, twelve orthogonal machining simulations were carried out to analyze the effect of tool geometries on temperature generated and chip formation. The results show that by increasing the rake angle, the machining performance is improved due to the low temperature generated on the machined surface, as well as low cutting force, stress, and strain. On the other hand, increasing/decreasing the clearance angle, does not significantly affected the cutting force, stress, and strain, consequently it does not affected the temperature generated. For the chip formation, the highest temperature occurred in the sliding region due to the work piece material adheres to the cutting tool and shear occurs within the chip, the frictional force is very high; consequently heat is generated from this sticking regio

Prediction of Turning Performance in Various Machining Parameter Using FEM

In recent years, the applications of finite element method (FEM) in metal cutting operations have proved to be effective in studying the cutting process and manufacturing process. The simulation result is useful for both researchers and tool makers to optimize the cutting process by designing new tools. Simulation and modelling were performed in two-dimensional and threedimensional for designing the new component prior to fabricating. These are very useful for reducing time and cost consumption in designing automotive parts. The FEM simulation just only requires computational tool and FEM simulation package. The present work aims to predict of performance three-dimensional orthogonal of cutting operations using FEM software (Deform-3D). Some important information such as cutting force, stress, strain and generated temperature during machining process were studied and analysed. Orthogonal cutting simulations were conducted to study the effect of cutting speed, feed rate and depth of cut on the cutting force, the effective-stress, strain and generated temperature in turning process. FCD 500 (ductile cast iron) was used as the work material and cutting tool was DNMA 432 (uncoated carbide tool, SCEA = 0; BR = -5; SR = -5 and radius angle 55o). The cutting parameters varied were cutting speed (100 m/min, 150 m/min and 200 m/min), feed rate (0.1, 0.25 and 0.4 mm/rev), and depth of cut (DOC) (0.3, 0.6 and 0.9 mm). The performance was showed by the simulation results that show by increasing the cutting speed, it causes decreasing in cutting force, effective stress and strain, but the generated temperature during the chip formation process increases. High value of feed rate resulted in bigger cutting force, stress, strain and generated temperature. In addition, bigger cutting force and high generated temperature occurred at high depth of cut

Effect of Rake Angle on Stress, Strain and Temperature on the Edge of Carbide Cutting Tool in Orthogonal Cutting Using FEM Simulation

Demand for higher productivity and good quality for machining parts has encourage many researchers to study the effects of machining parameters using FEM simulation using either two or three dimensions version. These are due to advantages such as software package and computational times are required. Experimental work is very costly, time consuming and labor intensive. The present work aims to simulate a three-dimensional orthogonal cutting operations using FEM software (deform-3D) to study the effects of rake angle on the cutting force, effective stress, strain and temperature on the edge of carbide cutting tool. There were seven runs of simulations. All simulations were performed for various rake angles of -15 deg, -10 deg, -5 deg, 0 deg, +5 deg, +10 deg, and +15 deg. The cutting speed, feed rate and depth of cut (DOC) were kept constant at 100 m/min, 0.35 mm/rev and 0.3 mm respectively. The work piece used was ductile cast iron FCD500 grade and the cutting tool was DNMA432 series (tungsten, uncoated carbide tool, SCEA = 0; and radius angle 55 deg). The analysis of results show that, the increase in the rake angle from negative to positive angle, causing the decrease in cutting force, effective stress and total Von Misses strain. The minimum of the cutting force, effective stress and total Von Misses strain were obtained at rake angle of +15 deg. Increasing the rake caused higher temperature generated on the edge of carbide cutting tool and resulted in bigger contact area between the clearance face and the workpiece, consequently caused more friction and wear. The biggest deformation was occurred in the primary deformation zone, followed by the secondary deformation zone. The highest stress was also occurred in the primary deformation zone. But the highest temperature on the chip usually occurs in secondary deformation zone, especially in the sliding region, because the heat that was generated in the sticking region increased as the workpiece was adhered by the tool and later it was sheared in high frictional force.

Machining Simulation of AISI 1045 and Carbide Tool Using FEM

In recent years, the applications of finite element method (FEM) in metal cutting operations have proved to be effective in studying the cutting process and chip formation. In particular, the simulation results can be used for both researchers and machine tool makers to optimize the cutting process and designing new tools. Many researches were done on two-dimensional simulation of cutting process because the three-dimensional versions of FEM software required more computational time. The present work aims to simulate three-dimensional orthogonal cutting operations using FEM software of Deform-3D. Orthogonal cutting finite element model simulations were conducted to study the effect of cutting speed on effective-stress, strain and temperature in turning process. AISI 1045 was used as work material and cutting tool was TNMA 332 (uncoated carbide tool, SCEA = 0; BR = -5; SR = -5 and radius angle 60o). The emphasis on the designed geometries are limited to the changes in the cutting speed between 100 m/min and 450 m/min. The machining parameters of feed rate and depth of cut were kept constant at 0.35 mm/rev and 0.3 mm respectively. The simulation results show that by increasing the cutting speed causes a decrease in cutting force and effective-strain. On the other hand, increasing in cutting speed will increase effective -strain and temperature of the chip formed

Diallel analysis for seed yield and related traits in an energy crop jatropha curcas

Six parents (P1, P2, P3, P4, P5 and P6) half diallel population of Jatropha curcas were evaluated to determine the combining ability, genetic components of variance and heterosis for yield contributing traits. Diallel analysis showed that both additive and dominance gene action was responsible for the genetic regulation of all the traits under study. The cross combination P1 × P3 showed the highest positive specific combining ability for seed yield per plant. Combining ability results were also in close agreement with the findings of estimate of genetic components of variance. The seeds per fruit (89%) and 100-seed weight (93%) showed maximum narrow sense heritability. Seed yield per plant showed high mid parent (254.13%) and better parent (202.36%) heterosis in the cross combinations of P2 × P5 and P1 × P3, respectively. The parents of P1, P2, P3 and P5 were found to be superior for seed yield components when used in cross. Considering seed production for each plant, the hybrids P1 × P2, P1 × P3, P2 × P5 and P4 × P6 could be selected for the development of hybrid varieties

Kesan suhu pensinteran terhadap sifat mekanik dan mikrostruktur alumina-zirkonia yang difabrikasi dengan kaedah pengacuan suntikan seramik

Kesan suhu pensinteran terhadap sifat mekanik dan mikrostruktur bahan komposit alumina-zirkonia telah dikaji. Jasad hijau alumina-zirkonia difabrikasi dengan menggunakan kaedah pengacuan suntikan seramik menggunakan sistem bahan pengikat pelbagai komponen. Jasad perang yang terhasil selepas proses penyahikatan disinter pada suhu 1400, 1450, 1500, 1550, 1600 dan 1650°C selama 2 jam. Selanjutnya nilai ketumpatan, kekerasan dan keliatan patah bagi jasad tersinter diukur. Mikrostruktur jasad tersinter ditentukan dengan menggunakan mikroskop imbasan elektron (SEM). Kajian menunjukkan nilai ketumpatan, kekerasan dan keliatan patah bagi jasad tersinter meningkat sejajar dengan peningkatan suhu pensinteran. Hasil uji kaji juga mendapati pada suhu pensinteran 1650°C sifat mekanik bahan mencapai keadaan maksimum. Penumpatan jasad tersinter 98% menghampiri ketumpatan teori dengan nilai kekerasan 16.9 GPa dan keliatan patah mencecah 3.95 MPa.m1/2. Keputusan tersebut dapat dikaitkan dengan mikrostruktur bahan yang padat didorong oleh tumbesaran ira yang lengkap

Effect of Rake Angle on Stress, Strain and Temperature on the Edge of Carbide Cutting Tool in Orthogonal Cutting Using FEM Simulation

Demand for higher productivity and good quality for machining parts has encourage many researchers to study the effects of machining parameters using FEM simulation using either two or three dimensions version. These are due to advantages such as software package and computational times are required. Experimental work is very costly, time consuming and labor intensive. The present work aims to simulate a three-dimensional orthogonal cutting operations using FEM software (deform-3D) to study the effects of rake angle on the cutting force, effective stress, strain and temperature on the edge of carbide cutting tool. There were seven runs of simulations. All simulations were performed for various rake angles of -15 deg, -10 deg, -5 deg, 0 deg, +5 deg, +10 deg, and +15 deg. The cutting speed, feed rate and depth of cut (DOC) were kept constant at 100 m/min, 0.35 mm/rev and 0.3 mm respectively. The work piece used was ductile cast iron FCD500 grade and the cutting tool was DNMA432 series (tungsten, uncoated carbide tool, SCEA = 0; and radius angle 55 deg). The analysis of results show that, the increase in the rake angle from negative to positive angle, causing the decrease in cutting force, effective stress and total Von Misses strain. The minimum of the cutting force, effective stress and total Von Misses strain were obtained at rake angle of +15 deg. Increasing the rake caused higher temperature generated on the edge of carbide cutting tool and resulted in bigger contact area between the clearance face and the workpiece, consequently caused more friction and wear. The biggest deformation was occurred in the primary deformation zone, followed by the secondary deformation zone. The highest stress was also occurred in the primary deformation zone. But the highest temperature on the chip usually occurs in secondary deformation zone, especially in the sliding region, because the heat that was generated in the sticking region increased as the workpiece was adhered by the tool and later it was sheared in high frictional force

Study on machinability effect of surface roughness in milling kenaf fiber reinforced plastic composite (unidirectional) using response surface methodology

The surface roughness factor (Ra) of a milled kenaf reinforced plastic are depending on the milling parameters (spindle speed, feed rate and depth of cut). Therefore, a study was carried out to investigate the relationship between the milling parameters and their effects on a kenaf reinforced plastic. The composite panels were fabricated using vacuum assisted resin transfer molding (VARTM) method. A full factorial design of experiments was used as an initial step to screen the significance of the parameters on the defects using Analysis of Variance (ANOVA). If the curvature of the collected data shows significant, Response Surface Methodology (RSM) is then applied for obtaining a quadratic modelling equation which has more reliable in expressing the optimization. Thus, the objective of this research is obtaining an optimum setting of milling parameters and modelling equations to minimize the surface roughness factor (Ra) of milled kenaf reinforced plastic. The spindle speed and feed rate contributed the most in affecting the surface roughness factor (Ra) of the kenaf composite