Papers by Author: Jaharah Abd Ghani

Abstract: This study was carried out to investigate how the high-speed milling of Inconel 718 using ball nose end mill could enhance the productivity and quality of the finish parts. The experimental work was carried out through Response Surface Methodology via Box-Behnken design. The effect of prominent milling parameters, namely cutting speed, feed rate, depth of cut (DOC), and width of cut (WOC) were studied to evaluate their effects on tool life, surface roughness and cutting force. In this study, the cutting speed, feed rate, DOC, and WOC were in the range of 100 - 140 m/min, 0.1 - 0.2 mm/tooth, 0.5 - 1.0 mm and 0.2 - 1.8 mm, respectively. In order to reduce the effect of heat generated during the high speed milling operation, minimum quantity lubrication of 50 ml/hr was used. The effect of input factors on the responds was identified by mean of ANOVA. The response of tool life, surface roughness and cutting force together with calculated material removal rate were then simultaneously optimized and further described by perturbation graph. Interaction between WOC with other factors was found to be the most dominating factor of all responds. The optimum cutting parameter which obtained the longest tool life of 60 mins, minimum surface roughness of 0.262 μm and resultant force of 221 N was at cutting speed of 100 m/min, feed rate of 0.15 mm/tooth, DOC 0.5 m and WOC 0.66 mm.

Abstract: Oil palm workers perform daily activities that exposed themselves to various ergonomics risk factors. To harvest oil palm fruits from tall trees, specific technique is required. To quantify the ergonomics risks factors, postural analysis was conducted using Quick Exposure Check (QEC) system. It was found oil palm workers were exposed to many postural problems while performing harvesting and collecting fresh fruit bunch (FFB) activities. However, to quantify the actual load, many limitations of the QEC have been revealed such the missing of legs assessment, the crude analysis for arm and shoulder, no pushing and pulling assessment and the biased may be existed due to the workers perception on the ergonomics factors. Thus, it can be concluded that QEC system was not suitable for conducting postural analysis during harvesting in oil palm plantation especially in tall trees due to the above limitations.

Abstract: Inconel 718 is a material exhibiting characteristic that are able to maintain strength and integrity at elevated temperatures, but it is well known as a material with poor machinability. This paper presents a study of the performance in high speed machining of TiAlN/AlCrN nanomultilayer PVD coated Inconel 718 with minimum lubrication. Investigations have been made into the effects of cutting speed, feed rate and depth of cut (DOC) on the tool life. A toolmakers microscope and a scanning electron microscope (SEM) were used to examine the tool wear and chemical attrition, respectively, on the cutting tool during machining. In the machining of aged Inconel 718, the cutting tool experienced attrition, abrasion and notch wear throughout the experiment. Notch wear was found to be the dominant failure mode during milling; this wear appeared severe when localized flank wear reached the critical zone. The influence of radial depth despite the cutting speed, well known as having the most significant effect on tool life, is also discussed.

Abstract: The purpose of this study is to investigate the effect of turning parameters on the surface integrity of Inconel 718. The turning parameters studied were cutting speed of 90, 120, 150 m/min, feed rate of 0.15, 0.25, 0.25mm/rev and depth of cut of 0.3, 0.4, 0.5 mm under minimum quantity lubricant (MQL) using coated carbide tool. surface response methodology (RSM) design of experiment using Box-Behnken approach has been employed consisting of various combination of turning parameters Surface roughness, surface topography, microstructure and the micro hardness of the machined surface were studied after the machining process. Feed rate was found to be the most significant parameter affecting the surface roughness. The optimum parameter was obtained with Ra equal to 0.243 µm at cutting speed of 150 m/min, feed rate of 0.25 mm/rev and depth of cut of 0.3mm. A mathematical model for surface roughness was developed using Response Surface Methodology. The effect of turning parameters and factor interactions on surface roughness is presented in 3D graphical form, which helps in selecting the optimum process parameters to achieve the desired surface quality.