Evaluation on the tribological properties of double fractionated palm olein at different loads using pin-on-disc machine

The use of vegetable oil-based lubricant as a lubricant in various applications has increased and it is eyed by the industry due to its superior tribological properties, besides possessing the potential to replace petroleum-based lubricants. Palm olein is one of alternative lubricants that could be suitable and attractive as a lubricant to be studied due to its advantages and large production in the country. Thus, in this study, the behavior of palm olein characteristics was investigated by using pin-on-disc experiment, in which a hemispherical pin was loaded against the rotating grooved disc. The experiments via sliding were performed with pin-on-disc tester using pure aluminum as the material for hemispherical pin and SKD11 for disc. The test was implemented by dropping continuous flow of palm olein as lubricating oil on sliding surface at different loads applied, which were 10N, 50N, and 100N. The wear rate of the pin and the friction coefficient were also investigated. Moreover, the surface roughness before and after the experiment was analyzed as well. All the results obtained were compared to hydraulic oil and engine oil- SAE 40. From the analysis, the friction coefficient acquired from lubricated with palm olein was the lowest for both conditions. The wear rate obtained for the three lubricants increased from 10N to 100N load for palm oil, but decreased for hydraulic and engine oil-SAE 40. Meanwhile, the wear rate obtained for lubrication with hydraulic oil showed the lowest value compared to Engine oil-SAE 40 and double fractionated palm olei

Nanofluids, micro-lubrications and machining process optimisations − a review

The lubrication is a prime requirement of metal cutting industries to assure high quality performance. The conventional technique of coolant flow is less economical and eco-friendly. Recently, nano fluids found better cutting fluid in machining due to potential thermal and heat transfer properties. The role of micro-lubrication techniques and process optimization are equally important for improving process performance. The literature review presents the findings of different researchers in the field of nano fluids and micro-lubrication techniques. The experimental studies were focused on better process performance using micro-lubrication techniques, especially nanofluid MQL with optimized process parameters. The thermal conductivity of water based TiO2 nano fluid shows improvement by 22% in base fluids. The case study discussed which is focused on preparation and characterization of nano fluid, experimental setup and optimization of process parameters by Jaya algorithm. Finally, application of nano fluid, and challenges during nano fluid preparation is identified. The scope of research work is recommended for further study to obtain an economical, eco-friendly manufacturing process

SYNTHESIZING AND EVALUATION OF NEW COPPER-TUNGSTEN BASED EDM ELECTRODE FOR MACHINING HARDENED MATERIALS

By using Electrical discharge machining (EDM) it is possible to machine any materials that are difficult to machine by using conventional machining technique as long as it is electrically conductive. The performance of EDM is highly depending on the type of electrode being used, the power supply system, and the dielectric system. Copper-Tungsten electrode is the higher in wear resistance but it is difficult to manufacture due to variation of melting point and zero miscibility of copper (Cu) with Tungsten (W). Thus, new modified Copper-Tungsten electrodes were synthesized taking into consideration the variety of melting point and zero miscibility. Ball milling was used to synthesize the new electrode material and Taguchi method is used to design and analyse the experiment. Material removal rate (MRR) and electrode wear (EW) are the main parameters used for testing the performance between the existing Copper-Tungsten (Cu-W) electrode and the new developed electrode. Machining variables selection show that the gap voltage, peak current and pulse on time are the most important ones that contribute on material removal rate, electrode wear and surface roughness (Ra). Results of milling process indicate a clear change in the thickness of crystalline and d-spacing of the milled powder after five hours milling time. The performance of Cu-WC-Si electrode shows an improvement in MRR by an average of 22.5% when milled for 5 to10 hours. The EW of 10 to 20 hours milled Cu-WC-Si improved by an average of 62 % from that achieved by using Cu-W electrode. The performance of Cu-WC-Ti and Cu-WC-Ti-Si electrode show clear improvement in the electrode wear but at the expense of MRR. It is reduced by an average of 86% for Cu-WC-Ti and by 70.1% compared with that achieved by using Cu-W electrode. Si additive improve TWR of Cu-WC-Si electrode where it shows the lowest TWR (10%) compared with that achieved by Cu-WC-Ti (466%) and Cu-WC-Ti-Si (37%). The contribution of milling variables on the performance of the new developed electrodes shows that milling time is the most important variable

Fatigue Performance Evaluation of Gears used in Off-Highway Drivelines

Gears are the core of power transmission systems. The study of their fatigue performances is essential for the companies dealing with the design and manufacturing of transmissions. The work here presented faces the study of pitting and bending fatigue performances of gears mounted on Off-Highway drivelines. This work was carried out under the formulation of "High Apprenticeship PhD" and was financed by Carraro Drive Tech. The research activity was executed partly inside the Company and partly at the University. The work started from the study of standards on gear design, especially ISO 6336 for cylindrical gears. Then the commercial software packages oriented to gear design were studied. Using this background, the gear durability tests for axles' validation performed by Carraro Drive Tech in the last years were modeled. The bending and pitting allowable fatigue curves were then estimated using the calculated stress and the life exhibited during the analyzed tests. Results obtained showed that the statistical scatter on bending and pitting fatigue performances may be remarkable. The allowable limits obtained by statistical inference at high survival probabilities resulted lower than the corresponding values declared by the standards, at least for the analyzed applications. The work was then focused on the study of tooth-root bending fatigue of gears, planning a test campaign involving different case-hardening steels coming from the areas where the Company is localizing the production of its components. Both static and fatigue comparative tests were performed on plain case-hardened specimens realized in order to resemble as more as possible the teeth surface state of a specific gear used by the Company. The steels exhibited high mechanical strength and similar characteristics, in line with the best case-hardened steels presented in the literature, independently from the origin area. Additional attention was paid to 20MnCr5 steel, carrying out bending fatigue tests also on notched specimens and gears. Experimental data were then used as starting point in the application of the different gear design methods reported in ISO 6336, with the purpose of investigating their reliability. The correlation between the fatigue curves obtained on specimens and gears is of particular interest for companies dealing with the design of power transmission systems, since the fatigue tests on specimen are potentially faster, more inexpensive and easier than using gears. Furthermore, the use of specimens allows to compare the manufacturing process of different suppliers directly in terms of experimental endurance limits. This approach is more detailed than using the standardized curves of ISO 6336, where the fatigue behavior is given only on the base of the steel quality, that is defined by a number of quality controls that do not consider explicitly the fatigue limit. The experimental behavior of the gear was resembled only partially by the methods, especially for notch sensitivity. For this reason, the experimental data collected in this work were used to develop and improve the design methods of the standard, leading to more satisfactory results. The endurance limit of specimens and gears resulted located in the range of 50,000 $\div$ 300,000 cycles, that are values much shorter than the 3,000,000 of cycles reported in ISO 6336 standard. The gear testing procedure presented in the work resulted more complete and effective than current testing procedures of the Company, being able to characterize the whole fatigue curve in much shorter time. The study of the bending fatigue performances was accompanied with the SEM observations of specimens' fracture surfaces, the analysis of residual stress induced by case-hardening treatment, the influence of grinding on case-hardened surfaces and the presence of a mean stress. Results were discussed and compared to recommendations of ISO 6336, finding in some cases only a partial agreemen

The tool:workpiece interaction when machining welded hardfacing using PCBN tools

The work presented in this thesis is concerned with turning chromium carbide based hardfacings using PCBN tools. The chip formation and tool wear process was studied by quick-stop and machining tests. Cutting temperature was investigated by means of a remote thermocouple and the chip-tool interface temperature was simulated by an ANSYS Finite Element Analysis model. Cutting performance of PBN tools from different suppliers was compared in field cutting tests. Hardness, microstructure and the adhesion between the workpiece and cutting tool material were assessed.ln the turning process, saw-tooth chips were formed, with a short chip:tool contact length. Quick-stop tests revealed that the machining process involved fracture of large carbides ahead of the cutting edge in the primary zone. Temperature measurements showed that the cutting temperature for the hard facing material was lower than that with titanium alloy but much higher than that with machining mild steel. The cutting temperature predicted at the tool chip interface was in the range of 600-700°C when cutting hard facing.The tool wear process was found to involve three main progressive stages - from small scale edge chipping to large scale flaking and fracture. Four types of wear were identified: flank wear, microchipping, flaking of the rake face and delamination of the flank face. Abrasion appears to be the principal flank wear mechanism and it showed a minimum value for different speeds but increased with feedrate. The main mechanism for microchipping involved failure through the CBN particle boundaries. Flaking of the rake face occurred in the later stages and transgranular fracture was the main mechanism.In field tests, PCBN material from various sources achieved different cutting performance, which reflected the structural differences in the PBN materials. A dense structure with strong particle binding is essential for satisfactory performance of PCBN in this application

Advances in Microfluidic Technologies for Energy and Environmental Applications

Microfluidics have aroused a new surge of interest in recent years in environmental and energy areas, and inspired novel applications to tackle the worldwide challenges for sustainable development. This book aims to present readers with a valuable compendium of significant advances in applying the multidisciplinary microfluidic technologies to address energy and environmental problems in a plethora of areas such as environmental monitoring and detection, new nanofluid application in traditional mechanical manufacturing processes, development of novel biosensors, and thermal management. This book will provide a new perspective to the understanding of the ever-growing importance of microfluidics

Advances in Microfluidic Technologies for Energy and Environmental Applications

Microfluidics have aroused a new surge of interest in recent years in environmental and energy areas, and inspired novel applications to tackle the worldwide challenges for sustainable development. This book aims to present readers with a valuable compendium of significant advances in applying the multidisciplinary microfluidic technologies to address energy and environmental problems in a plethora of areas such as environmental monitoring and detection, new nanofluid application in traditional mechanical manufacturing processes, development of novel biosensors, and thermal management. This book will provide a new perspective to the understanding of the ever-growing importance of microfluidics

Surface integrity in metal machining - Part I: Fundamentals of surface characteristics and formation mechanisms

The surface integrity of machined metal components is critical to their in-service functionality, longevity and overall performance. Surface defects induced by machining operations vary from the nano to macro scale, which cause microstructural, mechanical and chemical effects. Hence, they require advanced evaluation and post processing techniques. While surface integrity varies significantly across the range of machining processes, this paper explores the state-of-the-art of surface integrity research with an emphasis on their governing mechanisms and emerging evaluation approaches. In this review, removal mechanisms are grouped by their primary energy transfer mechanisms; mechanical, thermal and chemical based. Accordingly, the resultant multi-scale phenomena associated with metal machining are analyzed. The contribution of these material removal mechanisms to the workpiece surfaces/subsurface characteristics is reviewed. Post-processing options for the mitigation of induced surface defects are also discussed

SYNTHESIZING AND EVALUATION OF NEW COPPER-TUNGSTEN BASED EDM ELECTRODE FOR MACHINING HARDENED MATERIALS

By using Electrical discharge machining (EDM) it is possible to machine any materials that are difficult to machine by using conventional machining technique as long as it is electrically conductive. The performance of EDM is highly depending on the type of electrode being used, the power supply system, and the dielectric system. Copper-Tungsten electrode is the higher in wear resistance but it is difficult to manufacture due to variation of melting point and zero miscibility of copper (Cu) with Tungsten (W). Thus, new modified Copper-Tungsten electrodes were synthesized taking into consideration the variety of melting point and zero miscibility. Ball milling was used to synthesize the new electrode material and Taguchi method is used to design and analyse the experiment. Material removal rate (MRR) and electrode wear (EW) are the main parameters used for testing the performance between the existing Copper-Tungsten (Cu-W) electrode and the new developed electrode. Machining variables selection show that the gap voltage, peak current and pulse on time are the most important ones that contribute on material removal rate, electrode wear and surface roughness (Ra). Results of milling process indicate a clear change in the thickness of crystalline and d-spacing of the milled powder after five hours milling time. The performance of Cu-WC-Si electrode shows an improvement in MRR by an average of 22.5% when milled for 5 to10 hours. The EW of 10 to 20 hours milled Cu-WC-Si improved by an average of 62 % from that achieved by using Cu-W electrode. The performance of Cu-WC-Ti and Cu-WC-Ti-Si electrode show clear improvement in the electrode wear but at the expense of MRR. It is reduced by an average of 86% for Cu-WC-Ti and by 70.1% compared with that achieved by using Cu-W electrode. Si additive improve TWR of Cu-WC-Si electrode where it shows the lowest TWR (10%) compared with that achieved by Cu-WC-Ti (466%) and Cu-WC-Ti-Si (37%). The contribution of milling variables on the performance of the new developed electrodes shows that milling time is the most important variable