摘要: Cutting fluid plays an important role in machining processes to achieve dimensional accuracy, reduce tool wear, and improve tool life. Use of flood cooling conventionally used in machining is not cost effective and consumption of huge amount of cutting fluids is not health and environmental friendly. Therefore, one of the alternatives is to use minimum quantity of lubrication (MQL) in machining process. MQL is eco-friendly and has economical advantage on manufacturing cost. Study of the effects of MQL on burrs and aspect ratio should be carried out because burrs and aspect ratio are important issues in microdrilled parts used as microfluidic channels in bio-medical applications. In case of micromachining, flood cooling is not recommended to avoid any possible damage of the microstructures. As a result alternative solutions are sought. This paper investigates and compares burrs and aspect ratio in dry microdrilling and microdrilling with the presence of MQL on aluminium alloy 1100. The relationship among tool diameter, feed rate, and spindle speed on the area affected by burrs and drilled hole aspect ratio are analysed. The values of aspect ratio for both conditions show that there is slight improvement on aspect ratio in MQL over dry drilling. MQL has significant influence on affected area by burrs. It is observed that low spindle speed, high feed rate, and bigger drill diameter should be used along with MQL to reduce burrs.
摘要: The study demonstrates laser welding of titanium alloy Ti6Al4V using middle range power Nd:YAG laser. Butt welding cross section views were analyzed to understand the influence of several scanning parameters to the welding beads shapes and material characteristic changes. Pulse laser was used to perform welding on titanium alloys Ti6Al4V. It was found out that fusion zone can appear in two layers which could give clues to internal temperature distribution during the scanning process.
摘要: Sustainable manufacturing has become popular among manufacturers and industrialists due to the increase in environmental issues, health impacts and stringent law enforcement. The use of vegetable oils as metalworking fluids is one way to implement manufacturing sustainability. Palm oils are commonly used as cooking oils. Further, palm oil is also the main oil sources in Southeast Asia besides petroleum. Therefore, the potential use of palm oil as functional lubricant for future replacement of petroleum-based oil is indeed important. In this study, the refined, bleached and deodorized (RBD) palm olein has been formulated into various properties of modified RBD palm oil (MRPO) by transesterification process at different molar ratio of RBD methyl ester (FAME) with trimethylolpropane (TMP). Next, the MRPOs are compared with synthetic ester on lubrication and tribology tests according to standard based on American Society for Testing and Materials (ASTM). The results observed that MRPO have outstanding performance in lubrication and tribological behavior. MRPO2 recorded the highest viscosity index and the lowest coefficient of friction which are 496 and 0.06, respectively. MRPO2 showed to be an alternative biodegradable cutting fluid in promoting sustainable manufacturing activities by reducing the bad impact on environment and health.
摘要: Copper and aluminum are widely used in electronic industries for their excellence in electric and thermal conductivity. Joining these different material in scale of micro is hardly difficult for their obvious different in thermal properties. Melting these materials during welding process will create intermetallic compound which possesses new material properties. The melted zone became extremely brittle thus increase the possibility of failure due to cracks and concentrated loads. To overcome this problem, fundamental study is needed to characterize the material behavior against heat induction under various processing parameters. This study is an attempt to characterize the performance of Nd-YAG laser in micro joining of Al 1100 and Cu 101.
摘要: This paper highlights the influence of titanium hydride particle on the rheological behaviour of nickel-titanium feedstock used in the metal injection process. The ratio of 50at% nickel and 50at% titanium hydride with 2 different powder loadings (65.5vol% and 67.5vol%) were investigated. A Rosand RH2000 capillary rheometer was used to determine the flow behaviour of feedstocks. The feedstocks were characterized at different temperature ranging from 150°C and 170°C and shear rate ranging from 50/s and 4442.63/s. The results showed on pseudo-elastic behaviour flow of NiTi feedstock which is suitable for injection moulding process.
摘要: The unique properties of Inconel 718 make it a challenging material to machine especially in ball end milling operations due to high cutting force and temperature concentrated at the cutting zone. These essentially lead to accelerated tool wear and failure resulting in high costs and loss of production. In this research, finite element numerical simulation was performed using AdvantEdge to simulate ball end milling using an 8mm TiAlN coated carbide tool. Response Surface Methodology (RSM) is applied by using a 3 level 3 factorial Box-Behnken design of experiment with different combinations of cutting speed, feed rate, and depth of cut parameters with a selected range of parameters to simulate finishing operations. Temperature contour from finite element analysis showed that the highest temperature occurs near the depth of cut line just before the chip separates from the workpiece. Using multiple linear regression, a quadratic polynomial model is developed for maximum cutting force and a linear polynomial model peak tool temperature response respectively. Analysis of Variance (ANOVA) showed that feed rate had the most significance for cutting force followed by depth of cut. Also, cutting speed was found to have little influence. For peak tool temperature, cutting speed was the most significant cutting parameter followed by feed rate and depth of cut.
摘要: This paper details experimental results when turning Ti-6Al-4V using water-miscible vegetable oil-based cutting fluid. The effects of coolant concentration and working conditions on tool flank wear and tool life were evaluated. L27 fractional factorial Taguchi array was employed. Tool wear (VBB) ranged between 28.8 and 110 µm. The study concluded that a combination of VOs based cutting fluid concentration (10%), low cutting speed (58 m/min), feed rate (0.1mm/rev) and depth of cut (0.75mm) is necessary to minimise VBB. Additionally, it is noted that tool wear was significantly affected by cutting speeds. ANOVA results showed that the cutting fluid concentration is statistically insignificant on tool flank wear. A notable increase in tool life (TL) was recorded when a lower cutting speed was used.
摘要: The aim of this paper is to investigate the effect of chemical treatment on the flexural properties of the composite. Oil Palm Empty Fruit Bunch Fibers (OPEFB) reinforced Vinylester composite were prepared in this study. Soxhlet extraction together with sodium hypochlorite bleaching methods was used for chemical treatment. The diameter of fibers was reduced from a range of 250-350 μm to 10-15 μm by treatment. Shape and texture of the fibers transformed from solid brown colored strings into a white gel. Thermogravimetric Analysis (TGA) test was carried to investigate the effect of treatment on the thermal properties of natural fibers. Vinylester composites were fabricated using untreated and bleached OPEFB fibers. The bending test results showed the bleached fibers displayed greater flexural properties compared to untreated fibers, where the time of bleaching was an important factor in the treatment process.
摘要: Hyperelastic materials are unique materials that have high tendency to stretch and its highly non-linear behaviour is commonly investigated using hyperelastic constitutive models. The aim of this paper is to investigate the sensitivity of Mooney-Rivlin material constants; C1 and C2 values in order to observe the behavior and pattern of the stress-stretch graph for silicone-kenaf composite. There were no previous studies done in regards to assess the mechanical behaviour of the stress-stretch curve for silicone-kenaf biocomposite by varying the Mooney-Rivlin material constants. The material constant, C1 and C2 are varied into few cases and the patterns of stress-stretch curves are studied. It was found that variations of C1 and C2 material constants could contribute differently on the mechanical properties of silicone-kenaf composite. Thus, the results and findings of this study could be further enhanced by future study to gain deeper understanding on the hyperelastic materials behaviour and Mooney-Rivlin hyperelastic constitutive model.