Abstract. Dry machining is an eco-friendly machining process and its importance in the manufacturing industries should be taken seriously. Machining without the use of any cutting fluid is becoming increasingly more popular due to concerns regarding the safety of the environment and reducing cost. Dry and wet turning of T6061 aluminium alloy was performed on a lathe by using Silicon Nitride (Si 3 N 4 ) inserts as the cutting tool. Tool wear behaviour of Si 3 N 4 cutting tool were studied with the aim of finding the optimum cutting conditions for both dry and wet machining. Machining was performed at four different cutting speeds; 292, 388, 518 and 689 m/min using two different cutting parameters (feed rate, f = 0.2 mm/rev, depth of cut, d = 0.1 mm and f = 0.4 mm/rev, d = 0.2 mm). Material removal rate (MRR) was also obtained and the temperature at the tool-chip interface were measured using an infrared (IR) thermometer as to see the effect of temperature rise during machining. Dry machining with smaller cutting parameters resulted in lower wear rates by 37 to 48% for all four cutting speeds. Nevertheless, reduction of wear rate by 38 to 57% was found from wet machining. The optimum cutting speed for both dry and wet machining of T6061 aluminium alloy using Si 3 N 4 cutting tool was found to be 518 m/min for both cutting parameters. However, the optimum cutting parameters are apparently with the feed rate of 0.4 mm/rev and depth of cut of 0.2 mm. At the optimum cutting speed, the tool tip temperature for dry machining was higher than wet machining by 40 and 51% for f = 0.2 mm/rev and f = 0.4 mm/rev respectively. Dry machining of T6061 Aluminium alloy can be more suitable particularly at higher cutting speed with interrupted cutting operations.
Dry machining is a clean machining process and it will be considered as a necessity for manufacturing industries in future. Dry machining is environmental friendly and safe to be performed. Regardless of decreasing tool life due to lack of lubricants, choosing dry machining over wet machining may be a wiser choice since the cost of purchasing and disposing the cutting fluids can contribute to a higher cost. Tool wear intensities of TiN and TiCN coated tools using both dry and traditional wet machining was studied with the aim in finding the optimum cutting speed from three different cutting speeds (318, 394 and 490 m/min) with a feed rate of 0.6 mm/rev and depth of cut of 0.4 mm. Tool tip temperature was also analyzed to see the effect of temperature rise at the tool-chip interface. TiCN coated tool performed better than TiN coated tool since the wear rate for TiCN coated tool is smaller by 40-48 % when compared to TiN coated tool for dry machining for all three cutting speeds. The optimum cutting speed for dry machining of T6061 Aluminium alloy using TiN and TiCN coated tools is 394 m/min. Tool tip temperature for dry machining is also slightly higher than wet machining by 19 and 32 % for TiN and TiCN coated tools respectively at the optimum cutting speed. Dry machining of T6061 Aluminium alloy can be a more suitable eco-friendly machining process particularly at high cutting speed for interrupted cutting operations.
Abstract. Pewter alloys made from tin, copper and antimony powders were sintered using microwave and conventional vacuum sintering. Three different compositions of the pewter alloy were used; 91Sn6Cu3Sb, 94Sn4Cu2Sb and 97Sn2Cu1Sb. The effect of densification and microstructure of the pewter alloys from varying sintering time and sintering mode were examined and compared. Samples were compacted at 40kN and sintered at 220°C. Samples in the conventional furnace were sintered 60 minutes and 120 minutes, while samples in the microwave furnace were sintered for 15 and 30 minutes. Samples sintered at longer sintering times resulted in higher density for both sintering methods. Microwave sintering produced samples with slightly smaller grain size than the conventionally sintered samples resulting in a better densification. There were no new phases formed from the sintering of pewter alloy.
Two compositions of pewter alloy were sintered using both microwave and conventional vacuum sintering, and the effects of sintering time, temperature and weight percentage of copper and antimony on the mechanical and structural properties were examined for both sintering methods. Microwave sintered samples had finer microstructures, higher densities, higher hardness and tensile strength compared to the conventionally sintered samples and traditionally cast pewter. By increasing the copper and antimony contents, higher hardness was achieved. Better mechanical properties were found after microwave sintering after shorter sintering times compared with conventional sintering, but longer sintering times resulted in better diffusion for both sintering methods. The microwave sintered samples in general were capable of achieving similar amounts of diffusion to those conventionally sintered for the same time. But the total sintering process is much faster in microwave heating than in conventional heating due to the rapid heating effect.
Microwave processing ceramics is emerging fast as a new field of ceramic processing and material synthesis. The past year has witnessed significant progress in the aspects of commercialization and application of the technology to new areas. Further research states that Titanium Carbide (TiC) is the best cutting tool due to its high melting point and by that reason this project aims to show the difference between conventional sintering, microwave sintering and Hot Isostatic Pressing (HIP). Two different compositions consisting of 97TiC3Ni and 93TiC7Ni were sintered using conventional furnace, microwave furnace and HIP. Density, hardness and microstructure analysis were carried out on these TiC inserts. 97TiC3Ni produced higher density and hardness values compared to 93TiC7Ni for all three different methods. Microwave sintering produced the highest density and hardness values compared to conventional sintering and HIP. Microwave produced samples with improved density and hardness in a shorter processing time which is 93% faster than conventional sintering and 50% faster than HIP.
In manufacturing industries, workpiece clamping is one of the basic requirement prior to machining process as the clamping system is responsible to maintain the workpiece rigidity and withstand the cutting force generated from the machining process. Besides, Clamping device is one of the reasons which influence the surface integrity of a part. Clamping workpieces for machining can be challenging especially for intricate non-symmetric geometry and vulnerable parts. In this study, a new system has been designed and developed where the workpiece is submerged in a fluid and the fluid is completely frozen to form ice that holds the workpiece rigidly. This ice clamping system can hold any parts of the workpiece regardless of their geometry and fragility. To freeze the desired workpiece, the energy required for 942 cm3 of clamping fluid was 98.43 kJ. Total freezing time was 90 minutes. Further development on the system is required in terms of improving freezing time and de-freezing of the work-piece.
Abstract. Air Gap membrane distillation (AGMD), a special type of energy efficient membrane distillation process, is a technology for producing freshwater from waste water. Having some benefits over other traditional processes, this method has been able to draw attention of researchers working in the field of freshwater production technologies. In this study, a basic AGMD system with flat coolant plate has been modified using a specially designed channelled coolant plate of portable size to observe its effect over the production rate and performance of the system. Attempt has been made to increase the amount of distillate flux by using the "fin effect" of the channelled coolant plate. A finned plate have been used instead of a flat coolant plate and experiments were conducted to compare the effect. Coolant temperature and feed temperature of the system have been varied from 10°C to 25°C and 40°C to 70°C respectively. Comparing the data, around 50% to 58% distillate enhancement has been observed for channelled coolant plate. Also, it was seen that the enhancement was higher for higher feed temperatures and coolant temperatures. With these findings, a better performing AGMD module has been introduced to mitigate the scarcity of freshwater.
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