The purpose of the present investigation is to study the feasibility of decreasing the shell thickness for a statistically controlled rapid casting solution of lead alloy using three-dimensional printing technology. Starting from the identification of a component/benchmark, technological prototypes were produced with different shell thickness. Measurements on a coordinate measuring machine helped in calculating the dimensional tolerances of the castings produced. Some important mechanical properties were also compared to verify the suitability of the castings and further results are supported by microstructure analysis. The study suggested that the shell thickness having a value less than the recommended one is more suitable from a dimensional accuracy and an economic point of view. The provided data from the experimentation are extremely useful for the industrial application of the considered technology. The result indicates that at 1 mm shell thickness, the hardness of the casting improves from the recommended 12 mm. Further, production costs and production time have been reduced by 45.75 and 43 per cent, respectively, in comparison with the 12 mm recommended shell thickness.
Within the limitations of the current study, flexural strength of the reinforced PMMA interim fixed dental prosthesis was significantly higher (P < 0.0001) when compared to the unreinforced PMMA interim fixed dental prosthesis. The use of silane treated unidirectional glass fibres is an effective method of reinforcing interim fixed restorations made of PMMA resins.
Electrical discharge machining (EDM) is a well-known nontraditional manufacturing process to machine the difficult-to-machine (DTM) materials which have unique hardness properties. Researchers have successfully performed hybridization to improve this process by incorporating powders into the EDM process known as powder-mixed EDM process. This process drastically improves process efficiency by increasing material removal rate, micro-hardness, as well as reducing the tool wear rate and surface roughness. EDM also has some input parameters, including pulse-on time, dielectric levels and its type, current setting, flushing pressure, and so on, which have a significant effect on EDM performance. However, despite their positive influence, investigating the effects of these parameters on environmental conditions is necessary. Most studies demonstrate the use of kerosene oil as dielectric fluid. Nevertheless, in this work, the authors highlight the findings with respect to three different dielectric fluids, including kerosene oil, EDM oil, and distilled water using one-variable-at-a-time approach for machining as well as environmental aspects. The hazard and operability analysis is employed to identify the inherent safety factors associated with powder-mixed EDM of WC-Co.
The purpose of the present investigation is to study and compare the feasibility of decreasing the shell wall thickness for rapid casting solution of brass and lead alloys using three-dimensional printing (3DP) technology. Starting from the identification of components/benchmarks, technological prototypes have been produced at different shell thicknesses using lead and brass alloys. Measurements on a coordinate measuring machine helped in calculating the dimensional tolerances of the castings produced. Some important mechanical properties are also compared to verify the suitability of the castings and further results are supported by microstructure analysis. The study suggested that the production of sound casting for minimum wall thickness depends on pouring temperature and weight density. It has been observed that IT grades comparable to machining can be obtained with 3DP for lower pouring temperature alloys. Further feasibility of obtaining minimum shell thickness is more dependent on pouring temperature than weight density. Based on improved dimensional accuracy and microstructure analysis, the saving of costs up to 45.75 per cent and time up to 43 per cent can be achieved over the recommended one in the case of lead alloy for the selected benchmark/component. For brass alloy casting saving of costs and time up to 40.05 and 32.84 per cent, respectively, has been achieved.
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