Abstract: Three dimensional printing (3DP) as rapid casting (RC) solutions has transformed over centuries from black art to science, but the metallurgical impinge on the process responsible for change in mechanical properties (like: surface finish, hardness, dimensional stability etc.) are still disputed. The purpose of the present research paper is to review metallurgical affect of 3DP based RC solution. The result of study suggests that prominent reason found to be responsible for improving the mechanical properties of RC is control of heat transfer rate while solidification (thus reducing dendrite formation).
Abstract: The purpose of the present study is to experimentally investigate rapid moulding solutions for plastic components using silicon moulding technique. Starting from the identification of component, prototypes with two different type of plastic material were prepared under different vacuum moulding conditions. Measurements on the coordinate measuring machine helped in calculating the dimensional tolerances of the plastic components produced. Some important mechanical properties were also compared to verify the suitability of the components. The study highlighted the best settings of orientation and type of plastic material for the selected component from dimensional accuracy and economic point of view as rapid moulding solution for plastic components. Final components produced are acceptable as per IS standard UNIEN20286-I (1995). This process ensures rapid production of pre-series technological prototypes and proof of concept at less production cost and time.
Abstract: Rapid prototyping (RP) has been in evidence for the past twenty years and is being widely used in diverse areas, from the building of aesthetic and functional prototypes to the production of tools and moulds for technological prototypes. The purpose of the present study is to experimentally investigate the rapid moulding (RM) solutions for plastic components using polyjet printing (PP) technique. Starting from the identification of component/benchmark, prototypes with three different type of plastic material were produced, at different orientation and support material. Measurements on the coordinate measuring machine helped in calculating the dimensional tolerances of the plastic components produced. Some important mechanical properties were also compared to verify the suitability of the components. The study highlighted the best orientation, support material quantity and type of plastic material for the selected component from dimensional accuracy and economic point of view as RM solution for plastic components. This process ensures rapid production of pre-series technological prototypes and proof of concept at less production cost and time.
Abstract: Wear behavior of the HVOF deposited NiCr and Stellite-6, coatings on Fe-base alloy steel were evaluated by the pin-on-disc techniques. The coatings were significantly harder and less porous. SEM/EDAX and XRD techniques were used to analyse the worn out surface and wear debris. The Fe2O3 was identified as the major phase in the wear debris. The wear mechanism is mild adhesive wear in nature. The coatings protected the substrate steels against the adhesive wear significantly.
Abstract: The wire electrical discharge machining (WEDM) is widely used for machining workpieces having complex geometries. A wire electrode of diameter 0.25 mm is moved coaxially between two guides and electrical energy in the form of electrical pulses is applied to remove material from the workpiece. In this study, the effect of key process parameters on wire wear of shallow cryogenic treated brass wire electrode used in WEDM was investigated experimentally. Five process parameters, namely Type of wire, Pulse width, Time between two pulses, Wire tension and Servo reference voltage have been considered. Taguchi experimental design has been applied to investigate the optimal parameters for minimum wire wear ratio (WWR). The experimental results indicate that Type of wire; Pulse width and Time between two pulses have a significant effect on WWR. The analysis of variance of mean and analysis of variance of S/N ratio on data was performed to identify the significant factors in order to establish the relative significance of parameters for WWR. It is found experimentally that shallow cryogenic treatment decreases the WWR. Increasing pulse width increases the WWR, where as increasing Time between two pulses decreases WWR. The results have been validated by three confirmation runs for optimum WWR.
Abstract: This paper investigates the effect of electric discharge machining (EDM) process parameters and powder mixed in dielectric on surface properties of three die steel work materials; namely High Carbon High Chromium (HCHCr), EN 31 and Hot Die Steel (HDS). The mechanism of material deposition from the suspended powder and/or tool electrode is reported. Current emerged as the most significant factor affecting the microhardness along with powder mixed in the dielectric and electrode material. Amongst the two electrode materials, copper-tungsten along with tungsten powder had the best microhardness. Selected samples were analyzed for X-ray Diffraction (XRD) followed by microstructure analysis using a Scanning Electron Microscope (SEM). The results showed significant material transfer from the electrode as well as powder either in free form or in compound form. It was concluded that surface modification of die steels can be done by incorporating simple modifications in the EDM set-up resulting in higher microhardness and superior wear resistance of the machined surface.
Abstract: Surface modifications using the powder mixed electric discharge machining (PMEDM) process has gained a lot of research interest in recent few years. The present paper investigates the material transfer from the powder suspended in dielectric, electrode and dielectric material for enhancing the surface properties measured in terms of the microhardness of the machined surface for two kinds of die steels (H11 and H13). Four different powder materials aluminium, copper, graphite and tungsten were mixed with dielectric during machining with three different dielectric materials namely kerosene, EDM oil and refined mineral oil. Other process parameters were varied at suitable levels. Maximum increase in microhardness was observed with addition of tungsten powder and with tungsten-copper electrode even at lower current. Current significantly affected the transfer mechanism of material on the machined surface but was dwarfed by the very significant affect of powder which had the largest contribution. A relative comparison of microhardness between deposited and non-deposited regions showed an increase of 37% for H11 and 56% for H13 due to addition of powder. The photomicrographs of the machined surface also supported the material transfer from powder, electrode as well as dielectric forming compounds that suitably improve the surface properties of H11 and H13 die steel.
Abstract: Fused Deposition Modeling (FDM) is a relatively new prototyping technique in which parts can be produced rapidly and accurately. The component produced by FDM can be utilized for investment casting or it can be used for development of dies. The present work started with the identification of the bench mark/component. Prototypes were built with ABS plastic material and measurements were made on the co-ordinate measuring machine from which IT grades were calculated to check the dimensional accuracy of the components. The purpose of this study is to find whether the FDM process is capable of producing a pattern for manufacturing a die for hand tool with good dimensional accuracy. The study involves best settings of machine by varying the part orientations and studying the effect on the consumption of the model material, support material and the time taken for production. Measured mechanical properties like micro hardness indicated the suitability of the process. Final components produced are acceptable as per ISO standard UNI EN 20286-I (1995) and DIN16901.The results of study suggest FDM process lies within ± 6 sigma and value of cp, cpk is greater than 1 which conforms that FDM process is highly capable process for industrial applications.