International Journal of Additive and Subtractive Materials Manufacturing (13 papers in press)
Mechanical and Microstructural Characterization on Direct Metal Laser Sintered Inconel 718
by Jinoop A.N., Kanmani Subbu S., R. Arockia Kumar
Abstract: Direct metal laser sintering (DMLS) is one of the additive manufacturing technologies which al-lows the fabrication of complex components in layer by layer technique with melting and solidifica-tion of powder raw material by laser heat source. This paper investigates about the mechanical and microstructural characteristics such as bulk density, porosity, micro hardness and surface roughness on Inconel 718, a nickel super alloy made by using DMLS. Bulk density and porosity finds good agreement with the components fabricated by casting. Micro hardness and surface roughness along the surface of the component was investigated and also surface roughness along the build direction was inspected. The phases present in the processed Inconel 718 was found by using X- ray diffrac-tometer. Optical microscopy and scanning electron microscopy was used to examine and understand the microstructure of as-built Inconel 718 without post-processing effects.
Keywords: Laser; DMLS; Inconel 718; characterization; mechanical; microstructure;additive man-ufacturing.
Effect of heat treatment on mechanical properties and microstructure of Ti/Al sheet metal joint using laser beam welding
by Kuppusamy Kalaiselvan, A. Elango, N.M. Nagarajan, N. Mathiazhagan
Abstract: Industry demands new materials to meet its requirements for that dvanced technics are adopted to find solution through research. One such attempt is use of laser beam welding to join Ti/Al dissimilar alloy for aerospace and other applications. It is still a challenge to achieve satisfactory joint between these dissimilar alloys. In the present work, Ti6Al4V and AA2024 alloys thin sheet combinations are welded using Nd: YAG pulsed laser welding unit. Subsequently the welded joints are subjected to age hardening and the results are compared with weld joints prior to aging. Test results reveal that aging treatment brings strength for the structure more than 60% and laser beam welding is suitable for dissimilar metal joining.
Keywords: Nd: YAG welding; Heat treatment; Microstructure; Mechanical properties.
Special Issue on: CPIE-2016 Present and Futuristic Manufacturing
AN EXPERIMENTAL STUDY OF SURFACE ROUGHNESS IN DOUBLE TOOL TURNING PROCESS
by Rathinam Kalidasan, Selvaraj Senthilvelan, U.S. Dixit
Abstract: The objective of this investigation was to determine the influence of machining parameters on the surface roughness of AISI 1050 steel and grey cast iron workpieces. It was observed that the surface roughness decreases with the increase in cutting speed. On increasing the feed for AISI 1050 steel, initially the surface roughness decreased up to 0.12 mm/rev feed and thereafter it increased, but for grey cast iron it increased with feed for all cutting conditions. The surface roughness was not affected significantly by tool separation distance. Compared to single tool turning process, the double tool turning produced much better surface finish. As a consequence, it is possible to reduce the cost of machining by suitably targeting the process parameters. An approximate cost analysis has been done to support this claim.
Keywords: double tool turning; surface roughness; cutting speed; infra-red camera; cutting temperature; profilometer; cast iron; steel; cost analysis; spanzipfel.
Experimental Study and Empirical Modelling of Laser Surface Finishing of Silicon Carbide
by Ketema Bobe Bonsa, Woldetinsay Jiru, Mamilla Ravi Sankar, U.S. Dixit
Abstract: Laser surface modification is an innovative method of polishing hard to machine ceramics for industrial applications. Laser has wide applications in industries due to a wide range of available and easily controllable power. It modifies any surface for high surface finishing applications. Silicon carbide is composed of carbon and silicon atoms forming a strong bond. It can be used in different applications like turbine components, ball valve parts, heat exchangers and semi-conductors. In this work, silicon carbide substrate material was irradiated using CO2 laser at different parameters (laser power 50─500 W and scan speed of 300─800 mm/min). After laser surface irradiation, surface roughness and its morphology were investigated. Laser irradiation improved the surface finish. The morphology of improved surface is free from any cracks. The Rockwell hardness test results show that the hardness of laser polished surface is about twice the original hardness.
Keywords: laser; ceramic; surface finishing; silicon carbide; surface roughness; hardness; CO2 laser; design of experiments; energy dispersive X-ray spectroscopy; morphology.
Estimation of Cutting Forces in Conventional and Ultrasonic-Vibration Assisted Turning Using Inverse Modelling
by U.S. Dixit, Vinod Yadav, Varun Sharma, Pulak Pandey, Anish Roy, Vadim Silberschmidt
Abstract: In this work, cutting forces in conventional and ultrasonic-vibration assisted turning are estimated using an inverse method to evaluate the velocity-dependent friction and fracture toughness based on a few tests in conventional turning. The inverse methodology requires the data on cutting and feed forces at two specified cutting speeds. Analytical expressions are employed to estimate the cutting forces in conventional as well as ultrasonic-vibration assisted turning. The suggested method was verified with experimental data. The validation of the direct model with the finite-element results available in the literature was also carried out. A sensitivity analysis revealed a significant effect of friction on cutting forces. Thanks to its simplicity, the proposed procedure may find a good application in industrial practice.
Keywords: cutting forces; ultrasonic-vibration assisted turning; friction; inverse method; fracture toughness; machining; Johnson-Cook model; Ti-6246; 4340 hardened steel; orthogonal cutting.
Parametric Optimization for Micro Electric Discharge Drilling Process
by Ravinder Kumar, Inderdeep Singh
Abstract: Electric discharge machining (EDM) is gaining significant industrial consideration due to its characteristic of machining difficult to machine materials, irrespective of their hardness. Growing product miniaturization further extends the application of EDM for the production of components featured with micro cavities. In the present experimental investigation, micro holes were drilled in the copper workpiece using tungsten electrode of diameter 120
Keywords: Micro electric discharge machining; micro holes; material removal rate; tool wear rate.
Machining of Hardened AISI H-13 Steel using Minimum Quantity Eco-Friendly Cutting Fluid
by Kishor Kumar Gajrani, Dhanna Ram, Ravi Sankar Mamilla, Uday Shanker Dixit, P.S. Suvin, Satish Vasu Kailas
Abstract: Conventionally cutting fluids are applied in the form of flood to improve machining performance and tool life. However, the use of cutting fluid has detrimental effect in the form of environmental pollution and occupational health hazard. Researchers are trying to develop alternate methodologies to reduce or eliminate cutting fluids during machining. In this study, indegenously developed eco-friendly green cutting fluid (GCF) is used with minimum quantity cutting fluid (MQCF) technique during machining of hardend AISI H-13 steel. Cutting force, feed force and centre line average (CLA) surface roughness were measured at different cutting conditions. Performance of MQCF was compared with flood coolant using GCF and dry machining. The morphology of the rake face of the tool was examined with optical microscope and surface profilometer. Cutting force, feed force, coefficient of friction and CLA surface roughness was reduced with MQCF using GCF as compared to flood coolant and dry machining.
Keywords: green cutting fluid; hard machining; minimum quantity cutting fluid; mist; hardened AISI H-13 steel; tool-chip contact length; minimum quantity lubrication; turning; surface roughness; cutting tool.
EFFECTS OF PARAMETERS ON BURR HEIGHTS & DIAMETRAL ERROR IN DRY DRILLING
by Anuj Vats
Abstract: Burr formation similar to chip genesis is a common caution in conventional metal cutting operations in which material removal by direct tool-workpiece contact cause chip generation, variation in hole quality & post cutting finishing. In the present work effects of various process parameters on burr type, entry, exit burr heights, roundness & diametral error obtained while drilling Aluminium alloy 6082 has been investigated. Equations to predict the burr heights to be obtained for different values of machining parameters were also formulated such that a tradeoff between MRR and deburring costs can be drawn for subsequent stages of machining.
Keywords: Burr; Burr height prediction; Drilling; Burr types; Roundness; Diametral error; Burr height minimization.
Experimental Investigation on Drilling of Borosilicate Glass using Micro-USM with and without Tool Rotation: A Comparative Study
by Sandeep Kumar, Akshay Dvivedi
Abstract: The application of microproducts is increasing rapidly in various fields such as automobiles, electronics, microfluidics, bio-MEMS etc. These micro products are generally made of hard and brittle materials e.g. glass, quartz, ceramics and silicon etc. The machining of these materials in micro-domain is a difficult task. Micro-ultrasonic machining (micro-USM) is a preferred process for machining of hard and brittle materials. But high tool wear and low aspect ratios limits its industrial use. This investigation compares the effect of tool rotation on material removal rate and hole overcut. Additionally aspect ratio was measured. The variable process parameters for the investigation were power rating, static load, slurry concentration and abrasive size. Imaging was used for qualitative analysis of tool wear. The experimental results reveal that micro-USM with tool rotation resulted in higher material removal rate, lesser hole overcut, high aspect ratios and lesser tool wear in compared with micro-USM without tool rotation.
Keywords: Micro-USM; Tool rotation; Microholes; Microfluidics; Hole overcut; Glass.
Influence of Glycerin-air Dielectric Medium on Near-dry EDM of Titanium Alloy
by Krishnakant Dhakar, Akshay Dvivedi
Abstract: Ti-6Al-4V is one of the most commonly used titanium alloy. The applications involve in the area of aerospace, chemical engineering, biomedical implants, marine industries etc. The electrical discharge machining (EDM) is an unconventional machining process. It is widely used to produce complex profiles on electrically conductive materials. Near-dry EDM is a process variant of the EDM process. Generally, it uses water-air mixture as a dielectric medium. Near-dry EDM is an environment friendly process. In this investigation near-dry EDM of Ti-6AL-4V was investigated with glycerin-air dielectric medium. The one-factor-at-a-time approach was used for experimentation. The process parameters selected for experimentation were current, duty factor, lift setting, sensitivity setting, flushing pressure, liquid flow rate and gap control. The responses measured were material removal rate and surface roughness. The experimental results revealed that glycerin-air dielectric medium produced higher MRR with fine surface finish even at higher current and wear ratio of the process was also less than one percent.
Keywords: Near-dry electric discharge machining; Dielectric medium; Material removal rate; Surface roughness.
Fabrication of Micro-features on 304 Stainless Steel (SS-304) using Nd:YAG Laser Beam Micro-Machining
by Rasmi Ranjan Behera, P.M. Babu, Kishor Kumar Gajrani, Ravi Sankar Mamilla
Abstract: In the present study, micro-channels and micro-dimples are fabricated with different dimensions on the surface of SS-304 alloy by pulsed Nd:YAG laser beam micro-machining. The effect of various laser parameters on the machining performance characteristics are evaluated. The effect of process parameters viz. laser scanning speed, current, laser pulse frequency and pulse duration are studied using argon gas. The width or diameter and depth of micro-features are considered as the output responses. 3-D laser surface profilometer is used to study and measure the dimensions of fabricated micro-features. The results showed that the selection of micro-feature size is critical to achieve desired machining results. All the processing parameters have noticeable effect on the geometry and quality of micro-features. The dimensions (diameter, width and depth) of micro-features are decreased with higher scanning speed and increased with increase in pulse frequency, pulse duration as well as current. The appropriate combination of parameters can yield the better results for quality and size of micro-features. Lower scanning speed with higher pulse frequency with a proper set of current and pulse duration can be used in order to fabricate micro-channel whereas higher scanning speed and lower pulse frequency can be used to obtain micro-dimples.
Keywords: Laser beam micro-machining; Millisecond pulsed Nd:YAG laser; Stainless steel SS-304; Micro-features; Micro-channels; Micro-dimples; Laser energy density; Surface topography; Spatter deposition.
Delamination Study on Newly formulated Ni-P Coated Glass fiber / Nanowire Reinforced Polymer (GFRP) Composite Using Grey Relational Analysis
by Anand Gobiraman, Alagumurthi N, Elansezhian R, Palanikumar K
Abstract: Hybrid polymer composite nowadays are used extensively as an alternative material for the conventional materials. Drilling of the composite is an important secondary operation performed to make complicated structures. In drilling, delamination phenomenon is the major criteria to be considered. In the current study, Grey relational analysis with Taguchis L25, 5-level orthogonal array is used for optimizing the machining parameters such as spindle speed, feed rate and diameter of the drill with respect to delamination at the inlet and exit of the drilled hole of Ni-P - GF / Al2O3 nanowire reinforced hybrid composite. The optimal drilling parameter is determined by the grey relational grade for multiple performance characteristics. From the it is clear that the drill diameter is the most influence factor followed by the feed rate and the spindle speed. The experimental results state that the delamination characteristics of the hybrid composite be improved at optimal drilling conditions.
Keywords: Drilling; Delamination; Polymer Composite; Taguchi’s Optimization; Grey relational analysis.
Process Modelling and Investigations in to the Electrochemical Discharge Drilling (ECDD) of Soda-Lime-Silica- Glass
by NITHIN BALAN, Ladeesh Gopinath, Aneesh Thankappan, Manu R
Abstract: Electro-Chemical Discharge Machining (ECDM) is a hybrid non-conventional machining process that combines the features of Electro Chemical Machining (ECM) and Electro Discharge Machining (EDM). ECDM is an effective micro-machining process for non-conducting materials like glass, ceramics, composites, quartz, etc. The present study attempt to analyze the effects of process parameters including applied voltage, electrolyte concentration, frequency and duty factor on material removal rate (MRR). A widely used response surface design called Box-Behnken Design was used to conduct the experiments. From the analysis of variance, significant factors that contribute MRR can be ranked in the descending order of duty factor, frequency and voltage. The effect of electrolyte concentration is found to be insignificant. A strong interaction between duty factor and frequency is identified in controlling MRR. From the microscopic images of the machined surface, thermal spalling is identified as a significant mechanism for material removal along with thermal melting and chemical etching.
Keywords: Electro-Chemical Discharge Machining; Box-Behnken Design; Material Removal Rate.