Senthilkumaran

Scopus Publications

Studies on wettability of stainless steel 316L powder in laser melting process
Journal of Engineering Science and Technology, 2014
Numerical and experimental investigations on laser melting of stainless steel 316L metal powders
Kurian Antony, N. Arivazhagan, K. Senthilkumaran
Journal of Manufacturing Processes, 2014
This paper presents numerical and experimental investigations on laser melting of SS grade 316L powder on top of AISI 316L substrate using a pulsed Nd:YAG laser. The objectives of the present study are to understand the effect of process parameters such as laser power, scanning speed and beam size on geometry characteristics of the melt zone and ball formation. We formulated a moving heat source problem and obtained transient temperature solutions using commercial finite element solver. The geometry characteristics of the melt zone are evaluated from the temperature solutions and compared with experimental results. The effect of laser parameters on the geometry, morphology and homogeneity of single track realization was methodically analyzed by utilizing characterization tools such as laser particle size analyzer, macro and microscopic inspection, Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The results presented in this paper are beneficial to realize homogenous layer formation in additive manufacturing processes involving powder melting by laser beam.
Influence of laser melting process parameters on surface roughness behavior for SS316l powder
Journal of Corrosion Science and Engineering, 2013
Studies on absorptivity and marangoni flow during laser sintering
T. Rohit, Antony Kurian, K. Senthilkumaran, N. Arivazhagan
Advanced Materials Research, 2013
Selective laser sintering (SLS) / melting (SLM) is a manufacturing technique which holds a very special place in the layer manufacturing process due to its widest range of material processing capability which no other technique can offer. It can process metals, rubber, composites, polymers and ceramics etc. As laser sintering technique is emerging as an advanced manufacturing technique, it is importance to study the phenomenon which affect the fabrication process, hence a study is undertaken to simulate the physical phenomenon such as laser absorption and Marangoni effect. By studying these phenomena, a much better control of the physical processes is possible during the laser sintering process of commercially pure titanium grade 2.
Hot Corrosion Behavior of Friction Welded AISI 4140 and AISI 304 in K 2SO-60% NaCl Mixture
N. Arivazhagan, K. Senthilkumaran, S. Narayanan, K. Devendranath Ramkumar, S. Surendra, S. Prakash
Journal of Materials Science and Technology, 2012
Understanding the behavior of weldment at elevated temperatures and especially the corrosion behavior has become an object of scientific investigation recently. Investigation has been carried out on friction welded AISI 4140 and AISI 304 in molten salt of K2SO4–60% NaCl environment at 550, 600 and 650 °C under cyclic condition. The resulted oxide scales in the weldment have been characterized systematically by surface analytical techniques. From the results of the experiments, it is observed that the scale thickness on low alloy steel side was higher than that on stainless steel side. Furthermore, weld interface has been found to be more susceptible to degradation than base metals due to inter diffusion of element across the interface and the formation of intermetallic compound. The influences of welding parameters and the temperature of exposure on the hot corrosion behavior of the weldment were discussed in this paper.
Statistical modeling and minimization of form error in SLS prototyping
K. Senthilkumaran, P.M. Pandey, P.V.M. Rao
Rapid Prototyping Journal, 2012
Purpose – The purpose of this paper is to report experimental investigations performed to analyze the effect of process parameters on the shape accuracy of selective laser sintered (SLS) parts.Design/methodology/approach – The effect of process parameters, namely build orientation, laser power, scan speed, cylinder diameter and build chamber temperature has been studied on shape accuracy by using geometric tolerances such as cylindricity and flatness. Central composite design (CCD) is used to plan the experiments and a second order regression model has been developed to predict flatness and cylindricity. The significance of process variables on flatness and cylindricity has been evaluated using analysis of variance technique.Findings – It is observed that interaction effects are more dominant than individual effects. In case of cylindricity, it is found that the interaction between the scan speed and orientation is the dominant factor next to the orientation and quadratic effect of the geometry. In case o...
3D digitization of sub surface features using 3D GPR
V. S. Mahesh, K. Senthilkumaran, P. C. Jha
Proceedings of the ASME Design Engineering Technical Conference, 2011
Ground Penetrating Radars (GPR) finds its applications in civil engineering, archeology, earth sciences, military and environmental studies. This paper proposes a framework for using GPR as a digitizing technique that can make 3D digitization/measurement of the buried objects. Currently, the 3D radar volume data is acquired by dense subset of parallel 2D radar profiles. However, it results in a very large amount data and related processing time, and needs to be avoided due to the significant computer resources and processing time required to process the data. In order to achieve simplified and faster processing as well as to reduce memory requirements, it is often useful to convert the original image data to a more compact representation. The conversion removes as much of the redundant information as possible. Then the data is processed by removing noise initially and then eliminating undesired presence of ground surface echo. Further, propagation losses are compensated followed by segmentation and skeletonizing. However the accuracy of the 3D measurement depends upon number of parameters such as antenna design, scan paths, scan spacing and frequency which needs to be evaluated in detail. The framework presented in this paper would help to measure the buried objects accurately using 3D GPR.
Influence of building strategies on the accuracy of parts in selective laser sintering
K. Senthilkumaran, Pulak M. Pandey, P.V.M. Rao
Materials and Design, 2009
Shrinkage in selective laser sintering process is primarily influenced by material, process parameters and the geometry of the fabricated part. The part inaccuracy due to this shrinkage is overcome by calibrating and compensating it. Further improvements in accuracy of the part can be achieved by conducting more studies to appreciate the nature of deviations, by subjecting calibration part to varying build conditions. This paper presents the results of the experimental study carried out to understand shrinkage behavior in selective laser sintered polyamide 12 parts. Due to the inherent nature of the process, the shrinkage behavior is often influenced by exposure strategies, part positioning, part orientation, and other compensations applied to the part. When fabricated under different settings, shrinkage behavior of calibration parts tends to differ from usual. In the present work, the variations in error patterns due to different strategies in building the calibration part have been reported. The discussions presented in this paper on the shrinkage behavior of plastic parts are likely to make the process of compensation efficient and hence aid in improving the accuracy of the process.
New model for shrinkage compensation in selective laser sintering
K. Senthilkumaran, Pulak M. Pandey, P. V. M. Rao
Virtual and Physical Prototyping, 2009
This paper presents a new model for shrinkage and a new approach for shrinkage compensation to enhance the accuracy of parts produced by selective laser sintering (SLS)–a solid freeform fabrication process. The present prevailing approach as proposed by machine manufacturers is simple but not accurate. A new shrinkage model which accounts for part geometry as well as beam offset is proposed in this work. A new compensation scheme which accounts for nonlinear shrinkage is proposed, implemented and validated. The proposed compensation scheme compensates for shrinkage at every layer and at every hatch length, unlike a uniform compensation scheme applied to entire part. A new algorithm which accounts for this is developed and implemented. Experiments carried out with the new shrinkage model as well as with the new compensation scheme have shown significant improvement in the accuracy of the parts produced which establishes the effectiveness of the proposed methodology.
Shrinkage compensation along single direction dexel space for improving accuracy in selective laser sintering
K. Senthilkumaran, P. M. Pandey, P. V. M. Rao
4th IEEE Conference on Automation Science and Engineering Case 2008, 2008
This paper presents new approach for shrinkage compensation in selective laser sintering (SLS) process to improve the accuracy of parts produced. Shrinkage is compensated along single direction dexel space generated from the part geometry. The scaling factor used in this compensation is calculated from shrinkage model (It is the empirical relation between percentage shrinkage and the dexel length). This relation is obtained by designing and conducting experiments using Taguchi method. New shrinkage compensation method is developed to overcome non-uniform shrinkage by compensating the geometry along single direction dexel space. Software is developed to automate the compensation process. Two case studies were presented to quantify the effectiveness of the developed compensation approach over the existing compensation method. From the comparison experiments, the ability of the proposed compensation method in improving the accuracy of laser sintered parts is established.