Faculty Publications
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Item Real-Time Geometric Error (Form) Compensation on a Vertical Milling Machine(Springer Nature, 2024) Shanmugaraj, V.; Shruthi, G.; Shettigar, A.K.; Krishna, P.High-performance CNC milling machines are required for manufacturing precise components as there is a demand for consistency and quality are growing. The vital factor which plays a key role in the precision components manufacturing is the machine tools performance itself. Mainly, the causes of displacement errors are the effect of form errors, forces due to cutting actions, dynamic behavior of machine, etc. This paper proposes a new methodology in measuring and compensation of geometric error on a vertical milling machine which has three linear axes. The straightness error measured, and compensated for the individual axis with respect to the other two linear axes is discussed in this paper. A new methodology of applying flatness error correction is implemented by taking the current position of an axis into account. This error correction is implemented in real time in a vertical milling machine fitted with a CNC controller. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024.Item Analysis of Materials Expansion Properties for Computation of Thermal Error Compensation Values for Machine Tool Applications(Springer Nature, 2024) Shanmugaraj, V.; Shruthi, G.; Shettigar, A.K.; Krishna, P.One of the major causes of the total geometric inaccuracy of the machine is the thermo-mechanical error due to the deformation of machine tools, which is caused by both internal and external heat sources. Understanding the factors driving this is crucial to bring down errors to negligible values on machine tools. There are many different thermal factors, and it is a combination of all of these influences and their histories that determines the actual temperature on the distribution on the elements of machine tools. The expansion properties of the machine tool elements are analyzed in the computation of thermal expansion of these elements. Neural network as a part of artificial intelligence is widely used for this type of application as the data captured from the process is highly nonlinear. Giving the right data for the neural network training is at most important as this decides about the quality of neural network training. As the data is huge enough considering various conditions existing in the machining environment, the proper data pre-processing only will make the training much more effective. This paper’s main aim is to study the thermal expansion properties by properly analyzing the data. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024.Item Prediction and optimization of dimensional shrinkage variations in injection molded parts using forward and reverse mapping of artificial neural networks(2012) Gowdru Chandrashekarappa, G.C.; Krishna, P.The most significant process parameters affecting dimensional shrinkage in transverse and longitudinal directions of molded parts in Plastic Injection Molding (PIM) process are injection velocity, mold temperature, melt temperature and packing pressure. In the present work, ANN model was developed for forward and reverse mapping prediction. In forward mapping PIM process parameters are expressed as the input parameters to predict dimensional shrinkage, whereas in reverse mapping, attempts were made to predict an appropriate set of process parameters required for arriving at the required dimensional shrinkage. The trained network with one thousand input-output data randomly generated from regression equations reported by earlier researchers resulted in minimum mean squared error. The performance of developed model was compared with experimental values for ten different test cases. The results show that ANN model with both forward and reverse mapping is capable of prediction with an error level of less than ten percent. © (2012) Trans Tech Publications.Item Prediction of surface finish and optimization of machining parameters in turning(2012) Prasad, D.; Krishna, P.; Rao, S.S.Surface roughness plays a crucial role in the functional capacity of machined parts. In this work, experiments were carried out on a conventional lathe for different cutting parameters namely feed, spindle speed, depth of cut and tool nose radius according to Taguchi Design of Experiments. Radial acceleration readings were taken with an accelerometer. Optimum cutting parameters and their level of significance were found using Taguchi analysis (ANOVA). Regression analysis was carried out to identify whether the experimental roughness values have fitness characteristic with the process parameters. Recurrence Plots (RP) were obtained using the sensor signals which determine surface roughness qualitatively and Recurrence Quantification Analysis (RQA) technique was used to quantify the RP obtained. Surface finish was predicted using a feed forward back propagation neural network with RQA parameters, cutting parameters and acceleration data as inputs to the network. The validity and reliability of the methods were verified experimentally. © (2012) Trans Tech Publications.Item Low cost cpm machine for knee joint(2012) Metan, S.S.; Krishna, P.; Mohan Kumar, G.C.In today's world of industrialization, no single branch of Engineering and Technology can be considered independently. In order to increase productivity and profitability, industrial products are designed with the technology involving Mechanical and Electronics principles i.e. Mechatronics. Mechatronics has a vital importance in various fields such as agricultural, aviation, automobile, medical, etc. The scope of present work is to design, manufacture and test the low cost knee Continuous Passive Motion (CPM) machine. By using motorized device of CPM machine, we can gradually move the knee joints. This is not possible actively to the patient due to pain. The knee joint motion without patient's muscular effort is called as passive motion. The machine designed and developed in present work can achieve this. Once the patient is able to use his muscular power for his active joint motion, CPM is no longer medically necessary. In the present work, design and manufacturing of the Low Cost Knee CPM machine has been successfully done and is elaborated. The machine was manufactured and tested at one of the renowned Hospitals in Sholapur-India. The patient is exercised on CPM machine for three weeks and is observed to be improved to normal condition i.e. normal Range of Motion (ROM). © (2012) Trans Tech Publications, Switzerland.Item Machinability studies of low alloy steels by face turning method: An experimental investigation(Elsevier Ltd, 2013) Lalbondre, R.; Krishna, P.; Mohan Kumar, G.C.The present study is an experimental investigation on machinability of two low alloy steels, AISI 9320 and AISI 4340, by face turning method. The face turning method makes use of cylindrical steel specimen as a test piece and a triangular P-30 insert as a cutting tool for testing the machinability. The effectiveness of this method is assessed by studying: the cutting time required for the tool to reach flank wear up to 0.3mm (tool life criterion); tool wear development and wear mechanisms involved in machining; tool life studies and machinability indices of the work-material; surface roughness investigations of the machined surfaces; and chip morphology. The machinability tests undertaken in the current investigation follows some of the guidelines indicated in the international standards, ISO 3685:1993(E) and American Foundry Society (AFS) standard machinability tests. The results presented here demonstrate the ability of the face turning method: to evaluate the tool wear development and tool life studies; to rank the work material according to their machinability, to investigate surface roughness due to tool wear; to investigate chip morphology with crater wear and to characterize the machinability of steels under consideration. The face turning method used here is simple and effective for the given tool-work material pair. © 2013 The Authors. Published by Elsevier Ltd.Item Virtual Prototyping with Rigid Body Concept for the Development of Internal Combustion Engine(SAE International, 2017) Kumar, R.R.; Krishna, P.; Kuppast, V.V.The recent surge in the demand for the virtual application has led to the need for prototype testing that control the associated problem to a great extent. Consequently, a reduction in the costs of operating the actual prototype is envisaged. However, in some cases, just by adjusting input parameters alone could increase the success rate of these prototypes. During the design process, the functional prototyping is mainly used to evaluate the appearance of product and simulate its system level functioning. Multi-body dynamics analysis involves the simulation of rigid body systems under the application of forces or motions. Virtual prototype can substitute the physical prototype to perform a system level functioning of the product. The Internal combustion engine mechanism is considered for simulating the system level working with real time dynamic responses. Virtual prototype is created with a rigid body concept for an existing four stroke, single cylinder internal combustion engine mechanism to visualize the system level functioning and to find the displacement, velocity and acceleration of the piston on account of validation of the actual functioning of the engine. Virtual engine created by modeling individual parts of the product using CAD software and is simulated by using Hyper-Works computer aided engineering (CAE) tool. Finally, the validation of the functioning of the engine is done by comparing the results obtained by mechanism response (slider-crank mechanism; idealized for an internal combustion engine) of the engine using real time operating data collected experimentally. © 2017 SAE International.Item Machinability of Hardened Alloy Steel using Cryogenic Machining(Elsevier Ltd, 2018) Arun Kumar, S.; Yoganath, V.G.; Krishna, P.Machining of hardened alloy steels demand special cutting tools such as PCBN, ceramic. However, these cutting tools are uneconomical and also demand machine tool structures, which have high stiffness and vibration dampening properties. In the current trend towards Green manufacturing it is desired to produce more with less. Green manufacturing also emphasizes on an eco-friendly process. Hence, it is postulated to improve the machinability of these materials by alternate, economical means. One such alternative is cryogenic machining. In the current research work, it is envisaged to study the machinability of hardened alloy steel using commercially available cutting tools (coated carbide) under the influence of cryogenic as the coolant. Machinability factors under influence of cryogenic machining such as tool life, surface roughness and power consumption are studied. Results show that cryogenic as an alternative to coolant during machining of hardened materials increases the process efficiency by reducing energy consumption and also showed significant improvement in tool life. The process thus demonstrates the capability of replacing the special cutting tools that are required for hard turning applications. The portability of the setup for commercial use is also considered. © 2017 Elsevier Ltd.Item Experimental study of Mode i and Mode II interlaminar fracture toughness on aerospace structural composite T300/914(American Institute of Physics Inc. subs@aip.org, 2019) Sachin, S.; Shivananda Nayaka, H.S.; Santhosh, B.; Krishna, P.Carbon epoxy composite T300/914 which has wide applications in aerospace industries, as a structural material, has been analyzed, to determine the interlaminar fracture toughness. Laminates with a thickness of 4.6 mm, consisting of 48 layers of T300/914, are considered for estimating the inter-laminar fracture toughness. These specimens have been fabricated by hand layup method followed by controlled curing in an autoclave. Tests have been conducted in accordance with ASTM standards, for Mode I by Double Cantilever Beam (DCB) test and End Notch Flexure (ENF) test for Mode II. Pulse-Echo test results and C-Scan images of the specimens were also analyzed to locate the exact position of delamination. During the preliminary tests, it was found that the interlaminar fracture toughness varied, because of bonding of release film with the sides of the laminate. By Modified Beam Theory, Mode I and Mode II fracture toughness values of the prepared specimens were found to be 0.090 kJ/m2and 0.542 kJ/m2, respectively. It was also noted that the fracture toughness of the specimens from the same laminate varied with the degree of compaction. © 2018 Author(s).Item Experimental investigation of mode I interlaminar fracture toughness in T300/914 composite(Elsevier Ltd, 2020) Sachin, S.; Nayaka, S.H.; Santhosh, B.; Krishna, P.An aerospace structural material T300/914 has been studied to understand the Mode I interlaminar fracture toughness. For experimental analysis a Double Cantilever Beam (DCB) test is conducted on the laminate to estimate the Mode I interlaminar fracture toughness of the sample. A 48-layer laminate was prepared by hand layup process and an insert included at the mid plane to produce the artificial initial crack required for the test. All the tests are conducted in accordance to the ASTM standards. Pulse-Echo test results and C-Scan images of the laminate were analyzed to find the defects in the laminate. The data from DCB test were analyzed by Modified Beam theory, Compliance calibration method and modified compliance calibration methods to find the interlaminar fracture toughness. A crack length correction method is implemented for data reduction. Numerical analysis of the data derives results in accordance with the experimental analysis. © 2019 Elsevier Ltd. All rights reserved.