Department of Mechanical Engineering

Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

Cryogenic treatment has developed as a technique to improve the life of the cutting tool, especially tungsten carbide inserts. The present study investigates the effect of cryogenic treatment of cemented carbide (WC-Co) inserts at the different soaking period of 18 h (CT-18), 24 h (CT-24) and 32 h (CT-32) at a sub-zero temperature of −196 °C. The soaking period plays a crucial role in improving the wear resistance of the cryogenically treated tools. It is vital to determine the critical soaking period for the cryogenic treatment of cemented carbides. The mechanical and metallurgical characterization of cryogenically treated cemented carbide insert is carried out to understand the changes in the microstructure, grain size, chemical composition, microhardness and electrical conductivity after cryogenic treatment. The end milling experiments on maraging steel under dry environment are carried out using cryogenically treated inserts at different holding time and untreated inserts (UT). The machining performance of treated and untreated inserts are compared with respect to tool wear, surface roughness and cutting forces. The results revealed that cryogenic treatment is effective in resisting tool wear even at high spindle speeds. The cryogenically treated inserts exhibited higher tool life, better surface finish and lower cutting forces during machining at different spindle speeds. The optimum soaking time for cryogenic treatment of WC-Co inserts is found to be 24 h (CT-24) beyond which there is no improvement in microhardness and wear resistance. © 2018

World University root node

Journal of Manufacturing Processes

Influence of deep cryogenic treatment on performance of cemented carbide (WC-Co) inserts during dry end milling of maraging steel

The cryogenic machining and cryogenic treatment have already emerged as the sustainable manufacturing process of the future generation. The cryogenic treatment improves the cutting tool life, but the high cutting temperature developed during high-speed machining reduces the effect of cryogenic treatment of cutting tool. This study investigates the possible improvements in cutting tool life by combining cryogenic cooling and cryogenic treatment. The authors believe that these two techniques can replace conventional machining approaches using dry and wet machining conditions using coated carbide tools. The tungsten carbide-cobalt inserts are cryogenically treated (CT) at a soaking temperature of − 195.8 °C for a period of 24 h and are used to evaluate milling performance under dry, wet, and cryogenic cutting environments. The machining experiments are conducted on maraging steel MDN 250 using one factor at a time approach by varying spindle speed and keeping feed rate and depth of cut as constant. The cutting force, surface roughness, tool wear, and subsurface microhardness are some of the machining responses evaluated and compared with an untreated cutting tool (UT). The tool life improved up to 24% during cryogenic machining using CT tools at a spindle speed of 270 rpm. © 2019, Springer-Verlag London Ltd., part of Springer Nature.

International Journal of Advanced Manufacturing Technology

Experimental investigation of cryogenic end milling on maraging steel using cryogenically treated tungsten carbide-cobalt inserts

This work reports the development of a measurement technique for the estimation of thermal contact conductance at a polymer (Nylon)-metal(Copper) two dimensional interface having an annular contact under low external loading. The experimental setup consists of a vacuum chamber capable of achieving a pressure of 10−6 mbar. The chamber is fitted with electrical, thermocouple and fluid feed-throughs. Two dimensional temperature measurements are performed on the top surface of the polymer sample away from the boundary interface and are used to estimate the thermal contact conductance at the interface. The estimation process is accomplished by solving an inverse heat conduction problem using artificial neural networks coupled with Genetic algorithm. The actual pressure distribution at the annular Nylon-Copper interface is measured using a pressure sensitive film and the variation and the distribution of contact area between the mating surfaces is shown. The estimated values of thermal contact conductance obtained using the developed non-intrusive technique are found to be in good agreement with those reported in literature. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.

Heat and Mass Transfer/Waerme- und Stoffuebertragung

Non-intrusive measurement of thermal contact conductance at polymer-metal two dimensional annular interface

Pre-prints of the National Meeting of Japan Welding Society

Assessment of tool wear in friction stir welding of high carbon steel

The effect of dimpled surface configurations on heat transfer is investigated for multiple jets issuing from orifices arranged in a 3 × 3 array. The Reynolds numbers during these studies maintained in the range of 5000–40000. To assess the influence of jet and dimple pitch, the studies are performed for different dimple and orifice pitches (p = 3d, 4d, and 5d). Along with these cases, dimple depths of 0.25d and 0.5d and eccentricity between the orifice and the dimple are also studied. The distance between the orifice plate and the test surface is varied from 1d to 6d. To characterize the steady-state heat transfer from the heated target surface to the impinging air jet, the thermal image of the target surface captured with a thermal imaging camera is analysed with thin metal foil heater technique. To evaluate the effectiveness of jet impingement cooling of the dimpled surface, the average Nusselt number and coefficient of variance (COV) are calculated over a defined pitch area of ± p. It is observed that for the jet orifice and dimple pitches of three nozzle diameter (p = 3d), the flat plate is more efficient than a dimpled surface. However, for greater pitches (p ≥ 4d), the dimpled surface performed much better in comparison with the flat plate. In case of the shallow dimpled surface (t/d = 0.25), best heat transfer performance is observed for the pitch of 5d. The coefficient of variance (COV) suggests that the Nusselt number is more uniformly distributed for a pitch of 3d. © 2019 Elsevier Masson SAS

International Journal of Thermal Sciences

Effect of dimple pitch and depth on jet impingement heat transfer over dimpled surface impinged by multiple jets

This paper analyses the four-mecanum wheeled drive mobile robot wheels configurations that will give near desired performance with one fault and two faults for both set-point control and trajectory-tracking (circular profile) using kinematic motion control scheme within the tolerance limit. For one fault the system remains in its full actuation capabilities and gives the desired performance with the same control scheme. In case of two-fault wheels all combinations of faulty wheels have been considered using the same control scheme. Some configurations give desired performance within the tolerance limit defined while some does not even use pseudo inverse since using the system becomes under-actuated and their wheel alignment and configurations greatly influenced the performance. © 2019, DESIDOC.

Fulltext

Defence Science Journal

Behavioural fault-tolerant-control of an omni-directional mobile robot with four-mecanum wheels

In this work, a new method of selective heating is proposed to increase the deformation behaviour of cylindrical sintered aluminium preforms during the process. Initially, cold upsetting is carried out using 0.5 MN hydraulic press machine at 0.1 s −1 strain rate and the failure locations of the preforms are predicted for various initial relative densities with the aspect ratio of 1 during the deformation process. After the prediction of this failure location, various conditions of selective heating are attempted uniformly on the deformed preforms after a certain stage of deformation before the onset of the failure initiation, using portable gas cartridge at a different temperature and time to assess their consequence on formability behaviour. The detailed experimental results are evaluated for the formability of the selectively heated preforms under different variables such as flow stress, relative density, axial strain, formability stress index and stress ratio parameter. As a result, the initiation of failure and its progression can be delayed by selectively heating the samples before the onset of the failure initiation. Selective heating of the failure location may relieve the accumulated stresses and delay the onset of failure to a later strain level thereby increasing the formability of the metal. © 2019, The Indian Institute of Metals - IIM.

Transactions of the Indian Institute of Metals

Effect of Selective Heating on Formability and Densification of Powder Metallurgy Preforms During Upsetting

The Aluminum alloy AA6061-4 wt% boron carbide (B4C) composites were fabricated by stir casting. The diesinker Electric Discharge Machining (EDM) was performed to create rectangular channels on fabricated AA6061-B4C composite. The Taguchi experimental design (L-9) with current (I), pulse-on (T-On) and pulse-off (T-Off) time as input parameters. The Material Removal Rate (MRR) and Average Recast Layer Thickness (ARLT) were considered as responses. The ARLT and surface topography of the machined zone were analyzed from the SEM micrographs. The regression model was developed and ANOVA was performed. Results that the current and T-On are significant parameters affecting the MRR and ARLT respectively.

Materials Today: Proceedings

Fabrication and experimental study to optimize the recast layer and the material removal in electric discharge machining (EDM) of AA6061-B4C composite

The present study investigates the machining performance of AlCrN and AlTiN coated cemented carbide inserts during end milling of MDN 250 maraging steel. The mechanical and metallurgical characterization is carried out to determine the properties of the PVD coatings developed. The end milling experiments under dry, wet and cryogenic environment is carried out using coated uncoated inserts (UC) at different spindle speeds to evaluate the machining performance in terms of tool life, surface roughness and cutting forces. The coated inserts showed higher tool life, better surface finish, and low cutting forces during machining at different spindle speeds. It is found that the AlCrN coating had a better wear resistance and machining performance in comparison with AlTiN coating. The cryogenic environment reduced the surface roughness & cutting force and improved the tool life of the cutting tool compared to conventional dry and wet environment. It is revealed that coated tools along with cryogenic cooling can be employed for high-speed machining applications. © 2019 The Society of Manufacturing Engineers

Investigation on the performance of AlCrN and AlTiN coated cemented carbide inserts during end milling of maraging steel under dry, wet and cryogenic environments

A monolithic solver based on a diffuse-interface immersed-boundary (IB) approach for conjugate-heat-transfer (CHT) problems is presented. The IB strategy assumes that the solid which is "immersed" into the computational grid is occupied by a "virtual" fluid to facilitate construction of "unified" governing equations that are solved everywhere in the domain. A unified momentum equation is devised using the solid volume fraction that reduces to the Navier-Stokes equation outside of the solid and to the no-slip boundary condition inside of it. The "unified" energy equation is constructed in an analogous fashion reducing to a convective-diffusive equation in the fluid domain and a fully diffusive equation in the solid domain with different thermal conductivities (or diffusivities) for both domains. The resulting equations are solved in both domains simultaneously using a hybrid staggered and nonstaggered finite-volume (FV) framework for incompressible flows. The second-order accurate IB-FV solver is employed to carry out investigations for CHT problems in natural and forced convective regimes. Numerical studies for different fluid-to-solid conductivity ratios show that the monolithic IB-CHT solver is a fast, simple, and accurate framework for simulations of CHT problems for Boussinesq flows. © 2019 American Physical Society.