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

The present work is aimed at in-process estimation of surface roughness using cutting parameters along with cutting force, sound, and vibration in turning of Inconel 718 with cryogenically treated and untreated carbide inserts Initially, prediction models are developed by regression analysis using only cutting parameters and then using only force, sound, and vibration Later on, these models are modified to include all the parameters after performing correlation analysis for determining significant parameters The modified models are developed using only significant parameters from the cutting parameters and measured responses The prediction results of modified regression models are compared with experimental results and fine association of fit between measured and estimated surface roughness is confirmed Based on coefficient of determination (R
 2) values, the regression models are found to be better for estimating surface roughness Finally, it is found that modified regression models are estimating surface roughness with more than 90% accuracy which can be said as acceptable for the two types of inserts used Use of sound emitted while machining along with values of cutting parameters, force, and vibration to predict surface roughness has not been reported earlier particularly for Inconel 718 As cutting force, sound, and vibration can be measured during the turning process, this method can be useful for real-time control of the process to get the desired surface roughness for machining of difficult to cut material like Inconel 718

Estimation of surface roughness using cutting parameters, force, sound, and vibration in turning of Inconel 718

Sustainability is a vital issue for present and future generation, and it aims to obtain overall efficiency in terms of economic, environmental and social aspects. Inconel 825 belongs to the family of nickel-based super alloy and is widely used in the chemical and marine industries. This work attempts to investigate machining performance of Inconel 825 using physical vapor deposition-titanium nitrate inserts, with a focus on sustainable machining. The effect of cutting parameters, viz. cutting speed (v), feed (f) and depth of cut (d) on three aspects of sustainability has been explored in two different machining environments, viz. dry and minimum quantity lubrication (MQL). The experimental results show a significant improvement in MQL machining and tool wear, and cutting power is reduced by 16.57 and 8.47%, respectively, and surface roughness is improved by 10.41%. The interacting effects of parameters on responses are studied using 3-D surface plots; it shows cutting speed and feed are found as dominating parameters on all the three responses. The novelty of this work is to optimize the process for the sustainable production of components by optimizing the process parameters with multiple and conflicting objectives. The sustainable optimization using genetic algorithm provides surface roughness (Ra) as 0.49 µm, tool flank wear (VB) as 110.68 µm and cutting power (P) as 5.44 kW with better convergent capability having 4% deviation. For the application of manufacturing industry, an optimization table is generated for selection of optimum process parameters for achieving desired surface roughness with minimum VB or minimum P.

Sustainable machining: an experimental investigation and optimization of machining Inconel 825 with dry and MQL approach

Plentiful supply of coolant might enhance the machining cost and also generates environmental hazard. As a result, substitute methods are required to eliminate the problems encountered during use of coolant. In this investigation, the impact of cutting speed, feed and lubrication conditions (dry: no lubrication, oil: machining is performed with groundnut oil and nano fluid: machining performed with copper nano fluid) on surface roughness, tool wear and chip morphology in turning of H 11 steel with minimum quantity lubrication (MQL) were examined. Experiments were conducted using L18 orthogonal array. The results reveal that copper nanofluids with MQL provide a substitute for dry and oil machining. Response surface methodology has been used to derive optimal values and mathematical models. Tool wear was reduced by 66% and surface roughness by 40% while machining with copper nano fluids. The surface roughness and tool wear were decreased under optimal machining conditions. Generation of large notched tooth in chips has been minimised with copper nano fluids. Furthermore, the morphology of the chips were analysed for dry, oil and nano fluid under scanning electron microscope to observe the texture created.

Experimental investigation of copper nanofluid based minimum quantity lubrication in turning of H 11 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.

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

The hardened 18 % nickel maraging steels find potential application as an engine component for heavy vehicles and as armour metal in defence. The task lies in obtaining a good surface finish and minimal tool wear in hard machining of this high-strength material in a solution annealed and aged condition. The present work reports the optimal machining condition to obtain a good surface finish and lesser width of flank wear land during hard turning of maraging steel. The cutting speed, feed rate, and depth of cut are identified as the dominant parameters influencing the process responses. The working ranges of these machining parameters are set through the design of experiments, and an L27 orthogonal array is used for conducting the machining trials in a CNC lathe using cubic boron nitride (CBN) cutting inserts. The surface roughness is measured using a surface profilometer, while the width of flank wear land is found out using a video measuring system. The grey-based response surface methodology is used for analysis. A lower value of surface roughness (0.434 µm Ra) and lesser flank wear (0.0234 VBmax, mm) is obtained at optimal machining condition (cutting speed 174.28 m/min, feed rate 0.01 mm/rev, and depth of cut 0.3549 mm). Atomic force microscopy (AFM) images and P-profile graphs of machined surface are also examined. Furthermore, the temperature distribution is also simulated for the optimal machining condition using the DEFORM 3D software.

S. Siddharth

Papers

An investigation on surface finish and flank wear in hard machining of solution treated and aged 18 % Ni maraging steel