Percorrer por autor "Gangopadhyay, Soumya"
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- Investigating the effect of novel self-lubricant TiSiVN films on topography, diffusion and oxidation phenomenon at the chip-tool interface during dry machining of Ti-6Al-4V alloyPublication . Kumar, Ch Sateesh; Urbikain, Gorka; de Lacalle, Luis Norberto López; Gangopadhyay, Soumya; Fernandes, FilipeMachining of titanium alloys such as Ti-6Al-4 V can be very intimidating due to their low thermal conductivity leading to elevated cutting temperatures at the chip-tool interface (ICT). In this regard, the self-lubrication effect of coatings like TiSiVN represented by topography, oxidation, and diffusion at the chip-tool interface are crucial. Thus, the present work investigates the latter three mechanisms during dry machining of Ti-6Al-4 V titanium alloy with uncoated and TiSiVN coated Al2O3/SiC whiskers-reinforced ceramic cutting tools. The results reveal that the adhesion height (AH) and O% increases with cutting temperature, showing the dominant influence of cutting temperature on material adhesion and oxidation levels at the ICT. AH increases with increased cutting speed for both coated tools, indicating that the crater depth increment was not so severe for the coated tools. However, a drastic upward surge of crater depth for uncoated and TiSiN coated tools at 125 m/min cutting speed makes the crater edge near the ICT act as a chip breaker and facilitates the chip’s bending away from the tool face causing reduction in chip bend angles (BA). Additionally, the TiSiVN coating accounts to a reduction of approximately 23% in AH and 18% in Ti%, and 37% lower oxygen levels at the highest cutting speed when compared to the uncoated tool primarily due to lower cutting temperatures and self-lubricating behavior.
- Investigating the self-lubricating properties of novel TiSiVN coating during dry turning of Ti6Al4V alloyPublication . Kumar, Ch Sateesh; Urbikain, Gorka; De Lucio, Pablo Fernández; De Lacalle, Luis Norberto López; Pérez-Salinas, Cristian; Gangopadhyay, Soumya; Fernandes, FilipeThe machining of titanium alloys like Ti6Al4V has been challenging owing to their low thermal conductivity, making them highly difficult-to-cut. Many techniques have been adopted to improve machinability of Ti6Al4V titanium alloy and the durability of the cutting tools during its machining. Thus, to improve their machinability, the current work investigates the applicability of TiSiVN self-lubricating coating deposited on Al2O3–SiC ceramic cutting tools during continuous turning of Ti6Al4V alloy under dry cutting environment. The TiSiVN coating accounted for lower surface roughness and cutting temperatures under all conditions. Due to the formation of V2O5 at high temperatures that were observed during oxidation and machining tests in EDS and Raman spectroscopy, the TiSiVN coating helped in reducing friction and, thus, retained the crater wear area. In contrast, the worn area on the crater surface reduced for uncoated and TiSiN coated cutting tools due to a significant increase in nose depth decrement with increasing cutting speed. Furthermore, increased nose depth decrement resulted in the drop of machining forces when using TiSiN coated and uncoated cutting tools. However, the coating delamination due to oxidation was apparent which reduced the effectiveness of lubricious phases present in the cutting zone for TiSiVN coated tool.
- Performance evaluation of CrAlNAg-coated inserts with varying Ag content during roughing and finishing operations in face millingPublication . Fernandes, Filipe; Rajput, Sumit Singh; Upadhyay, Chandramani; Gangopadhyay, SoumyaThe performance of a novel hard solid lubricant coating, CrAlNAg, in the face milling operation of AISI 1045 medium carbon steel under the modes of roughing and finishing was investigated. Dry machining was carried out using CrAlN coated inserts with varying silver (Ag) contents ranging from 0 to 16 at.%. The objective was to evaluate the performance of the developed coatings under different machining conditions, which could potentially result in (a) a high material removal rate (rough machining) and (b) high surface finish and dimensional accuracy (finish machining). An in-depth analysis of the cutting forces in face milling was performed to assess the impact of the coatings under these machining conditions. During machining, the force components in the X, Y, and Z directions were measured using a cutting force dynamometer attached to the workpiece. The components of these forces concerning the tool edge were calculated using geometrical characteristics and mathematical formulations, enabling the identification of the true cutting forces and the most sensitive force components relative to the cutting parameters. Apart from cutting forces, chip temperature, tool wear, surface roughness, and chip characteristics were evaluated for different coating compositions under both machining conditions. Owing to superior coating-substrate adhesion and tribological characteristics, the CrAlNAg9 coating with around 8.6 at.% of Ag was found to significantly reduce dominant forces and chip temperature under both machining conditions. Furthermore, the same coating exhibited remarkable resistance to flank wear compared to other compositions of CrAlNAg coatings.