Performance Study of Surface Integrity of Inconel 625 by DoE Approach During WEDM Machining

In recent times, nickel-based super alloys are widely utilized in aviation, processing, and marine industries owing to their supreme ability to retain the mechanical properties at elevated temperature in combination with remarkable resistance to corrosion. Some of the properties of these alloys such as low thermal conductivity, strain hardening tendency, chemical affinity, and presence of hard and abrasives phases in the microstructure render these materials very difficult-to-cut using conventional machining processes. In this work, an experimental setup was developed and integrated with the existing electrical discharge machining system for carrying out powder-mixed electrical discharge machining process for Inconel 625. The experiments were planned and conducted by varying five different variables, that is, powder concentration, peak current, pulse-on time, duty cycle, and gap voltage based on the central composite design of response surface methodology. Effects of these parameters along with powder concentration were investigated on various surface integrity aspects including surface morphology, surface roughness, surface microhardness, change in the composition of the machined surface, and residual stress. Results clearly indicated that addition of powder to dielectric has significantly improved surface integrity compared to pure dielectric. Among the powders used, silicon has resulted in highest microhardness, that is, almost 14% more than graphite. Lowest surface roughness (approximately 50% less than pure kerosene) and least residual stress were obtained using silicon powder (approximately 8% less than graphite-mixed dielectric). Relative content of nickel was reduced at the expense of Nb and Mo after addition of powders like aluminum and graphite in dielectric during electrical discharge machining.

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Performance Study of Cryo-Treated End Mill Via Wet, Cryogenic, and Hybrid Lubri-Coolant-Milling Induced Surface Integrity of Biocompatible Mg Alloy AZ91D

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/09544062211017160 ◽

2021 ◽

pp. 095440622110171

Author(s):

Rahul Davis ◽

Abhishek Singh

Keyword(s):

Surface Integrity ◽

Sustainable Manufacturing ◽

Cutting Tools ◽

Cutting Speed ◽

Complete Healing ◽

Mg Alloys ◽

End Mill ◽

Performance Study ◽

High Cutting Speed ◽

Coated Cemented Carbide

The excellent biodegradability of the magnesium (Mg) alloys is gradually proving them as the potential substitutes to several biomedical implants such as chemotherapy ports or screws, which are required to be removed via secondary surgeries after a specific period of time. However, an early degradation of these alloys even before the complete healing of the damaged tissue, when exposed to the physiological atmosphere, has been limiting their full-fledged application. Some latest research articles suggest that such challenges can be effectively overcome by improving the surface integrity of Mg alloys using the sustainable manufacturing techniques, such as cryogenic machining. Recent literatures also report the outperformance of the cryogenically treated (cryo-treated) cutting tools for achieving an enhanced surface integrity. In this relation, the present research attempts to improve the surface integrity of one of the most commonly used biocompatible alloys of magnesium, known as AZ91D. For this reason, a TiAlN coated-cemented carbide end mill was used in an untreated and cryo-treated state amid wet, cryogenic, and hybrid-lubri-coolant-milling conditions. The milling and FESEM (field emission scanning electron microscopy) results showed a considerable improvement in the surface integrity in terms of an augmented surface roughness and microhardness at 56.52 m/min cutting speed with the cryo-treated end mill during hybrid-lubri-coolant-milling. At the high cutting speed hybrid-lubri-coolant-milling, the cryo-treated end mill attained 35.71% and 48.07% better surface finish than that of cryo and wet-lubri-coolant-milling, respectively. Although, the highest surface microhardness was achieved by the cryo-treated end mill amid cryo-lubri-coolant-milling, due to the poorest surface quality observed in terms of the maximum number of machining-induced cracks, the hybrid-lubri-coolant-milled surface was preferred over the cryo and wet-lubri-coolant-milled surfaces. Further, the FESEM and EDS (energy-dispersive X-ray spectroscopy) analyses confirmed the oxide layer produced by the cryo-treated end mill amid hybrid-lubri-coolant-milling, to be the thinnest (12.16 µm) and most uniform passivation layer.

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Effect of Machining Parameters on Surface Integrity in End Milling of Inconel 625

Advances in Forming, Machining and Automation - Lecture Notes on Multidisciplinary Industrial Engineering ◽

10.1007/978-981-32-9417-2_42 ◽

2019 ◽

pp. 505-515

Author(s):

Ramesh Rajguru ◽

Hari Vasudevan

Keyword(s):

Surface Integrity ◽

End Milling ◽

Inconel 625 ◽

Machining Parameters

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Influences of cryogenic CO2 and LN2 on surface integrity of inconel 625 during face milling

Materials and Manufacturing Processes ◽

10.1080/10426914.2021.1914850 ◽

2021 ◽

pp. 1-11

Author(s):

R. Anburaj ◽

M. Pradeep Kumar

Keyword(s):

Surface Integrity ◽

Face Milling ◽

Inconel 625

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Investigation of the Impact of Cutting Parameters on Surface Integrity in the End Milling of Inconel 625

Materials Science Forum ◽

10.4028/www.scientific.net/msf.969.762 ◽

2019 ◽

Vol 969 ◽

pp. 762-767 ◽

Cited By ~ 2

Author(s):

Ramesh Rajguru ◽

Hari Vasudevan

Keyword(s):

Residual Stresses ◽

Surface Integrity ◽

Cutting Parameters ◽

Rake Angle ◽

Inconel 625 ◽

Micro Hardness ◽

Machined Surface ◽

Radial Rake Angle ◽

Radial Depth ◽

The Impact

Nickel based super alloys, such as Inconel 625 is amongst the most difficult to machine, due to its low thermal conductivity and high strength at higher temperature. Although, they are used in aerospace exhaust systems and other applications, the strain hardening that results during the machining operation, which adversely affects surface integrity of machined surface of such materials especially in extensive applications, is a cause for concern. In this context, this study was carried out, involving the milling operation, using solid carbide tools coated with TiAlSiN, under specifically developed conditions for dry machining of the difficult to cut materials. The cutting parameters were 4 in number, namely radial rake angle, feed per tooth, cutting speed and radial depth of cut and the response parameters included surface integrity characteristics, such as residual stresses, surface roughness and micro-hardness. Based on the experimental analyses, it was found that the micro-hardness of machined surface was higher. Micro hardness of sub surface decreases with the depth (50,100,150,250μm) due to a reduction in the work hardening of the Inconel 625, underneath the surface layer. The residual stresses were analyzed using main effect plot, and it was seen that the residual stresses were significantly influenced by the radial rake angle, followed by feed per tooth.

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