Comparison between up-milling and down-milling operations on tool wear in milling Inconel 718

The demand for the use of nickel-based superalloy such as Inconel 718 is increasing in aerospace industry as it is efficient for energy and has excellent properties. In this paper, the experimental studies of tool wear mechanism and tool life in ball nose end milling of Inconel 718 is presented under minimum quantity lubricant (MQL) condition. The evaluations of the results are focusing on the comparison of up-milling and down-milling operations using physical vapor deposition (PVD) - coated carbide inserts. Machining parameters; depth of cut, feed rate and cutting speed are considered during the valuation. The experimental results showed that down-milling operation has better results in terms of tool wear than up-milling operation. Chipping on cutting tool edge was the primary reason that responsible to notch wear with prolong machining

Tool life of TiAlN PVD coated carbide tool in high-speed end milling of untreated inconel 718 under minimum quantity lubrication condition

This paper presents the tool life of the end milled Inconel 718, which is part of a material that is difficult to be machined. Previous researchers found that tool life in machining aged Inconel 718 is shorter compared with other materials. However, this observation required further investigation. Thus, a raw grade Inconel was proposed in this experiment. The experiments were performed using TiAlN-coated carbide. The studied milling parameters were the cutting speed, Vc, from 90 to 150 m/min; feed rate, fz, from 0.15 to 0.25 mm/rev; depth of cut, ap, from 0.3 to 0.5 mm; and radial depth of cut, ae=1 mm. The application of the cutting fluid used in this experiment was a minimum quantity lubricant, which had the advantage of cooling effectiveness and low consumption of cutting fluid. The results showed that the feed rate, fz, was the primary factor controlling the tool life. The combination of Vc=115 m/min, fz=0.15 mm/tooth, as well as ap=0.5 mm and ae=0.15 mm gave the longest tool life that served 95.38 min in operation

Tool Life Of TiAlN PVD Coated Carbide Tool In High-Speed End Milling Of Untreated Inconel 718 Under Minimum Quantity Lubrication Condition

This paper presents the tool life of the end milled Inconel 718, which is part of a material that is difficult to be machined. Previous researchers found that tool life in machining aged Inconel 718 is shorter compared with other materials. However, this observation required further investigation. Thus, a raw grade Inconel was proposed in this experiment. The experiments were performed using TiAlN-coated carbide. The studied milling parameters were the cutting speed, Vc, from 90 to 150 m/min; feed rate, fz, from 0.15 to 0.25 mm/rev; depth of cut, ap, from 0.3 to 0.5 mm; and radial depth of cut, ae=1 mm. The application of the cutting fluid used in this experiment was a minimum quantity lubricant, which had the advantage of cooling effectiveness and low consumption of cutting fluid. The results showed that the feed rate, fz, was the primary factor controlling the tool life. The combination of Vc=115 m/min, fz=0.15 mm/tooth, as well as ap=0.5 mm and ae=0.15 mm gave the longest tool life that served 95.38 min in operation

The influence of single-channel liquid CO2 and MQL delivery on surface integrity in machining of Inconel 718

Sustainable machining of difficult-to-cut materials requires effective cooling and lubrication techniques. To substitute conventional flood cooling and lubrication, different techniques such as cryogenic cooling and/or minimum quantity lubrication (MQL) can be used. Liquid carbon dioxide (LCO2) can be pre-mixed with different lubricants before its delivery to the cutting zone. This article investigates the influence of this recently developed cooling and lubrication method on surface integrity characteristics in milling of Inconel 718. Surface roughness, surface topography and microstructure were evaluated for flood lubrication, dry cutting and LCO2 machining using a single-channel LCO2 and MQL strategy. Moreover, two different lubricants were evaluated for MQL: (i) conventional MQL oil and (ii) solid lubricant molybdenum di-sulphide (MoS2). In addition to being environmentally friendly, MoS2 lubricated LCO2 showed comparable surface characteristics to flood lubrication. Also, the use of lubricated LCO2 resulted in higher part surface cleanliness compared to flood lubrication

Effects of milling methods, cooling strategies and end-mill coatings on machinability in high speed end-milling of Inconel- 718 using carbide end-mills

“Inconel-718 superalloy is used extensively in aerospace and nuclear industries due to its excellent properties such as: high strength-to-weight ratio, ability to retain its properties at high temperature, high corrosion and creep resistance. However, Inconel-718 is characterized as a “difficult-to-cut metal”, because it poses severe problems during machining such as: high temperature at the cutting zone due to low thermal conductivity, hardening tendency at elevated temperature, high cutting forces, rapid tool wear and high chemical affinity with many cutting tools. Appropriate cooling strategies, milling methods, tool coatings and cutting speeds play important roles in addressing these problems. This research presents the results of the effects of end-milling methods (Up and down-milling), cooling strategies (Conventional emulsion cooling, Minimum Quantity Lubrication (MQL), Liquid Nitrogen (LN2) and (MQL+LN2)) and tool coatings (Uncoated, AlTiN and GMS2) on cutting forces, cutter tooth frequency, tool wear, chip morphology and surface roughness in high-speed end-milling of Inconel-718 to improve its machinability and reduce cost. Firstly, a comparative investigation of milling methods and cooling strategies using uncoated tools was conducted and analyzed to find better milling method and three best cooling strategies to perform further experiments using coated tools. Results show that down-milling improves machinability. Then, the performance of three tool coatings and three best cooling strategies (MQL, LN2 and (MQL+LN2)), determined from first set of experiments was analyzed. Finally, the best cooling strategy and tool coating were determined for machining Inconel-718 at given parameters. Results show that MQL, an environmentally friendly cooling strategy, improves machinability and can successfully replace conventional emulsion cooling”--Abstract, page iv

Future research directions in the machining of Inconel 718

Inconel 718 is the most popular nickel-based superalloy, extensively used in aerospace, automotive and energy industries owing to its extraordinary thermomechanical properties. It is also notoriously a difficult-to-cut material, due to its short tool life and low productivity in machining operations. Despite significant progress in cutting tool technologies, the machining of Inconel 718 is still considered a grand challenge.This paper provides a comprehensive review of recent advances in machining Inconel 718. The progress in cutting tools’ materials, coatings, geometries and surface texturing for machining Inconel 718 is reviewed. The investigation is focused on the most adopted tool materials for machining of Inconel 718, namely Cubic Boron Nitrides (CBNs), ceramics and coated carbides. The thermal conductivity of cutting tool materials has been identified as a major parameter of interest. Process control, based on sensor data for monitoring the machining of Inconel 718 alloy and detecting surface anomalies and tool wear are reviewed and discussed. This has been identified as the major step towards realising real-time control for machining safety critical Inconel 718 components. Recent advances in various processes, e.g. turning, milling and drilling for machining Inconel 718 are investigated and discussed. Recent studies related to machining additively manufactured Inconel 718 are also discussed and compared with the wrought alloy. Finally, the state of current research is established, and future research directions proposed.<br/

A Review of Cooling and Lubrication Techniques for ‎Machining Difficult-to-cut Material

Superalloys have magnificent properties which make them widely applied in various industrial fields. They possess high mechanical properties such as high strength, high rupture resistance, and high resistance to corrosion and oxidation. Since they can maintain these properties even at elevated temperatures, they face some problems during the cutting and machining process. They are classified as difficult-to-cut alloys, which means that high heat is generated in the cutting zone due to their poor thermal conductivity. In addition, high friction takes place between the tool and the chip. To overcome these problems during their machining process, different cooling and lubrication techniques via suitable cutting fluids are highly recommended. In this study, we review the cooling and lubrication techniques that have been applied by authors in machining superalloys such as dry machining, flood cooling, high-pressure jet machining, minimum quantity lubrication and cooling, and cryogenic machining. The technique of each type followed by its advantages and disadvantages are mentioned

Machining of Inconel 718 nickel-based superalloy using nano-lubricants and liquid nitrogen

Utilization of cutting fluid incorporating graphene nanoplatelets (GNP) as well as application of liquid nitrogen (LN2) to the cutting area were investigated in drilling and turning of Inconel 718 iron-nickel-based superalloy in order to improve their machinability and reduce the use of mineral-based cutting fluids. The methodology was developed to establish correlations between the tribological properties of the surfaces and the role of interfacial friction on machining properties and understanding the improvements in machining from a microstructural point of view. In addition, response surface methodology (RSM) was employed to systematically optimized the cutting parameters. The results are presented in two parts: In ‎Chapter 3, a cutting fluid (CF) consisting of 70% water and 30% vegetable oil blended with GNPs was used in order to improve drilling performance of Inconel 718 alloy. The results showed that sliding of Inconel 718 workpiece using WC-Co drills with CF containing 54×10-5 wt.% graphene (GCF) reduced the coefficient of friction (COF) between the tool and workpiece surfaces from 0.16 to 0.08 as a result of formation of tribolayers on the sliding surfaces. A Similar tribolayer was observed when drilling under GCF condition which resulted in lower cutting torque and temperature, leading to lower surface roughness and subsurface microstructural deformation compared to conventional flooded and dry conditions. In ‎Chapter 4, turning experiments were conducted on the Inconel 718 using a stream of liquid nitrogen, and the effects of different cutting speed, feed rate and depth of cut values on the response factors, namely flank wear, cutting force and Ra surface roughness were investigated. Cryogenic cutting reduced flank wear compared to dry cutting, to values comparable to wear during flooded cutting. The results revealed that there could be an optimum set of values in which cryogenic cutting can provide a performance equivalent to the flooded cutting. Thus, experiments were designed according to RSM under cryogenic condition. Statistical analyses showed that cutting speed was the most influential parameter on flank wear and cutting force during cryogenic turning and a cutting speed of 81 m/min, a feed rate of 0.06 mm/rev and a depth of cut of 0.63 mm constituted the optimum set of cutting parameters considered in this investigation. Higher cutting speed and feed rate values can be used during the machining process by using a GNP-blended vegetable-based oil to shorten the cutting time, and thus, reduce the usage of cutting fluid for production of each part. Moreover, it was shown that complete omission of cutting fluid during the machining process would be feasible by employing cryogenic cutting. Liquid nitrogen evaporates after contacting the tool and workpiece surfaces leaving no contamination which eliminates the cleaning, recycling, and deposal costs after the machining process

Machinability of Waspaloy under different cutting and lubri-cooling conditions

Nickel-based super alloys are widely employed in critical applications, mainly in aerospace, marine, and chemical industries, concerning the production of high-performance artifacts. These alloys are considered as hard-to-cut materials, because of their modest machinability, so it is very difficult to implement in an industrial context high-speed machining processes that can lead to higher quality products, with improved mechanical characteristics and higher dimensional accuracy, and increase productivity. Among these alloys stands out Waspaloy, thanks to its very high mechanical properties, such as stiffness and strength to weight ratio. In order to implement effective machining processes, it is important to analyze the behavior of the material during machining in terms of variables of industrial interest (forces, tool wear, etc.). The aim of this paper is to disclose the results of an experimental investigation aimed to determine the effects of different cutting parameters on cutting forces, chip morphology, tool wear, and temperature at tool-chip interface, during orthogonal machining of Waspaloy (45 HRC). Experiments were performed in different lubri-cooling conditions (dry, wet, and cryogenic) and at varying cutting conditions (cutting speed and feed rate)