Research on surface integrity of grinding Inconel718

Inconel718 is widely used in the aerospace industry; the finished surface quality has significant effect on service performance of component. The surface integrity in grinding Inconel718 respectively by using a vitrified bond single alumina (SA) wheel and a resin cubic boron nitride (CBN) wheel were investigated. First, effects of different grinding parameters on grinding temperature and grinding force and grinding chips feature by using a SA and a CBN wheel respectively were investigated. Then, the surface roughness and topography by using a SA and a CBN wheel through single factor experiment were compared, and in the grinding parameters range of the present study, the better surface can be obtained by a SA wheel. Finally, surface integrity by using a SA wheel and the different grinding depth was studied and analyzed by the grinding temperature and the grinding force. It was possible to conclude that better surface can be achieved by using a SA, and taking a _p?=?0.005 mm, v _w?=?16 m/min, v _s?=?25 m/s for grinding Inconel718. In this grinding case, the surface roughness was Ra0.112 μm, the surface residual stress was +700Mpa, and the surface hardness was 440 HV; the depth of residual stress layer was 40～60 μm, the depth of softened layer was 30～40 μm and the depth of plastic deformation layer was 10～15 μm.     

Investigation of surface integrity in dry machining of Inconel 718

Machining of advanced aerospace materials have grown in the recent years although the diffucult-to-machine characteristics of alloys like titanium or nickel-based alloys cause higher cutting forces, rapid tool wear, and more heat generation. Therefore, machining with the use of cooling lubricants is usually carried out. To reduce the production costs and to make the processes environmentally safe, the goal is to move toward dry cutting by eliminating cutting fluids. This objective can be achieved by using coated tool, by increasing cutting speed, and by improving the product performance in term of surface integrity and product quality. The paper addresses the effects of cutting speed and feed on the surface integrity during dry machining of Inconel 718 alloy using coated tools. In particular, the influence of the cutting conditions on surface roughness, affected layer, microhardness, grain size, and microstructural alteration was investigated. Results show that cutting conditions have a significant effect on the parameters related to the surface integrity of the product affecting its overall performance.     

Improving surface integrity in finish machining of Inconel 718 alloy using intelligent systems

In machining of hard materials, surface integrity is one of the major customer requirements which comprise the study of the changes induced to the workpiece. Surface roughness and residual stress are often considered as the most significant indications of surface integrity. Inducing tensile residual stress during the machining processes is a critical problem which should be avoided or minimized to obtain better service quality and component life. This problem becomes more evident in the presence of rough machined surface because fatigue life of manufactured components might be decreased significantly. Inconel 718 superalloy is one of the hard materials used extensively in the aerospace industries. It is prone to tensile residual stress in machined surface. Thus, controlling and optimizing residual stress and surface roughness in machining of Inconel 718 are so needed. Intelligent techniques based on the predictive and optimization models can be used efficiently for this purpose. In this study, the optimal machining parameters including cutting speed, depth of cut, and feed rate were accessed by intelligent systems to evaluate the state of residual stress and surface roughness in finish turning of Inconel 718. The results of experiments and analyses indicated that implemented techniques in this work provided a robust framework for improving surface integrity in machining of Inconel 718 alloy. It was shown that cutting speed has more effect on surface integrity than other investigated parameters. Also, depth of cut and feed rate were found in the moderate range to obtain satisfactory state of tensile residual stress and surface roughness.     

Employing preheating- and cooling-assisted technologies in machining of Inconel 718 with ceramic cutting tools: towards reducing tool wear and improving surface integrity

The International Journal of Advanced Manufacturing Technology - This paper is motivated by the fact that machining of Inconel 718 involves rapid tool wear and poor surface integrity. We...     

Effect of high-pressure cooling on life of SiAlON tools in machining of Inconel 718

High-pressure cooling has proven to be very effective when machining with carbide inserts. Longer tool life and improved chip breaking are among the most commonly mentioned advantages. Nevertheless, this cooling method has been reported to reduce the life of ceramic tools in machining of heat-resistant alloys. The main reason for that is said to be the accelerated notch wear. Therefore, in this study, SiAlON ceramic inserts with improved resistance to notching were tested in machining of Inconel?718 under high-pressure cooling. The results were compared to conventional cooling. It turned out that, while notch wear was still slightly increased when high-pressure cooling was applied, it was no longer critical for the tool life. Flank wear, on the other hand, was reduced, which led to significantly longer tool life. The variation of the tool life appeared to be slightly less and chip breaking was considerably improved. This shows that, when used properly, high-pressure cooling can help to increase the productivity in machining of heat-resistant alloys with ceramic tools.     

Study of surface quality in high speed turning of Inconel 718 with uncoated and coated CBN tools

Inconel 718 is known to be among the most difficult-to-machine materials due to its special properties which cause the short tool life and severe surface damages. The properties, which are responsible for poor machinability, include rapid work hardening during machining; tendency to weld with the tool material at high temperature generated during machining; the tendency to form a built-up edge during machining; and the presence of hard carbides, such as titanium carbide and niobium carbide, in their microstructure. Conventional method of machining Inconel 718 with cemented carbide tool restricts the cutting speed to a maximum 30?m/min due to the lower hot hardness of carbide tool, high temperature strength and low thermal conductivity of Inconel 718. The introduction of new coated carbide tools has increased cutting speed to 100?m/min; nevertheless, the time required to machine this alloy is still considerably high. High speed machining using advanced tool material, such as CBN, is one possible alternative for improving the productivity of this material due to its higher hot hardness in comparison with carbide tool. This paper specifically deals with surface quality generated under high speed finishing turning conditions on age-hardened Inconel 718 with focus on surface roughness, metallographic analysis of surface layer and surface damages produced by machining. Both coated and uncoated CBN tools were used in the tests, and a comparison between surfaces generated by both tools was also discussed.     

Investigation and optimization of lubrication parameters in high speed turning of superalloy Inconel 718

Dry machining is sometimes less effective when higher machining efficiency, better surface finish quality, and severe cutting conditions are required. For these situations, semi-dry operations utilizing very small amount of cutting fluids called minimum quantity lubrication is expected to become a powerful tool and played a significant role in a number of practical applications. It has been observed from the literature survey that a systematic research work has to be carried out to determine the optimum quantity of lubricant with appropriate cutting conditions for achieving better machinability characteristics of a material. Hence, an attempt has been made in this paper to enhance the machinability characteristics in high speed turning of superalloy Inconel 718 using quantity of lubricant, delivery pressure at the nozzle, frequency of pulses, direction of application of cutting fluid, cutting speed, and feed rate as the process parameters. Results indicated that the use of optimized minimum quantity lubrication parameters under pulsed jet mode leads to lower cutting force, cutting temperature, and flank wear.     

The effects of cooling conditions on surface integrity in machining of Ti6Al4V alloy

This paper presents results from a comparative study of machining of Ti6Al4V alloy under dry, minimal quality lubrication, and cryogenic cooling conditions using coated tools at varying cutting speeds and feed rates. The influence of the cooling conditions on surface integrity and the product performance was studied in terms of surface roughness, metallurgical conditions, including microstructure, hardness, grain refinement, and phase transformation of the machined product. Results show that cooling conditions affect surface integrity of the product signifying the benefits of cryogenic cooling in improving the overall product performance.     

Experimental study of surface integrity and fatigue life in the face milling of inconel 718

The Inconel 718 alloy is widely used in the aerospace and power industries. The machining-induced surface integrity and fatigue life of this material are important factors for consideration due to high reliability and safety requirements. In this work, the milling of Inconel 718 was conducted at different cutting speeds and feed rates. Surface integrity and fatigue life were measured directly. The effects of cutting speed and feed rate on surface integrity and their further influences on fatigue life were analyzed. Within the chosen parameter range, the cutting speed barely affected the surface roughness, whereas the feed rate increased the surface roughness through the ideal residual height. The surface hardness increased as the cutting speed and feed rate increased. Tensile residual stress was observed on the machined surface, which showed improvement with the increasing feed rate. The cutting speed was not an influencing factor on fatigue life, but the feed rate affected fatigue life through the surface roughness. The high surface roughness resulting from the high feed rate could result in a high stress concentration factor and lead to a low fatigue life.     

Theoretical and experimental investigations of surface roughness,surface topography,and chip shape in ultrasonic vibration-assisted turning of Inconel 718

Journal of Mechanical Science and Technology - When processing difficult-to-cut materials, conventional turning (CT) typically suffers from the problems of large cutting force, difficult chip...     

Dry friction of steel under high pressure in quasi-static conditions

Measurements were carried out for static and kinetic friction coefficients for steel as a function of the normal pressure for two surface roughness conditions of the matrix: ground and sand blasted. The samples were interstitial free steels, the tests were done at room temperature, in quasi-static and dry contact conditions. Very high pressures were applied in the range of 230–1100 MPa in order to simulate the conditions of testing in severe plastic deformation processes of metals. A new device was designed for this purpose. The results showed a decrease of the friction coefficients with the applied normal stress with stronger dependence for sand blasted surfaces.     

Inconel718与硬质合金摩擦磨损特性的实验研究

利用UMT-2多功能摩擦磨损试验机对镍基合金Inconel 718与硬质合金刀具对偶时的摩擦磨损特性进行研究,揭示法向载荷和滑动速度对摩擦副摩擦因数的影响,通过SEM观察试样摩擦形貌并分析磨损机制.研究结果表明:摩擦副的摩擦因数随着法向载荷的增大而减小,随滑动速度的增大而增大;Inconel 718镍基合金与硬质合金对偶时的磨损机制主要为黏着磨损、磨粒磨损和氧化磨损.     

A new reverse engineering method to combine FEM and CFD simulation three-dimensional insight into the chipping zone during the drilling of Inconel 718 with internal cooling

ABSTRACT

The use of cooling lubricants in metal machining increases both the tool life and the quality of workpieces and improves the overall sustainability of production systems. In addition to fulfilling these main functions, the focus of machining processes is also related to the reduction of environmental pollution. This can for example be achieved by an optimized arrangement of the cutting tool cooling channels. Therefore, the active cutting edges of the tool should be effectively supplied with a sufficient amount of cooling lubricant. An analysis of the tribological stress is rather difficult because the complex contact zone is inaccessible. Hence, optical investigations are often limited to only observing the chip formation or analyzing the process without considering the influence of the chips.

This article presents an innovative method, which enables a deeper three-dimensional insight into the chip formation zone during drilling with internal cooling channels, considering the cooling lubricant distribution and chip formation. The chip formation simulation based on the finite element method and the computational fluid dynamics flow simulation are combined. In this way, the differences between the different geometric models that do not allow any joint generation of numerical information due to missing interfaces are overcome.     

电火花成型加工Inconel 718电极损耗及材料去除率研究

采用正交实验方法用铜电极对Inconel718合金材料进行电火花加工研究,研究了不同的加工参数(电流、周率、效率、间隙电压)对电火花加工Inconel718材料过程中的电极损耗和材料的去除率的影响,并对实验结果进行了主效应分析以及方差分析。结果表明:材料去除率随着电流和周率的增大而增大,电极损耗随着周率的增大而减小。在加工参数电流为10A,周率为100μs,效率为80%,间隙电压20V时获得较高的材料去除率;加工参数在电流为4A,周率为200μs,效率为20%,间隙电压20V时获得较小的电极损耗。     

An analysis of cutting-edge curves and machining performance in the Inconel 718 machining process

When considering the machining of materials used for aircraft components, the principal areas of interest usually include the manufacturing characteristics of the materials when they are machined with different cutting-edge curves, and the development of manufacturing processes that improve the machining precision, thereby reducing the time required to carry out secondary machining operations or error correction of the final component. A further area of concern is to develop manufacturing techniques that are capable of generating highly reliable aircraft components which ensure that flight safety is not compromised through component failure. This paper employs a Taguchi L9 experimental layout to investigate the optimal cutting parameters when machining Inconel 718 with the planar-type conical ball-end cutter, the S-type cutter, and the traditional conical ball-end milling cutter. The current results provide a valuable technical database for aircraft component manufacturers who are seeking to enhance their automatic manufacturing capabilities.     

切削参数与刀具几何形状对Inconel 718加工残余应力的影响

对Inconel 718高速切削加工过程中合金加工表面的残余应力进行研究,为优化材料切削参数提供参考。由试验结果可知,最大切削速度、最小进给量、中等切削深度和使用珩磨切削刃可以确保减少加工表面的残余应力,相应的表面也没有划痕区和粘附的碎屑。     

Single and multiobjective optimization of Inconel 718 nickel-based superalloy in the wire electrical discharge machining

Inconel 718 is widely used in high-temperature environments, high-performance aircraft, and hypersonic missile weapon systems; however, it is very difficult to machine using conventional techniques. This study employed an L9 Taguchi orthogonal array for the analysis of wire electrical discharge machining parameters when used for the machining of Inconel 718. Our aim was to determine the optimal combination of parameters to minimize surface roughness while maximizing the material removal rate. The Taguchi method is widely applied in mechanical engineering with the aim of identifying the optimal combination of processing parameters as they pertain to single quality characteristics. Unfortunately, Taguchi analysis often leads to contradictory results when seeking to rectify multiple objectives. To resolve this issue, this study implemented gray relational analysis in conjunction with Taguchi method to obtain the optimal combination of parameters to deal specifically with multiple quality objectives. For the dual objectives of surface roughness and material removal rate, the optimal combination of parameters derived using gray relational analysis resulted in a mean surface roughness of 2.75 μm. In L9 orthogonal array experiments, run 1 produced the best gray relational grade with mean surface roughness of 2.80 μm, representing an improvement of 1.8%. The material removal rate achieved after the application of gray relational analysis was 0.00190 g/s, whereas the L9 experiment achieved a material removal rate of 0.00123 g/s, representing an improvement of 54.5%.     

Effect of post-heat treatment on the microstructure and mechanical properties of laser metal deposition Inconel 718

Journal of Mechanical Science and Technology - The microstructure, hardness, and fracture strength of Inconel 718 fabricated with laser metal deposition are investigated. The solution treatment...