I declare that this thesis entitled “Prediction of ToolWearCharacteristics in Turning on Inconel718: Experimentation and Simulation” is the result of my own research except as cited in the references. The thesis has not been accepted for any degree and is not concurrently submitted in candidature of any other degree.
In aerospace applications Nickel-based super alloys are widely used due to their magnificent corrosion resistance and mechanical properties maintained at high temperature. Especially Machining of Ni based alloys is still a challenge in dry machining. Super alloys characteristics like high temperature, tensile strength, shear strength, strain hardening, decrease in thermal conductivity, built up edge formation and the occurrence of abrasive particles in their microstructures etc. are induce high thermo-mechanical loads at the tool-chip interface resulting in important wear of the tool . Cemented carbide inserts were not suitable to machine Ni based alloys at high speed since they cannot survive the conditions of acute high temperature and stress in the cutting zone. In general, the suggested range of cutting speeds up to 30 m/min for uncoated tools and up to 100 m/min when machining Ni-based alloys using cemented carbide inserts properly coated . Ceramic tools have been used gradually more In metal-cutting processes toolwear is a complex phenomenon occurring in various ways.
Inconel718 is well known as a difficult-to-cut material, so usually there is higher cutting force acting on the Inconel718 during the machining as compared to other less harder material (Devillez, Schneider, Dominiak, Dudzinski, & Larrouquere, 2007). The higher cutting force will cause the material to have higher surface microstructure dislocation especially in normal milling and turning machines (Thakur, et al., 2009). Therefore, the high speed machining (HSM) is introduced in order to reduce the cutting force on the cutting tool. The HSM was claimed low cutting force during the machining operation. The depth of cut, feed rate and cutting speed are those several factors which act as main parameters of machining (Soo, Aspinwall, & Dewes, 2004). These parameters are very important in machining process to obtain a good surface finish. During the machining operation of Inconel718, several of cutting force will produce due to change in the cutting parameter. The major problem faced by machinist during HSM of super alloys is short tool life. The force acting on the cutting tool leads to short tool life. The range of cutting tool life span is between 0.5min to 90min (Huang & Liang, 2005). According to (Qian & Hossan, 2007) stated that, notch wear, pitting, chipping, flanking are associated with cutting force.
Abstract: Superalloy, Inconel718 is used for manufacturing components in most of the advanced and critical application due to its superior properties .Surface quality of machined component play a vital role in function characteristics and life of product .Due to its peculiar characteristics machining of superalloy Inconel718 is difficult and costly .The present work is an attempt to make use of taguchi optimization technique to optimize cutting parameters during high speed turning of Inconel718 using tungsten carbide cutting tool .Taguchi method is a powerful design of experiment tool for engineering optimization of a process .It is an important tool to identify the critical parmeters. Anaysis of variance is used to study the effect of process parameters and established correlation among the cutting speed, feed and depth of cut with respect to Ra and toolwear. The result are further confirmed by experiments.
Productivity plays significant role in manufacturing market. The manufacturing industries are continuously challenged for achieving higher productivity with lesser time with high quantity products. In current state of economy and consequent market pressure has formed manufactured to simultaneously decrease the surface roughness affects wear resistance, ductility, tensile strength, fatigue strength etc. Cutting parameters (speed, feed, depth of cut) cutting speed has the highest impact on the surface roughness. Cutting speed is defined has the speed at which the work piece progress with respect to the cutting tool. Feed rate is defined as the distance the tool travels during one revoluation of part. Depth of cut is the distance that tool bit moves into the work. Usually measures in the thousands of an inch in millimetres. Turning process is used in the experimentation. Turning is one of the common metal cutting operation used for machining parts in manufacturing industry. In turning process surface quality is one of the most important performance measures. Surface roughness (Ra) is a widely index of product quality and in most cases a technical requirement for mechanical products.
Inconel718 is a nickel-based heat resistant super-alloy (HRSA) that is widely used in many aerospace and automotive applications. It possesses good properties like corrosion resistance, high strength, and exceptional weld-ability but it is considered as one of the most difficult alloys to cut. Recently researchers have focused on employing many machining strategies to improve machinability of Inconel718. This research work presents the experimentation of wet milling of Inconel718 using a carbide tool with biodegradable oil. Surface quality is the major aspect of machinability. Hence input parameters such as depth of cut, cutting speed, and feed rate are considered to study their effect on surface quality. Nine experimental runs based on an L9 orthogonal array are performed. Additionally, analysis of variance (ANOVA) is applied to identify the most significant factors among cutting speed, feed rate, and depth of cut. Moreover, this research work presents the Artificial Neural Network (ANN) model for predicting the surface roughness based on experimental results. The ANN based-decision-making model is trained by using acquired experimental values. Visual Gene Developer 2.0 software package is used to study the efficiency of ANN. The presented ANN model demonstrates a very good statistical performance with a high correlation and extremely low error ratio between the actual and predicted values of surface roughness and toolwear.
Allaudin et al.  modelled the cutting forces and observed that cutting force increase with an increase in feed and axial depth of cut. Flank and crater wear are the two main wear mechanisms that limit cutting tool performance. Flank wear is caused when the relief face of the tool rubs against the machined surface and on other hand crater wear occurs on the rake face of the tool and affects the geometry at the chip tool interface, which in turn affects the cutting force . Pavel et al. performed a number of experiments to investigate effect of toolwear on surface produced and observed that as flank wear increases with cutting time, machined surface became rougher. Also according to the ISO 8688-2, the tool rejection criteria of averaged flank wear 0.3 mm is used for tool replacement during machining . Tool life in turning and drilling of nickel alloys is widely investigated. Hence, tool life in milling has limited attention. Life of uncoated tools for machining of Inconel is very short as compared to the coated tools, also it is realized that very little work is done on analytical modelling of toolwear progression of the end milling cutters. Thus, the main focus of this research is to analyze the effect of progression of flank wear using nitrided tungsten carbide flat end milling cutter on surface produced.
A high nickel alloy is well known as a difficult-to-cut material. Nickel alloys work hardens rapidly. The high pressures produced during machining cause a hardening effect that makes further machining more difficult, and may also cause warping in small parts. Severe tool injury usually occurs in machining nickel alloys. Rapid toolwear in machining has long been recognized as a challenging problem [Ouh (1983), Zlatin (1975)]. So far, researches conducted for the machining of Inconel718 are mainly focused on machining characteristics [Komanduri(1986)], and the appropriate tool material, geometry, and cutting conditions for machining. There are several studies on the machining of nickel base alloys by ceramics in recent years [Narutaki et al (1993) Vigneau et al (1987)]. Comparatively, very few have been done to identify toolwear mechanism during machining of Inconel718.
The main challenge in machining is increasing productivity while maintaining products quality (Devillez et al ., 2007). In order to achieve the requirements, optimum parameters have to be selected. Many parameters are depending on the temperature during cutting such as cutting speed, tool life and mechanics of chip formation. Nevertheless, criteria such as tool life and cutting forces should not be neglected. A lot of cutting experiments need to be carried out to find the optimum parameters. It not only costs a lot but also time consuming. Therefore, finite element method is used to run the simulations.
The objective of this study was to investigate the influence of forging parameters on the microstructure uniformity and smallness in to improve mechanical properties of heavy forgings. To achieve these goals the following steps were taken into account. First, the microstructure objective function was defined and the forging parameters were defined. Then, an appropriate orthogonal array was constructed. After the above steps, proper constitutive equations and micro- structural models were implemented into Abaqus simulation software and finite element simulations were performed based on the arrangement of orthogonal array. Additionally, the results of the simulations were transferred into the Ta- gushi signal-to-noise (S/N) ratio. By doing this an optimum and poorest combi- nations of forging parameters were obtained. Finally, variance analysis (ANOVA) was performed to determine the significance of each parameter under investigation.
Surface roughness of the components or products is one of the important parameter in the engineering which is can represent the quality of the products. According to Rodriguez (2011), surface roughness has important role in the daily activities because the friction and wear in two solids sliding against each other are occurred frequently. Therefore, minimizing the surface roughness is very important in various industries such as automotive and aerospace. In EDM, many factors affecting the surface roughness such as, current, pulse on-time, pulse of-time and voltage. Surface roughness also affected by the type of working tool and workpiece used (S.Ahmad, 2013).
performed at 625 C, well below the temperatures studied in the present work (and thus out of the superplastic range), their study reveals the strong inﬂuence that precipitation on boundaries has on grain boundary sliding. The size of particles is critical and in their opinion stress concentration around small particles is relaxed by diﬀusion and by power- law dislocation creep for bigger particles. Other studies have pointed out that this argument can be extrapolated to the superplastic deformation region of ﬁne grain INCONEL718. 23) The hindering or even the inhibition of GBS by grain
one of the most fundamental cutting processes used. Surface roughness and Material Removal Rate are the main quality functions in turning of Inconel718 in dry conditions. The present work focuses on an experimental study to find the effects of insert nose radius and cutting parameters on surface roughness and material removal rate. The optimization of two response parameters (Surface roughness and Material Removal Rate) by four machining parameters (cutting speed, feed rate, depth of cut and nose radius) is investigated for better surface finish and high Material Removal Rate (MRR) during turning of Inconel718. A combined Taguchi method and Grey Relational Analysis (GRA) is used for the optimization. Analysis of Variance (ANOVA) is employed to find out contribution of each parameter. Four parameters are chosen as process variables: cutting speed, feed rate, depth of cut and nose radius each at three levels. The experiment plan is designed using Taguchi’s L9 Orthogonal Array (OA). Minitab statistical software is employed to create the plan and carrying out the analysis. The effects of various parametric combinations on the turning process are studied and an optimization strategy for a given set of parameter combination for better surface finish of the turned product is developed. The results show that feed rate and nose radius are the most important parameters that affect the surface finish and Material Removal Rate (MRR) in CNC turning process is greatly influenced by depth of cut followed by cutting speed. A prediction model is also developed separately for both surface finish and MRR using multiple regression analysis.
cutting speed, which had the most influence on the temperature . Many of the economic and technical problems of machining are caused directly or indirectly by this heating action. Excessive temperatures directly influence the temperatures of importance to toolwear on the tool face and tool flank and inducing thermal damage to the machined surface . All these difficulties lead to high toolwear, low material removal rate (MRR) and poor surface finish . In actual practice, there are many factors which affect these performance measures, i.e. tool variables (tool material, nose radius, rake angle, cutting edge geometry, tool vibration, tool overhang, tool point angle, etc.), workpiece variables (material, hardness, other mechanical properties, etc.) and cutting conditions (cutting speed, feed, depth of cut and cutting fluids). Many papers has been published in experimental based to study the effect of cutting parameters on surface roughness [4, 5], toolwear , machinability , cutting forces , power consumption , material removal rate . So it is necessary to select the most appropriate machining settings in order to improve cutting efficiency. Generally, this optimum parameter selection is determined by the operator’s experience knowledge or the design data book which leads to decrease in productivity due to sub-optimal use of machining capability this causes high manufacturing cost and low product quality [11, 12].
Abstract: Inconel718 is a superalloy, considered one of the least machinable materials. Tools must withstand a high level of temperatures and pressures in a very localized area, the abrasiveness of the hard carbides contained in the Inconel718 microstructure and the adhesion tendency during its machining. Mechanical properties along with the low thermal conductivity become an important issue for the toolwear. The finishing operations for Inconel718 are usually performed after solution heat treatment and age hardening of the material to give the superalloy a higher level of hardness. Carbide tools, cutting fluid (at normal or high pressures) and low cutting speed are the main recommendations for finish turning of Inconel718. However, dry machining is preferable to the use of cutting fluids, because of its lower environmental impact and cost. Previous research has concluded that the elimination of cutting fluid in these processes is feasible when using hard carbide tools. Recent development of new PCBN (Polycrystalline Cubic Boron Nitride) grades for cutting tools with higher tenacity has allowed the application of these tool grades in the finishing operations of Inconel718. This work studies the performance of commercial PCBN tools from four different tool manufacturers as well as an additional grade with equivalent performance during finish turning of Inconel718 under dry conditions. Wear tests were carried out with different cutting conditions, determining the evolution of machining forces, surface roughness and toolwear. It is concluded that it is not industrially viable the high-speed finishing of Inconel718 in a dry environment.
Another case study was conducted  on strategies of measure concerning free-form surfaces which may be used during in-process measurements of a workpiece on a CNC milling machine. In addition, it shows some supplement to conventional strategy of measurements of free-form surfaces directly on CNC machine tools are propose, considering such variable factors as the real working length and real working radius of applied milling cutter as well as its wear. Results of experimental and numerical investigations are presented which show how toolwear and small changes of real working length and real working radius of applied milling cutter influence the shape and accuracy of machining a work piece containing some free-form surfaces. The investigations made in this work concerned the determination of the changes of real working length of applied tool and its real offset radius as well as toolwear in the process of machining of free-form surfaces. The obtained results of performed investigations show, that collected information from both numerical simulations and experimental investigations is helpful for establishing the measurement strategy of free-form surfaces.
Gear hobbing is an efficient method to manufacture high quality and performance toothed wheels, although it is associated with complicated process kinematics, chip formation and toolwear mechanisms. The variant cutting contribution of each hob tooth to the gear gaps formation might lead to an uneven wear distribution on the successive cutting teeth and to an overall poor tool utilization. To study quantitatively the toolwear progress in gear hobbing, experimental-analytical methods have been established. Gear hobbing ex- periments and sophisticated numerical models are used to simulate the cutting process and to correlate the undeformed chip geometry and other process parameters to the expected toolwear. Herewith the wear development on the individual hob teeth can be predicted and the cutting process optimized, among others, through appropriate tool tangential shifts, in order to obtain a uniform wear distribution on the hob teeth. To determine the constants of the equations used in the toolwear calculations, fly hobbing experiments were conducted. Hereby, it was necessary to modify the fly hobbing kinemat- ics, applying instead of a continuous tangential feed, a continuous axial one. The experi- mental data with uncoated and coated high speed steel (HSS) tools were evaluated, and correlated to analytical ones, elaborated with the aid of the numerical simulation of gear hobbing. By means of the procedures described in this paper, toolwearprediction as well as the optimization of various magnitudes, as the hob tangential shift parameters can be carried out. 关DOI: 10.1115/1.1430236兴
exceeded the reference case and they were not suitable for cutting Inconel718 at this cutting speed (Fig. 2). The EDS (electron-dispersion spectroscopy) analyses were obtained using a scanning electron m icroscope in order to determ ine the chem ical elements present in the cutting tools (Fig.3, Fig. 4, and Table 5). From the EDS results we can see that the composition contains mainly Si, Al and C for the KYON 2100 SNGN tool, and that this cutting tool is subj ected to general BUE and crater wear. The KY ON 4300 SNGN cutting tool, having Al, O and Si in its structure, showed better performance at low cutting speeds, as shown in Fig. 2. The other inserts, KYON 2000 R N G N 12 07 00 and KYON4300 R N G N 120700, did not show a satisfactory performance. The KYON 2000 RNGN ceramic tool showed excessive wear compared to the other inserts (Fig. 2 and Fig.5). From the EDS analysis o f this cutting tool, one can see that the levels o f Si and Al are very high (Fig. 3), which contributes to the notch formation.
ABSTRACT: Electrical discharge machining process (EDM), the process parameters such as pulse on time, pulse off time, peak current, flushing pressure along with tool geometry are of great importance because they adversely affect the accuracy of machined features 1 . This paper presents the influence of each input parameters for investigating the effect of individual parameters on MRR, TWR and SR on Inconel718. The experimental results show that the pulse on time and peak current are the influencing parameters directly proportional to MRR and inversely proportional to TWR, SR 2 .
In general, machining is 3D-process for providing an understanding of mechanics of machining; the process is simplified into a 2D-process called as Orthogonal Cutting as shown in Figure 2.5. In orthogonal cutting, the workpiece is a flat plate (it can be a thin tube too) and is machined using a wedge-shaped tool with a rake angle of α and a relief angle of σ. The workpiece is moving at a cutting speed of V with a depth of cut to remove material. The width remains unaffected. An analysis based on the classical thin zone mechanics for materials that yield continuous chip with planar shear process (Merchant, 1989). The following assumptions were made: