Untreated Inserts Research Articles

Improvement of Machinability of Hardened Steel in Turning Operation Using Cryogenically Treated Cutting Tool

Hardened steels need special cutting tools like PCBN and ceramic to be machined. But these cutting tools aren’t cost-effective and require machine tool structures that are stiff and don’t let vibrations through. The current trend is to find other, less expensive ways to make these materials easier to work with. Cryo-treating cutting tools is an effective way to improve the way the tool materials work when they are cut. Cryogenically treated tungsten carbide inserts in dry turning operations were looked at in this study. For hard turning of hardened mild steel (48 HRC), the performance of cryogenically treated Tungsten Carbide (WC) inserts was compared with that of untreated inserts in terms of chip-tool interface temperature and surface roughness under dry cutting conditions. The cutting tool (Untreated and Treated), and cutting speed (375, 512, 706 rpm) were selected as experiment parameters at a constant feed rate of 0.0841mm/rev and depth of cut 1mm. The chip-tool interface temperature analysis results revealed that temperature increases with the increasing cutting velocities. A better surface finish can be found at a higher cutting speed. The lower value of Ra was found at 1.75 μm (without cryogenic treatment) and 1.05 μm (with cryogenic treatment) for cutting speed at 706 rpm.

Impact of cryogenic treatment on the performance of coated tungsten carbide inserts during machining of EN24 grade alloy steel

AbstractToday's industries need to be more productive, especially those that shape and machine materials. As a result, engineers and scientists are seeking for cutting tool materials and technologies that have high hot hardness, chemical stability, wear resistance, and toughness while also improving tool life or contact time. Cryogenic treatment of cutting tools has been proven to be a good way for increasing the contact time of any cutting tool material. This study presents the results of turning alloy steel (EN24 grade) using P20 grade carbide inserts under various conditions under continuous machining. Cutting speeds varied from 100 to 500 m/min (in increments of 100 m/min), with feed rates ranging from 0.1 to 0.4 mm/rev in stages of 0.1 mm/rev and a constant radial depth of cut of 1.5 mm were considered under dry machining conditions. Cryogenic treated/coated inserts are better than other inserts in terms of tool life for optimized parameters such as cutting speed 100 m/min, feed rate 0.1 mm/rev, and depth of cut 1.5 mm, according to the study's findings. Under similar conditions of cutting speed, feed rate, and depth of cut, coated/cryotreated inserts had a tool life increase of about 97.5% over uncoated/untreated inserts, a 50.58% increase over uncoated/crytreated inserts, and a 23.89% increase over coated and untreated inserts, respectively.

Effect of Cryo-Treated Cutting Tool End Milling on Custom 450 Stainless Steel.

Custom 450 stainless steel is the most desirable material across industries due to its widespread application in the aerospace, defense and marine industries. Stainless-steel materials are challenging to deal with and fall into the list of hard-to-process materials due to their low heat conduction coefficient and high mechanical properties. In this research work, end milling was carried out on Custom 450 stainless steel machined using TiAlN coated with tungsten carbide inserts that have been cryo-treated (CT) for 24 h (24 h) and 36 h (36 h), as well as untreated (UT) inserts. The inserts were evaluated in terms of feed force, feed rate and consistent depth of cut (ap) at various spindle speeds (S). Also examined were the tool morphology, chip anatomy and surface morphology of cryo-treated material compared to untreated inserts at various responses to cutting force (Fx, Fy, Fz), cutting temperature (Tc), vibration and surface abrasion. For inserts that have been cryo-treated for 36 h, the feed force (Fx) value was 44% and 5% less compared to inserts treated for 24 h and in UT inserts, respectively. Furthermore, for 24-h and 36-h CT inserts, feed force (Fx) was 12% and 20% less compared to a UT insert. Using 24-h cryo-treated inserts as opposed to UT inserts significantly reduced the surface roughness by 20%. Cutting inserts that have undergone cryogenic treatment have been observed to exhibit longer cutting tool life due to less wear and friction on the cutting edges.

Investigate the comparative performance of dry turning Monel 400 alloy by untreated and cryo-treated AlTiN carbide tools

ABSTRACT This study describes the cutting performance of Monel 400 alloy using a cryo-treated AlTiN carbide tool. The AlTiN carbide tool was cryo-treated at −196°C for 24 h of soaking at a cooling rate of 0.5°C/min and then tempered at 200°C for 2 h at a heating rate of 0.5°C/min. In this work, we evaluate and compare the hardness, composition, and phases of untreated and cryo-treated AlTiN-coated carbide inserts and also the turning performance of Monel 400 alloy. The machinability characteristics of cutting temperature, turning force, roughness parameter (Ra), form of chip, and SEM-EDS analysis of turned inserts are evaluated and then compared. It was found that the cryo-treated (CT) inserts offered a higher hardness value by 1.5% than the untreated (UT) ones, due to the formation of a new hard surface coating with cryogenic treatment. Cryo-treated AlTiN coated carbide inserts provided the following benefits over untreated ones: lower the cutting temperature at the cutting zone by a maximum of 10%; decreased the cutting force by 6–14%; reduced the Ra values in the turned surface by a maximum of 83%; a reduction in the size of the serrated form of chip; a reduced rate of insert wear; and lower deposition of work material constituents in the turned insert. The reason is enhanced resistance to wear due to an increase in hardness and the formation of a new hard surface coating with cryo-treated AlTiN coated carbide inserts, which was confirmed by analyses of hardness, SEM coupled with EDS, and X-ray diffraction. From the comparison of the characterisation and machinability indices of untreated and cryo-treated AlTiN coated carbide inserts, it was found that the cryo-treated AlTiN-coated carbide inserts provided the favourable turning performance of Monel 400 alloy.

Effects of cryogenic treatment on the performance of coated tungsten carbide inserts during milling of EN24 steel

Cryogenic treatment is one of the innovative techniques to improve the performance of cutting tools. The present study investigated the effects of cryogenic treatment on the performance of cutting tools, while machining (CNC milling) EN24 steel. The TiCN-coated tungsten carbide inserts (APKT09) were procured and exposed to shallow cryogenic treatment at −80 °C for 6 h and deep cryogenic treatment at −196 °C for 24 h independently. The experiments were designed using Taguchi’s L9 orthogonal array. Milling tests were performed by considering three cutting speeds (1900, 2200, and 2500 rpm), three feed rates (350, 440, and 530 mm/min), and three depths of cut (0.40, 0.65, and 0.90 mm) under dry cutting conditions. The machining performance of cryogenically treated and untreated inserts was evaluated in regard to the flank wear of the inserts and the surface roughness of the machined workpiece. Cryogenically treated inserts exhibited reduced flank wear and surface roughness than untreated inserts. The best flank wear and surface roughness performance were attained with the deep cryogenically treated inserts. Moreover, an improvement in the microhardness of the cryo-treated inserts was observed.

In-situ leakage behavior of polymer-metal hybrids under mechanical load

Abstract Tightness against media is a frequent requirement for technical components. Despite various standardized test procedures, failure regularly occurs during use. Often, no clear cause for failure can be determined afterwards. In this article, a new test setup is presented and applied, which allows an in-situ measurement during a mechanical load. A flow meter with a measuring range of 0.02 mL/min to 5 mL/min is used for this purpose. This makes it possible to determine leakage rates with time resolution and thus to identify the moment of failure or the causal failure load. This new method was applied directly to different aluminum inserts with a polyamide 66 (PA66) overmold. It was shown that no increase in leakage occurs until a maximum force is reached, even with multiple loads. This maximum force depends only on the pretreatment of the inserts and can be determined in a simple pull-out test independently of the test setup used here and can therefore be used for the design of assemblies. In the test, a maximum force of 100 N was achieved for untreated inserts, 140 N for adhesion promoter-coated parts and 600 N for etched inserts with a contact area of 48 mm2. With this results, a new link between adhesion and tightness can be shown, which of course is only valid for initial tight parts.

Application of statistical and soft computational techniques in machining of Nickel based supper-alloy using cryogenically treated tools for estimation of surface roughness

ABSTRACT In this paper, surface roughness prediction models are developed for turning of Inconel 718 using untreated and cryogenically treated inserts by using Dimensional Analysis, Response Surface Methodology (RSM) and Artificial Neural Network (ANN). Performance of untreated and treated tools is analysed using SEM, Energy-dispersive X-ray analysis, Vicker hardness test and electrical conductivity. For the established surface roughness models by dimensional analysis, RSM and ANN, the mean absolute errors for confirmation tests are 5.32%, 8.28% and 4.15% for untreated inserts and 4.95%, 6.01% and 4.20% for treated inserts, respectively. The effect of cutting parameters on surface roughness is analysed using the main effect plot and 3D surface plots. Based on correlation coefficient (R2 ) values, ANN modelling technique (R2 = 99.68%) is more accurate for predicting surface roughness. Thus, it can be an effective tool for analysing machining responses. The study also noted that while cutting at v= 60 m/min, f= 0.1 mm/rev and d= 0.5 mm, surface roughness and flank wear values are 0.5 µm and 0.45 µm and 0.777 mm and 0.627 mm for untreated and treated inserts, respectively. The use of treated tools resulted in 10% and 19% improvement in surface quality and tool life than the untreated tools.

Investigation of the effect of cutting parameters on the milling process of cryogenically treated aluminum alloy with cryogenically treated and untreated inserts, using the Taguchi and Gray Relational Analysis methods

The aluminum 6061 alloy is commonly employed in the automotive industry in the manufacture of rims, panels and even the chasses of vehicles and has excellent machinability. In this study, the surface of the cryogenically processed aluminum 6061-T651 alloy was milled using both untreated and cryogenically treated TiN-TiCN-Al2O3-coated cutting inserts. The Taguchi L18 orthogonal array was chosen as the experimental design. As the cutting parameters in the experiments, two different cutting inserts (untreated and cryogenically treated, TiN-TiCN-Al2O3-coated), three different cutting speeds (250, 350 and 450 m min−1) and three different feed rates (0.15, 0.30 and 0.45 mm/rev) were used. After each experiment, the surface roughness and wear values of the cutting inserts were measured, the latter after repeating the experiment five times. Wear and roughness values were optimized using the Taguchi method. Additionally, Gray Relational Analysis (GRA) was used for the combined optimization of wear and roughness values. The optimized findings determined using Taguchi optimization for minimum surface roughness were the cryogenically treated cutting insert, 250 m min−1 cutting speed and 0.45 mm/rev feed rate. The optimized findings for wear were the cryogenically treated cutting insert, 350 m min−1 cutting speed and 0.30 mm/rev feed rate. In the optimization with GRA, the common optimum parameters for surface roughness and wear were the cryogenically treated cutting insert, 250 m min−1 cutting speed and 0.15 mm/rev feed rate. According to the Taguchi and GRA results, the cryogenically treated cutting inserts performed the best in terms of minimum wear and surface roughness. The Gray-based Taguchi methodology proposed in this study was found to be effective in solving the decision-making problem in multi-specific results as wear and surface roughness.

Comparative investigations of cryo-treated and untreated inserts on machinability of AISI 1050 by using response surface methodology, ANOVA and Taguchi design

This study aims to focus on the machinability of the AISI 1050 workpieces with cutting inserts, treated under deep cryogenic heat (−146 °C), and with untreated ones, and to investigate the optimization of cutting parameters and heat treatment conditions for surface roughness and cutting force by using Taguchi mixed design and Response Surface Methodology (RSM). The machining experiment was performed on a CNC lathe with machining parameters such as three feed rates, three cutting speeds and a constant depth of cut under dry condition and with heat treatment condition. As is known, Taguchi design L18 (32 21) consists of three factors; cutting parameters with each one of three levels and heat treatment condition with two levels. The results of machining tests were evaluated considering surface roughness, vibrations and cutting force. Furthermore, chip morphology and wear led by cryo-treated and untreated inserts were detected with the aid of a scanning electron microscope. The results demonstrated that cryo-treated (CTI) insert had lower tool wear, vibration, and cutting force than untreated insert (UI) in all conditions. In aspect of chip morphology, untreated inserts had bigger and larger serrations than the treated inserts. In addition, according to Taguchi S/N ratio, optimal cutting parameters and heat treatment conditions were obtained from CHT1, V3, and f1 for the Fc and from CHT1, V1, and f1 for the Ra, respectively. Also, the most significant control factors on surface roughness and cutting force were feed rate depending on ANOVA results and RSM. Validation test results demonstrated that RSM and Taguchi mixed design calculated the cutting force (R2RSM (CTI and UI) = 99.99% and R2Tag. = 99.95%) and surface roughness (R2RSM (CTI) = 99.76%, R2RSM (UI) = 99.59% and R2Tag. = 99.12%). Therefore, RSM and Taguchi mixed design predicts highly well match experimental data with prediction data.

Investigation on the effect of cryogenic treatment on tungsten carbide milling insert with 11% cobalt (WC–11%Co)

The objective of this research is to evaluate the performance of cryogenically treated cemented carbide milling inserts with 11% cobalt content in face milling of EN19 steel. Two different deep cryogenic treatments at temperature of around − 193 °C were performed on the inserts, namely cryogenic treatment and cryogenic treatment and tempering. Uncoated tungsten carbide face milling inserts with 11% cobalt content were used in this research. Machining tests were conducted at the catalog recommended cutting parameters, and flank wear and nose wear of untreated, cryogenically treated and cryogenically treated and tempered inserts were compared to study the performance. The experimental investigation revealed that both cryogenic treated and cryogenic treated and tempered inserts showed 4–7% lesser flank and nose wear than the untreated inserts. The metallurgical examinations using indirect measurement technique revealed the phase transformation of cobalt from FCC to HCP which could have resulted in increased hardness, reduced friction coefficient and improved tool life.

Performance Evaluation of Cryogenic Treated and Untreated Carbide Inserts during Machining of AISI 304 Steel

The cutting tool in the machining process plays an important role as it acts on the working material. There are a few methodologies have been persued to improve tool life, for example traditional cooling, single layer coating, multilayer coating, heat treatment process, nitrogen cooling and latest being the cryogenic treatment which reported a significant improvement in cutting tool life, chip morphology, reduction in heat generation. Hence, the cryogenic treatment is emerged as the sustainable machining process. This paper presents machining of AISI 304 steel using both cryogenic treated (CT) and untreated (UT) cutting tool insert. The commercially available uncoated carbide insert has been cryogenically treated at -196°C for 24 hours soaking period. The machining test has been conducted under four different cutting speeds. The material characterization of cutting insert is studied by using scanning electron microscopy (SEM), hardness test, and microscopic image analysis has been carried out before and after cryogenic treatment. The cutting tool performance is assessed in terms of of wear, cutting temperature, chip morphology, surface roughness under the influence of cryogenic machining and the results are contrast with UT one. The exploratory findings reveals that the deep cryogenic treatment (DCT) with 24 hours soaking period, performed better wear resistance and improved surface roughness of the cutting tool. Also considerable reduction in the flank wear, crater wear, cutting temperature is obtained and found improved chip morphology.

Wear of WC inserts textured by shot peening and electrical discharge machining

In this paper, the wear and cutting performance of uncoated cemented tungsten carbide (WC) inserts textured by shot peening (SP) and electrical discharge machining (EDM) was compared to examine the hypothesis that texturing processes involving surface re-melting are inferior to processes based on surface plastic deformation. Lubricated orthogonal tube turning experiments demonstrated that the WC inserts with irregular rake face surface texture exhibit either longer or shorter tool lives than untreated inserts depending on the combination of surface roughness and residual stress. Higher roughness and compressive residual stress produced by SP led to increase in wear resistance and tool life by about 30% through reduction of the tool-chip contact area and the apparent tool-chip friction. Tensile surface residual stresses generated by EDM resulted in chipping of the tool and, hence, shorter tool life by more than 80% even when cutting forces were lowered. Moving the treated area away from the cutting edge neutralized the effect of texture on tool life. Based on the test results, surface modification of WC inserts through SP yielded better tool life performance than surface modification through EDM.

Comparative Study of some Machining Characteristics during Hard Turning of Alloy Steel with Untreated and Cryotreated Cermet Inserts

Enhanced tool life of cutting inserts are most suitable condition for higher productivity of a manufacturing industry. Several methods are found and employed for higher tool life of cutting inserts among which cryogenic treatment is considered as the most significant method but no adequate researches have been found concerning the impact of cryogenic treatment on cermet inserts especially in hard turning operation. Hence, in the current experimental investigation, the comparative assessment of various responses such as flank wear, crater wear, chip morphology, and chip compression ratio were carried out during machining of hardened steel with both untreated and cryo-treated cermet inserts under dry cutting condition. Wear on the rake faces and flank faces were studied using advanced optical microscope, while chip morphology was studied using SEM. The experimental result demonstrated that the uncoated deep cryotreated with tempered cermet insert delivered better results in comparison to other cermet inserts. Deep cryogenically treated with tempered insert was found to be more suitable during machining of hardened steel because of the enhancement of wear resistance, micro hardness and toughness.

Experimental investigation of various machining attributes and cost estimation during machining of hardened AISI 4340 steel with untreated and cryo treated cermet inserts

Now-a-days due to growing demand of high precision components to attain high performances, hardened steels with hardness above 45HRC have numerous applications in automotive gear, machine tool and die industry because of their superior characteristics (high thermal stability, high indentation resistance, high abrasiveness, low ductility and high value of hardness to modulus of elasticity ratio). For this, higher tool life of cutting inserts cryogenic treatment is considered as the most prominent method but no substantial researches have been found concerning the impact of cryogenic treatment on cermet inserts, especially in turning of hardened steels. Therefore, in the present experimental investigation, the comparative assessment of various responses such as cutting force, flank wear, crater wear, chip morphology and surface roughness were carried out during machining of hardened steel with both untreated and cryo-treated cermet inserts under dry cutting condition. Lastly, the input variables were optimized using Response Surface Methodology (RSM) to evaluate the tool life for the economic analysis. The experimental result demonstrated that the uncoated deep cryo-treated with tempered cermet insert delivered better results in comparison to other cermet inserts. According to cost analysis, uncoated and deep cryo-treated with tempered cermet insert was found to be the most cost saving among other cermet inserts at the optimum cutting condition.

A comparative machinability study on titanium alloy Ti-6Al-4V during dry turning by cryogenic treated and untreated condition of uncoated WC inserts

Titanium alloy is widely utilized in aerospace, nuclear power plant and medical applications due to its high hardness, corrosion resistance, specific strength and bio-compatibility. Titanium alloys are tough to machine because of its intrinsic properties such as the capability to maintain high strength at elevated temperatures, high hardness and low thermal conductivity. Moreover, titanium alloys lower thermal conductivity and high specific heat limit the effective removal of heat developed during machining through workpiece and chips. Thus it accumulates at the cutting zone. Present work deals with a comparative study on surface roughness, cutting force, and chip morphology during turning of Titanium alloy Ti-6Al-4V alloy with and without cryogenic treated uncoated tungsten carbide inserts. The cutting force and surface roughness resulting from machining with cryogenically treated inserts are comparatively lesser than machining with untreated inserts. This is due to more hardness, low thermal conductivity and high wear resistance of treated inserts.

Influence of deep cryogenic cooling on tool wear and surface roughness of coated tungsten carbide inserts using statistical techniques

Tool life enhancement with improved machining performance of existing turning inserts during hard turning process is an essential industrial requirement to reduce the manufacturing cost and to improve the surface finish with higher accuracy. The objective of this paper is to study the effects of Deep Cryogenic Cooling on coated tungsten carbide inserts and to evaluate their tool wear and resulting surface finish by conducting turning experiments on P20 tool steel material. To evaluate these properties, turning experiments were carried out as per the Taguchi’s design of experiments technique, by considering the three experimental parameters namely turning speed, depth of cut and feed rate. The effect of these parameters on tool wear and surface finish of the workpiece are analyzed by analysis of variance technique. The results indicated that feed rate had the highest influence of 71.85% on the surface finish of the machined surface, whereas the depth of cut influenced 14.86% & followed by turning speed which had 4.91% influence on surface finish. Similarly, for tool wear, it was found that turning speed had a significance value of 39.95% on tool wear followed by the depth of cut (37.95%) and feed rate (18.85%). The experimental data were used to develop the regression correlations for surface finish, and tool wear and confirmation tests were carried out to validate the models. The comparison between predicted and experimental values indicated a maximum deviation of around ±8% for surface roughness and ±11% for the observed tool wear. And scanning electron microscopic analysis of deep cryogenic treated inserts indicates a homogeneous distribution of η-carbides in cobalt matrix and a grain size refinement of α-phase compared to untreated inserts.

Application of ANN to estimate surface roughness using cutting parameters, force, sound and vibration in turning of Inconel 718

In this paper, artificial neural network approach is used to predict surface roughness using cutting parameters, force, sound and vibration in turning of Inconel 718. Experiments were performed by using cryogenically treated and untreated inserts, and various responses were measured. Then, these measured responses were used as input to the artificial neural network to predict surface roughness. It is found that the models developed by artificial neural network are predicting surface roughness with more than 98% accuracy. Further, the predictions obtained by artificial neural network are compared with the results of regression-based prediction models earlier proposed by the authors. The modified regression models were estimating surface roughness with more than 90% accuracy. Based on correlation coefficient values, the prediction results of modified regression model are compared with those obtained by artificial neural network. Finally, it is concluded that artificial neural network models are better for estimating surface roughness than the regression models and such predictions are useful for real-time control of the process to acquire the desired surface roughness.

Influence of deep cryogenic treatment on performance of cemented carbide (WC-Co) inserts during dry end milling of maraging steel

Cryogenic treatment has developed as a technique to improve the life of the cutting tool, especially tungsten carbide inserts. The present study investigates the effect of cryogenic treatment of cemented carbide (WC-Co) inserts at the different soaking period of 18 h (CT-18), 24 h (CT-24) and 32 h (CT-32) at a sub-zero temperature of −196 °C. The soaking period plays a crucial role in improving the wear resistance of the cryogenically treated tools. It is vital to determine the critical soaking period for the cryogenic treatment of cemented carbides. The mechanical and metallurgical characterization of cryogenically treated cemented carbide insert is carried out to understand the changes in the microstructure, grain size, chemical composition, microhardness and electrical conductivity after cryogenic treatment. The end milling experiments on maraging steel under dry environment are carried out using cryogenically treated inserts at different holding time and untreated inserts (UT). The machining performance of treated and untreated inserts are compared with respect to tool wear, surface roughness and cutting forces. The results revealed that cryogenic treatment is effective in resisting tool wear even at high spindle speeds. The cryogenically treated inserts exhibited higher tool life, better surface finish and lower cutting forces during machining at different spindle speeds. The optimum soaking time for cryogenic treatment of WC-Co inserts is found to be 24 h (CT-24) beyond which there is no improvement in microhardness and wear resistance.

Experimental Investigations to Study the Effects of Microwave Treatment Strategy on Tool Performance in Turning Operation

In the present study, microwave treatment has been used to enhance the tribological properties of single-point tungsten carbide (WC) cutting tool inserts such as wear resistance and hardness. The tool hardness and cutting parameters were considered to evaluate the performance of microwave-treated WC inserts in turning operation. The optimum cutting parameters were identified using response surface method (RSM)-based desirability approach. The relationship between cutting parameters and output responses, viz. flank wear, cutting force and surface roughness, was developed using the RSM. The investigations revealed that the increase in tool hardness due to complex carbide formation results in a significant reduction in tool wear, cutting forces and improvement in the surface finish of workpiece. Further, the statistical models results were validated with the experimental results. Metallurgical properties of treated and untreated tool inserts were analyzed using scanning electron microscope, x-ray diffraction method and Vickers microhardness tests. The results highlighted the importance of microwave treatment in enhancing the machining performance in turning operation.

Experimental results on the performance of cryogenic treatment of tool and minimum quantity lubrication for machinability improvement in the turning of Inconel 718

Inconel 718 is a popular, but difficult to machine, nickel-based supper alloy. Machining performance of this material can be improved by appropriate modelling and optimization. In the present study, response surface modelling and optimization for turning of Inconel 718 under four machining conditions: dry with untreated inserts, dry with cryogenically treated inserts, minimum quantity lubrication with untreated inserts and minimum quantity lubrication with cryogenically treated inserts is carried out. With the aim of improving the machinability of Inconel 718, an attempt has been made to examine the effect of cryogenic treatment of tool and minimum quantity lubrication in terms of indicators such as surface quality of workpiece, tool wear and material removal rate. Cutting speed, feed rate and depth of cut are used as the control parameters. Whereas, cutting force, tool vibration, cutting temperature, surface roughness and tool wear are the measured responses. Prediction models are developed for each response. Later, all the responses are optimized together by desirability approach and are validated using confirmation experiments. A spider plot is drawn to display the relationships among control and response parameters. The plot shows that application of minimum quantity lubrication with cryogenically treated inserts resulted in least cutting force, tool vibration, cutting temperature, minimum surface roughness of workpiece along with least tool wear and best material removal rate compared to other three conditions used. This clearly shows machinability improvement of Inconel 718.