Uncoated Inserts Research Articles

Performance Comparison of PCD Insert and Uncoated Insert in Novel CNC Green Machining of SS316L Stainless Steel for Maximizing Material Removal Rate

Aim: This research is about comparing the performance of poly-crystalline diamond (PCD) insert and uncoated cemented carbide insert for improving the material removal rate (MRR) in CNC turning. Materials and Methods: The material investigated in this research was SS316L. PCD insert was set as the experimental group and uncoated insert was set as the control group. The cutting parameters employed in this process were cutting speed, feed rate and depth of cut. Totally 27 samples per group were machined by using the selected parameters. Results: The mean MRR value obtained for the PCD tool is 0.22593 g/s, whereas it is 0.07600 g/s for the uncoated tool. The significance value obtained among the experimental group and control group is 0.000 (p<0.05). Conclusion: Within the limits of this study, the outcome of the research shows that MRR is more when the specimen is machined by PCD insert than machined by uncoated insert.

Comparison of Performances of Novel Titanium carbide tool Insert and Uncoated Tool in CNC Turning of HCHC D2 Steel for Minimizing Surface Roughness and Maximizing Material Removal Rate

Aim:-The Present study is focused on the comparison of performances of Titanium carbide(TIC) and Uncoated carbide tool inserts with CNC turning of HCHC D2 Steel for minimizing surface roughness and maximizing material removal rate. Materials And Methods:- Machining of HCHC D2 steel material was compared with Titanium carbide(TIC) and Uncoated carbide tool inserts. It was divided into two groups of 27 samples each. The samples were machined with two different tool inserts one was control group and other was experimental group. Results:- Surface roughness was decreased and material removal rate was increased when machining was done with TIC carbide compared to HSS tool insert (P=0.028).Conclusions: It is concluded that the surface roughness was decreased and material removal rate was increased when TIC carbide tool insert was used for machining.

On the mechanism of crater wear in a high strength metastable β titanium alloy

The primary wear mechanism of WC-Co tools when machining aerospace titanium alloy components is crater wear. The diffusion controlled dissolution and thus the crater wear rate is more apparent when machining the high strength, fatigue resistant metastable β titanium alloys: an expensive class of titanium alloy used in aerostructural components such as twin aisle aircraft landing gear parts. To characterise the mechanistic process of crater wear progression, outer diameter turning trials were conducted on the metastable β alloy, Ti-5553. Uncoated WC-Co inserts were used for time steps of 30, 60 and 900 s at a cutting speed of 70 m/min. The crater region was analysed using high-resolution SEM, X-EDS, WDS and STEM/TEM. Such targeted characterisation enabled the detailed mechanism of progressive crater wear in titanium machining to be further understood. In the crater wear process, rapid diffusion of Co into adhered Ti-5553 occurs within the crater zone, proceeded by decarburisation of the WC (hcp). Thermodynamic modelling and high-resolution imaging of the interface suggests Co facilitates the formation of Ti2Co, and possibly a liquid, within prior Co rich regions at WC grain boundaries. Subsequently, this creates regions that exhibit similar characteristics to a Kirkendall morphology due to accelerated C depletion and W–Ti dissolution. The formation of abrasive titanium carbides in the workpiece material increases as C is made available from the WC transforming to W (bcc) and through binder regions. Once the W (bcc) layer is formed the rapid decarburisation process is concentrated at prior Co-rich (heavily β stabilised) Ti regions, this degradation dictates the crater wear rate during the machining of Ti-5553. Now an understanding of the crater wear mechanism has been characterised for Ti-5553, tooling manufacturers can engineer the Co-binder volume fraction and distribution, to improve tool life and provide significant cost savings when machining metastable β titanium alloy components.

Simulation Analysis of the Influence of Coating on the Cutting Temperature Distribution inside the Insert

The coating on carbide insert surface can effectively reduce the transfer of cutting heat to the inside of the insert, improve the surface wear resistance and cutting performance, and ensure the service life. In this paper, the influence of coating on the heat conduction inside the insert is analyzed by two-dimensional heat transfer model, and the temperature distribution is quantitatively described. The simulation models of TiAlN-coated and -uncoated inserts are established, and the simulation results are compared. It is found that the cutting temperature of TiAlN-coated insert decreased by about 5% compared with that of uncoated cutting tools. The coating effectively reduced the conduction of cutting heat to the matrix, and the internal temperature of the matrix was significantly lower than that of uncoated cutting tools.

Machinability Investigations on Aerospace Custom 450 Alloy Using TiAlN/TiCN, TiCN/TiAlN Coated and Uncoated Carbide Tools

In this present research, the machinability studies of TiAlN/TiCN, TiCN/TiAlN coated and uncoated inserts were investigated on machining custom 450 alloy. The machining input parameters such as feed rate (f), cutting speed (V) and depth of cut (d) are set using orthogonal array. The machining output parameters such as surface roughness, tool wear and cutting forces were studied for its parametric contribution and it was analyzed using Analysis of Variance (ANOVA). Further, the tool wear obtained was studied using scanning electron microscopic images and energy dispersive spectroscopy analysis was conducted to check the addition of work material elements to the coated tool surface. The results show that, the feed rate is the most contributing factor in deciding resultant forces, surface roughness and tool wear respectively. TiAlN/TiCN coated carbide tool has obtained improved machinability, when compared to TiCN/TiAlN coated carbide and uncoated carbide inserts. To obtain one optimal level for all three responses of three types of tools, multi criteria decision making approach, named utility concept approach is selected. Based on the MCDM analysis, it is found that trial number 4 gives better experimental output of improved surface integrity, lower resultant force and less tool wear for all types of tools.

Experimental investigation on dry turned Monel 400 alloy surface parameters with uncoated and coated tool

Monel 400 alloy exhibits properties like high hardness, strength and toughness, and excellent resistance to corrosion. So, this alloy is especially used in defence, marine, power and chemical processing sectors. However, the cutting of this alloy generates high heat and reactivity with tool due to its inherent properties, which decreased the life of cutting tool and further deteriorated the surface integrity of the machined components. In general, any cutting operation surface quality of work material is very important.The present work assesses impact of tool (uncoated and PVD-TiAlN coated) on surface roughness parameters during dry turning of Monel 400 alloy. The cutting velocity, Vc (m/min) of 69 and 114, a feed rate, f (mm/rev) of 0.122 and cutting depth, t, (mm) of 1 was used to turned the samples. The cutting length of 25 mm was carried out per experiment. It was observed that the turning of Monel 400 with uncoated insert, with an increase in cutting length from the start to the end of cutting roughness values increased. A lowest average surface roughness value of 0.667 µm was observed during turning of Monel 400 with PVD-TiAlN coated insert with the current cutting conditions (114 m/min, 0.122 mm/rev and 1 mm). It reported that the significant reduction in surface roughness parameters were obtained with PVD-TiAlN coated insert over uncoated insert.

Experimental investigation of surface roughness and cutting force during machining of SS43100 by using coated and uncoated carbide inserts

Machining processes are the accurate metal removal processes for shaping components in the manufacturing industry. The main challenges of the manufacturing industry are to increase productivity and quality. Manufacturing industries are trying to reduce the cost of machined parts which are manufactured by different machined methods. Machining hard metals is a challenging task. In the presented research work machining parameters were investigated for machining of SS43100 by using coated and uncoated carbide tool inserts. Carbide tool inserts were coated by Ti16Zr using the PVD method of coating. Experiments were performed during the turning operation of SS43100 by coated and uncoated tool inserts. Cutting speed range were 150r.p.m, 250 r.p.m., 350 r.p.m., feed were 0.085 mm/rev, 0.095 mm/rev, 0.1 mm/rev. and depth of cut was 0.1 mm, 0.15 mm, and 0.2 mm selected as controlling factors. Surface roughness and cutting force were selected as response factors. Digital lathe tool dynamometer was used for cutting force measurement and ITI surface tester RS232 was used for surface roughness measurement. In the experimental study and analysis of output response parameters, Taghuchi L9 orthogonal array model has used The results obtained were optimized using the Taghuchi technique for cutting forces and surface roughness. The Taghuchi technique was performed for combinations of each input variable in linear fit model multivariate analytics. Experimental results were compared and models established supported by evidence.

Adhesion of Inconel 718 on Uncoated Tungsten Carbide Inserts in Interrupted Orthogonal Machining under MQL

Nickel-base super-alloys such as Inconel 718 are used for demanding applications in the industry. Their superior corrosion resistance and mechanical properties, especially under high heat and pressure, make them very attractive for highly stressed components. In contrast, their low thermal conductivity, work hardening tendency and high strength impose challenges for machining. In particular, occurring adhesion of the workpiece material on tungsten carbide (WC) inserts and tools is common hindering their life. In order to counteract this undesirable effect, cutting fluids are usually implemented. However, due to increased awareness of cutting fluids negative impact on the operator’s health and the environment, minimum quantity lubrication (MQL) is getting more attention among researchers and in the industry. In this study, the adhesion on the rake face of uncoated WC inserts under the application of MQL is observed. Inconel 718 workpieces prepared for orthogonal cutting trials are interrupted at variable intervals to allow more access for MQL to reach chip-tool interface. Mechanical load, coefficient of friction, adhesion area and chip-tool contact length on the rake face are investigated. It has been observed that interrupted machining can positively influence adhesion area and chip-tool contact length.

Analysis and Optimization of Cutting Tool Coating Effects on Surface Roughness and Cutting Forces on Turning of AA 6061 Alloy

The present work has been focused on cutting force (Fc) and analysis of machined surface in turning of AA 6061 alloy with uncoated and PVD‐TiB2 coated cutting inserts. Turning tests have been conducted on a CNC turning under dry cutting conditions based on Taguchi L18 (21 × 33) array. Kistler 9257A type dynamometer and equipment have been used in measuring the main cutting force (Fc) in turning experiments. Analysis of variance (ANOVA) has been applied to define the effect levels of the turning parameters on Fc and Ra. Moreover, the mathematical models for Fc and Ra have been developed via linear and quadratic regression models. The results indicated that the best performance in terms of Fc and Ra was obtained at an uncoated insert, cutting speed of 350 m/min, feed rate of 0.1 mm/rev, and depth of cut of 1 mm. Moreover, the feed rate is the most influential parameter on Ra and Fc, with 64.28% and 54.9%, respectively. The developed mathematical models for cutting force (Fc) and surface roughness (Ra) present reliable results with coefficients of determination (R2) of 96.04% and 92.15%, respectively.

Characterization and Wear Response of Magnetron Sputtered W–B and W–Ti–B Coatings on WC–Co Tools

In this work, α-WB2 and (W,Ti)B2 borides were applied as wear-resistant coatings to commercial WC–Co cutting inserts. Properties of coatings deposited by magnetron sputtering on WC–Co tools were studied. The crystal structure and chemical composition were analyzed. Vickers hardness and surface roughness were determined and wear test in semi-dry conditions was performed. The W–B and W–Ti–B coatings deposited on WC–Co substrate were smooth and very hard. However, titanium alloy W-B films with Vickers hardness of 3630 ± 260 HV0.02 were characterized by lower adhesion to the substrate, influencing the wear mechanism. Turning tests carried out on 304 stainless steel showed that the W–B film caused less wear compared to uncoated insert. Moreover, when W–B coating was applied, flank wear was reduced by 30% compared to uncoated WC–Co insert. Additionally, coating prevented chipping of the edge during cutting under test conditions. The research shows that W–B film deposited by magnetron sputtering has great potential as a coating for cutting tools for difficult-to-cut materials.

Coated Tungsten Carbide Inserts: Effects on Machinability in Turning of AISI 1020 Steel

How the different types of cutting inserts coatings influence on surface roughness and tool wear, taking these two factors as machinability criteria, in turning carbon steel bars AISI 1020 was investigated. Specimens of 36 mm in diameter and 200 mm in length tested were made. Uncoated inserts and coated WC tungsten carbide inserts with: TiN; TiN / Al2O3 and TiC / Al2O3 / TiN, were use. The tests were carried out on automatic parallel lathe, using the cutting parameters: 1500 rpm; a= 0,25 mm/rev; p= 0,4 mm; therefore, the cutting speed was Vc= 170 m/min. Roughness was measured in the roughness meter: Mitutoyo, Surftest-211, and a high resolution optical microscope was used to measure the flank wear, complementing with SEM electron microscopy. It was found that the lowest roughness Ra is obtained using Triple inserts showing a variation Ra = 2μm. The maximum flank wear VB = 300μm was taken as machinability criterion, to later determine the tool life for each insert. The uncoated insert life was 8 mim, and TiN coated insert life was 14.5 min, while the bilayer and trilayer coating inserts did not exhaust their life for 12,000 mm length machining. Uncoated and TiN-coated inserts showed strong wear and workpiece material build-up (BUE). The double and triple layer inserts did not show this phenomenon due to the Al203 compound which is chemically inert at high temperatures. The most prevalent mechanisms in the inserts wear was adhesion and abrasion. No direct or inverse relationship was found between wear and roughness.

Achieving machining effectiveness for AISI 1015 structural steel through coated inserts and grey-fuzzy coupled Taguchi optimization approach

Multi-objective optimization technique has become an essential step in the selection of cutting parameters. The intension of this research study is to analyze the performance characteristics of coated carbide inserts on their measured output responses during machining AISI 1015 steel. This paper targets to optimize the machining parameters such as speed, cutting depth, feed rate, cutting fluid flow rate, and coating material when multiple responses like surface roughness and flank wear were considered at the same time during turning. This research study also intends to examine scientifically the effect of machining parameters on quality measures during machining structural AISI 1015 steel. Cathodic arc evaporation–coated titanium aluminum nitride (TiAlN), titanium aluminum nitride/tungsten carbide-carbon (TiAlN/WC-C), and uncoated CNC inserts were used for the study. SEM and energy-dispersive X-ray analysis were performed to confirm the presence of coated elements. Micro-hardness was measured for coated, pure inserts, and TiAlN/WC-C-coated tool exhibited a higher hardness of 22.11 GPa compared with pure and coated tools. Five process parameters were used for this study, each at three stages. The experimental design was laid based on Taguchi’s L27 orthogonal array. In this research study, a multi-objective hybrid optimization technique comprising grey relation and fuzzy logic conjugated with the Taguchi design of experiments was used. The process parameters were optimized by grey relation analysis followed by fuzzification using Mamdani fuzzy engine and then optimized through Taguchi analysis. The parameter combination of speed 500 rpm, depth of cut of 1 mm, a feed rate of 0.05 mm/rev, cutting fluid flow rate at high level, and TiAlN/WC-C coating was found to be the optimum input parameters. The confirmatory test was also performed to validate the hybrid optimization approach.

Machinability evaluation of coated carbide inserts in turning of super-duplex stainless steel

Super-duplex stainless steel (SDSS) is a class of materials that possess excellent mechanical properties with enhanced corrosion resistance. Given the presence of several alloying elements and the existence of a two-phase microstructure, it can be argued that it is one of the few materials that are difficult to machine. Therefore, the present study attempts to establish an improved understanding of the state-of-the-art development in insert coatings capable of providing excellent tribological and thermal resistance properties. In this work, monolayers of AlTiN and AlCrN are PVD coated on commercial carbide inserts so as to compare and contrast the performance of nitride coatings in the dry turning of SDSS. This study evaluates the machining performance in terms of tool wear, chip characteristics, tool life and surface finish. The coated surfaces were observed through optical microscope, profilometers, scanning electron microscope and energy-dispersive X-ray spectroscopy to evaluate the morphological changes. The results of the work indicate that machining with PVD-coated AlTiN insert showed longer tool life, better surface finish and smaller chip thickness when compared to AlCrN-coated and uncoated inserts at low to moderate cutting speeds. The dominant wear mechanism was found to be adhesion, where during turning long continuous chips were formed for uncoated inserts and small segmented chips were formed for coated inserts at different machining parameters. Contrarily, the study also purportedly explores the improved performance of AlCrN-coated inserts over AlTiN-coated inserts at high cutting speed.

Wear Behaviour of Coated Cemented Carbide Inserts in an Oxygen-Free Atmosphere when Machining Ti-6Al-4V

The machining of difficult-to-cut materials such as titanium plays a key role in several industries such as aerospace or medical. Approaches to overcome many difficulties when machining these materials can be an appropriate coating system for cemented carbide cutting tools. However, the atmosphere under which machining takes place, influencing the chemical tool wear, has not been taken into consideration. This work examines the tribochemical wear resistance of TiN, TiAlN and CrAlN coated carbide tools under different atmospheric conditions when cutting Ti6Al-4V. Air, technically pure argon and silane-doped argon is used to determine the influence of different oxygen levels on the wear behaviour of the tools. It has been found that oxidation of tools and tool coatings plays a significant role in tool wear when dry cutting titanium. Best results were generated using CrAlN and uncoated inserts where an increase in tool life up 50 % can be achieved when cutting in oxygen levels corresponding to extreme high vacuum (XHV) adequate atmospheres by using silane-doped argon. The benefits of XHV adequate atmospheres also have an effect on TiAlN-and TiN based coatings, but the chemical interaction of Ti element in the coating with the workpiece material, which presumably reduces wear resistance of cutting tools, cannot be outweighted or equalised by applying oxygen free atmospheres.

Dry Machining Performance of AA7075-T6 Alloy Using Uncoated Carbide and MT-CVD TiCN-Al2O3-Coated Carbide Inserts

The present study examines dry machining performance of AA7075 T6 alloy using uncoated and MT-CVD TiCN–Al2O3-coated carbide inserts. Machining performance is assessed with regard to tangential cutting force, tool tip temperature and depth of flank wear. The performance of coated tool is compared to that of uncoated insert. In addition, different modes of tool wear and chip morphology are studied in detail. It is experienced that coated tool causes lower tool tip temperature and lesser flank wear than untreated counterpart. Apart from abrasion, adhesion and built-up layer formation; attrition wear is distinctly visible in case of uncoated tool. On the contrary, in addition to common wear modes, coated tool also experiences diffusion wear.

Influence of cutting insert (uncoated and coated carbide) on cutting force, tool-tip temperature, and chip morphology during dry machining of Inconel 825

During metal machining, tool material (substrate as well as coating) plays an important role to influence machinability of any work material. Dry machining performance of ‘difficult-to-cut’ aerospace superalloy Inconel 825 is studied herein. Machining experiments are conducted at different cutting speeds using uncoated carbide, and MT-CVD TiCN-Al2O3 coated carbide inserts. Machining performance is assessed in purview of magnitude of cutting force, approximate tool-tip temperature, and quantitative chip morphological parameters. Performance of coated tool is compared to that of uncoated insert. It is estimated that coated tool causes 39.79% reduction in tangential cutting force (at cutting velocity ∼121 m/min) when compared to uncoated counterpart. Higher tool-tip temperature of the coated insert caused higher chip curling. Shear band microhardness of chip (obtained by using coated tool) appear higher than that of uncoated insert.

Studies on chip morphology and modes of tool wear during machining of Ti-6Al-4V using uncoated carbide tool: application of multi-walled carbon nanotubes added rice bran oil as nanocutting fluid

In this work, machining performance of Ti-6Al-4V is studied in consideration with cutting force, tool-tip temperature, tool wear mechanisms, chip morphology and roughness of the machined surface. Machining experiments are carried out by varying cutting speed (Vc) with constant feed and depth-of-cut. Uncoated WC-Co insert is used as cutting tool. Multi-walled carbon nanotubes (MWCNTs) added rice bran oil is utilized to produce nanofluid minimum quantity lubrication (MQL) environment. Chip morphology along with measurable geometrical parameters including chip-tool contact length, equivalent chip thickness (H ch), segmentation spacing, segmentation frequency, shear band width, shear angle, chip hardness, etc. are studied in detail. Effects of Vc on cutting force, tool-tip temperature, depth of flank wear, and area of crater wear are discussed. Different tool wear mechanisms are identified as well. It is experienced that nanofluid MQL (NFMQL) outperforms traditional dry cutting as well as conventional MQL in purview of improved process performance.

Taguchi based Optimization of Coated and Uncoated Tool Insert for Turning Ti6Al4V using Grey Relation Analysis

The titanium alloy Ti6Al4V has been widely used due to its high strength to weight ratio. The titanium machinability is very troublesome because of its hardness, low elastic modulus at elevated temperature and thermal conductivity, and has high chemical affinity. In this paper we have studied surface roughness, material removal rate for CNC Turning of Ti6Al4Vby comparing it with two inserts, one is tungsten carbide coated having a coating of TiAlN and the other is the uncoated tungsten carbide inserts by varying the input parameters such as cutting Speed, feed rate, depth of cut (DOC). These experiments were based on Taguchi’s orthogonal array for three factor and three levels and experiments has been conducted based on L27 orthogonal array for turning operation on computer numerical control machine. Further optimization is done based on multi response optimization-Grey Relational Approach (GRA) to get the optimized parameter for the maximum Material Removal Rate (MRR) and minimum Surface Roughness (Ra). However the surface roughness of the coated insert was found to minimal than the uncoated insert in which the coating just improves the life of the cutting tool.

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.

Evaluation of physical indicators and tool wear during grooving of spheroidal cast iron with a novel WCCo/cBN (BNDCC) inserts

The WCCo/cBN (Boron Nitride Dispersed Cemented Carbide – BNDCC) cutting inserts fabricated by PPS (pulse plasma sintering) method constitute the novel tool materials with advantages of cemented carbide and cubic boron nitride tools. However, the cutting properties of these materials are not yet recognized. Therefore, this work is focused on the identification of BNDCC tools cutting performance during the grooving process of a hard-to-cut N-GJLA-XNiCuCr 15-6-2 spheroidal cast iron. The conducted studies involved the evaluation of a fundamental cutting process physical indicators, as cutting forces, vibrations and average coefficient of friction on the rake face. The tool wear mechanisms and tool life of the uncoated and coated (with TiN and TiAlN coatings) BNDDC inserts were identified and compared with ones obtained during cutting with a coated and uncoated cemented carbide (H3 and H10) tools. The obtained results showed that the adhesion wear mechanism of the coated and uncoated BNDCC inserts was dominant throughout the entire range of cutting speed. The application of the novel BNDCC inserts during grooving of spheroidal cast iron is more advantageous in terms of tool life, comparing to the coated cemented carbide inserts.