Tool Wear Morphology Research Articles

Cutting performances of MCD, SMCD, NCD and MCD/NCD coated tools in high-speed milling of hot bending graphite molds

Abstract The machining accuracy and service life of high-speed milling tools have a great influence on the surface roughness and dimensional precision of hot bending graphite molds used in the manufacture of 3D curved glass such as protective screens and rear covers of 3C electronic products. The microcrystalline diamond (MCD), submicrocrystalline diamond (SMCD), nanocrystalline diamond (NCD) and micro/nano-crystalline composite diamond (MCD/NCD) coatings were deposited on commercial corner radius end milling tools by using a hot filament chemical vapor deposition (HFCVD) equipment. The morphologies, phase structures and adhesive strength of various types of diamond coatings were systematically tested by Field emission scanning electron microscopy (FESEM), Raman spectroscopy and Rockwell indentation tests respectively. Besides, the tribological performances of various diamond coatings were assessed by the ball-on-disk rotational friction tester. Composite MCD/NCD coating exhibits good friction properties, superior wear resistance and satisfactory material removal rate during the process of sliding against graphite. Further high-speed milling experiments of graphite using bare WC-Co, MCD, SMCD, NCD and MCD/NCD coated milling tools were carried out to characterize their corresponding cutting performances and wear mechanism. Tool wear progressions of different kinds of milling tools with the cutting length were obtained. Moreover, tool wear morphologies were acquired by FESEM and machined surface roughness of graphite were measured by 3D surface profile meter. Results indicate that MCD/NCD coated milling tool exhibits excellent cutting performances compared to the other milling tools due to the comprehensive properties of better surface smoothness and higher adhesive strength with WC-Co substrates. What’s more, the machining dimensional accuracy and machined surface roughness during high-speed milling of hot bending graphite molds using MCD/NCD coated milling tool could meet the strict requirements of 3C electronic products even without the need or with less need for subsequent lapping and polishing.

Evaluation of graphene based nano fluids with minimum quantity lubrication in turning of AISI D3 steel

Minimum quantity lubrication is an extensively accepted lubrication system owing to its improved heat removal in the machining areas. The purpose of the current study is to examine the effectiveness of graphene based nanofluids in turning on D3 tool steel with minimum quantity lubrication. Experiments were executed with Taguchi’s L27 orthogonal matrix array. The effectiveness were examined with the machining parameters under environment (dry condition, flood lubrication and minimum quantity lubrication), cutting speed, feed rate and depth of cut in terms of surface roughness, cutting temperature, tool wear and chip morphology. A technique known as Preference Ranking Organization Method for Enrichment Evaluations were used to determine the imperative parameters governing the responses. The results reveal that graphene nanofluids with minimum quantity lubrication found to be a right substitute in reducing the surface roughness, tool wear and cutting temperature.

Comparative investigation of tool wear mechanism and corresponding machined surface characterization in feed-direction ultrasonic vibration assisted milling of Ti–6Al–4V from dynamic view

This paper mainly investigated the wear mechanism of universal coated carbide tools in feed-direction ultrasonic vibration-assisted milling (UVAM) of Ti–6Al–4V alloy through theorical analysis and experimental approaches, where the external ultrasonic vibration excitation was imposed on the workpiece. The rapid intermittent machining features, the generation mechanism of ultrasonic-frequency pulse cutting force and alternating friction, ultrasonic-frequency dynamic impact effect of resonant workpiece and considerable changes in tool trajectory and relative cutting speed in UVAM were analyzed from perspective of tool-workpiece dynamics and kinematics. Due to the ultrasonic-frequency friction between the tool and the workpiece, the minimum quantity lubrication (MQL) with biodegradable cutting fluid was firstly introduced in UVAM to improve the lubrication/cooling performance between tool and workpiece/chips interfaces. Three different machining methods, general milling, feed-direction UVAM and feed-direction UVAM&MQL, were sequentially carried out to comparatively investigate the tool wear mechanism and characterize tool wear and machined surface features. The corresponding machined surface quality including surface topography, surface profile and surface roughness under different tool wear states were presented to evaluate the tool wear condition. The results indicated that the tool wear mechanism in workpiece feed-direction UVAM system was dominated by ultrasonic-frequency dynamic load, where ultrasonic-frequency cutting force, ultrasonic-frequency friction, ultrasonic-frequency vibration impact and cutting inflection points of tool-tip trajectory worked together on the cutting edges. And the tool wear morphology in feed-direction UVAM was mainly characterized by tool-tip fracture, impact crack, friction traces and fatigue crack. The results of machined surfaces indicated that compared with the surfaces obtained in CM and general UVAM, the UVAM&MQL method could significantly improve the finished surface quality, which can also improve the tool wear to a certain extent.

Dry turning of AISI D3 steel using a mixed ceramic insert: A study

AISI D3 steel is a new kind of hardened tool steel with excellent wear resistance. This hard material receives wide promotion, investigation, and application in the die manufacturing industries. In the machining of AISI D3 steel, tool wear has a close relationship with the presence of different constituent elements in the workpiece material and cutting conditions. This study reports an improved experimental investigation approach to the analysis of effect of cutting speed, feed rate, and depth of cut on cutting forces, surface roughness, tool wear, and chip morphology in high-speed turning of AISI D3 steel using a hybrid TiN-coated Al2O3 + TiCN mixed ceramic insert. The range of each parameter is set at different levels for the analysis purpose. The experimental observations show that the cutting force is predominantly influenced by the feed rate accompanied by the depth of cut. The predominant factor influencing flank wear is the feed rate accompanied by the depth of cut and cutting speed. Feed rate is one of the dominating factors that influences the surface finish characteristics. The characterization of tool wear and chip morphology was performed by a scanning electron microscope supplied with energy-dispersive X-ray spectroscopy pattern. The results demonstrated that the predominant wear mechanism of the multilayered hybrid-coated tool was flank wear, crater wear, adhesion wear, and abrasive wear.

Tool wear and chip analysis after the hard turning of AISI D6 steel assisted by LN2

Sustainability is a concept which is widely considered nowadays, including in factories where machining operations are present. The search for methods able to improve the performance of industrial processes without damaging the environment or the worker’s health has been the main goal of several investigations. In this context, cryogenic machining is a technique that has been studied as an alternative to the use of mineral oil-based cutting fluids, mainly in the machining of titanium and nickel alloys. Investigations on the cryogenic machining of hard tool steels are still scarce in the literature. This article presents results from a series of turning trials under dry and cryogenic conditions using a hardened AISI D6 tool steel bar (57 HRC) as the workpiece. For the cryogenic machining tests, liquid nitrogen was delivered to the flank face, rake face and on both faces of PCBN inserts. The main cutting parameters (cutting speed, feed rate, and depth of cut) were kept constant during the trials. Tool wear and chip morphology were the output variables studied. The results show that the liquid nitrogen was able to reduce the cutting tool wear, providing a tool lifetime around 50% longer compared with the dry process. Moreover, the frequency of chip segmentation was diminished under cryogenic conditions in comparison with the dry process.

Fabrication and machinability analysis of squeeze cast Al 7075/h-BN/graphene hybrid nanocomposite

This article deals with fabrication and machinability analysis of squeeze cast Al 7075/h-BN/Graphene hybrid nanocomposite (HNC), which has been fabricated by reinforcing hexagonal boron nitride (0.5 wt% h-BN) and graphene nanoparticles (1 wt% GNPs). In order to utilize the self-lubricating property of h-BN and GNPs, their uniform mixing is essential, hence before squeeze casting of HNC ball milling (BM) technique has been employed which enables uniform mixing and also eliminates the agglomeration effect of nanoparticles. Scanning electron microscopy (SEM) and optical microscopic (OM) investigation confirm the uniform mixing of nanoparticles as well as refinement in the grain size. In order to examine the hardness of the proposed HNC, mechanical properties were investigated and observed improvement of 31.25%, 10.93% and 10.27% in the UTS, microhardness (Vickers) and Rockwell hardness respectively as compared to unreinforced Al 7075 alloy fabricated by stir casting. Based on the obtained results machinability analysis is performed considering numerous machining process parameter during CNC turning to investigate the influence of cutting speed (CS), feed rate (FR) and depth of cut (DOC) on surface roughness (SR), generated forces, tool wear and chip morphology of squeeze cast HNC subjected to dry and minimum quantity lubrication (MQL) machining. Finally, the acquired results are presented with the aid of comparative graphical presentation with squeeze casted conventional aluminium alloy.

Investigation of Tool Wear and Chip Morphology in Dry Trochoidal Milling of Titanium Alloy Ti-6Al-4V.

Titanium alloys are widely used in the manufacture of aircraft and aeroengine components. However, tool wear is a serious concern in milling titanium alloys, which are known as hard-to-cut materials. Trochoidal milling is a promising technology for the high-efficiency machining of hard-to-cut materials. Aiming to realize green machining titanium alloy, this paper investigates the effects of undeformed chip thickness on tool wear and chip morphology in the dry trochoidal milling of titanium alloy Ti–6Al–4V. A tool wear model related to the radial depth of cut based on the volume of material removed (VMR) is established for trochoidal milling, and optimized cutting parameters in terms of cutting speed and axial depth of cut are selected to improve machining efficiency through reduced tool wear. The investigation enables the environmentally clean rough machining of Ti–6Al–4V.

An investigation of thermal-mechanical interaction effect on PVD coated tool wear for milling Be/Cu alloy

In this paper, a comparative study is reported on tool wear morphology described by machining Be/Cu alloy at different cutting speed:200 m/min,400 m/min,600 m/min,800 m/min and 1000 m/min. The cemented tungsten carbide tools, both coated with TiAlN, are used to test tool life, and the flank wear extent and standard deviation are adopted to describe surface wear pattern. In order to explain the wear mechanism under different cutting speed, a series of theoretical calculation and experiment results were listed in this paper to explain adhesive effect on tool wear under different surface pressure, and results show that the adhesions and wear patterns would be affected by cutting speed and surface pressure. Comparing the relationship between cutting force, cutting heat, surface elements and tool wear, we can easily find out that the hard particle such as Cu and Be adhered to cutting edge to affect tool geometry and strengthen. Besides, the microstructure and generation probability are analyzed to discuss the crystal surface slipping effect on tool wear.

Effects of reinforced nanofluid with nanoparticles on cutting tool wear morphology

Superalloys are grouped as hard-to-cut materials with relatively poor machinability. Tool wear is considered one of the main machinabiliry attributes in machining superalloys. Although numerous works have been reported on factors governing tool life in machining superalloys, no study was found on the effect of nanoparticles stability on nanofluid performance and consequently resulted tool wear morphologies. In the present work, the nanoparticles were reinforced by means of improving the stability of the base fluid. To that accomplished, the surface active agent (surfactant) was added to the base cutting fluid as a reinforcing element. The effects of new lubricant on the tool wear morphology of A286 works parts were assessed.

End milling of DIN 1.2714 die steel with cryogenic CO2 cooling

Currently, cryogenic coolants are used instead of normal cutting fluid in transferring excessive heat from the cutting region and retaining cutting tool edge sharpness during the machining process, and to eliminate the hazardous effects of cutting fluids. In this investigation, end milling experiments with various cooling approaches were performed on DIN 1.2714 die steel using titanium aluminum nitrate-coated carbide tool inserts under dry, conventional coolant, and cryogenic CO2 environments. The end milling performance under CO2 environment has been compared with those under dry and wet conditions regarding cutting temperature (Tc), feed force (Fx), normal force (Fy), axial force (Fz), surface roughness (Ra), tool wear, surface and chip morphology, and residual stress. The consequences of these machining environments were evaluated. Using cryogenic CO2 cooling technique reduced the Tc values by approximately 50.49 % and 64.42 % compared with those of wet and dry conditions, respectively. Similarly, CO2 cooling diminished the cutting forces, namely, Fx, Fy and Fz. As a result, Ra values reduced by approximately 59.81 % and 67.15 % compared with those of wet and dry conditions, respectively. Cryogenic CO2 caused a significant reduction in surface damage and abrasion wear in the machined surfaces and cutting inserts, respectively. No substantial changes in residual stress were observed at the cut surfaces.

Performance analysis of cryogenically treated plus tempered carbide inserts in turning of Inconel 718 using cryogenic minimum quantity lubrication cooling technique

The present study deals with performance investigation of cryogenically treated plus tempered carbide inserts during machining of Inconel 718. A novel cooling approach of combined minimum quantity lubrication with cryogenic coolant, cryogenic minimum quantity lubrication is examined to improve the machinability of Inconel 718 and compared with dry, wet, minimum quantity lubrication, and cryogenic cooling conditions. Tool wear, cutting forces, and chip morphology were analyzed to evaluate the effect of cooling under different conditions. The results revealed that minimum quantity lubrication and cryogenic conditions exhibited superior performance than wet and dry conditions. However, severe tool fracture and cutting forces were observed in cryogenic machining which is an outcome of hardened surface of nickel alloy due to cryogenic fluid. Cryogenic minimum quantity lubrication was understood to be the best machining condition generating least cutting force and tool wear. Furthermore, examining chip morphology under scanning electron microscopy revealed that cryogenic minimum quantity lubrication performed stable machining.

Tool wear and chip morphology in high-speed milling of hardened Inconel 718 under dry and cryogenic CO2 conditions

This paper details an investigation into the performance of PVD tungsten carbide coated ball nose milling inserts when conducting high-speed cutting of Inconel 718 under eco-friendly machining methods of cryogenic carbon dioxide (CO2) and dry cutting conditions. The experiments were performed at varying cutting parameters of; cutting speed: 120–140 m/min, feed rate: 0.15–0.25 mm/tooth, and axial depth of cut: 0.3–0.7 mm. The radial depth of cut was kept constant at 0.4 mm. A new cryogenic CO2 cooling system was introduced for efficient and consistent cooling performance during cutting. The analysis includes the tool life, tool wear patterns and mechanisms as well as its relationship with the chips’ morphology. The experimental results showed that cryogenic and dry cutting conditions reported approximately similar tool wear patterns. The tool wear started with smooth abrasion and chipping around the depth of cut line, which then progressed into flank wear and finally notching and flaking via mechanisms of abrasive and adhesive wears. However, severe BUE was repeatedly observed under dry cutting, which widened the flaking and accelerated the notching. Hence, cryogenic CO2 showed significant improvement towards increasing the tool life to a maximum of 70.8% relative to dry cutting. The consistent cooling effect by the cryogenic CO2 managed to efficiently reduce the cutting temperature at the cutting point to 80% compared to dry cutting, which is believed to be the main factor causing the aforementioned improvement. The strong influence of cutting conditions and tool wear patterns upon the chip morphology was also evident. Compared to cryogenic cutting, the shape and colour of the chips were found to be severe, distorted, and darker in dry cutting, which confirmed that it was thermally affected by the high cutting temperature.

Experimental study of the influence of the process parameters in the milling of Al6082-T6 alloy

ABSTRACTIn this study, end milling operations were conducted on Al 6082-T6 alloy by different cooling environments, cutting speeds or velocities (Vc), feed rates (f). The experimental results were statistically examined using the TOPSIS technique and the ANOVA test. Further, the effect of influencing process parameters, namely, cooling environment, feed rate, and cutting velocity on the various output responses, namely, cutting temperature (Tc), feed force (Fx), normal force (Fy), axial force (Fz) and average surface roughness (Ra) were studied. Tool wear and surface morphology, cut surfaces 2D and 3D profile investigation were performed to analyse the cut surfaces at various conditions. The ANOVA test output showed the cooling environment, f and Vc were the influencing cutting parameters affecting the different performance characteristics of end milling. The overall milling performance of the Al 6082-T6 alloy has been enhanced through proper selection of the optimal parameters setting, namely, wet cooling, f 0.02 m/tooth, and Vc 125 m/min by TOPSIS analysis.

Machinability improvement in Inconel-718 by enhanced tribological and thermal environment using textured tool

Machinability of Inconel-718 superalloy in conventional approach is poor—this fact necessitates advanced technological adoption such as improved surface topography over used cutting tool. Recently, the performance of textured tool has been investigated to explore its potential benefits in achieving favourability in machining of superalloy. In that context, the impact of tool texturing, cutting speed and machining time on some of the prominent machinability indices like cutting forces, tool wear, surface finish and chip morphology has been deliberately investigated. The performance comparison of non-textured and textured tool has been conducted at cutting speed of 80, 120 and 180 m min−1 and at successive increment of machining times up to 10 min. Moreover, the scanning electron microscope analysis of worn tool edges was carried out to comprehend the wear mechanism. Furthermore, the thermal analysis was done for dedicated textured tooling condition. Results revealed that the textured tool performs better to ensure lower tool wear (VB), reduced cutting forces (Fc), lower surface roughness (Ra) and acceptable form of chips. The spots of textured tool acted as fins to promote efficient heat transfer from cutting zone and reduced the effective chip–tool contact length to cause less friction.

Study on characteristics in high-speed milling SiCp/Al composites with small particles and high volume fraction by adopting PCD cutters with different grain sizes

Silicon carbide particle–reinforced aluminum matrix (SiCp/Al) composites were milled at a high speed by adopting polycrystalline diamond (PCD) tools, which the diamond grain sizes were 5, 10, 25, and 32 μm. The machined materials were SiCp/Al composites which the volume fraction was 45% and grain size of SiC particles was 5 μm. The tool wear resistance and wear morphology of polycrystalline diamond cutters were investigated. And it centered on the effects of diamond grain sizes on the cutting forces as well as the machined surface roughness. The obtained results indicated the difference of corresponding tool wear resistance between larger SiC particles and smaller SiC particles during high-speed milling SiCp/Al composites with higher volume fraction. When the grain size and volume fraction of SiC granules are 5 μm and 45%, the tool wear resistances of four diamond grain sizes were all far higher than those of tools in machining composites with higher volume fraction (56%) and larger 60-μm SiC particles. And the PCD tools of larger diamond grain size acted on better wear resistance. Both the corresponding cutting forces and surface roughness were also smaller. As cutting distance increased, the variation law of cutting forces had a good correspondence with the tool wear of PCD cutters of different diamond grain sizes. The machined surface roughness had a decreasing trend in general, but the fluctuation range was tiny. The main wear morphology was flank wear and slight wear groove marks. And there was no chipping of cutting edge and coarse wear groove marks. A large amount of the machined materials was adhered on flake face in the cutting process, but built-up edge was not formed.

End milling of AISI 304 steel using Minimum Quantity Lubrication

Minimum Quantity Lubrication (MQL) is currently recognized a substitute to Flood lubrication method. This work aimed on use of vegetable oil as cutting fluid under MQL. Experimental work was performed on AISI 304 steel using Taguchi’s L18 orthogonal array. Cutting speed, Environment and Feed were selected as the input variables. The responses observed are surface roughness, tool wear and chip morphology. The optimization of multi criteria decision making is attained using TOPSIS technique. The importance of the work is focusing in selecting olive oil for machining. The deep and stretched particles of the olive oil give a greater capability to take up stress and provide dense lubrication. The experimental results were analysed by means of ANOVA. Finally, a Scanning Electron Microscope (SEM) is used to observe the tool wear and chip morphology and Atomic Force Microscope (AFM) to examine the 3-Dimensional profile of the surfaces generated.

Analysis of EN24 steel in turning process with copper nanofluids under minimum quantity lubrication

Minimum quantity lubrication (MQL) is a method which consumes lubricant at a minimum level. In this research work, the usage of copper nanofluids with MQL in turning on EN24 steel is presented. The experiments were performed based on L18 orthogonal arrays by varying the cutting speed, feed rate and environment such as oil with flood lubrication (Oil + FL), oil with minimum quantity lubrication (Oil + MQL) and nanofluids with minimum quantity lubrication. To evaluate the effect of process parameters, the responses, namely, surface roughness and tool wear, were examined. In this study, complex proportional assessment method is used to determine the optimal combination in reducing the surface roughness and tool wear. The results showed that suggested method is appropriate in deciding the best cutting conditions and that nanofluid is the most significant parameter on reducing the surface roughness and tool wear. Further, scanning electron microscope was used to examine the tool wear and chip morphology. Atomic force microscope was also used to observe the three-dimensional view of the machined surface.

An experimental study on investigation of machining of nickel based super alloy 718

Abstract The current paper is an experimental study concerning the machinability of super alloy 718 involving high speed turning operation. Ceramic inserts under three different speeds with fixed feed and depth of cut have been invoked in the experimentation. The impacts of machining parameters on the tool wear were studied using SEM micrographs. The experimental analysis shows that the triangular Al2O3 ceramic insert offers the most effective cutting performance in the machining of super alloy 718. The ceramic cutting tools were acutely affected by the cutting speeds as seen from the SEM and EDS analysis. The present work has unconcealed attention-grabbing findings regarding the tool wear mechanisms with regard to the machining of nickel alloy 718. The most prominent phenomenon of cutting tool wear was found to be the Adhesion wear. The resulting tool wear and chip morphology have been extensively studied.

Investigate the Fluctuation Size in Thrust Force and Chip Morphology in Drilling

Drilling is a widely used production method, having a broad range of applications taking part in machining operations. The length of the cutting edge of the drill causes variations in cutting speed, resulting in undesired outputs. In order to decrease this adverse impact in drilling, selecting higher point angles is an obligation, associated with three different kinds of feed rates and spindle speeds. The aim of this study is to investigate the effect of feed rate, spindle speed, and point angle on the fluctuation size in thrust force besides the effect of the fluctuation size in thrust force on the surface roughness, tool wear and chip morphology. In conclusion, while higher point angles provided optimum outputs such as lower fluctuation size in thrust force, less tool wear, better surface quality and continuous chip form, the effect of feed rate and spindle speed on these outputs varied depending on each other. With the stability in fluctuation size in thrust force, less tool wear took place, and better surface quality and continuous chip form were achieved. However, due to the effect of vibrations, higher fluctuation size in thrust force caused undesired outputs, such as poor surface quality, more tool wear, removal chip in short and brittle form during the drilling operations.

Machined channel quality and tool life using cermet micro-mill in micro-milling aluminum alloy

Based on the superiority of self-developed cermet micro-mill over commercial cemented tungsten micro-mill in our previous work, the cutting characteristics, machined channel quality, and tool wear were investigated in this work, aiming at the evaluation of tool performance of this cermet micro-mill during micro-milling aluminum alloy 2024. Burrs and dimensional accuracy of machined channels, tool wear, and chip morphology were analyzed at various cutting parameters. The machining and forming mechanism related with cermet micro-mill were thoroughly discussed. It indicated that the cutting conditions can be optimized to enhance the performance of cermet micro-mills. The optimum cutting parameter can produce not only the good quality and high dimensional accuracy of channel with few small burrs but also the tool wear to a small degree ever after micro-milling of 10–20 min. The cermet micro-mill also exhibited the good capacity to break the chip. The good performance of cermet micro-mill was attributed to its good chemical stability and high hardness, especially the gained sharper tool tips and edges, and their better stability.