Uncoated Tungsten Carbide Tools Research Articles

A framework for simulation-based multi-objective optimization and knowledge discovery of machining process

The current study presents an effective framework for automated multi-objective optimization (MOO) of machining processes by using finite element (FE) simulations. The framework is demonstrated by optimizing a metal cutting process in turning AISI-1045, using an uncoated K10 tungsten carbide tool. The aim of the MOO is to minimize tool-chip interface temperature and tool wear depth, that are extracted from FE simulations, while maximizing the material removal rate. The effect of tool geometry parameters, i.e., clearance angle, rake angle, and cutting edge radius, and process parameters, i.e., cutting speed and feed rate on the objective functions are explored. Strength Pareto Evolutionary Algorithm (SPEA2) is adopted for the study. The framework integrates and connects several modules to completely automate the entire MOO process. The capability of performing the MOO in parallel is also enabled by adopting the framework. Basically, automation and parallel computing, accounts for the practicality of MOO by using FE simulations. The trade-off solutions obtained by MOO are presented. A knowledge discovery study is carried out on the trade-off solutions. The non-dominated solutions are analyzed using a recently proposed data mining technique to gain a deeper understanding of the turning process.

Experimental investigation of top burr formation in high-speed micro-end milling of titanium alloy

ABSTRACTSuperalloys with burr-free parts are most preferably used in biomedical, aerospace, marine and automotive applications. In order to reduce the global pollution content, industries strive to execute stringent green manufacturing technologies. There is a need to investigate the different available tools in high-speed micro-milling process to achieve desired burr free with good surface finish on super alloys without using traditional coolants. In machining of titanium and its alloys, because of low thermal conductivity and reactivity with tool materials instigate the burr formation on work material and lowers the tool performance. The main objective of this article is to investigate the top burr formation in high-speed micro-end milling of alpha + beta-titanium alloy-grade 23 ELI (Ti-6Al-4V) under dry cutting conditions using Uncoated and physical vapor deposition coated AlTiN, TiAlN tungsten carbide end mills. Machining performance of the three cutting tools was compared. From the comparison of cutting tools for machining titanium alloy-grade 23, it is found that coated TiAlN tools produce less burr formation than coated AlTiN and uncoated tungsten carbide tools.

Microstructural characteristics of Alloy 718 and Waspaloy and their influence on flank wear during turning

The present study deals with the influence of the microstructures of two wrought superalloys on the flank wear of uncoated cemented tungsten carbide tools in turning. Tool life tests have been performed in order to compare the flank wear development during machining of Alloy 718 and Waspaloy. Additionally, microstructural aspects, such as hardness, grain size as well as types and quantities of hard, abrasive phases have been determined and compared for both machined superalloy workpieces.The results show that Alloy 718 is associated with faster flank wear progression as compared with Waspaloy. The difference in wear is not likely to be the result of higher thermal and mechanical loads on the tool during machining Alloy 718. Characterization of obtained flank wear topographies after removal of adhered workpiece material revealed that abrasive wear is the dominant wear mechanism during machining both superalloys with the investigated cutting parameters. Varying extents of abrasive tool wear during cutting of the two alloys are therefore the likely reason for the different wear rates. In connection to that, significantly larger quantities of hard phases, specifically primary MC-type carbides and TiN-inclusions were found in the Alloy 718 workpiece which can explain the faster flank wear progression during machining this alloy.

High-pressure water-jet-assisted machining of Ti555-3 titanium alloy: investigation of tool wear mechanisms

The main objective of this study is to investigate uncoated tungsten carbide tool wear mechanisms for high-pressure water-jet machining of the Ti555-3 titanium alloy. A comparative study has been undertaken (i.e. conventional versus assisted machining) based on numerous experimental tests. These tests have been accompanied by the measurement of the cutting forces and flank wear. It is concluded that the high-pressure water-jet assistance can greatly increase tool life compared to conventional machining, for all cutting conditions. The gain in tool life depends on the severity of the cutting condition. The analyses performed for each test (i.e. SEM, EDS and 3D profilometer) made it possible to monitor the tool wear and to investigate the main wear mechanisms. Based on these analyses, adhesion wear appears to be the most influential mechanism and it is accelerated by an increase in water-jet pressure. Monitoring of the wear profile made it possible to study the evolution of crater wear and material chipping during machining.

Chip morphology as a performance predictor during high speed end milling of soda lime glass

Soda lime glass has application in DNA arrays and lab on chip manufacturing. Although investigation revealed that machining of such brittle material is possible using ductile mode under controlled cutting parameters and tool geometry, it remains a challenging task. Furthermore, ability of ductile machining is usually assed through machined surface texture examination. Soda lime glass is a strain rate and temperature sensitive material. Hence, influence on attainment of ductile surface due to adiabatic heat generated during high speed end milling using uncoated tungsten carbide tool is investigated in this research. Experimental runs were designed using central composite design (CCD), taking spindle speed, feed rate and depth of cut as input variable and tool-chip contact point temperature (Ttc) and the surface roughness (Rt) as responses. Along with machined surface texture, Rt and chip morphology was examined to assess machinability of soda lime glass. The relation between Ttc and chip morphology was examined. Investigation showed that around glass transition temperature (Tg) ductile chip produced and subsequently clean and ductile final machined surface produced.

Machinability of Soda Lime Glass in High Speed End Milling

Ductile regime machining can produce crack free surface on brittle material under certain controlled cutting conditions. Although end milling is a versatile process, it has not been frequently applied for machining soda lime glass. The brittle nature of the soda lime glass makes the machining difficult. Soda lime glass is a strain rate and temperature sensitive material. Therefore, high speed machining can be beneficiary to achieve ductile surface with low roughness. Hence, proper combination of cutting parameters needs to identify. In this paper, the effects of cutting parameters such as spindle speed, feed rate and depth cut on the surface roughness parameters Ra, Rq and Rt are investigated to assess machinability of soda lime glass during high-speed end milling. Regression models are generated and process parameters are optimized using the Central Composite Design (CCD) of Response Surface Methodology (RSM). The uncoated tungsten carbide tool was used to conduct milling operation. Experimental verification of optimal condition, spindle speed 40,000 rpm, feed rate 10 mm/min and depth of cut 34 µm confirmed that ductile surface with Ra, Rq and Rt of 0.33µm, 0.49µm and 6.59 µm respectively possible to achieve.

An Experimental Investigations in Turning of Incoloy 800 in Dry, MQL and Flood Cooling Conditions

The current research involves the performance analysis in turning Incoloy 800 in dry, minimum quantity lubrication (MQL) and flooded cutting scenario. Two types of MQL namely MQL1 (150 ml/h) and MQL2 (230 ml/h) have been implemented. Flooded cooling rate has been fixed as 600 ml/h. Low budget uncoated tungsten carbide tool of ISO designation CNMG 120408 tool is utilized to accomplish the turning experiments. Grey relational method is used to ameliorate the cutting process restrictions (feed, cutting-speed, and depth of cut), in order to have minimum roughness of surface and tool flank wear. Later analysis of variance (ANOVA) is carried out to analyze the impact of turning variables on responses. The outcomes obtained show that the roughness of surface and the tool wear both are minimal under MQL conditions whereas performance under MQL2 is more favorable than MQL1.

Study of flank wear topography and surface-deformation of cemented carbide tools after turning Alloy 718

An investigation is reported on the characterization of an uncoated tungsten carbide tool used for machining of a Ni-Fe based superalloy (Alloy 718). Scanning electron microscopy (SEM) in combination with white-light interferometry (WLI) was applied to study the flank wear surface topographies both directly after the turning test and when the adhered workpiece material was removed by etching. The obtained results show that the thin layers of adhered workpiece material present on the flank wear land can obscure the wear topography. Removal of adhered workpiece material from the worn areas of interest is therefore necessary to reveal features of worn tool surfaces. SEM observations of worn WC grains revealed that abrasion is an active wear mechanism during cutting. Complementary analysis by the electron backscatter diffraction (EBSD) technique revealed that worn WC grains are additionally characterized by significant strain which suggests the contribution of plastic deformation to the flank wear. Plastic deformation of WC is likely caused by high thermal and mechanical loads acting on the tool during machining.

Flank wear characteristics of WC-Co tools when turning Alloy 718 with high-pressure coolant supply

In the present study, the tool wear mechanisms of uncoated cemented tungsten carbide (WC-Co) tools during machining Alloy 718 with high-pressure coolant supply are investigated. Worn flank faces are analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). With increasing spiral cutting length, larger areas on the tool surface are subjected to erosion of Co-binder by the coolant jet impact. Moreover, the amount and morphology of workpiece-precipitates adhered on worn flank surfaces are influenced significantly by the extent of flank wear land (due to increasing spiral cutting length). The reasons for the obtained results are addressed with respect to the underlying mechanisms. Possible implications for the tool wear behavior are discussed.

Finite Element Method Based Modeling for Tool Wear Prediction in Orthogonal Cutting Process

Finite element method (FEM) plays vital role in simulation of many complex problems in fields such as machining, automotive, aerospace, etc. Tool wear is one of the machining problems that is essential in research due to its importance and its effect on product quality and cost. This paper shows the utilization of finite element method in modeling of two dimensional orthogonal cutting process to predict tool wear of uncoated tungsten carbide tool using Abaqus/CAE program. The simulation methodology included the implementation of Johnson-Cook (J-C) model to define the material behavior. Also, the adaptive meshing technique (ALE) is used in simulation the cutting process to combine the advantages of Lagrangian technique that is commonly used in solid mechanics analysis and Eulerian techniques that is commonly used in fluid mechanics analysis. The objective is to predict tool wear location on tool face by using finite element method and compare the results with the experimental work.

Experimental investigation of surface roughness in high-speed micro end milling of near alpha titanium alloy

Super alloys are widely used in many applications such as aerospace, automotive, biomedical, marine, mining and oil industries. In high-speed micro end milling (HSMEM) of super alloys, the proper selection of cutting tool is necessary to achieve good surface quality without burrs. Surface roughness characterisation is crucial on the work materials to achieve the desired production rate in limited time and at low cost. In this research work, surface roughness characterisation was investigated in order to opt for the better possible tool for machining Near Alpha Titanium Alloy Grade-12 under feasible conditions. The influence of machining parameters i.e. cutting speed, feed and depth of cut on surface roughness was investigated in the present work. Experiments were conducted under dry cutting conditions using Uncoated, PVD Coated TiAlN & AlTiN tungsten carbide tools. It was observed that machining with uncoated tungsten carbide tools generates less surface roughness on near alpha titanium alloy.

Friction Model for Tool/Work Material Contact Applied to Surface Integrity Prediction in Orthogonal Cutting Simulation

Tribological behavior at both tool/chip and tool/work material interfaces should be highly considered while simulating the machining process. In fact, it is no longer accurate to suppose one independent constant friction coefficient at the tool/chip interface, since in reality it depends on the applied contact conditions, including the sliding velocity and pressure. The contact conditions at both above mentioned interfaces may affect the thermal and mechanical phenomena and consequently the surface integrity predictions.In this article, the influence of contact conditions (sliding velocity) on the tribological behavior of uncoated tungsten carbide tool against OFHC copper work material was investigated. Series of tribology tests combined with numerical simulations of the contact process were performed under different sliding speeds and contact pressures, in order to identify the friction coefficient and the heat partition between OFHC copper and tungsten carbide. The friction coefficient in function of the sliding velocity was then integrated into a FE model of the orthogonal cutting of OFHC copper and applied to surface integrity prediction.

On the development of a dual-layered diamond-coated tool for the effective machining of titanium Ti-6Al-4V alloy

This work is focused on the development of a dual-layered diamond-coated tungsten carbide tool for machining titanium Ti-6Al-4V alloy. A hot-filament chemical vapor deposition technique was used to synthesize diamond films on tungsten carbide tools. A boron-doped diamond interlayer was added to a microcrystalline diamond layer in an attempt to improve the interface adhesion strength. The dual-layered diamond-coated tool was employed in machining at cutting speeds in the range of 70 to 150 m min−1 with a lower feed and a lower depth of cut of 0.5 mm rev−1 and 0.5 mm, respectively, to operate in the transition from adhesion- to diffusion-tool-wear and thereby arrive at suitable conditions for enhancing tool life. The proposed tool was then compared, on the basis of performance under real-time cutting conditions, with commercially available microcrystalline diamond, nanocrystalline diamond, titanium nitride and uncoated tungsten carbide tools. The life and surface finish of the proposed dual-layered tool and uncoated tungsten carbide were also investigated in interrupted cutting such as milling. The results of this study show a significant improvement in tool life and finish of Ti-6Al-4V parts machined with the dual-layered diamond-coated tool when compared with its uncoated counterpart. These results pave the way for the use of a low-cost tool, with respect to, polycrystalline diamond for enhancing both tool life and machining productivity in critical sectors fabricating parts out of titanium Ti-6Al-4V alloy. The application of this coating technology can also be extended to the machining of non-ferrous alloys owing to its better adhesion strength.

Effect of Surfactant and Tool Material on the Surface Roughness of Al 6061 IN Turning Operation

Surface finish is one of the primary user requirements for machined products. In this study, the anionic surfactant namely Sodium Dodecyl Sulfate is mixed with coolant to reduce the surface roughness of the turned work piece. Comparative study of surface roughness among dry turning, turning with conventional coolant and turning with surfactant mixed coolant has been done. It was observed that the surface roughness is reduced by using surfactant mixed coolant comparatively. The Surfactant concentration was varied from 0.3 gL−1 – 1.5 gL−1 in increment of 0.3 gL−1. The variations in the surface roughness of the turned work piece for different concentrations of Sodium Dodecyl Sulfate were estimated and illustrated. The maximum surface finish was obtained when surfactant reaches the concentration of 1.2 gL−1. Using the surfactant mixed coolant, the work piece was turned with coated and uncoated tungsten carbide tools in order to evaluate the effect of tool materials on surface roughness of turned work piece. The surface roughness values are measured using Perthometer and surface morphology was examined using Scanning Electron Microscope.

A Novel Cutting Concept of CFRP Composites for Extending the Life of Tool

This paper presents a novel concept for extending the life of the tools that are used in the milling process of carbon-fiber-reinforced plastic (CFRP) composites. Three types of tools were compared in milling tests; tool I: an uncoated tungsten carbide (WC-Co) tool, tool II: a polycrystalline diamond (PCD) tool, and tool III: a combination tool comprising a PCD layer surface with a thickness of 100 μm and a WC-Co substrate flank surface. The measurement of changes in cutting forces over cutting distance revealed that tool III had a better (tool) life performance than the other tools. Additionally, observation of changes in the edge profiles of the tools revealed that the effective edge sharpness of tool III remains constant during the milling tests. The difference between the wear rates of the PCD rake and WC-Co flank surfaces in tool III maintained a constant effective sharpness during the milling process, and it extended the tool life. Based on our findings, we concluded that using the difference between the wear rates of rake and flank surfaces is an effective technique for tool life extension in the milling process of CFRP laminates.

A Study on Drilling of AISI 304L Stainless Steel with Nanocomposite-Coated Drill Tools

Stainless steels are considered to be difficult to machine due to specific properties such as high toughness, work-hardening, and low heat conductivity. Built-up edge and irregular wear situations are often faced in the machining of stainless steel parts. In addition, various problems such as low surface roughness and breakage of drill tool occurred in the drilling of these materials. In this study, \({{{\rm nACo}}^{\circledR}}\) nanocomposite-coated and uncoated Tungsten Carbide (WC) tools were compared to specify the performance of nanocomposite coating in the drilling of AISI 304L stainless steel workpieces. The breakages and damages of \({{{\rm nACo}}^{\circledR}}\) nanocomposite-coated and uncoated WC drill tools were presented when the stainless steel parts were drilled. Drill tool tip damages were investigated by microscope, and surface roughness values of the drilled holes were measured. \({{{\rm nACo}}^{\circledR}}\)-coated WC drill tools were less damaged than uncoated WC drill tools due to the fact that \({{{\rm nACo}}^{\circledR}}\) coating reduced the drill tool–workpiece friction and increased the wear resistance. The surface roughness of the drilled holes with \({{{\rm nACo}}^{\circledR}}\)-coated WC drill tools was better than that of the drilled holes with the uncoated WC drill tools.

Optimization of Surface Roughness in Micro-High Speed End Milling of Soda Lime Glass Using Uncoated Tungsten Carbide Tool with Compressed Air Blowing

Soda lime glass is a very important material in diverse manufacturing industries, including automotive, electronics, and aerospace. In these applications, the glass surface needs to be defect free and without impurities. However, the machining of glass is difficult due to its inherent brittleness which leads to brittle fracture and easy crack propagation. This research investigates the high speed micro-end milling of soda lime glass in order to attain ductile regime machining. It has been found by other researchers that ductile mode machining can avoid brittle fracture and sub-surface cracks. Also, in this study, a special air delivery nozzle is used to blow away the resultant chips and keep the machined surface clean. To accomplish this, Design Expert software and a commercial NC end mill were used to design and perform the machining runs, respectively. The surface roughness of the resultant surfaces was later analyzed with a surface profilometer. Microphotographs of the machined surfaces were also taken in order to see how effective the air blowing method is. The results of surface roughness measurements were then used to develop a quadratic empirical model for surface finish prediction. Finally, desirability function and genetic algorithms were used to predict the best combination of cutting parameters needed to obtain the lowest surface roughness. The predictions were later tested by experiments. The results demonstrate that this type of machining is viable and the roughness obtained is very low at 0.049 μm.

TEMPERATURE MEASUREMENT OF A CUTTING TOOL IN TURNING PROCESS BY USING TOOL WORK THERMOCOUPLE

Temperature at the cutting point of the tool is a crucial parameter in the control of the machining process. Due to advancement in the machining processes, a special attention has been given on the life of a tool. To achieve this, the best way is to apply the coating to the tool. In this study, coated and uncoated tungsten carbide tools were used and temperature occurred during machining were measured. Among the number of temperature measuring methods, the tool-work thermocouple technique is used as it is easy to install and inexpensive as compared to other methods. The procedure for the working of Tool-work thermocouple and method of calibration is described in this paper.

Degradation modes and tool wear mechanisms in finish and rough machining of Ti17 Titanium alloy under high-pressure water jet assistance

This article presents the results of an experimental study on the Ti17 titanium alloy, which was carried out to analyze tool wear and the degradation mechanisms of an uncoated tungsten carbide tool insert. Two machining conditions, roughing and finishing, have been studied under different lubrication conditions. The experimental procedure included measurement of the cutting forces and the surface roughness. Different techniques have been used to explain the tool wear mechanisms. Distribution maps of the elemental composition of the titanium alloy and the tool inserts have been created using Energy Dispersive X-ray Spectroscopy (EDS). An area of material deposition on the tool rake face, characterized by a high titanium concentration has been observed. The width of this area and the concentration of titanium, decrease when increasing water jet pressure. The study shows that wear mechanisms, with and without high-pressure water jet assistance (HPWJA) are not the same. For example, for the roughing condition using conventional lubrication, the temperature in the cutting area becomes very high, this causes plastic deformation of the cutting edge which results in its rapid collapse. By contrast, this problem disappears when machining with HPWJA. In addition, the evolution of flank wear (VB) is stabilized with high-pressure lubrication. In this case, the most critical degradation mode is due to notch wear (VBn) leading to the sudden rupture of the cutting edge.

Experimental Study of tool Wear Mechanisms in Conventional and High Pressure Coolant Assisted Machining of Titanium Alloy Ti17

Titanium alloys are known for their excellent mechanical properties, especially at high temperature. But this specificity of titanium alloys can cause high cutting forces as well as a significant release of heat that may entail a rapid wear of the cutting tool. To cope with these problems, research has been taken in several directions. One of these is the development of assistances for machining. In this study, we investigate the high pressure coolant assisted machining of titanium alloy Ti17. High pressure coolant consists of projecting a jet of water between the rake face of the tool and the chip. The efficiency of the process depends on the choice of the operating parameters of machining and the parameters of the water jet such as its pressure and its diameter. The use of this type of assistance improves chip breaking and increases tool life. Indeed, the machining of titanium alloys is generally accompanied by rapid wear of cutting tools, especially in rough machining. The work done focuses on the wear of uncoated tungsten carbide tools during machining of Ti17. Rough and finish machining in conventional and in high pressure coolant assistance conditions were tested. Different techniques were used in order to explain the mechanisms of wear. These tests are accompanied by measurement of cutting forces, surface roughness and tool wear. The Energy-dispersive X-ray spectroscopy (EDS) analysis technique made it possible to draw the distribution maps of alloying elements on the tool rake face. An area of material deposition on the rake face, characterized by a high concentration of titanium, was noticed. The width of this area and the concentration of titanium decreases in proportion with the increasing pressure of the coolant. The study showed that the wear mechanisms with and without high pressure coolant assistance are different. In fact, in the condition of conventional machining, temperature in the cutting zone becomes very high and, with lack of lubrication, the cutting edge deforms plastically and eventually collapses quickly. By contrast, in high pressure coolant assisted machining, this problem disappears and flank wear (VB) is stabilized at high pressure. The sudden rupture of the cutting edge observed under these conditions is due to the propagation of a notch and to the crater wear that appears at high pressure. Moreover, in rough condition, high pressure assistance made it possible to increase tool life by up to 400%.