Terms Of Tool Life Research Articles

Influence of GnP additive to vegetable oil on machining performance when MQL-assisted turning Alloy 718

The current study demonstrates through experiment the effect of solid lubricant assisted minimum quantity lubrication (MQL) on the machining performance when turning Alloy 718 with cemented carbide tools. A powder of nanosized (~30 nm) graphite nanoplatelets (GnP) was dispersed (0.2% vol.) in a vegetable oil-based lubricant “ECOLUBRIC E200L” and used in MQL-assisted machining. The effect of cutting conditions on the machining performance parameters such as forces, tool wear, surface finish, and vibrations generated was studied. Results demonstrate a significant improvement of the machining performance when MQL-assisted turning of Alloy 718 with GnP-modified oil in terms of tool life, surface finish and process stability.

Protective coatings for ceramic superplastic forming dies: An initial study on protective coating performance

AbstractSuperplastic forming is an advanced manufacturing process, typically restricted to low volume and high value products. Refractory ceramics are a low cost option to substitute the high temperature resistant steels and other alloys conventionally used in superplastic forming dies, but their brittle nature is a limiting factor for most superplastic forming applications. Suitable surface coatings have shown a significant effect on wear resistance and can be employed to improve the ceramic performance in terms of tool life. This paper focuses on an initial study on protective coatings for superplastic forming ceramic dies to evaluate their effectiveness under superplastic forming conditions. Tests are conducted using a dedicated test rig built where the die‐blank interaction under superplastic forming conditions is replicated at laboratory scale. Two coating materials are tested and surface wear is compared with the uncoated surface of a particle‐reinforced fused silica refractory superplastic forming ceramic die. Results show that the selected coating materials have poor protective performance in comparison with the uncoated ceramic die, but they demonstrate the ability to assess protective coatings performance under superplastic forming conditions at a laboratory scale.

The role of PVD coating and coolant nature in wear development and tool performance in cryogenic and wet milling of Ti-6Al-4V

The aim of this research work is to investigate and understand the wear mechanisms that determine tool life for PVD-coated and uncoated tools in face milling of Ti-6Al-4V over a relevant range of cutting data in cryogenic (CO2) and wet conditions. The interaction between the PVD coating, the coolant nature and the cutting data is also studied. The results reveal that the main wear mechanism which determines the tool life in wet conditions, for both PVD-coated and uncoated tools, is chipping/partial destruction of the cutting edge over the whole range of cutting data. This mechanism is based on the lateral propagation of comb cracks, resulting in partial removal of the cutting edge. In the case of cryogenic cooling (liquid carbon dioxide), any lateral crack propagation, and therefore chipping, is greatly delayed, resulting in longer tool life compared to emulsion cooling with the appropriate cutting data. Accordingly, abrasive wear (flank wear) is not the determining wear mechanism for tool life with either uncoated or PVD-coated tools. Moreover, the PVD coating does not contribute to tool life in milling of Ti-6Al-4V, irrespective of the coolant nature. The SEM analysis also shows that cryogenic cooling reduces or prevents flaking tendency of the coating. The results clearly indicate that increased cutting data decreases or eliminates the difference between cryogenic cooling and conventional emulsion in terms of tool life. However, the cryogenic coolant (CO2) can provide up to 6 times longer tool life compared to emulsion using the right combination of cutting data. In order to take full advantage of the potential of cryogenic cooling to improve productivity, it is essential to find the optimal range of cutting data.

COMPARATIVE STUDY OF WEAR BEHAVIOR OF M35 TOOL STEEL ON TREATED AND UNTREATED CUTTING TOOL ON LATHE MACHINE

The aim of this study is to reveal the enhancement of wear resistance of AISI M35 tool steel by cryogenic treatment and Heat treatment by observing their tool life in terms of cutting length and surface roughness value obtained. Cryogenic treatment is often referred as cryo treatment, is an add-on process to the conventional heat treatment. In the experimentation process we have made two single point cutting which have undergone through heat treadment and cryogenic treatement. Those two tools we have fitted on standard all gear lathe machine. On Lathe machine we have conducted experimentation process for tool life keeping Speed (N), Feed (F), and Depth of Cut (D) as a input process parameters and tool life in terms of Cutting length and roughness value as a output parameter. Along with various angles and faces of tool the tool nose radios plays a very important role in producing good surface finish on component. Hence effect of this radius also has studied in this experimentation. Considering the length of paper we have not included microstructural details of material gone under processes.

Influence of the heat treatment on the microstructure and machinability of titanium aluminides produced by electron beam melting

Additive manufacturing (AM) has been emerging as a promising fabrication technology for polymers and metal products. This technology is able to fabricate complex shape components with high geometrical freedom and allows to reduce the overall waste material, as the powder can be recycled several times, and time from drawing to production can be consistently reduced. In the case of materials for aerospace applications, like TiAl alloys, conventional machining is needed to obtain the required surface finish. The machinability is strongly dependent on the specific alloys and on the production technology used, leading to different microstructures, that can be tuned undergoing the alloys to several treatments after the AM process. The paper focus on the effect of post processing treatment on hardness, structural properties and machinability of Ti48Al2Nb2Cr obtained by electron beam melting process. Untreated and heat treated alloys were considered. Turning tests were carried out under dry conditions by using cemented carbides cutting tools coated with TiCN-Al2O3-TiN. The structure, microstructure and hardness of the material were studied and related to machinability, that was evaluated in terms of tool life and surface integrity, focusing on both surface and sub-surface alterations. Tool wear, cutting forces, chip morphology and surface roughness were also analyzed. Adhesion prevailed on abrasion as main wear phenomenon, leading to cutting edge breaking. Results indicated a higher machinability of the alloys that underwent post processing treatment because of the different microstructure and crystalline phases induced. Indeed, α2 and β phases present in heat treated material enhanced the formation of built up edge, acting as protective layer and then slowing down the degradation phenomena. Also the lower porosity leaded to a lower diffusion phenomenon, positively affecting the tool life.

Techno-economic analysis of blanking punch life improvement by environment friendly cryogenic treatment

Cryogenic treatment is an environment friendly supplementary process to conventional heat treatment used to improve wear resistance of tool and die steels. The potential of cryogenic treatment on AISI D2 die steel under laboratory conditions is well researched and documented. However to ensure the sustainable use of this technology in real life manufacturing, techno-economical analysis is required to be undertaken. Hence, a small scale production unit manufacturing medical instruments was identified and impact of cryogenic treatment on AISI D2 steel blanking punch was evaluated in terms of tool life, part quality and pecuniary gain. The cryogenically treated punches were inserted into the die and subjected to blanking of medical grade stainless steel sheets under real life manufacturing conditions. The improved wear resistance of cryogenically treated punch resulted in approximately 60% production rise and savings of 3.5% of annual turnover. Punch life was studied and correlated to part quality in term of burr size to divulge wear behavior of blanking punch. The AISI D2 steel samples were also prepared and subjected to laboratory tests comprising of metallographic observations and hardness. It was found that laboratory tests were not reliable enough to predict improvements in mechanical properties. The mechanism responsible for augmented wear resistance by cryogenic treatment was identified to be conversion of retained austenite in to martensite and precipitation of fine secondary carbides.

Tool life and tool wear in taper turning of a nickel-based superalloy

Due to their high ductility and strain hardening coefficient, high mechanical strength and hardness even in high temperatures, chemical affinity with almost every tool material, and low thermal conductivity, nickel-based superalloys are known to present very low machinability. Some researchers point out that taper turning may prolong tool life as ramping may distribute tool wear along tool edge, avoiding the presence of notch wear in the end of the depth of cut, which usually occurs in the tools used in turning of these alloys. In this work, tool life, tool wear, and resulting surface roughness of Inconel 625 were evaluated for taper turning in comparison with straight turning. In taper turning, double feed was tested to compensate metal removal rate reduction (since in this operation, the feed length is doubled), and in order to avoid roughness increase caused by the higher feed, a wiper tool was used. Results show that taper turning was not successful in terms of tool life, although the furrowing mechanism of the tool coating caused by the hard burr formed, that leads to notch wear, was avoided. This mechanism was replaced by strong adhesion that promoted rapid and wide flank wear. Feed increase has also produced microchipping due to the extra load on the tool edge. Although wiper tool had provided better finishing when high feed was employed, conventional tool seems to be more suitable for tapering considering tool life.

Experimental investigation of the tool wear in micro-milling of stainless steel 316

The objective of this paper is to experimentally investigate the micro-machinability of stainless steel 316 under both dry and minimum quantity lubrication conditions. The machinability was assessed in terms of tool wear, tool life, cutting forces and surface finish. The tool life was characterised as the amount of material removed, instead of the conventional cutting times. The machining performance under MQL is superior to the dry machining for both process conditions in terms of the tool life. The magnitude of the machining forces showed cyclic pattern for both MQL and dry machining. The SEM images and the cutting force signals suggested that the dominant mode of the tool wear in micro-milling is edge chipping and abrasive wear at the tool tip. The surface roughness at the bottom of the slots improved significantly with the application of MQL for all levels of the tool wear.

Application of Different Cooling Strategies in Drilling of Metal Matrix Composite (MMC)

Conventional cutting fluids are known for being expensive, polluting and a non-sustainable part of modern manufacturing processes. Global industrial trends are leaning towards environmental and health friendly technologies. CO2 cooling is an innovative and sustainable method, capable of replacing conventional oil-based cutting fluids under various conditions. The current study intends to cover the indexable insert drilling of aluminium-silicon carbide (Al-SiC) metal matrix composite (MMC) using different diamond coated carbide inserts. Al-SiC composite containing 20% wt. of SiC was used as workpiece material under different cooling strategies. Response Surface Methodology (RSM) and SEM analysis were incorporated to evaluate the tool performance and to understand the wear development in drilling of MMC. Performance tests were carried out at various cutting data and cooling strategies (external CO2, external emulsion, internal CO2 and internal emulsion) in order to study the output in terms of tool life, surface finish and diameter difference of the holes. The results revealed an advantage in the favour of CO2 cooling concerning tool life, precision and surface finish. Drilling with internal supply of CO2 significantly improves the tool life. The internal supply of CO2 generated the best precision and surface finish compared to the other cooling strategies. The test results clearly indicate that the tool failure for internal CO2 is governed by the flaking of the diamond coating in contrast to a combination of flank wear and flaking for emulsion. The results from the external cooling strategy show that there is no significant difference between emulsion and CO2 while the internal cooling strategy shows that CO2 provides the best results. Since the shape and the surface of the hole are generated by the cutting edge of the periphery insert, the wear development on the periphery insert is the main factor which governs the tool life, surface finish and the diameter difference. This can be explained by the internal CO2 strategy that protects the periphery insert.

Machinability study and process optimization in face milling of some super alloys with indexable copy face mill inserts

Hard-to-cut materials such as stainless steels and nickel-based super alloys are widely applied in different critical areas, e.g., aerospace and automotive components and chemical plants. Complex parts used in these areas are machined by recently developed indexable copy face mills with round inserts. This work aims to apply such inserts for studying machinability and process cost optimization during face milling of several hard alloys including SS 403cb+ (a new grade of stainless steel), Inconel 718, and Inconel 625 with indexable copy face mills. Machining experiments on these alloys are performed at different cutting speed and feed rate combinations, and machinability is studied in terms of tool life and wear, material removal rate, cutting forces, and force coefficients. The extended Taylor's tool life model that includes both the cutting speed and feed rate are also used to determine the model coefficients. Using standard cost optimization model, process parameters are optimized considering the trade-off between material removal rate and tool life. The coefficients estimated for the extended Taylor's tool life model are also validated. Findings reveal that machinability of Inconel 625 is poorest among the three alloy materials considered. Also, machining cost is found to be about 5 and 6 folds for Inconel 718 and Inconel 625, respectively, as compared to that for SS 403cb+ when considering a fixed volume to be removed at the optimized speed and feed combinations of each material.

Optimisation of Spindle Speed and Feed Rate for Drilling of Al-SiCp Metal Matrix Composites using ANOVA and Genetic Algorithm

This paper presents the influence of the spindle speed and feed rate of the drilling on machinability of metal matrix composites (MMC) manufactured using stir casting technique. The drilling of MMC is carried out using Ti-Al-N coated and uncoated solid carbide drills. Analysis of variance technique is used to find the percentage of contribution for each drilling parameters and then regression equations were developed to find the thrust force and torque. The drilling parameters were also optimized using Genetic Algorithm. For the optimum values of spindle speed and feed rate, the tool life in terms of tool wear and number of holes drilled was compared for the cases of coated and uncoated drills. From the analysis, it was inferred that feed rate is the significant factor affecting thrust force and torque. Coated solid carbide drill performed than better than the uncoated carbide drill.

Study o f Coated TiN and TiC on Cutting Tools f or t he PVD and CVD Coated Tungsten Carbide by Sand Blasting Pretreatment o f Nickel and Carbon

It has been well established that advanced surface coatings on cutting tools improve wear resistance by modifying the contact conditions between the chip and tool interface. As a result of the recent developments in cutting tool industry, coated tools have made a significant contribution to the metal cutting operations in terms of tool life, cutting time and machining quality. The challenge of modern machining industries is focused mainly on the achievement of high quality, in terms of work piece dimensional accuracy, surface finish, high production rate, less wear on the cutting tools, economy of machining in terms of cost saving and increase the performance of the product. In general, the most important point in machining processes is the productivity, achieved by cutting the highest amount of material in the shortest period of time using tools with the longest life time. The present research work describes the development, Mechanical, Tribological performance of Nano material coating of TiN,TIC, on Tungsten Carbide cutting tool. The Mechanical, Tribological properties of TiN,TIC, are to be compared with uncoated Tungsten carbide cutting tool. And also different coating methods like Chemical Vapour Deposition, Physical Vapour Deposition Method, can be used for comparision.The present work will help to find the tool life and wear behaviour of the each coated tool and it will help to find the best tool coating applicable for the cutting tool. The experiments of Mechanical, Tribological properties tests have to be conducted as per ASTM standards. SEM analysis has to be done for investigating the surface morphology of Tungsten Cutting tool. The coated cutting tool have to be modelled using suitable assumption and analyzed by means of finite element method using ANSYS software. Both results of Experimental and ANSYS software are to be compared.

The Correlation of the Volumetric Wear Rate of Turning Tool Inserts With Carbide Grain Sizes

The objective of this paper is to analyze the effect of different carbide grain sizes on the tool material volume worn away from straight tungsten–carbide–cobalt (WC–Co) turning inserts. A previously developed metrology method for assessing the tool material volume worn away from milling inserts is adapted for quantifying the volumetric tool wear (VTW) of turning inserts. Controlled turning experiments are conducted at suitable points in the feed-speed design space for two sets of uncoated inserts having different carbide grain sizes. Three levels of Ti–6Al–4V stock removal volumes (10-cm3 each) are analyzed. For each insert, the tool material volume worn away (in mm3) as well as the three-dimensional (3D) wear profile evolution is quantified after each run. Further, the specific volumetric wear rate and the M-ratio (volume of stock removed to VTW) are related to the material removal rate (MRR). The effect of carbide grain size on VTW is examined using scanning electron microscopy and elemental analysis. Finally, the inverse dependence of the M-ratio on MRR enables the definition of actual usable tool life in terms of its efficiency in removing stock, rather than being based on a tool geometry related metric.

Machinability of an experimental Ti-Ag alloy in terms of tool life in a dental CAD/CAM system.

Titanium is difficult to machine because of its intrinsic properties. In a previous study, the machinability of titanium was improved by alloying with silver. This study aimed to evaluate the durability of tungsten carbide burs after the fabrication of frameworks using a Ti-20%Ag alloy and titanium with a computer-aided design and computer-aided manufacturing system. There was a significant difference in attrition area ratio between the two metals. Compared with titanium, the ratio of the area of attrition of machining burs was significantly lower for the experimental Ti-20%Ag alloy. The difference in the area of attrition for titanium and Ti-20%Ag became remarkable with increasing number of machining operations. The results show that the same burs can be used for a longer time with Ti-20%Ag than with pure titanium. Therefore, in terms of tool life, the machinability of the Ti-20%Ag alloy is superior to that of titanium.

On Machinability Study and Process Optimization in Face Milling of Some Alloys with Indexable Copy Face Mill Inserts

Hard-to-cut materials such as stainless steels and nickel-based super alloys are widely applied in different critical areas, e.g., aerospace and automotive components and chemical plants. Complex parts used in these areas are machined by indexable copy face mills with round inserts. This work aims to apply such inserts for studying machinability and process cost optimization during face milling of several hard alloys including stainless steel SS 403cb+, Inconel 718, and Inconel 625 with indexable copy face mills. Machining experiments on these alloys are performed at different cutting speed and feed rate combinations, and machinability is studied in terms of tool life and wear, material removal rate, cutting forces, and force coefficients. The extended Taylor's tool life model that includes both the cutting speed and feed rate are used to determine the model coefficients. Using standard cost optimization model, process parameters are optimized considering the trade-off between material removal rate and tool life. The coefficients estimated for the extended Taylor's tool life model are also validated. Findings reveal that machinability of Inconel 625 is poorest among the three alloy materials considered. Also, machining cost is found to be about 5 and 6 folds for Inconel 718 and Inconel 625, respectively, as compared to that for SS403cb+ when considering a fixed volume to be removed at the optimized speed and feed combinations of each material.

Evaluating the Effect of PCD End Mill’s Nose Radius on Machinability of Titanium Alloy Ti-6Al-4V in High Speed Milling

Tool nose radius is an important geometrical parameter in the design of the tool. Due to its direct contact with the workpiece surface it have significant effect not only on the resulting surface quality but also on the tool life. Use of an end mill without nose radius can easily blend during machining due to a lot of stresses acting on the edge of the tool while the large nose radius end mill can increase the strength and rigidity of the tool but can also contribute in increasing the friction between the tool and the workpiece. Therefore careful selection of tool nose radius is important and especially important for Polycrystalline Diamond, PCD insert as this tool material has recently shown great success in terms of tool life, surface roughness and productivity over coated and uncoated carbide tools in high speed end milling of titanium alloy Ti-6Al-4V and with the use of correct tool geometry it can be further helpful in increasing tool life and surface quality. This study therefore investigates the effect of various nose radii’s (R0.1,0.2,0.4,0.8,1.2,1.6,2.4,3.2) and complete round insert end mill on cutting forces and heat distribution between tool and the chip for PCD insert and compare the results with multi-layer (Al2O3+TiAlN+TiN) coated carbide tool at high speed cutting conditions using 3-D finite element numerical simulations. Results have shown that both tools due to their difference in thermal and mechanical properties have different behavior under the conditions studied especially when the complete round insert tool is used. The use of small nose radius tool when nose radius rn is less than the axial depth of cut ap, the forces and the temperature remains quite low and slightly increases with the increase of radius until rn is smaller than ap but when rn gets larger than ap and only some portion of nose radius is involved in cutting, then forces and temperature increases considerably. While when complete round insert end mill is used the forces and temperature significantly drops (more than 50% than the largest nose radius tool studied) at the same ap for PCD insert but for multi-layer coated carbide tool it drops only slightly (20% than the largest nose radius tool studied). The reason for this difference lies in the fact that PCD tool has lower toughness, high hot strength and is more brittle than carbide tools and therefore maximum advantage can be taken only when small nose radius is used or when complete round insert tool is used as complete round insert have uniform stress distribution and also provides more stability for PCD tool material while large nose radius tool increases friction and also has more heat penetration in the tool thus resulting in higher cutting forces and temperature thus ultimately contributing in high wear of tool. While on the other hand carbide tools are only beneficial when smaller nose radius tool is used rather than round shape because of lower hot strength of the material.

Tool wear in turning ceramic reinforced aluminum matrix composites—A review

Cutting tool wear during turning of ceramic reinforced aluminum matrix composites was reviewed. Though tools of different materials, such as tungsten carbide, coated tungsten carbide, ceramics, cubic boron nitride, polycrystalline cubic boron nitride, chemical vapor deposition diamond coated tungsten carbide, and polycrystalline diamond were used for turning the aluminum matrix composites, better performance of polycrystalline diamond tools was observed in terms of tool life. The results obtained by many researchers indicated that dominant tool wear mechanism was abrasion, and tool life was mainly affected by flank wear during turning of these composites. The flank wear increased on increasing particulate size or weight fraction of reinforcement. Flank wear of the cutting tool also increased with increasing cutting speed, feed, and depth of cut; however, cutting speed was the most significant parameter affecting flank wear, followed by feed. Influence of depth of cut on flank wear was limited or insignificant.

Single-crystal diamond tools formed using a focused ion beam: Tool life enhancement via heat treatment

We describe a technique to improve diamond cutting tools used in nanometer- and micrometer-scale machining and formed via focused-ion-beam (FIB) micromachining. Although FIB irradiation is an effective means of fabricating arbitrary miniature shapes in diamond cutting tools, FIB irradiation induces a non-diamond phase, as well as Ga ion implantation, in the irradiated area. This adversely affects the performance of the ultra-precision machining process, especially in terms of tool life and the quality of the machined surface. To eliminate the affected layer, we applied heat-treatment techniques and investigated the optimum thermal profiles. A temperature of 500°C applied to the cutting tool provided optimal machining of nickel phosphorus. The tool life was significantly improved, and a tool life similar to that of a non-irradiated diamond tool was obtained. The quality of the machined surface was also improved markedly owing to superior tool wear and adhesion resistance.

Experimental Effect of Cryogenic MQL Cutting 304 Stainless Steel

Cryogenic MQL is a kind of green machining technology of the combination of cryogenic air and minimal quantity lubrication (MQL). The aim of this research is to determine if the cryogenic MQL technique in turning with Cutting tool with internal cooling structure gives some advantages in terms of tool life, surface roughness and cutting chip breaking. This paper reports the results obtained from turning tests, at one feed rates (0.12mm/r) and one depth of cut (0.4mm) and different cutting speeds (43m/min, 108m/min, 217m/min), and the results obtained show that using cryogenic MQL had some advantages in terms of tool wear, surface roughness and cutting chip breaking compared to using dry cutting and cryogenic air cutting. And the results obtained show that when cryogenic MQL and cryogenic air cutting were applied to high speed cutting, they had more advantages.

PREDICTION OF TOOL WEAR DURING TURNING OF EN9 WORK MATERIAL AGAINST COATED CARBIDE INSERT USING VIBRATION SIGNAL PROCESSING

In this era of high technology maintenance management systems, condition based maintenance (CBM) is extensively acknowledged. It seeks optimum utilization of the system without altering the quality. The state of a single point cutting tool, w.r.t wear if unobserved while functioning, may affect quality adversely. Condition monitoring helps to establish trend. It can be used to define the tool life in terms of the measured parameter like force, pressure, voltage, vibration etc. Condition monitoring plays a vital role in monitoring the condition of critical parts. In this research work, turning operation is selected with the various work material and tool combination while machining En-9 steels with coated carbide insert as the cutting tool. More precisely, it is the flank wear in the cutting tool, which is concentrated upon in this research work as it is one of the most significant parameter in analyzing the effects of condition monitoring. The research work exhibits important information such as the relationship between tool wear and tool vibration acceleration, time and tool wear and number of cuts and tool wear. The outcome of the research work also delivers with the trend generation that helps monitoring the condition of the cutting tool and also in the prediction of the tool life.