Cubic Boron Nitride Inserts Research Articles

Investigation on the Application of Worn Cutting Tool Inserts as Burnishing Tools

The amount of wear in cutting tools used in all machining processes is around 1 % to 2 % evaluation of the non-wearing areas of the inserts is economically beneficial. This study aims to test the usability of the non-wearing regions of the waste tungsten carbide (WC), cubic boron nitride (CBN) and ceramic inserts as a rolling tool in the deep rolling method and to observe their performance. The turned workpieces were deep rolled with three different types of waste-cutting tools (WC, CBN and ceramic) in different machining parameters (rolling force, number of passes, and feed rate). As a result, surface roughness and microhardness values obtained in deep rolling operations with these inserts were similar to those in deep rolling operations with other rolling tools. It has been determined that ceramic inserts perform better in deep rolling processes in terms of microhardness, and WC inserts perform better in terms of surface roughness. Thus, it has been determined that waste WC, CBN and ceramic inserts can be used in the deep rolling method.

EFFECTS OF VIBRATION CONDITIONS ON MACHINABILITY OF AISI 52100 BEARING STEEL

This study focused on determining the effects of the cooling condition in the conventional and ultrasonic-assisted turning of AISI 52100 steel. AISI 52100 steel has been widely used in the bearing, mold, and automotive industries because of its superior wear resistance and mechanical properties. However, its high wear resistance caused poor machinability in conventional machining methods. Low surface quality, rapid tool wear, high cutting temperature, and high cutting force are the main difficulties in the conventional machining of AISI 52100 steel. On the other hand, ultrasonic-assisted machining has become widely used in the past decades for the machining of materials that have low machinability in conventional methods. Conventional turning and ultrasonic-assisted turning were selected as machining methods. Ultrasonic-assisted turning experiments were conducted under 20 and 30 kHz vibration frequencies. Cubic Boron Nitride (CBN) cutting tools were used in machining experiments. In machining operations 50, 100, and 150 m/min cutting speeds were selected, and feed rate (0.1 mm/rev) and depth of cut (0.5 mm) were kept constant in experiments. Minimum quantity lubrication technique which used 1% Al2O3 nanoparticle additives cutting fluid and dry cooling methods were used. CBN insert was used as a cutting tool. The effects of cutting speed, cutting method, and cooling condition on surface quality, cutting force, cutting zone temperature, and cutting tool wear were studied experimentally. Analysis of Variance (ANOVA) was carried out to determine the significance of the effects of input variables on process outputs. As a result of this study, it is determined that combined UAT and nanoMQL have significant effects on the process outputs.

Performance and analysis of sputtered CBN inserts in machining

Sputtered inserts used in facing, turning, sanding, cutting, knurling and drilling operation can increase the quality of the product. It is now possible to create nanofilms of incredible capabilitites which tends to remarkable advancements made in thin film coating processes.Wear resistant type coatings are done to provide a cost effective measure to minimize the ability of two mate jobs which gradually wear away by abrasion orelse of friction. In this case of enhancing tool life, Cubic Boron Nitride(CBN) is chosen to obtain good surface finish and increased productivity. With this sputtering coating technique, Cubic Boron Nitride(CBN) insert is selected for thin film of coating with Tungsten Carbide. The main aim of this technique is to increase the machinability and surface qualities of cutting tools to extend their life span. A small chipping in tool may entirely damage the quality of product and also increase the production cost. So, Life span of tool plays a important role in all machining operations. The Cubic boron nitride is characterized by its roughness, chemical structure composition and grain distribution.Further Microstructure characterization studies such as SEM, TEM and XRD are to be carried out in future studies.

The Precision Analysis of Cutting Edge Preparation on CBN Cutting Inserts Using Rotary Ultrasonic Machining.

This paper is focused on the issue of preparing the cutting edge microgeometry of cutting inserts made of cubic boron nitride (CBN). The aim of this research was to investigate the possibilities of rotary ultrasonic machining (RUM) for preparing asymmetric cutting edge microgeometries of various shapes (chamfers, circular, and elliptical rounding and their combinations) on a CBN cutting tool. In this article, a new type of advanced cutting edge preparation method is presented. CBN is relatively resistant to the most often used (abrasive) methods of cutting-edge preparation, due to its very high hardness (which is a prerequisite property for machining difficult-to-cut materials). Such hard materials could be processed using advanced manufacturing methods, and rotary ultrasonic machining (RUM) is one such method. Experiments have shown that RUM can be used for machining CBN. However, high hardness is not the only challenge here. For cutting edge preparation, it is necessary to achieve an adequate accuracy of size and dimensions. The presented paper analyzes the suitability of the RUM process for processing CBN inserts. The results of the experiment showed that this method can be used for preparing asymmetric cutting edge microgeometries with various shapes.

Analysis of form Error and Roughness of Hardened Steel Workpieces Internally Turned with Different Tools in Long Overhangs

Abstract Internal turning process is a very important and widely used process for enlarging and finishing holes. Especially for the components that work with external members, this operation needs to assure surface and geometric quality. In that case, the correct definition of working parameters will directly contribute to the quality of component. Aim of the current research was to analyse the form error and the roughness of workpieces submitted to internal turning process using boring bars in long overhangs with three different internal tools (steel, carbide and antivibrating tool). For the experiments, heat-treated DIN EN 1.2842 (ISO 90MnCrV8) steel with 58 HRC of hardness was submitted to boring process using CBN (cubic boron nitride) inserts, and a boring bar with the most possible rigid clamping system (Easy Fix). The workpiece roughness and circularity were measured using a profilometer and a form error measuring machine. The measurements provided the data to identify the boring bar levels of stability, and the workpiece micro and macro geometric errors. The experiments allowed to conclude that, for all toolbars, the evaluated errors kept constant with increasing L/D ratio during stable clamping conditions, without any vibration. On the other hand, higher values of overhangs, limited to L/D>4.25 for steel tool, can cause serious damages in the cutting system if the antivibration tools or the carbide will be not used.

Sustainable Machining: Tool Life Criterion Based on Work Surface Quality

Extending the use of a component without compromising its intended functionality is the neatest approach to enhance sustainability. From this perspective, limiting the working life of a cutting tool based merely on the blunting of its cutting edge to a specific value is highly questionable. The very question that serves as the motivation for this work is, “why should tool life criterion be based on the shape of the tool when all that matters for business is the quality of the part being machined?”. This work puts forward a tool life criterion based on the surface quality of the machined part. The proof of the concept is provided by a series of face-turning experiments performed on a commonly used alloy steel using the following cutting inserts in dry conditions: (1) uncoated carbide; (2) coated carbide; and (3) cubic boron nitride (CBN). It is found that different combinations of tooling and cutting parameters lead to entirely different values of surface roughness at the same level of flank wear, thus raising the possibility of extending the working life of the tools. Overall, the CBN inserts yielded the longest tool life values, especially at high levels of cutting speed. Being more economical in respect of acquisition cost than the CBN inserts and more effective than the uncoated carbide inserts regarding tool life, the coated carbide inserts came out as the most sustainable tooling option. Finally, it is concluded that a tool life criterion based on work surface roughness can yield longer tool life values and make the machining process more sustainable. For the experimental work reported herein, the surface-quality based tool life criterion yielded on average 23% longer tool life. The presented work is novel as it presents a new approach to extend the working life of cutting tools without compromising the other sustainability measures. The outcomes are expected to find applicability in all sectors of the metal cutting industry, which are striving for elongations in tool life and improvements in work surface quality.

Replacement analysis of ceramic insert by CBN insert in vertical lathe

This work analyzes replacing an insert made of ceramic with an insert made of CBN (Cubic Boron Nitride). The inserts are cutting tools used in machining. We will start by presenting a brief account of what machining is, what is applicable in this research and the properties of the two cutting tools. We will also include our objective and justification for carrying out the project. Next, we will describe all of the equipment and tools used in the process to verify results, detailing the function of each one. We will explain our method step by step and show the properties of each insert and their use. We will compare the inserts during operations, and some results will be analyzed graphically in order to obtain a better picture of the behavior of the inserts. We will finish the paper by summarizing and calculating the results, on a cost-benefit ratio, thereby allowing us to determine the most viable replacement insert for use in industry.

Experimental investigation on machining behavior in dry turning of nickel based super alloy-Inconel 600 and analysis of surface integrity and tool wear in dry machining

Recently, most companies are striving to reduce the cost incurred in production to enhance productivity. The machining behaviour is analyzed by considering various parameter. In general, nickel based super alloy are termed as hard materials which result in more tool failures. Inconel 600, nickel alloy, is machined using dry cutting conditions using gear lathe with cubic boron nitride (CBN) tool. The statistical technique, analysis of variance (ANOVA) was adopted to establish the correlation between the machining parameter and response parameter using CBN inserts. Linear regression equation for surface roughness (SR) were used to predict the responses. ANOVA result for SR concluded that cutting speed has 95% contribution followed by feed rate (4%) and depth of cut (1%). ANOVA result for tool wear (TR) concluded that cutting speed has 80% contribution followed by feed rate (18%) and depth of cut (2%). R- square predicted value for SR and TR are 81.3% and 89.11% respectively.

Cutting parameters optimization for surface roughness during dry hard turning of EN 31 bearing steel using CBN insert

Hard turning has evolved as an economical process for machining of hardened parts compared to cylindrical grinding process. The surface roughness, dimensional and geometrical accuracies achieved by hard-turning process are similar to those achieved by grinding process. Cubic boron nitride (CBN) is generally used as cutting tool in hard turning. Bearing bush is used on feed rollers end shafts upon which bearings which are used in super finishing machines in bearing industries. These bearing bushes are manufactured using very hard material of hardness 60 HRC which requires very high surface finish and accuracy. Surface roughness plays vital role in bearing applications and hard turning can be used to achieve the required high surface finish and maintain close tolerances and accuracies. In this present work, experiments were conducted on hardened EN31 steel using Hardinge hard turning machine using CBN tools under dry conditions to study the effect of cutting parameters on surface roughness and to obtain optimum cutting parameters for minimizing surface roughness by using Taguchi L9 Orthogonal array method and ANOVA. The minimum surface roughness achieved for optimum conditions was 0.1492 µm, it was compared with ground bearing bush and found that the hard turned bearing bush has better surface roughness than ground bearing bush.

Study on Factors which Make CBN Insert can Turn S45C Steel Have Surface Roughness Less than Ra 0.4

Grinding process is necessary final process of making cylindrical parts with less than Ra 0.4 surface roughness. Generally we cannot obtain good surface quality without grinding process. As the experience of the authors, using CBN (Cubic Boron Nitride) insert to turning cylindrical parts could be obtained Ra 0.438 surface roughness. The surface roughness result is similar to ground parts. This result becomes the main focus of the study. Authors study to find out factors affecting CBN performance in turning with CBN to obtain less than Ra 0.4 surface roughness. According to the study, it was found that tool contact area allied to surface roughness. The experiment is turning S45C medium carbon steel under the following condition: Cutting speed is 300 m./min, Feed is 0.05 mm./rev and depth of cut is 0.1 mm. Experiment under the same condition in different contact area. Modify contact area of CBN insert to be 5,10,15,20 and 25 mm. and testing in order. CBN insert standard type contact area is 0 mm. Compare test results of modified CBN inserts with standard type result. The results of experiments were as follows: 1) Turning steel with CBN contact area 10 mm. was obtained Ra 0.456 surface roughness, 2) Turning steel with CBN contact area 15 mm. was obtained Ra 0.293 surface roughness, Thus less than Ra 0.4 surface roughness.

Turning titanium metal matrix composites (Ti-MMCs) with carbide and CBN inserts

Despite excellent mechanical and physical features of titanium metal matrix composite (Ti-MMC), hard and abrasive ceramic particles within the matrix structure, as well as high price, may lead to severe difficulties on machining and machinability of Ti-MMCs. Review of literature denotes that only limited studies are available on machining Ti-MMCs with commercial cutting tools under various cutting conditions and cutting tools/inserts. Furthermore, limited studies are available on machinability attributes of Ti-MMC under various cutting conditions used. Therefore, to remedy the lack of knowledge observed, this work intends to report turning Ti-MMCs with carbide, and cubic boron nitride (CBN) inserts under various cutting conditions. The mean values of surface roughness (Ra) and directional cutting forces, as well as flank wear (VB) were studied as the machinability attributes. The microstructural evaluations were conducted to discover the wear modes. Furthermore, the statistical tools were used to present the factors governing machining attributes studied. Adhesion, abrasion, and oxidation were observed as the principle wear modes on the flank sides of the tested inserts. According to experimental results and statistical analysis, the Ra and VB could be controlled by cutting parameters only when CBN inserts were used. Despite the inset used, factors governing both responses were not identical. Although average cutting forces were directly affected by cutting parameters used, however, the relatively low correlation of determination (R2) of directional cutting forces can be attributed to effects of cutting speed, elevated temperature in the cutting zone as well as rapid tool wear which are all correlated to others.

A comparative study on performance of CBN inserts when turning steel under dry and wet conditions

Cutting fluids is the most unsustainable components of machining processes, it is negatively impacting on the environmental and additional energy required. Due to its high strength and corrosion resistance, the machinability of stainless steel has attracted considerable interest. This study aims to evaluate performance of cubic boron nitride (CBN) inserts for the machining parameters includes the power consumption and surface roughness. Due to the high single cutting-edge cost of CBN, the performance of significant is importance for hard finish turning. The present work also deals with a comparative study on power consumption and surface roughness under dry and flood conditions. Turning process of the stainless steel 316 was performed. A response surface methodology based box-behnken design (BBD) was utilized for statistical analysis. The optimum process parameters are determined as the overall performance index. The comparison study has been done between dry and wet stainless-steel cut in terms of minimum value of energy and surface roughness. The result shows the stainless still can be machined under dry condition with 18.57% improvement of power consumption and acceptable quality compare to the wet cutting. The CBN tools under dry cutting stainless steel can be used to reduce the environment impacts in terms of no cutting fluid use and less energy required which is effected in machining productivity and profit.

Artificial neural network based tool wear estimation on dry hard turning processes of AISI4140 steel using coated carbide tool

AbstractNowadays, finishing operation in hardened steel parts which have wide industrial applications is done by hard turning. Cubic boron nitride (CBN) inserts, which are expensive, are used for hard turning. The cheaper coated carbide tool is seen as a substitute for CBN inserts in the hardness range (45–55 HRC). However, tool wear in a coated carbide tool during hard turning is a significant factor that influences the tolerance of machined surface. An online tool wear estimation system is essential for maintaining the surface quality and minimizing the manufacturing cost. In this investigation, the cutting tool wear estimation using artificial neural network (ANN) is proposed. AISI4140 steel hardened to 47 HRC is used as a work piece and a coated carbide tool is the cutting tool. Experimentation is based on full factorial design (FFD) as per design of experiments. The variations in cutting forces and vibrations are measured during the experimentation. Based on the process parameters and measured parameters an ANN-based tool wear estimator is developed. The wear outputs from the ANN model are then tested. It was observed that as the model using ANN provided quite satisfactory results, and that it can be used for online tool wear estimation.

PREDICTION AND INVESTIGATION OF SURFACE ROUGHNESS WHILE TURNING SG IRON WITH CUBIC BORON NITRIDE (CBN) AND TUNGSTEN CARBIDE INSERTS

This work compares the effect of cubic boron nitride (CBN) and multilayer (TiCN+Al2O3+TiN) coated tungsten carbide (WC) tools during the turning of spheroidal graphite (SG) nodular iron. Nodular irons have more ductility which is required in mechanical components that demand high fatigue resistance like crankshafts, cam shafts, bearing caps and clutch housings. The impact of various process parameters like the depth of cut, cutting speed and feed on the surface roughness (Ra) of SG iron is studied and optimized using the response surface model. The chip morphology is also discussed for evaluation of the quality of the turned surface. The experimental outcomes reveal that the WC tool offers a high surface finish at the optimal combination of the cutting speed at 102 meter/minute, feed at 0.051 millimeter/revolution and depth of cut at 0.5 millimeter and that, for the CBN insert, at 245 meter/minute of cutting speed, 0.051 millimeter/revolution of feed and 0.75 millimeter of depth of cut.

Performance Evaluation of Hard Turning for AISI M2 Die Steel with Coated and Non-Coated CBN Inserts

Hard Finish Turning has been Widely Acknowledged as an Excellent Alternative for the Traditional Grinding, Especially it Enables many Intricate Machining Profiles Possible, in a Single Machining Set-up. Cubic Boron Nitride (CBN) Inserts are Usually Used for Hard Turning of Superior Hardened Steel Parts to Very High Degree of Accuracy, Geometry and Surface Texture. the Performance of CBN is of Significant Importance for Hard Finish Turning, because of the High Single Cutting Edge Cost. an Array of Experiments are Conducted with Two Different Types of Low Content CBN Insert Grades, 1) Tin Coated Insert CB7015, 2) Non Coated Insert BN250 by Using a Tool Holder MTJNL2525M16 in a LT20 Classic ACE Turning Centre. the Surface Roughness is Inspected by SJ201P Surfinish Mitutoyo Profile Tester. the Parameters Determined during the Experiments are MRR, Ra, and Tool Life in Minutes, Number of Parts Machined. A Satisfactory Match has been Reached by Comparing Mathematical Model Tool Life Using Experimental Data from the General Taylor’s Tool Life Equation and Experimentally Measured Tool Life. the Cost Analysis is Carried out by Gilbert’s Approach Indicates that the Cost Incurred per Part Produced is Lesser in Tin Coated Insert. the Proposed Methodology can Help to Optimise the Hard Finish Turning Process for AISI M2 Die Steel, and Also in Evaluating the Performance of CBN Tin Coated Insert over Non-Coated Insert.

Investigation of TiN Coated CBN and CBN Cutting Tool Performance in Hard Milling Application

Cubic Boron Nitride (CBN) and TiN Composite Coated CBN combines the thermal stability, super abrasiveness and cost effectiveness for hard machining applications. This paper reports the results of a study addressing wear performance of these CBN and TiN based coated CBN inserts (SNMN090308) for face milling of 61 HRC hardened 90MnCrV8 tool steel. Machining test conditions are obtained after dynamic stability simulation of cutting tools and machine tools. The tool wear and cutting forces are also analyzed and the results are presented.

Performance evaluation of CBN, coated carbide, cryogenically treated uncoated/coated carbide inserts in finish-turning of hardened steel

In the present work, the performance of cubic boron nitride (CBN) inserts was compared with coated carbide and cryogenically treated coated/uncoated carbide inserts in terms of flank wear, surface roughness, white layer formation, and microhardness variation under dry cutting conditions for finish turning of hardened AISI H11 steel (48–49 HRC). The flank wear of CBN tools was observed to be lower than that of other inserts, but the accumulated machining time for all the four edges of carbide inserts were nearer to or better than the PCBN inserts. Results showed that tool life of carbide inserts decreased at higher cutting speeds. The surface roughness achieved under all cutting conditions for coated-carbide-treated/untreated inserts was comparable with that achieved with CBN inserts and was below 1.6 μm. The white layer formation and microhardness variation is less while turning with cryogenically treated carbide inserts than the CBN and untreated carbide. At low to medium cutting speed and feed, the performance of carbide inserts was comparable with CBN both in terms of tool life and surface integrity.

Taguchi's technique in machining of metal matrix composites

This paper presents the study on Taguchi's optimization methodology, which is applied to optimize cutting parameters in turning of age hardened Al6061-15% vol. SiC 25 µm particle size metal matrix composites with Cubic boron nitride inserts (CBN) KB-90 grade using steam as cutting fluid. Analysis of variance (ANOVA) is used to study the effect of process parameters on the machining process. This procedure eliminates the need for repeated experiments, time and conserves the material by the conventional procedure. The turning parameters evaluated are speed, feed, depth of cut, nozzle diameter and steam pressure. A series of experiments are conducted using PSG A141 lathe (2.2 KW) to relate the cutting parameters on surface roughness, tool wear, cutting force, feed force, and thrust force. The measured results were collected and analyzed with the help of the commercial software package MINITAB15. As well, an orthogonal array, signal-to-noise ratio is employed to analyze the influence of these parameters. The method could be useful in predicting surface roughness, tool wear, cutting force, feed force and thrust force as a function of cutting parameters. From the analysis using Taguchi's method, results indicate that among the all-significant parameters, steam pressure is the most significant parameter.

Evolution during time of tool wear and cutting forces in the case of hard turning with CBN inserts

The objective of this paper is to determine the evolution of descriptive parameters during time when machining a hard material (alloyed steel 52 HRC-1900 MPa) with a cubic boron nitride (CBN) tool. The resulting experimental data enable the analysis of cutting characteristics such as tool life, cutting forces, surface roughness and tool wear to be carried out. A large part of this paper aims at studying the turning of hard materials with CBN inserts, the correlation between wear evolution and the direction of cutting forces during high-speed machining. Due to cost considerations, these trial campaigns were carried out to obtain a maximum of results with a minimum number of attempts. Based on the experimental results, this paper shows that the geometry of the cut evolves considerably relative to the lifetime of a CBN tool. Cutting forces increase gradually with the increase of the cutting distance and the tool flank wear. Metallurgy state of the surfaces obtained is good and results essentially from the piece–tool interaction in hard turning. Wear of CBN tools does not directly or appreciably affect the manufactured surface.

Hard turning of tempered DIN 100Cr6 steel with coated and no coated CBN inserts

Recent improvements in the machine tools technology (specially the stiffness and positioning accuracy) as well as the advent of the cubic boron nitride (CBN) ceramic cutting tools made the finishing operations for machining hardened steel parts possible, using tools with defined cutting geometry in substitution to the traditional grinding operations. The advantages presented by the hard turning are sufficiently attractive for many plants, however these are still reluctant to adopt and substitute a well known and dominated process (grinding) for other one not totally understood. Aiming to expand the knowledge of the processing effects of hard turning on the finishing of the machined workpiece, as well as the effects on the tool wear life. Series of experiments with seven different types of CBN inserts had been carried out using inserts with wiper geometry, coated with TiAlN and TiN as well as with no coated ones. The cutting parameters had been specified in such a form to cover the entire field recommended by tool suppliers. The machined part was an axle of DIN 100Cr6 steel tempered to 62 HRc. All the machining operations were carried out at a Mazak-Quick-Turn using an tool holder DCLNR-164D with insert geometry ISO CNGA120408SO1020 with edge with T preparation with 0.102 mm × 20°. The tool wear control was carried out using an optic microscope Zollern Saturn and a roughness profiler Hommelwerk T8000. Following parameters were parameters were determined: VB MAX , R a, material removal rate and the tool life determined by the Taylor's equation obtained for theoretically ideal cutting conditions. Preliminary analyses of the results compares with the literature indicating that they are significant.