Cutting Speed Vc Research Articles

Optimisation of milling parameters using neural network

The purpose of this study was to design and test an intelligent computer software developed with the purpose of increasing average productivity of milling not compromising the design features of the final product. The developed system generates optimal milling parameters based on the extent of tool wear. The introduced optimisation algorithm employs a multilayer model of a milling process developed in the artificial neural network. The input parameters for model training are the following: cutting speed vc, feed per tooth fz and the degree of tool wear measured by means of localised flank wear (VB3). The output parameter is the surface roughness of a machined surface Ra. Since the model in the neural network exhibits good approximation of functional relationships, it was applied to determine optimal milling parameters in changeable tool wear conditions (VB3) and stabilisation of surface roughness parameter Ra. Our solution enables constant control over surface roughness parameters and productivity of milling process after each assessment of tool condition. The recommended parameters, i.e. those which applied in milling ensure desired surface roughness and maximal productivity, are selected from all the parameters generated by the model. The developed software may constitute an expert system supporting a milling machine operator. In addition, the application may be installed on a mobile device (smartphone), connected to a tool wear diagnostics instrument and the machine tool controller in order to supply updated optimal parameters of milling. The presented solution facilitates tool life optimisation and decreasing tool change costs, particularly during prolonged operation.

The analysis of surface topography during turning of Waspaloy with the application of response surface method

This paper presents the analysis of surface topography during longitudinal turning of Waspaloy. The primary objective of the work was to determine the optimal machining conditions enabling the minimization of surface roughness parameters. Experimental studies were performed with the application of fractional plan (with 1 block and 9 systems). The carried out experiment included the measurements of surface topographies formed after turning with variable cutting conditions (cutting speed vc, cutting depth ap and feed f). Subsequently the measured quantities have been applied to the optimization procedure based on the application of response surface method (RSM). In order to obtain the optimal cutting parameters, the maximization of total utility function was carried out. Results revealed that the minimal surface roughness parameters values during turning of Waspaloy with the cubic boron nitride (CBN) inserts can be obtained for the: f=0.05 mm/rev, ap =0.23 mm and vc =452 m/min.

Investigation of chips morphology after turning of materials applied in aerospace industry

In the paper is presented analysis of chips morphology after turning of three groups of modern materials applied in aerospace industry: titanium alloys, stainless steels and heat resistant alloys. Various feed rates f and corner radiuses r e as well as recommended cutting speed vc for given group of work material were applied in machining tests. Range of burrs on thinner edges of chips and serration on the chips surface occurrence were identified dependent on work material and uncut chip thickness (values of the f and r e ). In the research height h and distance b between the burrs as well as distance a between serrated segments were measured. It was identified two kind of burrs connected with different physical phenomenon and specified h and b dimensions.

Monitoring and Control of Manufacturing Process to Assist the Surface Workpiece Quality When Drilling

There is a variety of reasons for the installation of a monitoring system in a manufacturing process. Hole-making mainly drilling is one of the most common operation used and usually is carried out as one of the last steps in the production process. Holes in rotating turbine and compressor disks are among the most highly-stressed geometric features of jet-engines. For manufacturers of jet-engine components it is important to assess the quality of these at an early stage in the manufacturing of the product. The use of commercially available monitoring systems in hole-making has been successful in individual cases so far. Major reasons for this lack of effectiveness are the large material variations within one production batch, the overall difficult machinability of the materials applied, the small lot size which makes “teach-in” operations ineffective. The paper describes a design of adaptive control system for drilling process of aerospace critical components. The proposed system is directed towards the real time control of selected surface roughness parameter. Proposed model for monitoring and control consists of two subsystems: surface roughness prediction subsystem and decision making subsystem. The artificial neural network was employed to calculate surface roughness parameters throughout process monitoring indices such as torque Mz, force Fz, power P and cutting conditions feed f, cutting speed vc. Due to ability to predict nonlinear behaviour and quickly calculate future values, artificial neural networks are ideal for both predictive and adaptive controllers. Test samples were nickel based super alloy Udimet 720 used in discs for gas turbine engines. The experimental results show that predicted values of surface roughness are very close to the values measured experimentally. Advantages of the proposed subsystem for surface roughness prediction are simplicity, computational power and speed, capacity and ability to learn from system changes as they become.

IMPROVING THE QUALITY OF TECHNOLOGICAL SURFACES OF MACHINES OF COMPOSITE COATINGS

Nickel matrix coatings were sprayed by the Casto-Dyn 8000 torch on a steel substrate, and then subjected to straight turning. Determining of the optimum geometry of indexing is now synonymous with the selection of the optimum shape and dimensions of the insert and of an appropriate holder. According to cutting board, it was selected square, triangular, trigon inserts, made of carbide and of cubic boron nitride (borazon). Machining of nickel-based coatings was carried out for the cutting speed vc = 214 m/min in the case of treatment with borazon inserts, vc = 107 m/min in case of plates treated with tungsten carbide cutting, using the feed f =0.06 mm/rev and the depth of cut ap = 0.3 mm. Metal cutting the surface of steel samples coated with a composite coating containing 15% Al2O3 based on nickel, conducted for the cutting speed vc = 157 m/min when machining with borazon inserts and for vc = 83 m/min inserts with tungsten carbide for feed f = 0.06 mm/rev and depth of cut ap = 0.3 mm. Highly precise finishing of flame spraying composite and alloy coatings was carried out using turning by tool with borazon inserts. Flank (VB) and attack (KB) of turning tool wear while maintaining a constant length of spiral cutting (LSC) were determined. The effect of the shape and grade of inserts upon the geometric structure of the composite coatings and is considered in the paper. The article can determine the shape and grade of inserts is necessary to obtain sufficient quality of the shaft of centrifugal pumps with a composite coating.

SURFACE TEXTURE ANALYSIS AFTER BALL END MILLING WITH VARIOUS SURFACE INCLINATION OF HARDENED STEEL

Abstract In this paper, an analysis of various factors affecting machined surface texture is presented. The investigation was focused on ball end mill inclination against the work piece (defined by surface inclination angle a. Surface roughness was investigated in a 3D array, and measurements were conducted parallel to the feed motion direction. The analysis of machined surface irregularities as a function of frequency (wavelength A), on the basis of the Power Density Spectrum - PDS was also carried out. This kind of analysis is aimed at valuation of primary factors influencing surface roughness generation as well as its randomness. Subsequently, a surface roughness model including cutter displacements was developed. It was found that plain cutting with ball end mill (surface inclination angle a= 0°) is unfavorable from the point of view of surface roughness, because in cutter’s axis the cutting speed vc ~ 0 m/min. This means that a cutting process does not occur, whereas on the machined surface some characteristics marks can be found. These marks do not appear in case of a* 0°, because the cutting speed vc * 0 on the fill I length of the active cutting edge and as a result, the machined surface texture is more homogenous. Surface roughness parameters determined on the basis of the model including cutter displacements are closer to experimental data for cases with inclination angles a* 0°, in comparison with those determined for plain cutting (a= 0°). It is probably caused by higher contribution in surface irregularities generation of plastic and elastic deformations cumulated near the cutter’s free end than kinematic and geometric parameters, as well as cutter displacements.

Investigation and FEA-based simulation of tool wear geometry and metal oxide effect on cutting process variables

In machining, it is clearly noticed that the cutting tool wear influences the cutting process. However, it is difficult with experimental methods to study the effects of tool wear on several machining variables. Thus, in the literature, some earlier studies are performed separately on the effect of tool flank wear and crater wear on cutting process variables (such as cutting forces and temperature). Furthermore when the workpiece material adheres in cutting tool, it affects considerably the heat transfer phenomena. Accordingly, in this work the finite element analysis (FEA) is performed to investigate the influence of combination of tool flank and crater wear on the local or global variables such as cutting forces, tool temperature, chip formation on the one hand and the effects of the oxidized adhesion layer considered as oxide (Fe2O3/Fe3O4/FeO) on the heat transfer in cutting insert on the other hand. In this investigation, an uncoated cutting insert WC–6Co and medium carbon steel grade AISI 1045 are used. The factorial experimental design technique with three parameters (cutting speed Vc, flank wear land VB, crater wear depth KT) is used for the first investigation without adhesion layer. Then, only linear investigation is performed. The analysis has shown the influence of the different configurations of the tool wear geometry on the local or global cutting process variables, mainly on temperature and cutting. The simulation’s results show also, the highly influence of the oxidized adhesion layer (oxide Fe2O3/Fe3O4/FeO) on the heat transfer.

Adaptive Control System to Assist the Surface Workpiece Quality when Drilling

Article deals with design of adaptive control system for drilling process of aerospace critical components. The system proposed in this paper is directed towards real the time control of surface roughness parameter Ra. Proposed model for monitoring and control consists of surface roughness prediction system and decision making subsystem. The artificial neural network was employed to calculate surface roughness parameter Ra through of process monitoring indices such as torque Mz, force Fz, power P and cutting conditions feed f, cutting speed vc. Test samples were nickel based super alloy Udimet 720 used as a basic constructional material of discs for gas turbine engines.

Deformation Induced Surface Hardening when Turning Metastable Austenitic Steel AISI 347 with Different Cryogenic Cooling Strategies

In terms of production costs and manufacturing time there is a permanent effort to shorten the process chain by combining different process steps. For metastable austenitic steels there is the opportunity of an integrated surface hardening during machining. This leads to an increase of the wear resistance and fatigue strength of highly loaded components. For this purpose, high deformations combined with low temperatures during the material removal process are needed. To achieve this an insert with a chamfered cutting edge is used to enlarge the passive forces. The central challenge is to keep the temperatures in the cutting zone at a sufficient low level during turning AISI 347. Cryogenic coolants like liquid nitrogen (LN2) or carbon dioxide (CO2) offer an opportunity to keep the process temperature at low values. In this context, the influence of different cryogenic cooling strategies are compared with dry cutting. Additionally, the cutting parameters feed f and cutting speed vc are varied. To detect cause and effect relationships measurements of the passive force, workpiece surface temperature, formed martensite content and micro hardness are performed.

A New Approach to Build a Heat Flux Model of Milling Processes

During the finishing milling process of thin-walled workpieces, deformations occur due to the mechanical and thermal influences. Hence, the manufacturing quality may be affected. The aim of a research project at the iwb is to simulate thermally caused deformations and deriving methods to reduce them. Two approaches subsume the term “reduction methods”: the use of less deformation-causing process parameters or alternatively – if this approach is insufficient – to compensate the deformation.Simulating thermally induced deformations necessitates a description of the heat input, which is caused by the milling process. Furthermore, this description needs to be valid for the whole spectrum of process parameters recommended for the used tool. The model of the heat source is based on milling experiments with an in-process measurement of the thermally caused deformations. The experimental results allow differentiating between thermally and mechanically induced deformations due to the restriction on an end milling finishing process. However, these measurements only provide a relation between process parameters (variation of cutting speed vc, feed per tooth fz and width of cut ae) and deformations. The simulation model, which will be described within this paper in detail, provides the relation between a variable heat input and its resulting deformations. The experimental and the simulative relations together are leading to a heat source model in dependence of the process parameters.

Application of Taguchi Method and Surface Response Methodology to Evaluate Of Mathematical Models to Chip Deformation when Drilling With Coated and Uncoated Twist Drills

The paper deals with the methodology and suitability of mathematical models applying analysis of the signal-to-noise (S/N) ratio as well as analysis of variance (ANOVA) and surface response methodology (RSM) on effect of TiAlN coating on chip ratio when drilling with HSS Co5 twist drill with diameter of 8 mm. Experimental work was performed according to design of experiment (DoE) Taguchi method. Cutting speed vc (m/min) and feed f (mm/rev) were selected as control factors in three levels and chip ratio K was used as a response variable. The main aim of this study is to establish relevant methodology for short term testing and find adequate mathematical model for chip ratio parameter K = f(vc, f) as a function of cutting condition when drilling with PVD coated and uncoated tool. Statistical software Minitab 14 was employed to process and evaluate of experimental data. The effect of feed and cutting speed on chip ratio was investigated through analysis of the signal-to-noise (S/N) ratio and analysis of variance. Equations for chip ratio K as a function of control factors were developed.

Cutting Data Influence on Cutting Forces and Surface Finish during Sintered Carbide Turning

The paper presents research of turning of super hard materials, like sintered carbides, with PCD (polycrystalline diamond) tools. Sintered carbides with cobalt, as metal binder, with good properties of abrasion resistant in high temperature environment are used as construction material. These materials, produced by a powder metallurgy process, are difficult-to-machine because of their high hardness and brittleness. In the work, a special attention was paid on the cutting force component Fc and surface finish, in the form of roughness parameter Ra, at variable cutting data (cutting speed vc, feed f and depth of cut ap). The test stand for research was consisted of the precise lathe, work piece (a tungsten carbides rod with 25% Co content), tool holder of DTGNR 2020K16 type, insert of TNGA type with PCD edges, Kistler force dynamometer and Taylor Hobson profilometer. Taguchi design and ANOVA analysis were applied.

Research of Surface Finish during Titanium Alloy Turning

The paper presents research of titanium alloy (Ti6Al4V) and pure titanium turning with sintered carbide tool of rounded shape. Finish machining was performed on the work piece in the form of a fragment of ball. Several roughness parameters were chosen for the purpose to the surface finish analysis. Results were compared for the pure titanium and its alloy. The test stand for research was consisted of the precise CNC lathe with a special devices, like force dynamometer, roughness and roundness measurement systems. In the work a special attention was paid on the influence of the cutting data (cutting speed vc , feed f and depth of cut ap) on the surface quality.

Microstructural analysis of wear micromechanisms of WC–6Co cutting tools during high speed dry machining

This original study investigates the damages of WC–6Co uncoated carbide tools during dry turning of AISI 1045 steel at mean and high speeds. The different wear micromechanisms are explained on the basis of different microstructural observations and analyses made by different techniques: (i) optical microscopy (OM) at macro-scale, (ii) scanning electron microscopy (SEM), with back-scattered electron imaging (BSE) at micro-scale, (iii) energy dispersive spectroscopy (EDS), X ray mapping with wavelength dispersive spectroscopy (WDS) for the chemical analyses and (iv) temperature evolution during machining. We noted that at conventional cutting speed Vc≤250m/min, normal cutting tool wear types (adhesion, abrasion and built up edge) are clearly observed. However, for cutting speed Vc>250m/min a severe wear is observed because the behavior of the WC–6Co grade completely changes due to a severe thermomechanical loading. Through all SEM micrographs, it is observed that this severe wear consists of several steps as: excessive deformation of WC–6Co bulk material and binder phase (Co), deformation and intragranular microcracking of WC, WC grain fragmentation and production of WC fragments in the tool/chip contact. Thus, the WC fragments accumulated at the tool/chip interface cause abrasion phenomena and pullout WC from tool surface. WC fragments contribute also to the microcutting and microploughing of chips, which lead to form a transferred layer at the tool rake face. Finally, based on the observations of the different wear micromechanisms, a scenario of WC–6Co damages is proposed through to a phenomenological model.

Low Frequency Vibration Assisted Drilling of Aluminium Alloys

In the present study the vibration drilling process of light weight materials and compound stacks has been investigated. Fiber-metal compound materials provide excellent mechanical properties which make them a major choice in lightweight applications. Especially in aircraft industry the use of multi-layer materials is significantly increased during the last few years. To join parts of dissimilar materials usually rivets or bolts are applied as fasteners. Therefore it is necessary to machine boreholes with partially very high quality requirements. Because of the different material properties the machining process of serial stacks imposes high demands to the cutting tools and requires certain process strategies. Previous investigations revealed that the bore surface can be damaged during the extraction of the hot and sharp metallic chips. Besides the risk of thermal damage the main issue lies in an erosive expansion of the borehole diameter due to the reaming of metallic chips at the borehole surface. The chip extraction can be significantly improved by low frequency assisted vibration drilling. In that case the axial tool movement is superimposed by a sinusoidal oscillation (in this case 1.5 per revolution) which is provided by the tool holder. Under certain cutting conditions this leads to a controlled chip breakage. Compared to conventional drilling the process parameters, cutting speed vc and feed f are supplemented with the amplitude A of the oscillation and the frequency f which represents the amount of vibrations per revolution of the tool. This causes radical changes to the kinematics of the process and therefore of the cutting conditions and chip formation. For a better understanding of the process a kinematic model for a two-flute cutter was developed which allows calculating the undeformed chip shape in dependency of the four cutting parameters vc, fz, A and f. The model also helps to predict whether a discontinuous cut will be achieved or not. To characterize the process and chip shape the following parameters are optionally calculated within the model: maximum chip thickness, chip radian, effective feed, feed speed at the moment of tool entrance and exit (for one chip). Experimental drilling trials in Al2024 T351 were used to evaluate the calculated parameters. The chip thickness and radian as well as the cutting time show a very good correlation to the calculations. It is interesting that the measured cutting forces are much lower compared to the theoretical values according to the Kienzle cutting force equation. Additionally it was found that the measured cutting force is strongly decreasing with an increasing cutting speed. Infrared images of the drilling process in Ti6Al4V were used to analyze the temperature close to the cutting zone and to observe the chip evacuation during the process. It was found that the cutting temperature is up to 50% lower when using vibration drilling. Furthermore it was shown that this effect is strongly dependent on the chip extraction. It is important that the chips do not stack in the drilling flute during the process. A chip breakage is facilitated by a decreasing ratio between feed and amplitude. At the same time an increasing material removal rate degrades the chip extraction even if the chips are separated. Besides the advantages of vibration drilling a major issue was found to be chipping at the cutting edges or even tool breakage. This could be avoided by a reduction of the oscillation amplitude and /or feed. Under consideration of these correlations the productivity of the drilling process and the bore hole quality in CFRP/Ti6Al4V-stacks could be significantly increased. The investigations have shown that vibration assisted drilling represents a huge opportunity, especially in the field of drilling composite materials. However further investigations are necessary to better understand this very complex process.

Tool-Life Model for Ceramics through Experimental Design in High Speed Machining (HSM) of 36NiCrMo16 Steel

This paper describes a method for determining the life of cutting tools and ceramic when machining at high speed using the methodology of experimental design. The methodology is applied to determine the effect of cutting parameters on the tool’s life. Flank wear has been considered as the criteria for tool failure and the wear was measured using a Nikon measuring microscope. Further testing was stopped and the insert rejected when an average flank wear greater than 0.30 mm was reached. The exponential model was applied to determine the correlation between cutting time and the independent variables. The results indicated that the cutting speed Vc was a dominant factor on the tool’s life, followed by the criterion of flank wear VB* finally, the f and ap. The analysis of longitudinal monitoring of wear over time via the model (14) shows that the shape of the wear obeys the universal law of usury of any mechanical part.

Optimization of high-pressure jet assisted turning process by Taguchi method

A B S T R A C T A R T I C L E I N F O This paper outlines the Taguchi optimization methodology, which is applied to optimize cutting parameters in high-pressure jet assisted turning when machining Inconel 718. Turning parameters evaluated are the diameter of the nozzle Dn, the pressure of the jet P, the cutting speed Vc, the feed rate f and the distance between the impact point of the jet and the cutting edge d. The experiments were conducted by using L27 (3 13 ) orthogonal array as suggested by Taguchi. Signal-to-Noise (S/N) ratio and Analysis of Variance (ANOVA) are employed to analyze the effect of high-pressure jet assisted turning parameters on the main cutting force and surface roughness, in other words to find optimal levels of the process parameters. The study shows that the Taguchi method is suitable to solve the stated problem with minimum number of trials.

Effect of Cutting Parameters on Surface Texture of Flame Sprayed Coatings

Coatings were turned by two tools: a) ISO 2R 2525K10, geometry and cutting parameters recommended by Messner Eutectic Castolin Company (tool angle β = 90o, approach angle κr = 45o, nose radius rε =0,8 mm, clearance angle α = 6o, rake angle γ = -5o) b) bit tool with CBN WNGA080408S01030A insert mounted in DWLNRL-2525M08 holder (cutting inserts β = 80o, approach angle κr = 95o, nose radius 0,8 mm, clearance angle α = 6o, rake angle γ = -6o). The influence of cutting speed, feed rate, depth of turning on the coating surface roughness was estimated. The following cutting parameters: cutting speed Vc = 45 214 m/min, feed rate f = 0,04 0,196 mm/rev, depth of cut ap = 0,05 0,3 mm. The lowest value of the roughness Ra = 0,5μm of the coatings were obtained by using cutting tools and parameters and bit tool: Vc = 214 m/min, f = 0,06 mm/rev, ap = 0,3 mm.

FINISHING INTERMETALLIC COATINGS IN ORDER TO REDUCE THE SURFACE ROUGHNESS

The paper presents a shape and grade of inserts depending on the surface roughness of the intermetallic coatings NiAl and Ni3Al. Intermetallic coatings on nickel based were sprayed with a torch Casto-Dyn 8000 on the steel samples. Thermal spraying intermetallic coatings have been high surface roughness, and therefore they must to be finishing. Experimental research was conducted for unalloyed steel samples with thermal spraying NiAl and Ni3Al intermetallic coatings. Before applying coatings, the samples surface was properly prepared by stream abrasive working, degreasing and finally by cleaning of oxidation products. To testing cutting inserts shape selects square and trigon made tungsten carbide and cubic boron nitride (borazon). Machining intermetallic nickel based coatings were carried out for the cutting speed vc = 214 m/min in the case of after-machining with inserts of borazon, vc = 107 m/min cutting inserts for tungsten carbide, used feed fn = 0.06 mm/rev and depth of cut ap = 0.3 mm. Intermetallic coatings are characterized by high resistance to tribology wear. These materials are used in such fields of technology, such as: electronics, energy, defense, automotive, aviation, shipbuilding, and more industry. The NiAl and Ni3Al intermetallic have found widespread applications as high – temperature structural material due to their high melting point, low density, good thermal conductivity and excellent oxidation resistance. The paper proposes the finishing flame sprayed intermetallic coatings.

Tool life evaluation of cutting materials in hard turning of AISI H11

The aim of this experimental study is to evaluate the tool life of each cutting material used in dry hard turning of AISI H11, treated at 50 HRC. This steel is intended for hot work, is free from tungsten on CrMoV basis, insensitive to temperature changes and has a high wear resistance. It is employed for the manufacture of the moulds and inserts, module matrices of car doors and helicopter rotor blades. The tests of straight turning were carried out using the following cutting materials: carbides (H13A and GC3015), ceramics (mixed CC650 and reinforced CC670) and cermets (CT5015 and GC1525). Experimental results enable us to study the influence of machining time on flank wear VB of these cutting materials and to determine their lifespan for this cutting regime (depth of cut ap = 0.15 mm, feed rate f = 0.08 mm/rev and cutting speed Vc = 120 m/min). It arises that mixed ceramic (insert CC650) is more resistant to wear than cutting materials. Its tool life is 49 min and consequently, it is the most powerful.