Experimental studies of the cutting force and surface morphology of explosively clad Ti–steel plates

The present work pertains to the study of clad material such as titanium plated steel in drilling process. The study was conducted for two types of indexable insert drills with different configuration of the tool coatings (TiAlN/AlTiN + TiN and TiAlN/TiN), the same geometry of insert and fixed machining conditions. Drilling process was assessed by the analysis of thrust force, torque and signal fluctuations of PSD function. In this context, surface morphology of the drilled holes and contact area was analysed. It has been observed that the use of the PSD function allows assessment of the drilling process in different layers of clad materials. Also was found that the parameters of the surface morphology are dependent upon the type of layers of the clad and the type of drill. Furthermore the reduction in torque results in obtaining smaller values of surface roughness parameter especially in the area of volume parameters of the bearing area curve.     

Optical Detections From Worn and Unworn Titanium Compound Surfaces

Wear-induced roughness in terms of grooves, sharp ridges, and edges leads to scattering of the reflected light and leads unavoidably to a reduction of the optical signals in a standard specular geometry. However, by using a double-layer system consisting of titanium aluminum nitride (TiAlN) on top of a titanium nitride (TiN) layer we obtain an increase in the reflected light as a result of wear. The relative change of reflectance of light from the tribological TiAlN coated surface to the underlying layer of TiN is similar for non-worn surfaces and for surfaces exposed to an abrasive wear process. The induced roughness reduces the signals from worn samples, in a standard specular geometry, by up to 30% compared with unworn samples. Our model system of TiAlN coatings on top of ‘optical’ signal layers of TiN deposited on a 100Cr6 steel substrate, was exposed to a reciprocating wear process with up to 10⁵ repetitive cycles in a linear tribometer. The worn TiAlN layers of thicknesses up to 3 μm, with strongly developed grooves and ridges, were subsequently used for the reflectance measurements. The results show that optical reflectance monitoring is a potential technique for intelligent determination of a residual thickness of realistic tribological coatings prior to complete wear.     

An experimental investigation into the comparison of the performance characteristics of TiN and ZrN coatings on split point drills using the static and stochastic models of the force system as a signature

This paper presents a comparison of the performance characteristics of TiN (Titanium nitride) and ZrN (Zirconium nitride) coatings on split point drills. The objective of this work was to choose the better coating for machining tough materials like INCONEL. This leads to an increased productivity of drilling holes in certain components of environmental control systems and fuel control systems (in aerospace industry) made of tough materials like INCONEL. The comparison of the performance characteristics was based on the measurement of the mean values and dynamic fluctuations of the cutting force and the number of holes drilled under the same optimum machining conditions. The measurements were carried out using two specially designed piezoelectric dynamometers. The dynamometer was calibrated from static and dynamic outputs and techniques were employed for increasing the measuring accuracy and reducing the cross interference by obtaining the elements of the tranfer function. Power spectrum plots of the drift force, axial force and torque were obtained so that these plots may be used as a signature. Results show that the ZrN coating is better than the TiN coating because (a) the mean values of the axialforce, drift force and torque are smaller, thus improving the roundness, (b) the dynamic flutuations of the forces and torque about the mean are smaller thus improving the surface quality of the holes produced, (c) the number of holes before the failure of the drill is about three times more for a ZrN coated split point drill as compared to a TiN coated drill.     

涂层钻头加工不锈钢磨损机理研究

研究了TiN、TiAlN、TiCN三种高速钢涂层专用麻花钻头钻削加工1Cr18NigTi奥氏体不锈钢时的刀具寿命以及刀具表面涂层的磨损特性。通过研究刀具寿命以及对刀具前刀面涂层磨损形态和元素成分的变化规律，揭示了三种涂层钻头的磨损机理。结果表明：在中低速、湿切削的情况下，TiCN涂层要优于TiAlN涂层，明显优于TiN涂层；TiCN涂层高速钢专用钻头较TiAlN、TiN涂层高速钢专用钻头更加适合不锈钢的钻削加工。研究结果对提高不锈钢钻削加工效率与加工质量具有重要意义。     

Influence of cutting speed on cutting force,flank temperature,and tool wear in end milling of Ti-6Al-4V alloy

Tool wear is one of the most important problems in cutting titanium alloys due to the high-cutting temperature and strong adhesion. Recently, the high-speed machining process has become a topic of great interest for titanium alloys, not only because it increases material removal rates, but also because it can positively influence the properties of finished workpiece. However, the process may result in the increase of cutting force and cutting temperature which will accelerate tool wear. In this paper, end milling experiments of Ti-6Al-4V alloy were conducted at high speeds using both uncoated and coated carbide tools. The obtained results show that the cutting force increases significantly at higher cutting speed whether the cutter is uncoated carbide or TiN/TiAlN physical vapor deposition (PVD)-coated carbide. For uncoated carbide tools, the mean flank temperature is almost constant at higher cutting speed, and no obvious abrasion wear or fatigue can be observed. However, for TiN/TiAlN PVD-coated carbide tools, the mean flank temperature always increases as the increase of cutting speed, and serious abrasion wear can be observed. In conclusion, the cutting performance of uncoated inserts is relatively better than TiN/TiAlN PVD-coated inserts at a higher cutting speed.     

Evaluation of the performance of coated carbide tools in face milling TC6 alloy under dry condition

Titanium and its alloys are well known as the typical different-to-cut materials because of their low thermal conductivity, high chemical reactivity, and low modulus of elasticity. During machining of titanium alloy, advanced high-speed, high-efficiency processing technologies are adopted to improve the production efficiency and reduce the production costs. The main goal of this work is to compare the performance of physical vapor deposition (PVD)-coated (TiN/TiAlN) and chemical vapor deposition (CVD)-coated (TiN/Al₂O₃/TiCN) carbide inserts in face milling TC6 alloy. To this end, the present paper reviewed the main works on the application of PVD- and CVD-coated tools in machining titanium alloys and the material performance of TC6 alloy, especially the machinability in machining process. Several tool life tests and tool wear experiments were carried out on a milling center with a five-axis spindle drive. Cutting forces were measured with a Kistler dynamometer. The failure modes and chip morphology were observed. Surface roughness and tool wear evolution were determined. The wear mechanism was discussed to compare the performance of PVD and CVD-coated tools. The main conclusions of this work were that the cutting tools made with PVD coating (TiN/TiAlN) had the excellent tooling quality and the main wear mechanisms were spalling and adhesion. PVD-TiN/TiAlN insert was more suitable to milling TC6 alloy than CVD-TiN/Al₂O₃/TiCN insert.     

Effects of different cooling conditions on twist drill temperature

In the past, many researchers have studied wear developed on drilling tools mainly due to the high temperatures generated which accelerate thermally related wear mechanisms and thereby reducing tool life. This paper deals with an experimental investigation on the effect of an internal coolant approach (for different air pressure) on drill bit temperature, comparing it with an external coolant approach and dry cutting. Drill temperatures were measured by inserting standard thermocouples through the coolant (oil) hole of TiN/TiAlN-coated carbide drills. Experimental studies have been conducted using Al 2014 alloy materials. In the drilling tests, cutting conditions had different spindle speeds, coolant approaches and feed rate values. The settings of drilling parameters were determined by using the Taguchi experimental design method. An orthogonal array, the signal-to-noise (S/N) ratio, and the analysis of variance (ANOVA) were employed to analyse the effect of coolant approaches and drilling parameters. The objective was to establish a model using multiple regression analysis between spindle speed, coolant (air) pressure and feed rate with the drill bit temperature. Mathematical models for drill bit temperature are proposed that agree well with the experiments.     

Laser removal of TiN from coated carbide substrate

Sustainable manufacturing requires the extended usage of materials and reuse of hard metal tooling. In general, titanium nitride (TiN) coating gives enhanced hardness and wear resistance to the surfaces of engineering tools. However, the high hardness makes it difficult to re-grind or refurbish TiN-coated materials, especially TiN-coated cutting tools. This paper presents the results of laser decoating of TiN from TiN-coated tungsten carbide (WC) substrates. Laser decoating was performed using a KrF excimer laser. The effect of laser fluence, number of pulses, frequency, scanning speed and beam overlap on the decoating performance was investigated in detail. A two-dimensional symmetric finite element model (FEM) was established to elucidate the temperature and stress fields created during the laser decoating process. Successful laser decoating of TiN coating from the WC substrate was demonstrated. It was found that decoating with a laser fluence of 4 J/cm², scanning speed of 2 mm/s, frequency of 25 Hz and a beam overlap of 91% gives best results for removing an area of TiN coating to its 3 μm thickness. The surface roughness of the best samples was found to be in the order of 0.8–0.9 μm Ra. The experimental and FEM investigation suggested that the decoating of TiN follows combined explosion and evaporation mechanism.     

Tribological Behavior of TiAlN,AlTiN, and AlCrN Coatings at Boundary Lubricating Condition

In this study, ~?3.5 µm thick multilayer titanium alumina nitride (TiAlN), alumina titanium nitride (AlTiN), and alumina chromium nitride (AlCrN) coatings were deposited on the H13 steel surface by cathodic arc physical vapor deposition (CAPVD) method. The tribological performance of the coatings was evaluated by a tribometer at boundary lubrication condition. Then, coating surfaces were observed by optical microscope, optical profilometer, and atomic force microscope to evaluate the morphological changes, wear volumes, and tribofilm thickness. Also, scanning electron microscopy (energy dispersive X-ray) and X-ray photoelectron spectrometry analyses were applied to coating surfaces for the tribochemical evolution of the tribofilm. Results showed that AlCrN coating performed the best tribological behavior at boundary lubricated condition, when compared to TiAlN and AlTiN coatings and it can be used as a wear resistant cam tappet coating in internal combustion engines.     

钛合金微小孔钻削试验研究

应用自行研制的TiC涂层和类金刚石（DLC）涂层硬质合金钻头以及市售硬质合金钻头（WC-Co）对钛合金材料进行微小孔钻削性能对比试验,研究了进给速度与切削力和扭矩的关系,分析了刀具的磨损特征以及孔的表面质量和孔入口处的毛刺情况。结果表明：DLC涂层硬质合金钻头比普通硬质合金钻头和TiC涂层硬质合金钻头更适合加工钛合金材料微小孔。     

Influence of tool material on dynamics of drilling of GFRP composites

Drilling trials have been carried out on glass Fibre reinforced plastics (GFRP) with plain high speed steel (HSS), TiN coated HSS and tipped tungsten carbide drills. Most of the defects in drilling of composites are due to thrust force experienced by the workpiece. The parametric influence on cutting force was experimentally evaluated. The experimental results show that the defects toleranced drilling can be attained by proper selection of cutting parameters and tool material. This is substantiated by monitoring flank wear, hole shrinkage and acoustic emission during drilling.     

Analysis of temperature changes on the twist drill under different drilling conditions based on Taguchi method during dry drilling of Al 7075-T651

In this work, effects of drilling parameters (drilling depth, feed rate, and spindle speed) on the twist drill bit temperature and thrust force in the dry drilling of Al 7075-T651 material were experimentally investigated. During dry drilling experiments, drill bit temperature and thrust forces were measured. Drill temperatures were measured by inserting standard thermocouples through the coolant (oil) hole of TiN/TiAlN- coated carbide drills. The settings of drilling parameters were determined by using the Taguchi experimental design method. An orthogonal array, the signal-to-noise (S/N) ratio, and the analysis of variance (ANOVA) are employed to analyze the effect of drilling parameters. The objective was to establish a model using multiple regression analysis between spindle speed, drilling depth, feed rate, and drilling method with the drill bit temperature and thrust force in a Al 7075-T651 alloy material. The study shows that the Taguchi method is suitable to solve the problems with a minimum number of trials as compared with a full factorial design .     

Optimization of surface roughness in end milling Castamide

Castamide is vulnerable to humidity up to 7%; therefore, it is important to know the effect of processing parameters on Castamide with and without humidity during machining. In this study, obtained quality of surface roughness of Castamide block samples prepared in wet and dry conditions, which is processed by using the same cutting parameters, were compared. Moreover, an artificial neural network (ANN) modeling technique was developed with the results obtained from the experiments. For the training of ANN model, material type, cutting speed, cutting rate, and depth of cutting parameters were used. In this way, average surface roughness values could be estimated without performing actual application for those values. Various experimental results for different material types with cutting parameters were evaluated by different ANN training algorithms. So, it aims to define the average surface roughness with minimum error by using the best reliable ANN training algorithm. Parameters as cutting speed (V _c), feed rate (f), diameter of cutting equipment, and depth of cut (a _p) have been used as the input layers; average surface roughness has been also used as output layer. For testing data, root mean squared error, the fraction of variance (R ²), and mean absolute percentage error were found to be 0.0681%, 0.9999%, and 0.1563%, respectively. With these results, we believe that the ANN can be used for prediction of average surface roughness.     

离子镀TiAlN工具涂层的微结构与切削性能

研究并比较了TiAlN和TiN涂层的成分、微结构、力学性能与抗氧化性及涂层铣刀的高速切削性能和涂层钻头的切削性能。结果表明,TiAlN和TiN涂层同为单相的NaCl型结构,并都呈现择优取向的柱状晶,TiAlN涂层的硬度远高于TiN涂层的硬度,TiAlN涂层的抗氧化温度明显高于TiN涂层的抗氧化温度。在高速铣削条件下,TiAlN涂层铣刀的后刀面磨损速率仅为TiN涂层铣刀的约四分之一。在钻孔数相同时TiAlN涂层钻头的磨损量也显著低于TiN涂层钻头。TiAlN涂层刀具的使用寿命显著高于TiN涂层刀具。     

Application of neural network technique to high energy milling process for synthesizing ZnO nanopowders

An artificial-neural-network (ANN) model was developed to estimate the crystalline size of ZnO nanopowder as a function on the milling parameters such as milling times and balls to powder ratio. This nanopowder was synthesized by high energy mechanical milling and the required data for training were collected from the experimental results. The synthesized ZnO nanoparticles are characterized by X-ray diffraction (XRD) and scanning electron microcopy (SEM). It was found that artificial neural network was very effective providing a perfect agreement between the outcomes of ANN modeling and experimental results with an error by far better than multiple linear regressions. An optimization model and this experimental validation of the ball milling process for producing the nanopowder ZnO are carried out.     

Analysis of the life of cemented carbide drills with modified surfaces

The performance of cemented carbide cutting tools during machining is influenced not only by the mechanical properties of the coating and substrate but also by the topographies of their surfaces. A tool with good coating and substrate properties but unsuitable topographies may exhibit accelerated wear and, consequently, impaired performance. In this work, drills coated using physical vapor deposition (PVD) were produced with different substrate textures, which in turn generated different coating textures. The surface roughness values of the coated drills were measured together with the residual stress at the interface between substrate and coating. Drilling tests were performed and tool wear was measured during the machining process. Two different tool coatings were studied: TiAlN and TiAlCrSiN. The goal was to study how the characteristics of the substrate and coating (material, surface topography, and residual stress) influence tool life. Tool life experiments were carried out using drilling tests in AISI 1548 steel, which is often used in crankshafts. The primary tool wear mechanism was attrition in all the drills. The main conclusion of this work is that the tool with the lowest roughness and a TiAlCrSiN coating had the best performance in the conditions tested here.     

Finite element and experimental investigation of temperature changes on a twist drill in sequential dry drilling

The drilling process is highly non-linear. Coupled with a thermo-mechanical machining, localized heating and temperature increases in the workpiece are caused by the rapid plastic deformation of the workpiece and by the friction along the drill-chip interface. The cutting temperature at the tool-chip interface is an important factor which directly affects workpiece surface integrity, tool wear, and hole diameter and cylindricity in the drilling process. In this study, the effects of sequential dry drilling operations on the drill bit temperature were investigated both experimentally and numerically. Drill temperatures were measured by inserting standard thermocouples into the coolant (oil) hole of TiN/TiAlN-coated carbide drills. Experimental studies were conducted using two different workpiece materials, AISI 1040 steel and Al 7075-T651. The drill bit temperature was predicted using a numerical computation with Third Wave AdvantEdge finite element method (FEM) software, which is based on Lagrangian explicit. The results obtained from the experimental study and finite element analyses (FEA) were compared. Reasonable agreement between the measured and calculated drill bit temperature results were found for sequential dry drilling.     

The role of stepover ratio in prediction of surface roughness in flat end milling

Surface roughness prediction studies in end milling operations are usually based on three main parameters composed of cutting speed, feed rate and depth of cut. The stepover ratio is usually neglected without investigating it. The aim of this study is to discover the role of the stepover ratio in surface roughness prediction studies in flat end milling operations. In realising this, machining experiments are performed under various cutting conditions by using sample specimens. The surface roughnesses of these specimens are measured. Two ANN structures were constructed. First of them was arranged with considering, and the second without considering the stepover ratio. ANN structures were trained and tested by using the measured data for predicting the surface roughness. Average RMS error of the ANN model considering stepover ratio is 0.04 and without considering stepover ratio is 0.26. The first model proved capable of prediction of average surface roughness (Ra) with a good accuracy and the second model revealed remarkable deviations from the experimental values.     

Development of artificial neural network models to study the effect of process parameters on burr size in drilling

Burr size at the exit of the holes in drilling is a quality index and hence it becomes essential to predict the size of the burr formed in order to cater to the demand of product quality and functionability. In this paper, artificial neural network (ANN)-based models have been developed to study the effect of process parameters such as cutting speed, feed, drill diameter, point angle, and lip clearance angle on burr height and burr thickness during drilling of AISI 316L stainless steel. A multilayer feed-forward ANN; trained using error back-propagation training algorithm (EBPTA) has been employed for this purpose. The input-output patterns required for training are obtained from drilling experimentation planned through Box-Behnken design. The simulation results demonstrate the effectiveness of ANN models to analyze the effects of drilling process parameters on burr size.     

Experimental investigation and analysis of thrust force in drilling cast hybrid metal matrix (Al–15%SiC–4%graphite) composites

Composite materials are used in different engineering applications and are continuously displacing conventional materials due to their excellent properties. This paper discusses the influence of drilling parameter on thrust force in drilling Al 6061/15%SiC 4%Gr metal matrix composites. The composite materials are fabricated by stir casting method. The experiments are conducted on computer numeric control vertical machining centre using titanium nitride coated solid carbide twist drills of 4 mm, 8 mm and 12 mm diameter under dry conditions. A response surface analysis is carried out. The effect of drilling parameters on thrust force is studied and presented. The results indicated that feed rate is the main parameter which influences the thrust force in drilling of hybrid metal matrix composites.