Tool wear mechanisms in axial ultrasonic vibration assisted milling in-situ TiB2/7050Al metal matrix composites

The in-situ TiB₂ particle reinforced aluminum matrix composites are materials that are difficult to machine, owing to hard ceramic particles in the matrix. In the milling process, the polycrystalline diamond (PCD) tools are used for machining these materials instead of carbide cutting tools, which significantly increase the machining cost. In this study, ultrasonic vibration method was applied for milling in-situ TiB₂/7050Al metal matrix composites using a TiAlN coated carbide end milling tool. To completely understand the tool wear mechanism in ultrasonic-vibration assisted milling (UAM), the relative motion of the cutting tool and interaction of workpiecetool-chip contact interface was analyzed in detail. Additionally, a comparative experimental study with and without ultrasonic vibration was carried out to investigate the influences of ultrasonic vibration and cutting parameters on the cutting force, tool life and tool wear mechanism. The results show that the motion of the cutting tool relative to the chip changes periodically in the helical direction and the separation of tool and chip occurs in the transverse direction in one vibration period, in ultrasonic vibration assisted cutting. Large instantaneous acceleration can be obtained in axial ultrasonic vibration milling. The cutting force in axial direction is significantly reduced by 42%-57%, 40%-57% and 44%-54%, at different cutting speeds, feed rates and cutting depths, respectively, compared with that in conventional milling. Additionally, the tool life is prolonged approximately 2-5 times when the ultrasonic vibration method is applied. The tool wear pattern microcracks are only found in UAM. These might be of great importance for future research in order to understand the cutting mechanisms in UAM of in-situ TiB₂/7050Al metal matrix composites.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-020-00294-2     

复合材料的切削加工表面结构与表面粗糙度

普通金属材料的切削加工理论表面粗糙度可以用公式计算。复合材料经切削加工后其表面留有各种凹凸缺陷,这些谷峰轮廓并非由刀刃直接切出,故不宜用现有普通材料的公式计算其理论表面粗糙度。纤维增强复合材料的切削加工表面结构和粗糙度与切削方向密切相关。颗粒增强复合材料无方向性,其已加工表面结构和粗糙度主要受增强颗粒硬度和粒度以及含量控制。增强体与基体的界面强度及切削刀具和工艺条件对复合材料加工表面粗糙度有很大影响。      

Optimization of Machining Characteristics for Al／SiCp Composites using ANN／GA

The present work is focused on optimization of machining characteristics of Al/SiCp composites.The machining characteristics such as specific energy,tool wear and surface roughness were studied.The parameters such as volume fraction of SiC,cutting speed and feed rate were considered.Artificial neural networks(NN) was used to train and simulate the experimental data.Genetic algorithms(GA) was interfaced with ANN to optimize the machining conditions for the desired machining characteristics .Validation of optimized results was also performed by confirmation experiments.     

An Experimental Investigation on Ultrasonic Vibration-Assisted Grinding of SiO2f/SiO2 Composites

Fiber-reinforced ceramic matrix composite (FRCMC) have been widely used in aerospace and other high-technology fields due to their excellent mechanical and physical properties. However, FRCMC is a kind of typical material with anisotropic and inhomogeneous structure; thus, it is difficult to guarantee the precision and surface quality using traditional machining. The present paper employed ultrasonic vibration-assisted grinding (UAG) to machine 2.5D woven SiO_2f/SiO₂ composites. By comparing the grinding force, surface microstructure, chip formation, surface topography and surface roughness with and without ultrasonic vibration for the machining of SiO_2f/SiO₂ composites, the feasibility of UAG on FRCMC was investigated experimentally. In addition, the effects of the process parameters (including spindle speed, feed rate, grinding depth, grain mesh size and ultrasonic power) on grinding force and surface roughness were studied through an orthogonal experiment. The research obtained can be a useful technical support for the development of UAG in the machining of FRCMC.     

Impact of graphite particle on milling of Al/15Al2O3 and Al/15Al2O3/5Gr composites

ABSTRACT

Hybrid Metal Matrix Composites (MMCs) are a new class of composites, formed by a combination of the metal matrix and more than one type of reinforcement having different properties. Machining of MMCs is a difficult task because of its heterogeneity and abrasive nature of reinforcement, which results in excessive tool wear and inferior surface finish. This paper investigates experimentally the addition of graphite (Gr) on cutting force, surface roughness and tool wear while milling Al/15Al₂O₃ and Al/15Al₂O₃/5Gr composites at different cutting conditions using tungsten carbide (WC) and polycrystalline diamond (PCD) insert. The result reveals that feed has a major contribution on cutting force and tool wear, whereas the machined surface roughness was found to be more sensitive to speed for both composite materials. The incorporation of graphite reduces the coefficient of friction between the tool–workpiece interfaces, thereby reducing the cutting force and tool wear for hybrid composites. The surface morphology and worn tool are analyzed using scanning electron microscope (SEM). The surface damage due to machining extends up to 200 µm for Al/15Al₂O₃/5Gr composites, which is beyond 250 µm for Al/15Al₂O₃ composites.     

Turning of aluminum metal matrix composites: influence of the reinforcement and the cutting condition on the surface layer of the workpiece

Aluminum metal matrix composites (Al-MMCs) are difficult to machine. The reinforcement of aluminum using ceramic particles accelerates tool wear. Moreover, demanded machining accuracies or properties of the surface layer are difficult to achieve. In the present study, the effect of silicon carbide reinforcement particles on the surface layer of the workpiece was investigated using multiple cutting conditions for dry turning. Three differently reinforced Al-MMCs regarding the volume percentage (17% and 30%) and the particle size (0.6 μm and 3 μm) and their non-reinforced matrix were considered as the workpiece materials. The reinforcement and the cutting condition affect the results of turning. A greater particle volume percent improves the surface roughness and decreases the tensile stress in the surface. The smaller particle size caused a lower tensile stress in the surface. A general effect of the particle size on the workpiece roughness can not be concluded. The most important cutting parameter for the surface layer of the workpiece is the feed. Greater feeds decrease the tensile stress in the surface, but deteriorate the surface quality.     

超声制备SiCp增强铝硅合金复合材料的磨损性能研究

研究使用功率超声制备SiCp颗粒增强铝基复合材料的新方法,并对所制得不同粒度SiCp的复合材料进行了组织分析和磨损性能的测试。实验结果表明,利用功率超声可以制备出颗粒在基体中均匀分布的复合材料,可增加SiCp的复合量,使SiCp与基体间润湿性良好。小粒度的SiCp颗粒增强复合材料较大尺寸的复合材料的耐磨性要好。     

SiCp/Al复合材料微弧氧化膜的组织结构及性能

采用微弧氧化技术对SiC体积分数分别为17vol%和55vol%的两种SiCp/Al复合材料进行处理。分析了两种材料微弧氧化膜的组织、形貌、相组成,测定了膜层的粗糙度、显微硬度、结合力,考察了膜层的耐磨和耐蚀性。结果表明:SiC的含量对SiCp/Al复合材料微弧氧化膜的表面形貌、粗糙度、相组成、结合力及摩擦磨损性能均有影响。17vol%SiCp/2009Al复合材料的微弧氧化膜较55vol%SiCp/6061Al复合材料更平整,微孔大小更均匀。55vol%SiCp/6061Al复合材料的微弧氧化膜的粗糙度(3.308 μm)比17vol%SiCp/2009Al复合材料(2.140 μm)大,表面熔融物堆积更多。两种材料的微弧氧化膜中均含有Al、Si、O、C、W等元素。55vol%SiCp/6061Al复合材料的微弧氧化膜中Mullite(SiO₂-Al₂O₃)相、α-Al₂O₃相、β-Al₂O₃相较多。17vol%SiCp/2009Al复合材料的微弧氧化膜的结合(38.55 N)较55vol%SiCp/6061Al(11.5 N)复合材料好。55vol%SiCp/6061Al复合材料的微弧氧化膜摩擦系数较大,磨损较严重。微弧氧化处理能有效改善两种SiCp/Al复合材料的耐蚀性。      

Studies on Machining Parameters While Milling Particle Reinforced Hybrid (Al6061/Al2O3/Gr) MMC

In this article, response surface methodology has been used for finding the optimal machining parameters values for cutting force, surface roughness, and tool wear while milling aluminum hybrid composites. In order to perform the experiment, various machining parameters such as feed, cutting speed, depth of cut, and weight (wt) fraction of alumina (Al₂O₃) were planned based on face-centered, central composite design. Stir casting method is used to fabricate the composites with various wt fractions (5%, 10%, and 15%) of Al₂O₃. The multiple regression analysis is used to develop mathematical models, and the models are tested using analysis of variance (ANOVA). Evaluation on the effects and interactions of the machining parameters on the cutting force, surface roughness, and tool wear was carried out using ANOVA. The developed models were used for multiple-response optimization by desirability function approach to determine the optimum machining parameters. The optimum machining parameters obtained from the experimental results showed that lower cutting force, surface roughness, and tool wear can be obtained by employing the combination of higher cutting speed, low feed, lower depth of cut, and higher wt fraction of alumina when face milling hybrid composites using polycrystalline diamond insert.     

Single-point scratching of 6061 Al alloy reinforced by different ceramic particles

Aluminium alloys reinforced by ceramic particles have been widely used in aerospace and automotive industries for their high stiffness and wear resistance. However, the machining of such materials is difficult and would usually cause excessive tool wear. The effect of ceramic particles on the cutting mechanisms is also unclear. The purpose of this study is to investigate the cutting mechanisms and the relationship between specific energy of scratching and depth of cut (size effect). The single-point scratch test was carried out on 6061 Al and its composites reinforced by Al₂O₃ and SiC ceramic particles using a pyramid indenter. The results indicated that the scratch process was composed of rubbing, ploughing, plastic cutting and reinforcement fracture. A simple model was proposed to interpret the apparent size effect. The effect of reinforcement on the specific energy was correlated to the ratio of volume fraction to particle radius. The paper found that for machining MMCs, a larger depth of cut should be used to maintain a lower machining energy, especially for those with a larger ratio of volume fraction to particle radius.     

Effects of Lubricant Condition and Tool Wear in Hard Turning of Novel-Abrasion-Resistance (N-AR) Cast Iron

Advanced materials, such as high abrasion resistant cast iron, have great applications for abrasive and erosive environments. Since the amount and the hardness of the microstructural carbides constituents in this material is extremely high, the abrasion-resistance cast iron is generally difficult to be machined with traditional cemented carbide tool. The hard and abrasive particles in this material can remarkably shorten the cutting tool life through abrasion of tool face and deterioration of cutting edge. In this article, Cubic Boron Nitride (CBN) cutting tool has been used to machine a novel-abrasion-resistance (N-AR) cast iron. The performances of CBN tool under different lubrication conditions were evaluated in view of tool wear, cutting force, and surface roughness (Rz). Further more, the wear rate of CBN tool under different machining condition and the mechanism of the CBN tool in machining of this type of work materials has also been investigated.     

Effect of submicron size SiC particles on microstructure and mechanical properties of AZ31B magnesium matrix composites

The magnesium matrix composites reinforced with three volume fractions (3, 5 and 10 vol.%) of submicron-SiC particles (∼0.5 μm) were fabricated by semisolid stirring assisted ultrasonic vibration method. With increasing the volume fraction of the submicron SiC particles (SiCp), the grain size of matrix in the SiCp/AZ31B composites was gradually decreased. Most of the submicron SiC particles exhibited homogeneous distribution in the SiCp/AZ31B composites. The ultimate tensile strength and yield strength of the 10 vol.% SiCp/AZ31B composites were simultaneously improved. The study of interface between the submicron SiCp and the matrix in the SiCp/AZ31B composite suggested that submicron SiCp bonded well with the matrix without interfacial activity.     

Finite element simulation of the micromachining of nanosized-silicon-carbide-particle reinforced composite materials based on the cohesive zone model

A finite element method based on the cohesive zone model was used to study the micromachining process of nanosized silicon-carbide-particle(SiCp) reinforced aluminum matrix composites. As a hierarchical multiscale simulation method, the parameters for the cohesive zone model were obtained from the stress-displacement curves of the molecular dynamics simulation. The model considers the random properties of the siliconcarbide-particle distribution and the interface of bonding between the silicon carbide particles and the matrix.The machining mechanics was analyzed according to the chip morphology, stress distribution, cutting temperature, and cutting force. The simulation results revealed that the random distribution of nanosized SiCp causes non-uniform interaction between the tool and the reinforcement particles. This deformation mechanics leads to inhomogeneous stress distribution and irregular cutting force variation.     

A review on conventional and nonconventional machining of SiC particle-reinforced aluminium matrix composites

Among the various types of metal matrix composites, SiC particle-reinforced aluminum matrix composites (SiC_p/Al) are finding increasing applications in many industrial fields such as aerospace, automotive, and electronics. However, SiC_p/Al composites are considered as difficult-to-cut materials due to the hard ceramic reinforcement, which causes severe machinability degradation by increasing cutting tool wear, cutting force, etc. To improve the machinability of SiC_p/Al composites, many techniques including conventional and nonconventional machining processes have been employed. The purpose of this study is to evaluate the machining performance of SiC p/Al composites using conventional machining, i.e., turning, milling, drilling, and grinding, and using nonconventional machining, namely electrical discharge machining (EDM), powder mixed EDM, wire EDM, electrochemical machining, and newly developed high-efficiency machining technologies, e.g., blasting erosion arc machining. This research not only presents an overview of the machining aspects of SiC_p/Al composites using various processing technologies but also establishes optimization parameters as reference of industry applications.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-020-00313-2     

Fabrication of SiC particles-reinforced magnesium matrix composite by ultrasonic vibration

Magnesium matrix composites reinforced with two volume fractions (1 and 3%) of SiC particles (1 μm) were successfully fabricated by ultrasonic vibration. Compared with as-cast AZ91 alloy, with the addition of the SiC particles grain size of matrix decreased, while most of the phase Mg₁₇Al₁₂ varied from coarse plates to lamellar precipitates in the SiCp/AZ91 composites. With increasing volume fraction of the SiC particles, grains of matrix in the SiCp/AZ91 composites were gradually refined. The SiC particles were located mainly at grain boundaries in both 1 vol% SiCp/AZ91 composite and 3 vol% SiCp/AZ91 composite. SiC particles inside the particle clusters may be still separated by magnesium. The study of the interface between the SiC particle and the alloy matrix suggested that SiC particles bonded well with the alloy matrix without interfacial reaction. The ultimate tensile strength, yield strength, and elongation to fracture of the SiCp/AZ91 composites were simultaneously improved compared with that of the as-cast AZ91 alloy.     

Machinability of Metal Matrix Composites Reinforced by 3-D Network Structure

Metal matrix composites reinforced by three-dimensional (3-D) continuous network structure reinforcement (3DCNRMMC) are difficult to machine due to serious tool wear and poor surface roughness caused by the brittle and hard reinforcement which interpenetrate into ductile matrix. In order to achieve the approach of low cost of 3DCNRMMC, the machinability of it needs to be understood. The influences of three cutting parameters and volume fraction of reinforcement on cutting force were analyzed in detail. The results indicate that: (1) Due to the brittle phase(s) introduced into ductile matrix of composites, there is a large fluctuation of cutting force causing deterioration of machinability. The fluctuation ranges of cutting forces, initially increase rapidly with the increase of volume fraction of reinforcement and then decrease finally, are largest at the range of the volume fraction of 55–65%; (2) The influence of cutting parameters on cutting force is obvious. With the increases of cutting speed, cutting force decreases gradually unless cutting speed exceeds the value of 209 m/min. Cutting forces increase with increasing feed rate and depth of cut; (3) Owing to the large fluctuation of cutting force, there were some cratered surfaces caused by Si₃N₄ reinforcement pulling-out and flaking-off. Some brittle phase protruding from the machined surface caused the deterioration of machined surface.     

Multi-attribute optimization of end milling epoxy granite composites using TOPSIS

Epoxy granite composites are identified and recognized as better materials for machine tool applications due to inherent damping properties. However, end milling of these composites has not been explored much. Milling of epoxy granite composites presents a number of problems, namely, cutting forces and surface roughness appear during machining. This research work focuses on end milling of epoxy granite composite specimens using high-speed steel end mill cutter by varying the cutting conditions such as spindle speed and feed with a uniform depth of cut and selection of optimal machining parameters. The experimental runs of 27 different trials were carried out and three different attributes such as thrust force, tangential force, and surface roughness were analyzed. This research work presents a sequential procedure for machining parameters selection. Selection of optimal machining parameters is done on the basis of Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method.     

Optimization for Turning of Al-6061-SiC-Gr Hybrid Nanocomposites Using Response Surface Methodologies

Metal matrix composites have cemented their applicability in industrial sector by virtue of their excellent mechanical properties. However, work has largely been done on the studies related to macro/microsize particles. This work has been aimed to evaluate the influence of input parameters in turning of Al-6061-SiC-Gr hybrid nanocomposites. This article evaluates the effect of process parameters on the cutting force and average roughness of the machined surface in turning of Al-6061-SiC-Gr nanocomposites. The experiments were designed using CCD, and cutting force and roughness were evaluated using response surface methodology. Statistical models were generated. The results of the study indicated that feed rate and depth of cut are the major influencing factors in descending order for the cutting force. The analysis of surface roughness revealed that both these factors are having identical effect. The cutting speed had little effect on cutting force and an improvement is seen in surface finish. The experiments also revealed that tool wear is negligible for nanocomposites. The software-predicted values and the experimentally obtained values of the responses were acceptably close to each other with an error percentage of less than 5%. Using response surface optimization, optimal combinations of machining parameters are also obtained.     

铝基碳化硅精密铣削刀具磨损实验研究

针对铝基碳化硅切削加工中刀具易磨损、寿命低、切削难度大和加工成本高等问题,选用不同材料的硬质合金铣刀及金刚石铣刀进行切削加工实验,并利用扫描电镜和工具显微镜对高体积分数铝基碳化硅铣削时刀具磨损形态进行了分析研究.研究表明:硬质合金刀具前刀面和刃口磨损主要形式为粘结磨损和微崩刃,后刀面磨损主要为刻划磨损,而金刚石铣刀加工时刀具磨损很小;YG6X铣刀材料微观组织致密,抗磨损能力较强,宜粗加工时选用;金刚石刀体的硬度远大于SiC颗粒,且金刚石与工件的摩擦系数小,金刚石铣刀寿命远大于硬质合金铣刀,宜精加工时选用.     

Finite element simulation and experimental research on rotary ultrasonic grinding of titanium alloy北大核心CSCD

In order to study the effects of the abrasive grain size of core tool on grinding force in rotary ultrasonic grinding titanium alloy, abrasive grain in the shape of irregular polyhedron was modeled by cutting regular hexahedron with random interception plane on a hexahedron. Based on virtual grid method, a simulation model of core drill with multi abrasive grains randomly distributing on the end face of tool was built. A 3D finite element model of rotary ultrasonic grinding of titanium alloy was developed by using Deform-3D. The simulation value of grinding force in rotary ultrasonic grinding of titanium alloy Ti6Al4V with multi abrasive grains was obtained by Lagrangian incremental algorithm, and the effects of the abrasive grain size on grinding force was investigated. A series of experiments were conducted to validate the grinding force in rotary ultrasonic grinding of titanium alloy. The result proved that rotary ultrasonic grinding force decreased as abrasive grain size increased and the experimental result agreed well with the simulation result. The result shows that the multi abrasive grain tool model and the finite element model of rotary ultrasonic grinding have certain accuracy. A new way for multi abrasive grain tool relational investigation in rotary ultrasonic grinding has been provided.