Crater and flank wear resistance of cutting tools having micro textured surfaces

We have proposed cutting tools with various textured surfaces to increase cutting tool life. Our previous studies have developed cutting tools having periodical stripe-grooved surfaces on their rake face formed using femtosecond laser technology, which displayed high crater wear resistance in cutting of steel materials. In this study, the mechanism for suppressing the crater wear on the tool surface and the relationship between texture dimensions and wear resistance were investigated to provide a guideline for developing tools with textured surfaces. Furthermore, we newly introduced the textured surfaces into a flank face of cutting tools to improve flank wear resistance. Face milling experiments on steel materials exhibited that the newly developed tool having the textured flank face significantly reduced the flank wear. Moreover, the influences of texture dimensions and cutting conditions on the flank wear resistance were also discussed.     

A study of deformation of the machined workpiece and tool under different low cutting velocities with an elastic cutting tool

To understand the effects of cutting velocity, tool elastic deformation generated by high normal stresses during metal cutting processing and artificial tool flank wear on the cutting process, an iterative mathematical model for calculating the tool–workpiece contact problem was developed in this paper under the assumption of elastic cutting tools. In this model, the finite element method is used to simulate cutting of mild steel by the P20 cutting tool with constant artifical tool flank wear under the condition of three different cutting velocities. The results obtained in the simulation were found to match the experimental data reported by related studies. The simulation results also indicate that the thrust and the cutting forces are functions of cutting velocity. Besides, both the normal stress on the tool rake face and the residual stress of machined workpiece generally decrease with increase in cutting velocity. According to the findings in this study, though the residual stress of the machined workpiece decreases as the cutting velocity increases, its value is still higher than that in ordinary conditions due both to the influence of tool flank wear and tool elastic deformation. Also, the phenomenon of curvature at the workpiece end easily occurs.     

PCD刀具连续切削花岗岩的性能研究

用三种不同晶粒尺寸的自制PCD刀具,在三种切削速度下进行了花岗岩的湿式连续切削试验。对刀具前、后刀面的显微形貌特征进行了观测,分析了刀具失效机理,比较了不同晶粒尺寸及不同切削条件下刀具的切削寿命。对刀具后刀面磨损的测量结果表明,在三种切削速度下,粗颗粒PCD刀具显示出更长的刀具寿命;随着切削速度的增加,三种刀具的寿命都有所下降。SEM二次电子图像显示,PCD010和PCD005刀具的磨损机制为硬质点的机械磨损,而晶粒较粗的PCD030刀具的主要磨损机制为机械磨损,同时伴有穿晶磨损。     

TURNING STUDIES OF DEEP CRYOGENIC TREATED P-40 TUNGSTEN CARBIDE CUTTING TOOL INSERTS – TECHNICAL COMMUNICATION

In the present work, coated tungsten carbide tool inserts of ISO P-40 grade were subjected to deep cryogenic treatment at ?176°C. Turning studies were conducted on AISI 1040 workpieces using both untreated and deep cryogenic treated tungsten carbide cutting tool inserts. The turning performance was evaluated in terms of flank wear of the cutting tool inserts, main cutting force and surface finish of the machined workpieces. The flank wear of deep cryogenic treated carbide tools was observed to be lower than that of untreated carbide tools in machining of AISI 1040 steel. The cutting force during machining of AISI 1040 steel was lower with the deep cryogenic treated carbide tools when compared with the untreated carbide tools. The surface finish produced on machined AISI 1040 steel workpieces was superior with the deep cryogenic treated carbide tools as compared to the untreated carbide tools.     

ZTA陶瓷刀具连续切削淬硬T10A时的切削性能研究

研究两种自主研制的新型ZTA(Al2O3/Zr O2)陶瓷刀具切削淬硬T10A时的切削性能。刀具后刀面磨损量随切削深度和切削速度的增加而增大;刀具的主要磨损形态为后刀面磨损;主要磨损机理为后刀面磨粒磨损和部分粘结磨损。     

Tool crater wear depth modeling in CBN hard turning

Hard turning has been receiving increased attention because it offers many possible benefits over grinding in machining hardened steel. The wear of cubic boron nitride (CBN) tools, which are commonly used in hard turning, is an important issue that needs to be better understood. For hard turning to be a viable replacement technology, the high cost of CBN cutting tools and the cost of down-time for tool changing must be minimized. In addition to progressive flank wear, microchipping and tool breakage (which lead to early tool failure) are prone to occur under aggressive machining conditions due to significant crater wear and weakening of the cutting edge. The objective of this study is to model the CBN tool crater wear depth (K_T) to guide the design of CBN tool geometry and to optimize cutting parameters in finish hard turning. First, the main wear mechanisms (abrasion, adhesion, and diffusion) in hard turning are discussed and the associated wear volume loss models are developed as functions of cutting temperature, stress, and other process information. Then, the crater wear depth is predicted in terms of tool/work material properties and process information. Finally, the proposed model is experimentally validated in finish turning of hardened 52100 bearing steel using a low CBN content tool. The comparison between model predictions and experimental results shows reasonable agreement, and the results suggest that adhesion is the dominant wear mechanism within the range of conditions that were investigated.     

Wear of rotary carbide tools in machining of Al/SiCp composites

With the projected widespread application of Metal Matrix Composites, it is necessary to develop an appropriate technology for their efficient and cost-effective machining. This paper deals with the study of feasibility of rotary carbide tools in the intermittent machining of Al/SiCp composites. A rotary tool holder was designed and fabricated for this work. Experiments were designed using Taguchi Methods to analyse the influence of various factors and their interactions on the flank wear of rotary carbide tools during machining. A tool-life model describing the effect of process, tool and material dependent parameter on the magnitude of flank wear of a rotary carbide tool is proposed.     

An online optical system for inspecting tool condition in milling of H13 tool steel and IN 718 alloy

Tool wear adversely affects surface integrity due to higher cutting forces and temperatures. However, an accurate and efficient tool wear measurement is a challenging problem. The traditional direct tool wear measurement methods such as optical microscope and scanning electron microscope (SEM) leads to error of tool reassembly, tool orientation, and low accuracy, while the indirect measurement methods cause poor accuracy. In this paper, tool wear phenomena in milling of tool steel AISI H13 and superalloy Inconel 718 have been studied. A novel online optical system has been developed to integrate with a CNC machine to directly inspect and measure tool wear conditions in milling which minimizes the above-mentioned measurement errors in traditional methods. The evolutions of tool flank wear of PVD-coated inserts in end milling of the two materials were inspected to demonstrate the function of the optical measurement system. The tool wear evolution versus cutting time were obtained and examined. The characteristic images of fast tool wear in milling of Inconel 718 were captured using SEM and compared with the optical images to estimate flank wear. Three basic modes of tool wear—flank wear, nose wear, and crater wear—were compared and analyzed. A two-parameter method has been developed to evaluate both flank wear and nose wear with respect to cutting time in milling of Inconel 718. The advantages of the on-line optical tool inspection system were discussed.     

Online tool condition monitoring in turning titanium (grade 5) using acoustic emission: modeling

This paper presents an online prediction of tool wear using acoustic emission (AE) in turning titanium (grade 5) with PVD-coated carbide tools. In the present work, the root mean square value of AE at the chip–tool contact was used to detect the progression of flank wear in carbide tools. In particular, the effect of cutting speed, feed, and depth of cut on tool wear has been investigated. The flank surface of the cutting tools used for machining tests was analyzed using energy-dispersive X-ray spectroscopy technique to determine the nature of wear. A mathematical model for the prediction of AE signal was developed using process parameters such as speed, feed, and depth of cut along with the progressive flank wear. A confirmation test was also conducted in order to verify the correctness of the model. Experimental results have shown that the AE signal in turning titanium alloy can be predicted with a reasonable accuracy within the range of process parameters considered in this study.     

Use of Ceramic Tools in Hard Turning of Hardened AISI M2 Steel

Tool wear and machining performance of hardened AISI M2 steel in hard turning has been studied. Ceramic tools were used in the cutting tests without coolants, and the workpiece was heat treated to increase its hardness up to Re 60. Cutting forces, temperature, and tool wear were measured in the experiments and the effects of cutting conditions on these were investigated. Important aspects from the research are summarized as follows: 1. Flank wear was the dominant wear mode on the ceramic tool insert in hard turning. In contrast, crater wear was very small due to the ceramics high resistance against chemical reactions at high temperature. A notch was unlikely to be formed in the tool.

2. The initial flank wear rate mainly depends on the feed rate. High feed rates cause a high initial flank wear rate.

3. Depth of cut was the most important cutting parameter to affect cutting force variation, and the cutting force increased due to tool wear.

     

PCBN刀具高速切削抗氢钢HR-2的性能研究

采用不同CBN含量和晶粒结构的PCBN刀具,在不同切削速度下进行了HR-2抗氢钢的高速精密切削试验。通过对PCBN刀具前、后刀面的显微形貌特征进行观测,分析了刀具的失效磨损机理,研究了不同CBN含量及不同切削速度对刀具使用寿命的影响。对刀具磨损的测量结果表明,PCBN刀具高速切削HR-2时,CBN含量高的刀具显示出更长的使用寿命,且在130-200m/min区间为最佳切削速度区域。SEM和EDS分析结果表明,高速精密切削HR-2的磨损机理为氧化磨损、扩散磨损、粘结磨损,同时存在磨粒磨损以及引起的微崩刃现象。     

不同涂层刀具切削淬硬H13钢加工性能研究

为了研究不同涂层刀具切削淬硬H13钢的切削性能,进行了多层Ti化合物涂层、TiAlN涂层以及MTTiCN厚Al_2O_3TiN涂层材料刀具车削加工淬硬H13钢试验,分析了不同的涂层材料刀具与切削力、切削温度、涂层刀具磨损以及刀具寿命的关系。研究得出:多层Ti化合物涂层刀具受到三个方向的力都大于其它两种涂层的刀具,而且切削温度最高;用TiAlN涂层刀具切削时温度最低;切削过程中三种刀具后刀面磨损程度不同,发现多层Ti化合物涂层刀具磨损最为严重,寿命最短;MT-TiCN厚Al_2O_3Ti N涂层材料刀具比多层Ti化合物涂层刀具寿命长30%;TiAlN涂层刀具的切削寿命最长比多层Ti化合物涂层刀具寿命长45%。     

双重润滑条件下的刀具切削特性研究

为实现清洁切削技术,将Al2 O3包覆CaF2复合粉体作为添加相,采用真空热压烧结工艺制备了一种Ti(C,N)基自润滑金属陶瓷刀具(TMC刀具),研究了Ti(C,N)基金属陶瓷刀具在微量润滑作用下切削300M钢的切削性能,结果表明:双重润滑与干切削方式相比,其三向切削力FX、FY、FZ分别减小了36.8％、13.1％和...     

An investigation of tool wear in high-speed turning of AISI 4340 steel

A commercially available insert has been used to turn an AISI 4340 steel at speeds placed between 325 and 1000 m/min. The flank wear was measured in connection to cutting time. This is to determine the tool life defined as the usable time that has elapsed before the flank wear has reached the criterion value.It is shown that an increase in cutting speed causes a higher decrease of the time of the second gradual stage of the wear process. This is due to the thin coat layer which is rapidly peeled off when high-speed turning.The investigation included the realization of a wear model in relation to time and to cutting speed. An empirical model has also been developed for tool life determination in connection with cutting speed.On the basis of the results obtained it is possible to set optimal cutting speed to achieve the maximum tool life.     

Wear behaviour of alumina based ceramic cutting tools on machining steels

The advanced ceramic cutting tools have very good wear resistance, high refractoriness, good mechanical strength and hot hardness. Alumina based ceramic cutting tools have very high abrasion resistance and hot hardness. Chemically they are more stable than high-speed steels and carbides, thus having less tendency to adhere to metals during machining and less tendency to form built-up edge. This results in good surface finish and dimensional accuracy in machining steels. In this paper wear behaviour of alumina based ceramic cutting tools is investigated. The machining tests were conducted using SiC whisker reinforced alumina ceramic cutting tool and Ti[C,N] mixed alumina ceramic cutting tool on martensitic stainless steel-grade 410 and EN 24 steel work pieces. Flank wear in Ti[C,N] mixed alumina ceramic cutting tool is lower than that of the SiC whisker reinforced alumina cutting tool. SiC whisker reinforced alumina cutting tool exhibits poor crater wear resistance while machining. Notch wear in SiC whisker reinforced alumina cutting tool is lower than that of the Ti[C,N] mixed alumina ceramic cutting tool. The flank wear, crater wear and notch wear are higher on machining martensitic stainless steel than on machining hardened steel. In summary Ti[C,N] mixed alumina cutting tool performs better than SiC whisker reinforced alumina cutting tool on machining martensitic stainless steel.     

Wear mechanism maps of uncoated HSS tools drilling die-cast aluminum alloy

A map describing the flank wear characteristics of uncoated high-speed steel (HSS) tools is constructed under the condition of drilling die-cast aluminum alloy. Several wear mechanisms are revealed which describe different wear modes observed by SEM in uncoated HSS tools, including adhesive wear, adhesive and abrasive wear, abrasive wear, severely plastic flow, and thermal wear. In the map, there exists a minor wear region, which is called “safety cutting zone” to the HSS tools. This map will be a good reference for choosing suitable drilling parameters of uncoated HSS cutting tools.     

Analytical prediction of cutting tool wear

An analytical method is presented which enables the crater and flank wear of tungsten carbide tools to be predicted for a wide variety of tool shapes and cutting conditions in practical turning operations based only on orthogonal cutting data from machining and two wear characteristic constants. A wear characteristic equation is first derived theoretically and verified experimentally. An energy method is developed to predict chip formation and cutting forces in turning with a single-point tool from the orthogonal cutting data. Using these predicted results, stress and temperature on the wear faces can be calculated. Computer simulation of the development of wear is then carried out by using the characteristic equation and the predicted stresses and temperatures upon the wear faces. The predicted wear progress and tool life are in good agreement with experimental results.     

An analytical approach to cutting force prediction in milling of carbon fiber reinforced polymer laminates

ABSTRACT

A prediction model of cutting force for milling multidirectional laminate of carbon fiber reinforced polymer (CFRP) composites was developed in this article by using an analytical approach. In the predictive model, an equivalent uniform chip thickness was used in the case of orthogonal plane cutting, and the average specific cutting energy was taken as an empirical function of equivalent chip thickness and fiber orientation angle. The parameters in the model were determined by the experimental data. Then, the analytical model of cutting force prediction was validated by the experimental data of multidirectional CFRP laminates, which shows the good reliability of the model established. Furthermore, the cutting force component of flank contact force was correlated with the surface roughness of workpiece and the flank wear of tool in milling UD-CFRP composites. It was found that surface quality as well as flank wear has a co-incident varying trend with the flank contact force, as confirmed by the observations of the machined surfaces and tool wear at different fiber orientations. So, it can be known that low flank contact force be required to reduce surface damage and flank wear.     

硬质合金材料及其涂层对不锈钢加工中刀具边界磨损的影响

硬质合金刀具在不锈钢加工中,其刀具耐用度主要是取决于后刀面边界磨损而不是主切削刃后刀面的平均磨损量。为了提高刀具耐用度,就必须减小后刀面边界磨损。本文对奥氏体不锈钢（ＳＵＳ３０４） 在车削及铣削加工中,采用Ｍ２０ 、Ｋ２０ 和Ｚ２０ 材料以及ＴｉＮ、Ｔｉ（Ｃ,Ｎ） 和（Ｔｉ,Ａｌ）Ｎ 物理涂层（ＰＶＤ）的硬质合金刀具进行了耐边界磨损的研究     

TiAlN涂层硬质合金刀具铣削35CrMoSiV钢的切削性能研究

采用有和无PVD TiAlN涂层的细晶硬质合金铣刀对35CrMoSiV合金钢进行了干式端面铣削试验。分别测量了有、无涂层情况下铣刀后刀面径向磨损量和加工槽的表面粗糙度,通过光学显微镜观察了切屑,利用扫描电子显微镜(SEM)和电子能谱(EDX)分析了后刀面的磨损形态。研究结果表明:TiAlN涂层明显提高了硬质合金刀具的切削性能;硬质合金刀具后刀面磨损机制主要为粘着磨损和磨粒磨损,而涂层损伤是粘着磨损、剥层和氧化磨损共同作用的结果;在正常工作区内,提高铣削的转速和进给量,有利于减轻刀具的粘着,提高切削效率和质量。