Surface texturing is one of the emerging sustainable methods to improve the cutting tool performance. Wire cut EDM (electro discharge machining) is one of the most widely used methods to fabricate ...the micro-textures on the tool’s rake face. This method involves surface re-melting which soften the surface, reduces the surface hardness and generates tensile residual stresses on the surface. Although textured tool gives better performance in comparison with conventional tool, the lower surface hardness and tensile residual stresses in textured tool result in higher tool wear. In the present work, an attempt has been made by using laser shock peening without coating process (LSPWC) on the textured surface to induce compressive residual stresses and improve the surface hardness by grain refinement. The tool performance was studied for different HSS cutting tools such as un-textured, textured, only shock peened and textured with shock peened. The considered tool performance parameters in the present analysis are cutting forces, friction co-efficient, tool wear, machined surface quality and tool life. Results show that surface-modified HSS tools significantly improved the tool performance as compared to un-textured tools. The textured shock peened tool exhibits higher tool life compared to other tools (i.e., textured and only shock peened) due to higher surface hardness and by reduction of the chip contact area.
The ideal scenario for the implementation of a machining process is to be able to predict tool performance without the need to conduct practical experiments. However, in an industrial environment, ...each set of machining conditions is unique, since the machine-tool conditions, machined material, cutting tool, and fixture system can vary. This can lead to differences between the predicted values and practical results. In this context, the aim of this research was to show and discuss a tool performance test methodology and a tool-life prediction model using the three-dimensional (volumetric) wear parameter
W
RM
(volume of material removed from the tool) applied to hard turning with PCBN tools. The wear parameter
W
RM
is measured at the beginning of the tool life (up to 25%) by focus variation microscopy (FVM). The tool wear rate (WR
RM
) is then calculated based on the ordinary least squares (OLS) method, and the tool life is estimated (TW
RM
) adopting the volume of material removed from the tool (WR
Mmax
) as the criteria for the end of tool life. The tool-life model developed was capable of predicting the tool life with errors below 4% at the higher values of cutting speed adopted (
v
c
= 150–187.5 m/min), that is, the cutting speeds applied industrially. The methodology adopted and the model developed represent a significant time reduction in the experimental machining tests, streamlining the research and development of the cutting tool grades, as well as the machining process optimization.
Tool condition monitoring (TCM) in machining operations is crucial to maximise the useful tool life while reducing the risks associated with tool breakage. Unlike progressive tool wear, tool breakage ...occurs randomly, with more severe implications for workpiece quality, machining system stiffness, and even operator safety. Existing literature reviews on TCM focus on tool wear monitoring, including wear state recognition and remaining useful life prediction. However, a comprehensive review of tool breakage monitoring (TBM) techniques is lacking. Generic signal processing and intelligent decision-making methods cannot fully satisfy the practical requirements of the TBM. In addition, developing and evaluating TBM models using imbalanced data is more challenging. Herein, we present the first systematic review on TBM to bridge these limitations, and provide adequate guidance for avoiding catastrophic tool failures during cutting processes. Signal acquisition, feature extraction, and decision-making methodologies for the TBM are outlined and compared with related techniques for tool wear monitoring. The effects of data imbalance on TBM models are considered, and feasible solutions are provided at the data and algorithm levels. Finally, the challenges faced by the TBM are discussed, and potential research directions are suggested. The research and application of TBM techniques will certainly better empower various machining operations in response to intelligent manufacturing demands.
Display omitted
•Tool breakage monitoring techniques in machining operations are systematically reviewed.•The difference between tool wear and breakage monitoring are compared.•TBM data imbalance problems are discussed at the data and algorithm levels.•The performance metrics commonly used to evaluate TBM models are highlighted.•The specific research route of tool life cycle management is proposed.
When drilling the carbon fiber reinforced plastics (CFRP), the tool shape and surface coating both play important roles in the cutting performance, which are complex and comprehensive, and should be ...systematically studied. In this research, WC-6wt.%Co drills in typical shapes are prepared, on which high-performance composite diamond films are deposited by the hot filament chemical vapor deposition (HFCVD) method. It is firstly proved by drilling tests that the tool shape always acts as a determining factor that significantly influences the drilling force and machining quality, for either the uncoated or diamond coated drills. The shorter chisel edge, smaller actual point angle and the proper double point angles are all factors in their favor. By contrast, as-deposited diamond films can slightly reduce the drilling force, while sometimes it even deteriorates the hole quality, due to the edge roundness caused by the alkali-acid pretreatment and the film growth. However, the diamond films play critical roles in improving the wear resistance, elongating the lifetime and guaranteeing the stability of the machining quality in the long-duration drilling process. In addition, the tool lifetime is also closely associated with the tool shape, attributed to the different thrust forces, consequently the lifetime of the diamond coated standard twist drill is much shorter than those of all other coated ones.
•Composite diamond films are deposited on four drills in different shapes.•Effects of the tool shape and coating are distinguished.•The tool shape dominates the drilling force and machining quality.•Coating can elongate lifetime of drills and guarantee stability of hole quality.•For the same coated drills, tool shape also apparently affects the tool lifetime.
This study compares the performance of CVD coated tungsten-carbide tools having an intermediate Al2O3 layer to low content PCBN tools in hard turning of D2 tool steel (52HRC). Results revealed that ...the coated carbide tool can outperform PCBN in machining the selected workpiece material within a certain range of cutting speeds (cutting temperature range). This is associated with tribo-film formation on the coated carbide tool surface. SEM and EDS were used to study the wear patterns of the used cutting tools. The tribo-films were investigated using the X-ray photoelectron method (XPS). The cutting temperature was measured using tool-workpiece thermocouple technique. The formation of the tribo-films was found to be highly-dependent on the cutting temperature and friction kinetics control at the tool–chip interface. Lubricious Cr–O tribo-films formed on the surface of the coated carbide tool, improving tool life at cutting speeds up to 100m/min, which relates to an average tool–chip interface temperature up to 930°C.
•Temperature conditions during hard turning using PCBN tools vs. multilayer CVD coated carbide tools have been investigated.•Severing of cutting conditions requires different materials for surface protection.•Two options have to be considered: material with strong refractory properties and material with increased lubricious characteristics.•The main scientific finding is that XPS analysis showed the formation of Ti-O and Cr-O tribo-films at the interface of the coated carbide and moderates the tool wear.•In this case PCBN exposes its exceptional refractory properties and has the longer tool life due to its higher hot hardness.
Tool wear is one of the important indicators to reflect the health status of a machining system. In order to obtain tool’s wear status, tool condition monitoring (TCM) utilizes advanced sensor ...techniques, hoping to find out the wear status through those sensor signals. In this paper, a novel weighted hidden Markov model (HMM)-based approach is proposed for tool wear monitoring and tool life prediction, using the signals provided by TCM techniques. To describe the dynamic nature of wear evolution, a weighted HMM is first developed, which takes wear rate as the hidden state and formulates multiple HMMs in a weighted manner to include sufficient historical information. Explicit formulas to estimate the model parameters are also provided. Then, a particular probabilistic approach using the weighted HMM is proposed to estimate tool wear and predict tool’s remaining useful life during tool operation. The proposed weighted HMM-based approach is tested on a real dataset of a high-speed CNC milling machine cutters. The experimental results show that this approach is effective in estimating tool wear and predicting tool life, and it outperforms the conventional HMM approach.
Cutting tool characterization plays a crucial role in understanding the behavior of machining operations. The selection of a suitable cutting material, the operating conditions for the work piece, is ...necessary to yield good cutting-tool life. Several pieces of research have been carried out in cutting-tool characteristics for turning operation. Only a few pieces of research have focused on correlating the vibrations and stress with wear characteristics. This research article deals with stress induced in silicon carbide tool inserts and coated tool inserts while machining SS304 steel. Since this material is much less resistant to corrosion and oxidation it is widely used in engineering applications such as cryogenics, the food industry and liquid contact surfaces. Moreover, these materials have much lower magnetic permeability so they are used as nonmagnetic engineering components which are very hard. This article focuses on the machining of SS304 by carbide tool inserts and then, the cutting forces were observed with a tool dynamometer. Using observed cutting forces, the induced stress in the lathe tool insert was determined by FEA investigation. This research also formulates an idea to predict the tool wear due to vibration. Apparently, the worn-out tool vibrates more than new tools. Using the results, the relation between stress, strain and feed rate, depth of cut and speed was found and mathematically modeled using MINI TAB. It was observed that carbide tool inserts with coating withstand better than uncoated tools while machining SS304. The results were anticipated and correlation between the machining parameters furnished the prediction of tool life and obtaining the best machining outcomes by using coated tool inserts.
Tool condition monitoring (TCM) has been a constant field of research. Conventionally, some sensors are installed at specific parts of the machine, and by using the signal-processing techniques, the ...tool wear is estimated. In this article, a direct system based on image analysis has been developed to automate the in-process tool wear measurement. The method uses only a single camera installed inside the machine and a tree-stage measurement process composed of image treatment, image comparison, and wear measurement. Experimental results show that the detection of similar images has a success index rate (SIR) equal to 98.89%, whereas the measurement error of the average flank wear and the maximum flank wear is estimated to be 3.57% and 2.92%, respectively.
Green ceramics are the ceramic compacts before sintering, and there is no metallurgical bonding force between the powder particles. Therefore, it can be machined by traditional mechanical processing. ...Machining of green ceramics represents an alternative way to other shaping process, and offers a high degree of flexibility and economic efficiency for the machining of ceramic parts. In this paper, surface texturing with different geometrical characteristics was made on the flank face of the WC/Co carbide tools. Dry cutting tests on the green alumina ceramics were carried out with these flank-face textured tools and a conventional WC/Co carbide tool, the wear resistance of these flank-face textured tools was investigated. Results showed that there was only mild wear on the rake face, while flank face revealed serious abrasive wear. The flank wear of the flank-face textured tools was significantly reduced compared with that of the conventional one, and the flank-face textured tools with micro-scale grooves on the flank face parallel to the main cutting edge (AT-1) had the most improved flank wear resistance. Mechanism responsible was found that the textures on the flank face exhibited derivative-cutting phenomenon during dry cutting of green alumina ceramics, which served as the removal of hard inclusion between the tool-workpiece interface. The derivative-cutting was found to be beneficial to the decrease of the flank wear of the flank-face textured tools. The textures on the flank faces can also be acted as storage for powder chip which can protect the texture groove from abrasion. Textures on flank face had no obvious effect on the roughness of machined green alumina ceramic surfaces.
•WC/Co carbide tools with and without textured flank-face were made.•The wear resistance of tools with textured flank-face was improved.•The tools with grooves parallel to the main cutting edge were the most effective.•Textures on the flank face exhibited derivative-cutting phenomenon.•Derivative-cutting was beneficial to the decrease of flank wear of textured tools.
•Complete analysis of VB index and cutting edge wear in turning operations.•Conventional techniques plus image recognition and Tool Wear software.•Conventional measurements of edge wear used to train ...ANNs.•VB and edge number as inputs and remaining life of cutting edge as output.•Both strategies predict tool life time as accurately as industrial parameters.•VB from direct measurements and VB from ANN-based image processing software.•Second strategy is an automized process that requires no extra human-effort.
A two-step method is presented for the automatic prediction of tool life in turning operations. First, experimental data are collected for three cutting edges under the same constant processing conditions. In these experiments, the parameter of tool wear, VB, is measured with conventional methods and the same parameter is estimated using Neural Wear, a customized software package that combines flank wear image recognition and Artificial Neural Networks (ANNs). Second, an ANN model of tool life is trained with the data collected from the first two cutting edges and the subsequent model is evaluated on two different subsets for the third cutting edge: the first subset is obtained from the direct measurement of tool wear and the second is obtained from the Neural Wear software that estimates tool wear using edge images. Although the complete-automated solution, Neural Wear software for tool wear recognition plus the ANN model of tool life prediction, presented a slightly higher error than the direct measurements, it was within the same range and can meet all industrial requirements. These results confirm that the combination of image recognition software and ANN modelling could potentially be developed into a useful industrial tool for low-cost estimation of tool life in turning operations.
