Wear Mechanisms Of Cutting Tools Research Articles

Cutting performance and wear mechanisms of TiAlN PVD-coated cemented carbide tool in high speed turning of Ti-5Al-2Sn-2Zr-4Mo-4Cr alloy

The high-speed finish turning tests of Ti-17 titanium alloy (Ti-5Al-2Sn-2Zr-4Mo-4Cr) were carried out by using PVD cemented carbide tools with TiAlN coating. The machinability behaviors in terms of cutting forces, cutting temperatures, surface roughness, and tool service life were measured and evaluated under different machining parameter conditions, and the empirical prediction model of these variables were established depending on the cutting parameters. Incorporating the measured results of scanning electron microscopy (SEM) as well as energy dispersive spectroscopy (EDS), the initial tool wear patterns and the eventual wear patterns when the tool wear states meet the failure criteria were comparably investigated and analyzed. It was found that during the initial wear stage, the sticking wear zone and the sliding wear zone can be distinguished on the tool wear interface. The main wear patterns of are peeling off of coating material, crater wear of rake face, edge breakage and edge wear of tool tip after reaching the tool failure rejection criterion. The cutting tool wear mechanisms were systematically studied, and the results show that the wear mechanisms of a TiAlN PVD-coated carbide cutting tool in turning Ti-17 titanium alloy were dominated by the interaction wear effect among the adhesion, oxidation and diffusion between cemented carbide substrate and workpiece material.

Study of the Tool Wear Process in the Dry Turning of Al–Cu Alloy

Light alloy machining is a widely implemented process that is usually used in the presence of cutting fluids to reduce wear and increase tool life. The use of coolants during machining presents negative environmental impacts, which has increased interest in reducing and even eliminating their use. In order to obtain ecofriendly machining processes, it will be necessary to suppress the use of cutting fluids, in a trend called “dry machining”. This fact forces machines to work under aggressive cutting conditions, producing adhesion wear that affects the integrity of the parts’ surfaces. This study describes cutting tool wear mechanisms in machining of UNS A92024 samples under dry cutting conditions. Energy dispersive spectroscopy (EDS) analysis shows the different compositions of the adhered layers. Roughness is also positively affected by the change of the cutting geometry produced in the tool.

A novel finite element method for the wear analysis of cemented carbide tool during high speed cutting Ti6Al4V process

In the present research, three typical cutting tool wear mechanisms (abrasive wear, adhesive wear, and diffusive wear) were taken into consideration in the FE simulation of cutting tool with a specific user-defined subroutine. Based on the influence of temperature on the cutting tool wear form, a novel wear rate model was built integrating Usui, Takeyama, and Attanasio wear rate equation. The high-speed cutting tests were carried out on Ti6Al4V to determine the proposed wear rate model constant. The cutting forces and rack face wear morphologies obtained from FE simulation match well with those from experimental cutting tests. Finally, the effect of cutting parameters on tool wear was studied by FEM. The simulation results show that the impact of the cutting speed on the cutting tool life is more significant than that of feed rate, and the preferred ranges of cutting speed and feed rate for extending cemented carbide cutting tool in high-speed dry cutting Ti6Al4V are 90–150 m/min and 0.10–0.20 mm/r, respectively.

Coolant strategy influence on tool life and surface roughness when machining ADI

Austempered ductile iron alloys (ADI) are an interesting class of materials because of their unique microstructure and mechanical properties. When subjected to austempering treatment, ductile iron transforms to a microstructure consisting of ferrite and stabilized austenite rather than ferrite and carbide as in austempered steels. Because of the presence of stabilized austenite, austempered ductile iron (ADI) exhibits an excellent combination of strength and ductility together with good fatigue and wear properties. Accordingly, there is a growing interest in using ADI in several applications due to its mechanical properties. However, as with difficult-to-cut materials, the machinability rating of ADI is low and there is still a need to understand the impact of the cutting process parameters. Machinability of a material depends not only on its properties and microstructure, but also on the proper selection and control of process variables. The current work is focused on performing a machinability analysis of ADI in order to understand the effect of the cutting process parameters on the machined surface quality and tool life. It also studies the effect of different coolant strategies. Thus, the motivation of this study is to develop a better understanding of the influence of cutting parameters and cooling strategy to be able to machine ADI directly with acceptable tool life and cycle time. The design of experiments technique and response surface methodology is employed to analyze and model the measured responses. In addition, the cutting tool wear mechanisms are identified and discussed.

Influence of cutting tool geometrical parameters on tool wear in high-speed milling of Inconel 718 curved surface

High-speed machining provides an efficient approach for machining Inconel 718 with high quality and high efficiency. For high-speed milling of Inconel 718 curved surface, the geometrical characteristics are changing continuously leading to a sharp fluctuation of cutting force, which will aggravate the tool wear. As the wear mechanism of coated cutting tool is seriously affected by the cutting tool geometrical parameters, suitable geometrical parameters of cutting tool should be selected to avoid the cutting tool from being worn out very quickly. In this study, the influence of cutting tool geometrical parameters on tool wear in high-speed milling of Inconel 718 curved surface is investigated with coated cutting tool, and the cutting force in milling process is also analyzed. The results show that the cutting force variation can manifest the tool wear degree, and the failure type of coated cutting tool in plane milling and curved surface milling after the same cutting length is different. Furthermore, the cutting tool geometrical parameters seriously affect the tool wear and the tool life in high-speed milling of Inconel 718 curved surface. Concretely, the small rake angle has greater strength and has superiority, the relief angle increasing can enhance the tool life, and the tool life is decreased with the increasing of helix angle for the cutting tool, whose helix angle is larger than 30°. This study provides a theoretical basis for cutting tool wear mechanism and cutting tool geometrical parameter selection in high-speed milling of Inconel 718 curved surface, so as to guarantee the machining efficiency in high-speed milling of Inconel 718 curved surface.

Analysis of Element Diffusion between Alloy Cast Iron and WC/Co Cemented Carbides

An alloy cast iron has special properties by adding some alloying elements to the ordinary cast iron ASTMNo35A. Diffusion wear is one of the main cutting tool wear mechanisms in machining of the alloy cast irons. The diffusion of tungsten (W) and iron (Fe) between the alloy cast iron and the WC/Co cemented carbides was investigated in this paper by means of heating diffusion couple. It has be proved from the experiment that Fe in the alloy cast iron diffused a deeper distance in the WC/Co cemented carbides with the higher Co content; while the diffusion of W element in the WC/Co cemented carbides the alloy cast iron was not serious. The Vickers-hardness analysis of the alloy cast iron and K20 cemented carbide couple was determined. The elements diffusion impaired the hardness of the alloy cast iron and WC/Co cemented carbide cutting tool.

Analysis of wear of cemented carbide cutting tools during milling operation of gray iron and compacted graphite iron

Abstract Cast iron is used to manufacture engine blocks and heads due to its mechanical and physical properties. The thermal conductivity and vibration absorption are some fundamental properties for these applications. Compacted graphite iron (CGI) has higher mechanical strength than gray cast iron and can be a great advantage in these types of mechanical parts. Although mechanical and physical properties are similar for both materials, CGI is considered to have poor machinability compared to gray cast iron, even when compared to alloyed gray cast iron. So it is important to investigate the behavior of the CGI for the most important cutting processes. While CGI Grade 450 is used for cylinder blocks, CGI Grade 350 is proposed for cylinder heads, because of higher thermal conductivity and better machinability. In the present work, two grades of gray iron, used to produce diesel engine cylinder heads, were compared to CGI Grade 350. Machining involves extensive plastic deformation ahead of the tool in a narrow chip zone and friction between the rake face and the chip, and these factors can interact extensively with the tool materials and start the wear mechanism. The investigations of cutting tool wear mechanism became necessary to fit the parameters and reduce the problems of stopping the machine for tool change. This work contributes to a better understanding of wear mechanisms of cutting tools used in milling operation of alloyed gray cast iron and compacted graphite iron using high cutting speeds. The main objective of this work is to verify the influence of the workpiece material and the cutting conditions on tool life and tool wear mechanism. The cutting process used is the dry face milling. Cemented carbide tools of class ISO K coated with Al 2 O 3 , using the technique of chemical vapor deposition at medium temperature (MTCVD), were used. The main conclusions are that workpiece material strongly influences tool life and tool wear involves different mechanisms. The wear mechanisms observed on the rake face at these conditions were abrasion and adhesion, at the end of tool life. Adhesion was the main wear mechanism at higher cutting speeds.

Statistical surface roughness checking procedure based on a cutting tool wear model

Surface roughness is an important measure of quality in metalcutting. Because the surface roughness measure is related to cutting tool wear, this paper develops an efficient surface roughness monitoring and control procedure that combines statistical analysis and the physics of the cutting tool wear mechanism. Examples and data are taken from an actual machining operation.

A study of the cutting tool wear mechanism on the minor flank

It is well known that groove wear which is generated on the minor flank of a cutting tool is extremely harmful to surface finish in turning operations. The purposes of this study are to clarify the influences that the atmospheric gas and the physicochemical properties of the cutting tools and work materials have on groove wear, and also to propose a remedy to reduce the roughness on machined surfaces. The main findings of this research are as follows: (1) the atmospheric gas of a cutting environment has a considerable effect on the degree of groove wear formation; (2) groove wear is accelerated when easily oxidizable tool materials are used; (3) only slight groove wear develops when machining a work material which forms a stable oxide film on the tool surface; (4) thus the chemical reaction on the minor flank is the major cause of groove wear formation. From this, a practical remedy to reduce surface roughness caused by groove wear is proposed.