Development Of Crater Wear Research Articles

Influence of characteristic properties of PCD grades on the wear development in turning of β-titanium alloy (Ti5Al5V5Mo3Cr)

The high chemical reactivity and low thermal conductivity of titanium-alloys are the main reasons for not using PCD tools in machining of Ti-alloys. The aim of this recent research study on three different PCD grades involving tool life and wear development is to understand the role of characteristic PCD properties (i.e. grain size, its distribution and cobalt content) in machining of β-titanium alloy (Ti5Al5V5Mo3Cr). The results show a clear relationship between the characteristic PCD properties and the development of crater wear while abrasive wear does not play a dominant role in the evaluation of tool performance. Within a specific cutting data window PCD tools can contribute to improved machinability of Ti5Al5V5Mo3Cr compared to commonly used carbide tools. Different advanced analysis methods such as scanning electron microscopy (SEM) and (scanning) transmission electron microscopy ((S)TEM) in combination with energy dispersive X-ray spectroscopy (EDXS) and electron energy loss spectroscopy (EELS) have been applied to understand the basic wear mechanisms on the atomic scale. The performance results clearly show that the design of the PCD grade is one of the main factors for improving performance of the diamond tool in terms of wear development and tool life. Based on the presented results the crater wear development can be explained by atomistic processes.

Quantitative analysis on crater wear of cemented carbide inserts when turning Ti-6Al-4V

Process and rate of the crater wear development on the rake face of uncoated cemented carbide inserts were investigated when Ti-6Al-4V alloy was turned under dry cutting conditions. Contour maps were outlined to study the relationship between the area of the contour region and its wear depth. An effectively predictive method was proposed to predict wear-related quantities of the crater, including the crater depth, wear area, and wear volume. The predictive method was verified by the experiments with different cutting parameters. The development rate of the crater with the wear depth was acquired by analyzing the relationship between the area of the contour boundary region and its wear depth, and reasons on a sharp increase of the development rate were discussed at the wear depth of (KT-1) or (KT-2). The relationship between the area of the contour region and cutting time at a certain wear depth was proposed and could be used to predict the wear-related quantities of the crater.

Wear characteristic of alumina coated and alumina ceramic tools

The crater wear characteristic of an alumina coated cemented carbide tool and an alumina ceramic tool was investigated quantitatively based on the stress and temperature on the rake face, which were measured with a pair of divided tools and a thermocouple respectively. The cutting temperature was also calculated by finite difference method. The obtained wear characteristics indicated that the sintered alumina ceramic had several times higher resistance to crater wear than the CVD layer of alumina coated on the cemented carbide if the cutting temperature and stress were the same. The prediction of crater wear development using the wear characteristic of these tools, however, showed that the wear rate of the alumina coated tool depends on the thermal conductivity of the substrate and would be smaller than the wear rate of the alumina ceramic tool if a cemented carbide of high thermal conductivity is used as a substrate.

断続切削時の工具切れ刃摩耗と欠損発生の解析的予測

A characteristic equation of carbide tool wear in interrupted turning operation is derived and verified experimentally to hold well by measuring the distributions of wear, stress and temperature on rake face at the steady state. A computer simulation of crater wear development is then carried out by applying the wear equation, of which the characteristic constants are obtained from a single wear test. The change of cutting stress distributions on rake face at the engagement with the crater wear development is obtained experimentally. The crater wear does not any effect on the variation of cutting forces during the engagement but on the distributions of cutting stress at the instant of impact. A tool-chip contact length is limited within an area between the cutting edge and the front edge of crater at the moment of impact. For the arbitrary wear development, the transient variation of impact stress field within cutting edge during the edge engagement in interrupted turning is obtained though FEM calculation using the stress distribution obtained above. In collation of the most dangerous state of the transient stress with the fracture criterion at each element for the arbitrary wear state, both the variation of fracture probability distribution with number of interruption and the wear development with cutting distance can be also predicted.

Analytical Prediction of Three Dimensional Cutting Process—Part 3: Cutting Temperature and Crater Wear of Carbide Tool

Through the energy method proposed in the previous parts of this study, it is possible to predict chip formation and cutting force for a single point tool of arbitrary geometry. By using the predicted results together with an assumption made on the stress distribution on the tool face, the temperature distribution within chip and tool is obtained through a numerical analysis. A characteristic equation of crater wear of carbide tool is derived theoretically and verified experimentally. Computer simulation of crater wear development is then carried out by using the characteristic equation, and the predicted distributions of the stress and the temperature.

Cutting tool crater wear measurement by the lapping-comparator technique

A new contour mapping technique for the investigation of cutting tool crater wear development is presented. A transparent thermoplastic mold of a tool crater is made and lapped to show contour lines on an optical comparator. The lapping-comparator technique is simple and nondestructive. High accuracy and remarkable reproducibility are obtained. Advantages of the new technique are compared with the existing optical contour mapping method.

超硬工具のクレータ摩耗に及ぼすバイト取付け角の影響について(第1報)

Crater wear of cemented carbide tools has been studied by many investigators, and the importance of temperature at the chip-tool interface was pointed out. Temperature may be affected by many factors, i.e., cutting conditions, tool and work materials, and tool shape, etc. The authors performed an experiment of steel cutting by carbide tools with various entering angles and obtained a conclusion that the depth of crater wear varies with the entering angles and it has the maximum value when the angle is about 75 deg. or more in the conditios of the experiment. Also, the friction coefficient, change of the form of chip curl, the development of crater wear, and the cutting resistances were investigated.