A Fracture Mechanics Approach to the Prediction of Tool Wear in Dry High-Speed Machining of Aluminum Cast Alloys—Part 1: Model Development

The utilization of cast aluminum alloys in automotive industry continues to rise because of consumer demand for a future generation of vehicles that will offer excellent fuel efficiency and emissions reduction, without compromising safety, performance, or comfort. Unlike wrought aluminum alloys, the cutting speed for cast aluminum alloys is considerably restricted due to the detrimental effect of the alloy’s silicon constituencies on tool life. In the present study, a new wear model is developed for tool-life management and enhancement, in a high-speed machining environment. The fracture-mechanics-based model requires normal and tangential stresses, acting on the flank of the cutting tool, as input data. Analysis of the subsurface crack propagation in the cobalt binder of cemented carbide cutting tool material is performed using a finite element (FE) model of the tool-workpiece sliding contact. The real microstructure of cemented carbide is incorporated into the FE model, and elastic-plastic properties of cobalt, defined by continuum theory of crystal plasticity are introduced. The estimation of the crack propagation rate is then used to predict the wear rate of the cutting tool. The model allows the microstructural characteristics of the cutting tool and workpiece material, as well as the tool’s loading conditions to be taken into consideration. Analysis of the results indicates that the interaction between the alloy’s hard silicon particles and the surface of the cutting tool is most detrimental to tool life. The fatigue wear of the cutting tool is shown to be directly proportional to the silicon content of the alloy, silicon grain size, and to the tool’s loading conditions.

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A Fracture Mechanics Approach to the Prediction of Tool Wear in Dry High Speed Machining of Aluminum Cast Alloys: Part 1 — Model Development

Tribology ◽

10.1115/imece2005-80620 ◽

2005 ◽

Cited By ~ 1

Author(s):

Alexander Bardetsky ◽

Helmi Attia ◽

Mohamed Elbestawi

Keyword(s):

Fracture Mechanics ◽

Wear Rate ◽

Tool Wear ◽

Crack Propagation ◽

High Speed ◽

Cutting Tool ◽

Fe Model ◽

High Speed Machining ◽

Aluminum Cast Alloys ◽

Cast Alloys

The analysis of the mechanism of cutting tool wear in high speed machining of cast aluminum alloys is conducted in this research work. The result of analysis indicates that the interaction between the hard silicon constituencies of the alloy and the surface of the cutting tool is the most detrimental to tool life. The wear of the cutting tool in such interactions, governed by fatigue wear mechanism, is directly proportional to silicon content of the alloy, silicon grain size and to the tool’s loading conditions. In order to predict the tool wear in machining aluminum cast alloys, a new wear model is developed. The fracture mechanics approach in wear rate estimation is implemented in this model. As an input data for the tool wear modeling, the normal and tangential stresses, acting on the flank of cutting tool are used. The fracture mechanics analysis of the subsurface crack propagation in the cobalt binder of cemented carbide cutting tool material is performed using a finite element (FE) model of the tool-workpiece sliding contact. The real microstructure of cemented carbide is incorporated in the FE model of tool-workpiece contact, and elastic-plastic properties of cobalt, defined by continuum theory of crystal plasticity are introduced in the model by UMAT subroutine of the ABAQUS® FE software. The crack propagation rate, determined from FE modeling, is used then in the model of cutting tool wear, developed in this work. This model is capable to predict the wear rate of cutting tool, base on the microstructural characteristics of the cutting tool and workpiece material and the tool’s loading conditions. The model can be used for cutting tool life assessment and management in high speed machining of Al-Si alloys in an industrial setting.

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Evaluation of Tool Wear Suppressive Ability of Lubricants Usein in Minimum Quantity Lubrication Application in High Speed Machining of Cast Aluminum Alloys

Manufacturing Engineering and Materials Handling, Parts A and B ◽

10.1115/imece2005-80597 ◽

2005 ◽

Cited By ~ 1

Author(s):

Alexander Bardetsky ◽

Helmi Attia ◽

Mohamed Elbestawi

Keyword(s):

Tool Wear ◽

High Speed ◽

Cutting Tool ◽

Minimum Quantity Lubrication ◽

Metalworking Fluids ◽

High Speed Machining ◽

Cast Aluminum ◽

Tool Wear Rate ◽

Cast Aluminum Alloys ◽

Lubricant Composition

The disadvantages of conventional metalworking fluids such as disposal problems, health problems and economic factors have led to the development of strategies to reduce their amount in metalworking. Recently, Minimum Quantity Lubrication (MQL) technology was developed and it seems to be a suitable alternative for economically and environmentally compatible production. It combines the functionality of lubrication with an extremely low consumption of lubricant and has a potential to replace metalworking fluids application in machining operations. The MQL lubricants are formulated with two major groups of additives; anti-wear (AW) additives and extreme pressure (EP) additives. When such lubricants are applied to the cutting zone, protective layers are formed on the interacting surfaces of the workpiece and the cutting tool. These layers prevent direct contact between the tool and chip surfaces, and, therefore reduce friction forces and tool wear. In order to utilize MQL to its full potential, it is essential to select appropriate lubricant composition for particular work material and machining parameters. The experimental study of different compositions of MQL lubricants is reported. The effectiveness of the lubricants are determined in terms of their ability to protect the cutting tool in high speed machining of cast aluminum alloys, which are widely used in automotive industry. The main objective of this research is to quantitatively evaluate the ability of lubricant’s additive composition to reduce the tool wear. This is reached through the comparison between the tool wear rate measured during the machining of aluminum cast alloy with the application of MQL, and the tool wear rate obtained in dry machining of the same alloy. Two kinds of the lubricants are evaluated; vegetable and synthetic. The content of AW and EP additives in each kind of lubricant was varied on three levels in order to capture the effect of the lubricant’s composition on tool wear. The result of the MQL lubricants evaluation is discussed and the recommendations for optimal lubricant composition are made.

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Observations of Tool Life and Wear Mechanisms in High Speed Machining of Ti-6Al-4V With PCD Tools Using High Pressure Coolant Supply

World Tribology Congress III, Volume 2 ◽

10.1115/wtc2005-63367 ◽

2005 ◽

Cited By ~ 1

Author(s):

E. O. Ezugwu ◽

J. Bonney ◽

W. F. Sales ◽

R. B. da Silva

Keyword(s):

High Pressure ◽

Titanium Alloy ◽

Tool Life ◽

Wear Mechanisms ◽

High Speed ◽

Cutting Tool ◽

High Speed Machining ◽

The Past ◽

Pcd Tools ◽

High Pressure Coolant

Usage of titanium alloys has increased since the past 50 years despite difficulties encountered during machining. In this study PCD tools were evaluated when machining Ti-6Al-4V alloy at high speed conditions under high pressure coolant supplies. Increase in coolant pressure tend to improve tool life and minimise adhesion of the work material on the cutting tool during machining. Adhesion can be accelerated by the susceptibility of titanium alloy to galling during machining.

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