Modeling of the minimum cutting thickness in micro cutting with consideration of the friction around the cutting zone

Friction modeling between the tool and the workpiece plays an important role in predicting the minimum cutting thickness during TC4 micro machining and finite element method (FEM) cutting simulation. In this study, a new three-region friction modeling is proposed to illustrate the material flow mechanism around the friction zone in micro cutting; estimate the stress distributions on the rake, edge, and clearance faces of the tool; and predict the stagnation point location and the minimum cutting thickness. The friction modeling is established by determining the distribution of normal and shear stress. Then, it is applied to calculate the stagnation point location on the edge face and predict the minimum cutting thickness. The stagnation point and the minimum cutting thickness are also observed and illustrated in the FEM simulation. Micro cutting experiments are conducted to validate the accuracy of the friction and the minimum cutting thickness modeling. Comparison results show that the proposed friction model illustrates the relationship between the normal and sheer stress on the tool surface, thereby validating the modeling method of the minimum cutting thickness in micro cutting.     

Chip curling in metal cutting

Chip curling in metal cutting is considered. A method is proposed for determining the dimensions of the dead zone at the cutter tip on the basis of the chip’s geometric parameters.     

Nano-scale multilayered-composite coatings for the cutting tools

In machining, the tool life is one of the limiting criteria in the process; therefore, the development of wear-resistant material for the cutting tools is imperative. This paper presents a methodological approach to the design of nano-scale multilayered-composite coatings for cutting tools. A plasma-enhanced technology of filtered cathodic vacuum-arc deposition is used to coat the tools, which significantly extends the operational life of the cutting tools. Here, a three-layered architecture of coatings is proposed and each layer has a specific function. The engineered structural layers allowed for optimum combination of a high adhesion strength with the tool substrate and a minimum adhesion of the work material to the tool surface. The coating process is presented here alongside with the technological role of the layers. A study of the effect of the developed nano-scale multilayer composite coatings on the rates of tool wear was undertaken, and results were compared with the wear rates of uncoated and standard coatings. The results of a wide range experimental work are given in terms of flank wear and tool life for various machining conditions.     

Optimal methodology for cutting studies

The deficiencies of existing concepts regarding cutting are analyzed. A new approach is proposed on the basis of a standard experiment with a logical model of cutting.     

Optimization of cutting processes

Known criteria for the optimization of cutting processes are appraised. A new criterion for determining the optimal conditions in metal cutting is proposed.     

Production of slotted polymer filter tubes by deformational cutting

A method of producing adjustable slotted filter tubes is proposed; the operational characteristics of the tubes are determined as a function of the slot width.     

Identifying cutting processes and tools

A new methodology for investigating the cutting process and cutting tools as an integrated system of knowledge is proposed. This approach is fundamental to the creation of a universal automatic design system for cutting processes and tools.     

Selecting optimal cutting tools for lathes

A method is proposed for selecting optimal tool geometry and identifying the best lathe tool for specific applications from a catalog or database.     

A description of the lubricating action of the tribo-active components of cutting fluids

A multistage mechanism of lubrication layer formation during cutting is described and the necessary conditions for the formation of a lubrication layer are formulated. It is considered that the process of physical adsorption of the tribo-active components of the cutting fluid in the contact zone between tool and chip during metal cutting is one step in a multistage process which occurs in the interface capillary system. A mathematical model describing simultaneous diffusion and adsorption of tribo-active components in a single interface capillary is proposed. Some parameters for a model determining the efficiency of the lubricating action of surface-active additives are also proposed.     

Free-form curves cutting using flexible circular saw

A flexible circular saw, which can be used in a novel machining process for high-speed carbon fiber-reinforced plastic (CFRP) plate cutting, was developed. In this process, the saw is deflected like a bowl-like shape. A cross-section of the saw body then forms a circular arc. A curved line can therefore be cut without interference by the bowl-like deflection. In addition, the radius of the cross-section of the saw body can be controlled by adjusting the deflection. This process therefore allows curves to be cut with a varied radius using a single saw. This process can carry out high-speed curved-line cutting with a feed rate of 3 m/min on a CFRP plate. However, it is difficult to cut free-form curves using a flexible circular saw. Therefore, in this research, a new technique that can cut free-form curves using a flexible circular saw was proposed. Then, a cutting test applying the technique was carried out.     

“Peel cutting” – A new cutting method for difficult-to-cut workpieces with hard oxide surfaces

A new cutting method named “peel cutting” is proposed in this research to suppress notch wear in machining of metals with hard oxide surfaces. In general, metals are produced by hot deformation processes like rolling, forging, and extrusion, which cause hard oxide surfaces called scales on their surfaces. These hard scales need to be removed first in machining of precision parts. However, the machining causes the severe notch wear at the depth-of-cut position, where the tool contacts the hard scale. To solve this problem, the proposed peel cutting avoids this direct contact between the tool and the scale by inclining the end cutting edge at an extremely large inclination (oblique) angle. This extremely oblique cutting changes the material flow and generates a “burr-like chip”. In the proposed cutting method, the tool contacts only soft non-oxide metal under the scale during cutting. Cutting of titanium alloy Ti–6Al–4V is conducted by modifying commercial tools to provide extremely large inclination angles, and it is clarified that an inclination angle of 70 deg or greater is required to realize the proposed cutting. Tool wear in the proposed cutting of the alloy with a hard scale is also observed in comparison with the ordinary cutting, and the result verifies that the notch wear can be suppressed successfully by the proposed peel cutting.     

Theory and geometry of constrained cutting

The geometric parameters of tools in constrained cutting are determined. A new dynamic coordinate system is proposed, and conversion formulas to other coordinate systems are presented. The cross section of the cut layer in constrained cutting is described.     

Improving the stability of cutting on the basis of fractal,dimensional, and wavelet analysis

New characteristics are proposed for the assessment of cutting stability in the analysis of a vibroacoustic signal: the fractal dimensionality and the informational entropy. Wavelet analysis permits real-time diagnostics of the cutting stability. A neural-network model is proposed for regulating the stability of a dynamic cutting system.     

An adaptive control strategy for the abrasive waterjet cutting process with the integration of vision-based monitoring and a neuro-genetic control strategy

This paper presents an integrated approach for the monitoring and control of abrasive waterjet (AWJ) cutting process. A machine-vision-based monitoring approach was proposed to obtain the bore diameter of the focusing nozzle from time to time. A neuro-genetic approach, proposed by Srinivasu and Ramesh Babu (Appl Soft Comput 8(1):809–819, 2008) was employed as a control strategy to modify the process parameters, such as water pressure, abrasive flow rate, and jet traverse rate, so as to maintain the desired depth of cut, with changes in the diameter of the focusing nozzle monitored with a machine vision system. By combining the monitoring and control strategies, an integrated approach for adaptive control of AWJ cutting process is realized. The effectiveness of the proposed integrated approach for adaptive control of AWJ cutting process was shown by comparing the results obtained from the experiments with the process parameters suggested by the control strategy to achieve the desired depth of cut. From the results of the study, it is seen that the proposed monitoring system is capable of monitoring the focusing nozzle diameter with a mean absolute deviation of 0.05 mm and that the neuro-genetic strategy is capable of modifying the controllable process parameters to maintain the desired depth of cut with a mean absolute deviation of 0.87 mm.     

Resistance of titanium alloys to cutting

A thermomechanical model of the resistance of titanium alloys to cutting is proposed. The model takes account of the influence of the strain, strain rate, and temperature on the yield point. The maximum yield point in the chip-formation zone and at the front surface of the cutter is established. Analysis of elementary-chip formation in the turning of titanium alloys permits the determination of the temperature and cutting force.     

Lifespan prediction of cutting tools for high-value-added products

The traditional system for estimating lifespan of machining tools is based on the F. W. Taylor’s equation that uses fixed cutting factors. In this paper, an integrated model is proposed to get a better prediction of tool lifespan in machining process. The lifespan prediction of cutting tools having multiple affecting factors is studied here for machining parts with stochastic behavior of Taylor’s measuring parameter, k. The measuring variable k used to be regarded normally as a constant under predetermined conditions. In practice, lifespan of a tool lies in the range of a time interval rather than a fixed value. So, by calculating the impact of the stochastic variable k, a relative precise range of tool lifespan can be computed and this is particularly important for high-value-added products in manufacturing process because high-value-added products are usually extremely sensitive to the performance quality and failure cost of cutting tools, resulting in economic loss of the company both in terms of tool cost and product cost. A multiple linear regression approach is employed here to estimate the range of tool lifespan for the predictive model. A case study is conducted to show how this model works. The results of the improved manipulation of the parameters could influence the manufacturing system with a better control accuracy. To illustrate the significance of the transformed model, a case study was introduced that shows how the stochastic variable k influences the lifespan of a cutting tool. Relatively precise numerical results can be computed with this kind of analysis to direct a better comprehension of the factors for the cutting tools.     

一种零件切削加工工艺路线仿真方法

工艺路线快速仿真对于制造业而言有其重要意义.提出了工艺路线仿真算法,以零件形状特征描述为桥梁,建立工艺路线到加工特征的映射,然后将加工特征反映到零件三维模型上,从而实现零件三维模型的工艺演变.实例证明,该方法是一种简单有效的工艺路线仿真方法.     

Nondestructive assessment of the cutting properties of wheels with a single-layer diamond–galvanic coating

A new approach to determining the cutting properties of a diamond tool with a single-layer diamond–galvanic coating is proposed. The method is based on determining the concentration of diamond grains in the working layer of the tool.     

Finite element simulation for burr formation near the exit of orthogonal cutting

A coupled thermo-mechanical model of plane-strain orthogonal metal cutting including burr formation is presented using the commercial finite element code. A simulation procedure based on Normalized Cockroft–Latham damage criterion is proposed for the purpose of better understanding the burr formation mechanism and obtaining a quantitative analysis of burrs near the exit of orthogonal cutting. The cutting process is simulated from the transient initial chip formation state to the steady state of cutting, and then to tool exit transient chip flow by incrementally advancing the cutting tool. The predicted burr profile is compared with experimental data and found to be in reasonable agreement. The effect of the tool conditions and cutting conditions on the burr formation process was also investigated.     

On the modelling of abrasive waterjet cutting

Abrasive waterjet cutting operates by the impingement of a high-velocity abrasive-laden waterjet against the workpiece. The jet is formed by mixing abrasive particles with high-velocity water in mixing tubes and is forced through a tiny sapphire orifice. The accelerated jet exiting the nozzle travels at more than twice the speed of sound and cuts as it passes through the workpiece.This cutting process is being developed as a net-shape and near-net-shape machining process for cutting many metals and hard-to-machine materials. The narrow kerf produced by the stream results in neither delimitation nor stresses along the cutting path. This new technology offers significant advantages over traditional processes for its ability to cut through most sections of dense or hard materials without the need for secondary machining, to produce contours, and to be integrated into computer-controlled systems.The abrasive waterjet cutting process involves a large number of process and material parameters which are related to the waterjet, the abrasive particles, and workpiece material. Those parameters are expected to effect the material removal rates and the depth of cut. The purpose of the present work is to propose a model which is capable of predicting the maximum depth of cut for different types of materials using different process parameters. A comparison of the results of the proposed model and the models reported in the literature is introduced along with a discussion of the limitations of those models.On leave from: Mechanical Engineering Department, Suez Canal University, Egypt.On leave from: Industrial Production Engineering Department, Mansoura University, Egypt.On leave from: Mechanical Power Engineering Department, Alexandria University, Egypt.