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2017年 第5卷 第1期    刊出日期：2017-03-25

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Deformation, failure and removal mechanisms of thin film structures in abrasive machining

Cheng-Wei Kang, Han Huang

2017, 5(1):  1-19.  doi:10.1007/s40436-016-0165-2

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Thin film structures are becoming increasingly more important for industrial applications such as the making of solar panels, microelectronic devices and micro systems. However, the challenges encountered in the machining of thin film structures have been a bottleneck that impedes further wide spread uses of such structures. The development of material removal processes that are capable of producing a damage free surface at high removal rates is critical for cost effective production. Such development relies highly on a comprehensive understanding of the deformation, failure and removal mechanisms of thin film structures involved in mechanical loading. In this paper, the current understanding of the deformation characteristics of thin film systems was reviewed to provide important insights into the interfacial failure under mechanical loading, with focuses on the interfacial failure mechanisms and existing problems in the machining of thin film structures. The key characterization techniques were outlined. In particular, the recent progress in the abrasive machining of a thin film multilayer structure was summarized. The potential research directions were also presented in the end of the review.

Nano-machining of materials: understanding the process through molecular dynamics simulation

Dan-Dan Cui, Liang-Chi Zhang

2017, 5(1):  20-34.  doi:10.1007/s40436-016-0155-4

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Molecular dynamics (MD) simulation has been widely applied in various complex, dynamic processes at atomistic scale, because anMDsimulation can provide some deformation details of materials in nano-processing and thus help to investigate the critical and important issues which cannot be fully revealed by experiments. Extensive research with the aid of MD simulation has provided insights for the development of nanotechnology. This paper reviews the fundamentals of nano-machining from the aspect of material structural effects, such as single crystalline, polycrystalline and amorphous materials. The classic MD simulations of nano-indentation and nano-cutting which have aimed to investigate the machining mechanism are discussed with respect to the effects of tool geometry, material properties and machining parameters. On nano-milling, the discussion focuses on the understanding of the grooving quality in relation to milling conditions.

Laser conditioning and structuring of grinding tools-a review

Bahman Azarhoushang, Ali Zahedi

2017, 5(1):  35-49.  doi:10.1007/s40436-016-0167-0

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The conditioning of grinding tools is one of the most important factors for achieving an optimal grinding process. It influences the grinding forces and temperatures and, therefore, the achievable material removal rate, dimensional accuracy and the surface integrity of the workpiece. Furthermore, the roundness, profile accuracy and the wear of the grinding tools are strongly influenced by the conditioning process. The conditioning process should be matched to the abrasive type and the bonding of the grinding tool. Laser conditioning is a promising unconventional and non-contact method, which is able to condition all kinds of abrasives and bonding types. The main advantages of this novel method are no tool wear, good repeatability and controllability, high precision and a relatively short process time. Additionally, using this method grinding tools can be micro-structured. This paper reviews the literature on the laser conditioning of grinding tools, covering the associated setups, wheel conditioning and structuring mechanisms, and experimental results. It also discusses the technical barriers that have to be overcome before laser conditioning can be fully integrated into manufacturing.

System integration for on-machine measurement using a capacitive LVDT-like contact sensor

Yung-Tien Liu, You-Liang Kuo, Da-Wei Yan

2017, 5(1):  50-58.  doi:10.1007/s40436-016-0169-y

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In this study, an air-bearing capacitive linear variable differential transformer (LVDT)-like contact sensor with a rounded diamond tip was mounted to a desktop machine tool to construct an on-machine (OM) measuring system. The measuring system was capable of decoding the digital signals of linear encoders mounted on the machine tool and acquiring the analog signal of the contact sensor. To verify the measuring system, experimental examinations were performed on an oxygen-free copper (OFC) convex aspheric mold with a diameter of 5 mm and a curve height of 0.46 mm. The acquired signals were processed by the implemented Gaussian regression filter (GRF), removing the tilt of measured profile, and compensating for the radius of probe tip. The profile obtained was compared to that measured using a commercially available device, and a maximum deviation of 14.6 lm was found for the rough cutting. The compensation cutting was then performed according to the form error of OM measurement. As a result, the PV form error compared with the designed profile was reduced from 19.2 lm over a measured diameter of 4 mm to 9.7 lm over a measured diameter of 3.1 mm, or a percentage improvement of 35.4% in form accuracy. Through the examination for aspheric machining, the effectiveness of the implemented OM measuring system was demonstrated, and the technical details of system implementation were presented. Further improvement was suggested to reduce the diameter of probe tip and measuring force.

Fatigue life of machined components

A. Pramanik, A. R. Dixit, S. Chattopadhyaya, M. S. Uddin, Yu Dong, A. K. Basak, G. Littlefair

2017, 5(1):  59-76.  doi:10.1007/s40436-016-0168-z

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A correlation between machining process and fatigue strength of machined components clearly exists. However, a complete picture of the knowledge on this is not readily available for practical applications. This study addresses this issue by investigating the effects of machining methods on fatigue life of commonly used materials, such as titanium alloys, steel, aluminium alloys and nickel alloys from previous literature. Effects of turning, milling, grinding and different non-conventional machining processes on fatigue strength of above-mentioned materials have been investigated in detail with correlated information. It is found that the effect of materials is not significant except steel in which phase change causes volume expansion, resulting in compressive/tensile residual stresses based on the amounts of white layers. It is very complex to identify the influence of surface roughness on the fatigue strength of machined components in the presence of residual stresses. The polishing process improves the surface roughness, but removes the surface layers that contain compressive residual stresses to decrease the fatigue strength of polished specimens. The compressive and tensile residual stresses improve and reduce fatigue strength, respectively. Grinding process induces tensile residual stresses on the machined surfaces due to high temperature generation. On the other hand, milling and turning processes induce compressive residual stresses. High temperature non-conventional machining generates a network of micro-cracks on the surfaces in addition to tensile residual stresses to subsequently reduce fatigue strength of machined components. Embedded grits of abrasive water jet machining degrade the fatigue performance of components machined by this method.

Particle fracture and debonding during orthogonal machining of metal matrix composites

A. Pramanik, L. C. Zhang

2017, 5(1):  77-82.  doi:10.1007/s40436-017-0170-0

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This paper investigates the particle fracture and debonding during machining of metal matrix composite (MMC) due to developed stress and strain, and interaction with moving tool by finite element analysis. The machining zone was divided into three regions:primary, secondary and tertiary deformation zones. The tendency of particles to fracture in each deformation zone was investigated. The findings of this study were also discussed with respect to the experimental results available in the literature. It was found that particles at the cutting path in the tertiary deformation zone fractured as it interacted with tool. In the secondary deformation zone, particles interacted with other particles as well as cutting tool. This caused debonding and fracture of huge number of particles as those were moving up along the rake face with the chips. No particle fracture was noted at the primary deformation zone. The results obtained from finite element analysis were very similar to those obtained from experimental studies.

Comparative study between wear of uncoated and TiAlN-coated carbide tools in milling of Ti6Al4V

M. S. Uddin, Binh Pham, Ahmed Sarhan, Animesh Basak, Alokesh Pramanik

2017, 5(1):  83-91.  doi:10.1007/s40436-016-0166-1

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As is recognized widely, tool wear is a major problem in the machining of difficult-to-cut titanium alloys. Therefore, it is of significant interest and importance to understand and determine quantitatively and qualitatively tool wear evolution and the underlying wear mechanisms. The main aim of this paper is to investigate and analyse wear, wear mechanisms and surface and chip generation of uncoated and TiAlN-coated carbide tools in a dry milling of Ti6Al4V alloys. The quantitative flank wear and roughness were measured and recorded. Optical and scanning electron microscopy (SEM) observations of the tool cutting edge, machined surface and chips were conducted. The results show that the TiAlN-coated tool exhibits an approximately 44% longer tool life than the uncoated tool at a cutting distance of 16 m. A more regular progressive abrasion between the flank face of the tool and the workpiece is found to be the underlying wear mechanism. The TiAlN-coated tool generates a smooth machined surface with 31% lower roughness than the uncoated tool. As is expected, both tools generate serrated chips. However, the burnt chips with blue color are noticed for the uncoated tool as the cutting continues further. The results are shown to be consistent with observation of other researchers, and further imply that coated tools with appropriate combinations of cutting parameters would be able to increase the tool life in cutting of titanium alloys.