Factors affecting the surface quality of the ground WC-Co alloy

We study the influence of the interelectrode and anode voltages applied to the abrasive instrument, its pressure, and the sizes of abrasive particles and the rate of treatment on the surface roughness and topography of sintered WC-Co alloy after mechanical and electrochemical grinding. The optimal values of the parameters of treatment are determined. Published in Fizyko-Khimichna Mekhanika Materialiv, Vol. 43, No. 2, pp. 117–121, March–April, 2007.     

Anisotropy of surface roughness in diamond turning of brittle single crystals

This paper deals with an investigation of the effect of crystallographic orientation and process parameters on the surface roughness of brittle silicon single crystals in ultraprecision diamond turning. The process parameters involve the depth of cut, feed rate, and spindle speed. Experimental results indicate that anisotropy in surface finish occurs when the cutting direction relative to the crystal orientation varies. There exists a periodic variation of surface roughness per workpiece revolution, which is closely related to the crystallographic orientation of the crystals being cut. Such an anisotropy of surface roughness can be minimized with an appropriate selection of the feed rate, spindle speed, and depth of cut. The findings provide a means for the optimization of the surface quality in diamond turning of brittle silicon single crystals.     

Theoretical and empirical coupled modeling on the surface roughness in diamond turning

In this work, a theoretical and empirical coupled method is proposed to predict the surface roughness achieved by single point diamond turning, in which the surface roughness is considered to be composed of the certain and uncertain parts. The certain components are directly formulated in theory, such as the effects of the kinematics and minimum undeformed chip thickness. The uncertain components in relation to the material spring back, plastic side flow, micro defects on the cutting edge of diamond tool, and others, are empirically predicted by a RBF (radial basis function) neural network, which is established by referring to the experimental data. Finally, the particle swarm optimization algorithm is employed to find the optimal cutting parameters for the best surface roughness. The validation experiments show that the optimization is satisfied, and the prediction accuracy is high enough, i.e. that the prediction error is only 0.59–10.11%, which indicates that the novel surface roughness prediction method proposed in this work is effective.     

Influence of material swelling on surface roughness in diamond turning of single crystals

Abstract

The effect of material swelling on the surface roughness in ultraprecision diamond turning has been investigated. Experimental results from the power spectrum analysis indicate that the profile of the tool marks is distorted by the effect of swelling of the materials being cut. A good correlation exists between the surface roughness and the amount of swelling that has occurred in the machined layer. Radically different surface roughness profiles were obtained when machining aluminium and copper single crystals with the same cutting plane and tool shape. The difference in the machining behaviour could not be accounted for by elastic recovery alone but could be explained by considering the plastic deformation induced in the machined layer.     

Enhancement of surface wettability via micro-and nanostructures by single point diamond turning

Studies on surface wettability have received tremendous interest due to their potential applications in research and industrial processes. One of the strategies to tune surface wettability is modifying surface topography at micro-and nanoscales. In this research, periodic micro-and nanostructures were patterned on several polymer surfaces by ultra-precision single point diamond turning to investigate the relationships between surface topographies at the micro-and nanoscales and their surface wettability. This research revealed that single-point diamond turning could be used to enhance the wettability of a variety of polymers, including polyvinyl chloride(PVC), polyethylene 1000(PE1000), polypropylene copolymer(PP) and polytetrafluoroethylene(PFTE), which cannot be processed by conventional semiconductor-based manufacturing processes. Materials exhibiting common wettability properties(θ≈ 90°) changed to exhibit "superhydrophobic" behavior(θ 150°). Compared with the size of the structures, the aspect ratio of the void space between micro-and nanostructures has a strong impact on surface wettability.     

Hydrogen depth profile in phosphorus-doped, oxygen-free copper after cathodic charging

Spent nuclear fuel, in Sweden, is planned to be put in 50-mm thick copper canisters and placed in 500-m depth in the bedrock. Depending on the conditions in the repository, an uptake of hydrogen in the copper may occur. It is therefore necessary to establish how a hydrogen uptake affects the microstructure in both the surface and the bulk. Phosphorus-doped, oxygen-free copper has been cathodically charged with hydrogen for up to 3?weeks. The amount of hydrogen as a function of the distance from the surface was measured by two methods: glow discharge optical emission spectrometry and melt extraction. The penetration of the increased hydrogen content was about 50?μm. Extensive bubble formation took place during the charging. A model has been formulated for the diffusion of hydrogen into the copper, the bubble formation and growth. The model can describe the total amount of hydrogen, the number of bubbles and their sizes as a function of the distance from the surface. Bubbles close to the surface caused the surface to bulge due to the high hydrogen pressure. From the shape of the deformed surface, the maximum hydrogen pressure could be estimated with the help of stress analysis. The maximum pressure was found to be about 400?MPa, which is almost an order of magnitude larger than previously recorded values for electroless deposited copper.     

The correlation model of acoustic emission in fine diamond turning

The process of cutting of an aluminum alloy has been monitored by the acoustic emission method. Single-crystal natural and synthetic diamond tools have been used in the investigation. The comparative analysis has demonstrated that the correlation model of acoustic emission, which was put forward by Pan and Dornfeld, is valid for the conditions of fine diamond turning of aluminum alloys.     

Direct joining of oxygen-free copper and carbon-fiber-reinforced plastic by friction lap joining

Oxygen-free copper(Cu) was successfully joined to carbon-fiber-reinforced thermoplastic(CFRTP,polyamide 6 with 20 wt% carbon fiber addition) by friction lap joining(FLJ) at joining speeds of 200–1600 mm/min with a constant rotation rate of 1500 rpm and a nominal plunge depth of 0.9 mm.It is the first time to report the joining of CFRTP to Cu by FLJ. As the joining speed increased, the tensile shear force(TSF) of joints increased first, and decreased thereafter. The maximum TSF could reach 2.3 kN(15 mm in width). Hydrogen bonding formed between the amide group of CFRTP and the thin Cu_2O layer on the Cu surface, which mainly contributed to the joint bonding. The influence factors of the TSF of the joints at different joining speeds were discussed. The TSF was mainly affected by the joining area, the degradation of the plastic matrix and the number and the size of bubbles. As the joining speed increased,the influence factors varied as follows: the joining area increased first and then decreased; the degradation of the plastic matrix and the number and the size of bubbles decreased. The maximum TSF was the comprehensive result of the relatively large joining area, small degradation of the plastic matrix and small number and sizes of bubbles.     

不锈钢、无氧铜和铝合金的升温脱附谱研究

研究超高真空材料的升温脱附谱对于获得超高真空、提高极限真空度和指导真空系统的烘烤除气有重要的意义.作者设计并加工了研究超高真空升温脱附谱的实验设备,并用此设备测量了真空系统结构材料不锈钢、无氧铜和铝合金的升温脱附谱.     

KDP晶体单点金刚石切削加工表层力学性能的研究

压痕和刻划实验是测量材料弹性、塑性和断裂行为的最简单方法,磷酸二氢钾(简称KDP)作为优质的非线性光学材料,常用作光学频率转换器件和电光开关元件,一般采用单点金刚石削的方法加工此类零件.为了深入了解KDP晶体单点金刚石切削加工表层力学性能的变化规律,本文对KDP晶体单点金刚石切削加工表层力学性能指标如硬度H、断裂韧性Kc和残余应力σr方面的有关问题进行深入研究,并通过对KDP晶体(001)面不同晶向上的硬度检测,系统分析了KDP晶体加工表面晶向对材料硬度、断裂韧性和残余应力的影响,研究结果表明:KDP晶体的同一晶面的不同晶向硬度和断裂韧性具有强烈的各向异性.     

Correlation between edge radius of the cBN cutting tool and surface quality in hard turning

cBN cutting tools with superior mechanical properties are widely used in machining various hard materials. The microgeometry of cBN cutting tools, such as the edge radius, has great influence on the surface quality of components and tool life. For optimized tool geometry, it is crucial to understand the influence of the cBN cutting tool microgeometry on the machined surface quality. In this study, the attempt has been made to investigate the correlation between the cutting tool edge radius and surface quality in terms of the surface roughness and subsurface deformation through a FE simulation and experiment. Machining tests under different machining conditions were also conducted and the surface roughness and subsurface deformation were measured. Surface roughness and subsurface deformation were produced by the cutting tools with different edge radii under various cutting parameters. Both results from the FE simulation and machining tests confirmed that there was a significant influence on the surface quality in terms of both the surface roughness and subsurface quality from the edge radius. There is a critical edge radius ofcBN tools in hard turning in terms of surface quality generated.     

Special features of oblique fine diamond turning of aluminum alloys

The paper addresses special features of one of finishing edge cutting operations—oblique fine diamond turning of aluminum alloys. The results of investigation of acoustic emission signals and cutting forces at various speeds and cutting edge inclination angles are given.     

Status of research on non-conventional technology assisted single-point diamond turning

With the increasing use of difficult-to-machin materials in aerospace applications, machining requirements are becoming ever more rigorous. However, traditional single-point diamond turning(SPDT) can cause surface damage and tool wear. Thus, it is difficul for SPDT to meet the processing requirements, and it has significan limitations. Research indicates that supplementing SPDT with unconventional techniques can, importantly, solve problems due to the high cutting forces and poor surface quality...     

Investigation on diamond tool wear in ultrasonic vibration-assisted turning die steels

This paper presents comprehensive theoretical analyses and experimental investigations for evaluating the ultrasonic vibration-assisted turning (UVAT) of die steels with single-crystal diamond tools. The diamond tool wear was found to rely heavily on the feed rate and the cutting speed while being insensitive to the depth of cut and the tool relief angle under the cutting conditions used in the tests. The tool wear characteristics were further studied based on the observation of wear zone using Raman spectral analysis and energy-dispersive X-ray (EDX) analysis. The detection results of the tool worn topography, the phase transformation and the carbon diffusion of diamond crystals revealed that tool wear mainly occurred on the tool flank face due to the graphitization and the diffusion of the diamond tool. Analytical results of the function mechanisms of the ultrasonic turning indicated that the friction force between the tool flank face and the machined surface, which depended mainly on the ratio of the cutting speed and the vibration speed, could be effectively reduced in ultrasonic turning process. The analytical and experimental results indicated that compared with conventional turning (CT), the cutting performance, in terms of the tool life, was markedly improved by applying ultrasonic vibration to the cutting tool.     

New methods and instruments for evaluating surface quality of abrasive and diamond tools

This article presents results of research at the Scientific Research Institute for Measurements (Moscow) on new methods and instruments for evaluating the quality of abrasive surfaces and diamond tools, including installed grinding wheels. Translated from Izmeritel'naya Tekhnika, No. 11, pp. 19–21, November, 1996.     

铜箔轧制润滑状态与表面质量的研究

使用不同运动粘度的轧制油和在不同道次压下率条件下进行了铜箔冷轧实验。利用激光扫描共焦显微镜(LSCM)和表面粗糙度仪对铜箔轧后表面形貌进行了表征,得到铜箔轧制变形区膜厚比和摩擦系数。研究了轧制油运动粘度,道次压下率对铜箔轧制变形区油膜厚度、表面粗糙度和前滑值的影响,并从膜厚比、摩擦系数和表面质量3个方面对不同润滑条件下铜箔轧制变形区的润滑状态进行了界定。结果表明,轧制油运动粘度γ40≤15mm2/s时,膜厚比λ→0,摩擦系数μ≈0.1～0.2,属于边界润滑状态,表面质量较好;道次压下率20%<ε≤60%时,膜厚比λ→0,摩擦系数μ>0.1,属于边界润滑状态,表面质量较好。为得到高表面质量的铜箔,轧制油运动粘度应控制在10mm2/s左右,道次压下率控制在30%左右,也即,使铜箔轧制润滑状态控制在边界润滑状态为最佳。     

Heteroepitaxy of nickel and copper on diamond

Crystalline nickel and copper possess bcc lattices, the parameters of which are 1.2 and 1.35% smaller than that of diamond. Heteroepitaxial Ni and Cu films have been grown by magnetron sputtering on polished and then thermally annealed and etched {100} and {110} surfaces of natural diamond. The films exhibit island morphology and possess a highly perfect crystalline structure.     

Tool path generation of ultra-precision diamond turning: A state-of-the-art review

With the increasing market demand for optical complex surface parts, the application of multi-axis ultraprecision single-point diamond turning is increasing. A tool path generation method is very important to decrease manufacturing time, enhance surface quality, and reduce cost. Compared with the tool path generation of the traditional multi-axis milling, that of the ultra-precision single-point diamond turning requires higher calculation accuracy and efficiency. This paper reviews the tool path generation of ultra-precision diamond turning,considering several key issues: cutter location(CL) points calculation, the topological form of tool path, interpolation mode, and G code optimization.