Surface finish visualisation in high speed, ball nose milling applications

The majority of semiconductor devices are made up of silicon wafers. Manufacturing of high-quality silicon wafers includes numerous machining processes, including end milling. In order to end mill silicon to a nano-meteric surface finish, it is crucial to determine the effect of machining parameters, which influence the machining transition from brittle to ductile mode. Thus, this paper presents a novel experimental technique to study the effects of machining parameters in high speed end milling of silicon. The application of compressed air, in order to blow away the chips formed, is also investigated. The machining parameters’ ranges which facilitate the transition from brittle to ductile mode cutting as well as enable the attainment of high quality surface finish and integrity are identified. Mathematical model of the response parameter, the average surface roughness (Ra) is subsequently developed using RSM in terms of the machining parameters. The model was determined, by Analysis of Variance (ANOVA), to have a confidence level of 95%. The experimental results show that the developed mathematical model can effectively describe the performance indicators within the controlled limits of the factors that are being considered.

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Ultra-High Speed Grinding Using a CBN Wheel for a Mirror-Like Surface Finish

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.291-292.67 ◽

2005 ◽

Vol 291-292 ◽

pp. 67-72 ◽

Cited By ~ 2

Author(s):

M. Ota ◽

T. Nakayama ◽

K. Takashima ◽

H. Watanabe

Keyword(s):

Surface Finish ◽

High Speed ◽

High Efficiency ◽

Ground Surface ◽

Machining Process ◽

Grinding Wheel ◽

Cbn Wheel ◽

Ultra High Speed ◽

High Speed Grinding ◽

Grinding Conditions

There are strong demands for a machining process capable of reducing the surface roughness of sliding parts, such as auto parts and other components, with high efficiency. In this work, we attempted to grind hardened steel to a mirror-like surface finish with high efficiency using an ultra-high speed grinding process. In the present study, we examined the effects of the work speed and the grinding wheel grain size in an effort to optimize the grinding conditions for accomplishing mirror-like surface grinding with high efficiency. The results showed that increasing the work speed, while keeping grinding efficiency constant, was effective in reducing the work affected layer and that the grinding force of a #200 CBN wheel was lower than that of a #80 CBN wheel. Based on these results, a high-efficiency grinding step with optimized grinding conditions was selected that achieved excellent ground surface quality with a mirror-like finish.

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Tool life prediction by RSM for cryogenic milling of inconel 718

Industrial Lubrication and Tribology ◽

10.1108/ilt-04-2019-0166 ◽

2019 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Nurul Hayati Binti Abdul Halim ◽

Che Hassan Che Haron ◽

Jaharah A. Ghani ◽

Muammar Faiq Azhar

Keyword(s):

Tool Life ◽

Inconel 718 ◽

High Speed ◽

Metal Cutting ◽

Milling Process ◽

Average Error ◽

Depth Of Cut ◽

Content Type ◽

Radial Depth ◽

Ball Nose Milling

Purpose The purpose of this study is to present the tool life optimization of carbide-coated ball nose milling inserts when high-speed milling of Inconel 718 under cryogenic CO2 condition. The main aims are to analyze the influence level of each cutting parameter on the tool life and to identify the optimum parameters that can lengthen the tool life to the maximum. Design/methodology/approach The experimental layout was designed using Box–Behnken RSM where all parameters were arranged without combining their highest and lowest values of each factor at the same time. A total of 29 milling experiments were conducted. Then, a statistical analysis using ANOVA was conducted to identify the relationship between the controlled factors on tool life. After that, a predictive model was developed to predict the variation of tool life within the predetermined parameters. Findings Results from the experimental found that the longest tool life of 22.77 min was achieved at Vc: 120 m/min, fz: 0.2 mm/tooth, ap: 0.5 mm and ae: 0.2 mm. ANOVA suggests the tool life of 23.4 min can be reached at Vc: 120.06 m/min, fz: 0.15 mm/tooth, ap: 0.66 mm and ae: 0.53 mm. All four controlled factors have influenced the tool life with the feed rate and radial depth of cut (DOC) as the major contributors. The developed mathematical model accurately represented the tool life at an average error of 8.2 per cent when compared to the actual and predicted tool life. Originality/value These experimental and statistical studies were conducted using Box–Behnken RSM method under cryogenic CO2 condition. It is a proven well-known method. However, the cooling method used in this study is a new technique and its effects on metal cutting, especially in the milling process of Inconel 718, has not yet been explored.

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Separation and Transition Control on an Aft-Loaded Ultra-High-Lift LP Turbine Blade at Low Reynolds Numbers: High-Speed Validation

Journal of Turbomachinery ◽

10.1115/1.2437220 ◽

2006 ◽

Vol 129 (2) ◽

pp. 340-347 ◽

Cited By ~ 17

Author(s):

Maria Vera ◽

Xue Feng Zhang ◽

Howard Hodson ◽

Neil Harvey

Keyword(s):

Surface Roughness ◽

Mach Number ◽

Surface Finish ◽

High Speed ◽

Reynolds Numbers ◽

High Lift ◽

Low Reynolds Numbers ◽

Low Speed ◽

Transition Mechanism ◽

Low Reynolds

This paper presents the second part of an investigation of the combined effects of unsteadiness and surface roughness on an aft-loaded ultra-high-lift low-pressure turbine (LPT) profile at low Reynolds numbers. The investigation has been performed using low- and high-speed cascade facilities. The low- and high-speed profiles have been designed to have the same normalized isentropic Mach number distribution. The low-speed results have been presented in the first part (Zhang, Vera, Hodson, and Harvey, 2006, ASME J. Turbomach., 128, pp. 517–527). The current paper examines the effect of different surface finishes on an aft-loaded ultra-high-lift LPT profile at Mach and Reynolds numbers representative of LPT engine conditions. The surface roughness values are presented along with the profile losses under steady and unsteady inflow conditions. The results show that the use of a rough surface finish can be used to reduce the profile loss. In addition, the results show that the same quantitative values of losses are obtained at high- and low-speed flow conditions. The latter proves the validity of the low-speed approach for ultra-high-lift profiles for the case of an exit Mach number of the order of 0.64. Hot-wire measurements were carried out to explain the effect of the surface finish on the wake-induced transition mechanism.

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In Situ Analysis of Deformation Mechanics of Constrained Cutting Towards Enhanced Material Removal

Volume 2: Processes; Materials ◽

10.1115/msec2019-2970 ◽

2019 ◽

Author(s):

Yang Guo ◽

Jisheng Chen ◽

Amr Saleh

Keyword(s):

Free Surface ◽

Surface Finish ◽

Simple Shear ◽

Chip Formation ◽

Material Removal ◽

High Speed ◽

Image Correlation ◽

High Speed Imaging ◽

Deformation Mechanics

Abstract Chip formation in conventional cutting occurs by deformation that is only partially bounded by the cutting tool. The unconstrained free surface is a complication in determining the deformation of chip formation. The constrained cutting employs a constraining tool in the cutting process to confine the otherwise free surface and enable direct control of the chip formation deformation. A study has been made on the deformation mechanics of plane-strain constrained cutting using high speed imaging and digital image correlation (DIC) methods. For different constrained levels (including unconstrained free cutting), material flow of chip formation is directly observed; strain rate and strain in the chip as well as the subsurface region are quantified; cutting forces are measured; and surface finish are examed. The study shows that chip formation in constrained cutting can occur in two different deformation modes, i.e., simple shear and complex extrusion, depending on the constrained level. Constrained cutting in simple shear regime can reduce strain, reduce cutting force and energy, and improve surface finish compared to free cutting, therefore it is more efficient for material removal than free cutting. Constrained cutting in the complex extrusion regime imposes a significant amount of surface / subsurface deformation and consumes a very high cutting energy, and therefore is not suitable for material removal. Furthermore, the mechanics of chip formation in both free cutting and constrained cutting, especially the roles played by the free surface and the constraining tool, are discussed.

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Improving the surface finish in high speed milling of stamping dies

Journal of Materials Processing Technology ◽

10.1016/s0924-0136(02)00102-4 ◽

2002 ◽

Vol 123 (2) ◽

pp. 292-302 ◽

Cited By ~ 44

Author(s):

Luis N. López de Lacalle ◽

A. Lamikiz ◽

J.A. Sánchez ◽

J.L. Arana

Keyword(s):

Surface Finish ◽

High Speed ◽

High Speed Milling ◽

Stamping Dies

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Design and Testing of a Micro-Dynamometer for Desktop Micro-Milling Machine

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.902.267 ◽

2014 ◽

Vol 902 ◽

pp. 267-273 ◽

Cited By ~ 1

Author(s):

Samir Mekid

Keyword(s):

Surface Finish ◽

Cutting Forces ◽

High Speed ◽

High Surface ◽

Chip Thickness ◽

Micro Milling ◽

High Tech ◽

Machining Accuracy ◽

Microscopic Features ◽

Better Than

The emerging miniaturized high-tech products are required to have increased functionalities of systems within a volumetric size on the order of 1 cm3. Hence, the parts are mesoscopic with complex microscopic features of a few mm length with machining accuracy of better than 1 micrometer with secured surface integrity as components will require high surface finish, tensile stress and crack free surfaces in order to function reliably. One of the characteristics to be measured is the cutting forces on the parts being machined. This paper will present the design, manufacture and testing of a miniature dynamometer capable of measuring cutting forces within a low range of 50N but with a resolution better than 1 mN and high frequency since the micromachining involves small cutting forces but the spindle rotates at high speed. The dynamometer is capable of measuring forces in five directions (±x, ±y, and z). The instrument was calibrated and exhibit very good results leading to a true validation. This instrument is assembled on a micro milling desktop machine designed in-house. It will not only support predicting the surface finish and chip thickness but also monitoring tool wear evolution and hence prevents/reduce tool breakage known to be one of the main issues in micro-milling.

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Influence of nanofluid application on wheel wear, coefficient of friction and redeposition phenomenon in surface grinding of Ti-6Al-4V

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1177/0954405416636039 ◽

2016 ◽

Vol 232 (1) ◽

pp. 128-140 ◽

Cited By ~ 10

Author(s):

Dinesh Setti ◽

Sudarsan Ghosh ◽

Venkateswara Rao Paruchuri

Keyword(s):

Coefficient Of Friction ◽

Surface Finish ◽

High Speed ◽

Removal Rate ◽

Chemical Reactivity ◽

Surface Grinding ◽

Speed Ratio ◽

Depth Of Cut ◽

Work Surface ◽

Wheel Loading

Difficulties in the grinding of Ti-6Al-4V originate from the three basic properties: poor thermal conductivity, high chemical reactivity and low volume specific heat of the material. Under severe grinding conditions, all these factors together lead to the accelerated wheel loading and redeposition of chips over the work surface. Redeposition and wheel loading have a significant effect on the surface finish, grinding forces, power consumption and wheel life. In this study, water-based Al2O3 nanofluid as metalworking fluid is applied during the surface grinding of Ti-6Al-4V under minimum quantity lubrication mode after dressing the wheel with different dressing overlap ratios. The severity of the redeposition over the work surface was observed by measuring various surface profiles taken perpendicular to the grinding direction at several locations on the ground surface. The nanofluid application was able to prevent redeposition over work surface that became evident from the measured surface finish parameters that results along the grinding direction. Coefficient of friction was estimated On-Machine using the measured forces for different wheel work speed ratios, depth of cut and dressing overlap ratios. The results showed the effectiveness of nanofluid in reducing friction at high material removal rate (i.e. high depth of cut and high speed ratio) conditions when compared to the dry environment. From the measured forces variation with respect to the number of passes, it became evident that, nanofluid application delayed the frequency of wheel loading and grit fracturing cycle, which leads to the increase in the wheel life.

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