Metal Low Temperature Brittleness and Low Temperature Machining

Most metal materials tend to produce brittle fracture at low temperature. Nominal stress of producing brittle fracture is low, generally lower than yield limit. By use of this property, the machinability of the workpiece, tool life and workpiece surface quality can be improved. Classification and application of low temperature machining was introduced in the paper. Tests of low temperature machining were carried out. The test results show low temperature machining is superior to the cutting in normal temperature for the aspects of tool life and the roughness of workpiece surface.

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Cryogenic-LN2 and conventional emulsion assisted machining of hardened steel: Comparison from sustainability perspective

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

10.1177/0954405420971992 ◽

2020 ◽

pp. 095440542097199 ◽

Cited By ~ 3

Author(s):

Aqib Mashood Khan ◽

Ning He ◽

Wei Zhao ◽

Muhammad Jamil ◽

Hongjun Xia ◽

...

Keyword(s):

Energy Consumption ◽

Surface Quality ◽

Tool Life ◽

Cutting Parameters ◽

Hardened Steel ◽

Machining Processes ◽

Machine Shop ◽

Workpiece Surface ◽

Aisi 52100 ◽

Comparative Results

To achieve an excellent workpiece surface quality and longer tool life in the machining of hardened steel is an excessive challenge. Recently, conventional emulsion cooling assisted machining processes are being used to address this problem. However, such traditional processes have adverse effects on the environment as well as on the machine shop worker’s health. Hence, in this study, the effects of emulsion cooling and sustainable Cryo-LN2 cooling approach on sustainable metrics, such as surface roughness, energy consumption, tool life, and production cost in the external turning of AISI-52100 have been investigated and compared. The comparative results showed that the Cryo-LN2 technique outperformed emulsion cooling for all measured indices. The Cryo-LN2 assisted turning process not only improved surface quality but also consumed 18% less energy consumption and produced 70.9% low-priced products at aggressive cutting parameters as compared to the emulsion. The findings of the current study encourage metal processing industries to use such type of sustainable techniques at a machine shop. This study is based on the “ Think Green, Plan Green and Execute Green” strategy.

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Comparison between a conventional and an antivibrating boring bar in the internal turning of long overhangs

Design of Machines and Structures ◽

10.32972/dms.2020.025 ◽

2020 ◽

Vol 10 (2) ◽

pp. 145-149

Author(s):

Thomas Wallyson ◽

Zsombor Fülöp ◽

Attila Szilágyi

Keyword(s):

Surface Quality ◽

Tool Life ◽

Hardened Steel ◽

Workpiece Surface ◽

Boring Bar

The main objective of this work is to evaluate the use of an antivibrating in an internal turning tool in the machining of hardened steel, comparing it with a conventional solid bar, in order to verify if it is able to cut deep holes without damaging workpiece surface quality and tool life.

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ЦИФРОВОЙ ИЗОЛЯТОР В СПЕЦИАЛИЗИРОВАННОМ КОРПУСЕ, ВЫПОЛНЕННОМ ПО ТЕХНОЛОГИИ LTCC

Nanoindustry Russia ◽

10.22184/1993-8578.2020.13.3s.392.395 ◽

2020 ◽

Vol 96 (3s) ◽

pp. 392-395

Author(s):

В.А. Бутузов ◽

А.Е. Назаренко ◽

Н.Ю. Дмитриев ◽

В.А. Трофимов ◽

В.А. Косевский ◽

...

Keyword(s):

Low Temperature ◽

Data Rate ◽

Test Results ◽

Made In

Представлены результаты разработки цифрового изолятора на основе интегрального микротрансформатора в специализированном корпусе, выполненном по технологии низкотемпературной совместно обжигаемой керамики (LTCC). Согласно результатам измерений тестовых образцов максимальная скорость передачи данных разработанного цифрового изолятора - не менее 30 Мбит/с. The paper presents the results of the development of a digital insulator based on an integral microtransformer in a specialized package made in technology of low-temperature co-fired ceramics. The isolator is a microassembly consisting of a transceiver chip and an integrated transformer. According to the test results, the maximum data rate speed of the developed digital insulator is not less than 30 Mbit/s.

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Study of ultrasonic vibration–assisted thread turning of Inconel 718 superalloy

Advances in Mechanical Engineering ◽

10.1177/1687814019883772 ◽

2019 ◽

Vol 11 (10) ◽

pp. 168781401988377

Author(s):

Yu He ◽

Zhongming Zhou ◽

Ping Zou ◽

Xiaogang Gao ◽

Kornel F Ehmann

Keyword(s):

Surface Quality ◽

Ultrasonic Vibration ◽

Inconel 718 ◽

Gas Turbines ◽

Tool Path ◽

Machining Parameters ◽

Thread Cutting ◽

Workpiece Surface ◽

Inconel 718 Superalloy ◽

The Relationship

With excellent properties, high-temperature superalloys have become the main application materials for aircraft engines, gas turbines, and many other devices. However, superalloys are typically difficult to machine, especially for the thread cutting. In this article, an ultrasonic vibration–assisted turning system is proposed for thread cutting operations in superalloys. A theoretical analysis of ultrasonic vibration–assisted thread cutting is carried out. An ultrasonic vibration–assisted system was integrated into a standard lathe to demonstrate thread turning in Inconel 718 superalloy. The influence of ultrasonic vibration–assisted machining on workpiece surface quality, chip shape, and tool wear was analyzed. The relationship between machining parameters and ultrasonic vibration–assisted processing performance was also explored. By analyzing the motion relationship between tool path and workpiece surface, the reasons for improved workpiece surface quality by ultrasonic vibration–assisted machining were explained.

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Experimental investigation of the machining characteristics in diamond wire sawing of unidirectional CFRP

The International Journal of Advanced Manufacturing Technology ◽

10.1007/s00170-021-07146-8 ◽

2021 ◽

Author(s):

Lukas Seeholzer ◽

Stefan Süssmaier ◽

Fabian Kneubühler ◽

Konrad Wegener

Keyword(s):

Surface Quality ◽

Influencing Factors ◽

Material Properties ◽

High Surface ◽

Workpiece Surface ◽

High Surface Quality ◽

High Productivity ◽

Surface Temperatures ◽

Process Forces ◽

The Wire

AbstractEspecially for slicing hard and brittle materials, wire sawing with electroplated diamond wires is widely used since it combines a high surface quality with a minimum kerf loss. Furthermore, it allows a high productivity by machining multiple workpieces simultaneously. During the machining operation, the wire/workpiece interaction and thus the material removal conditions with the resulting workpiece quality are determined by the material properties and the process and tool parameters. However, applied to machining of carbon fibre reinforced polymers (CFRP), the process complexity potentially increases due to the anisotropic material properties, the elastic spring back potential of the material, and the distinct mechanical wear due to the highly abrasive carbon fibres. Therefore, this experimental study analyses different combinations of influencing factors with respect to process forces, workpiece surface temperatures at the wire entrance, and the surface quality in wire sawing unidirectional CFRP material. As main influencing factors, the cutting and feed speeds, the density of diamond grains on the wire, the workpiece thickness, and the fibre orientation of the CFRP material are analysed and discussed. For the tested parameter settings, it is found that while the influence of the grain density is negligible, workpiece thickness, cutting and feed speeds affect the process substantially. In addition, higher process forces and workpiece surface temperatures do not necessarily deteriorate the surface quality.

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Impact of Graphene Oxide on Zero Shear Viscosity, Fatigue Life and Low-Temperature Properties of Asphalt Binder

Materials ◽

10.3390/ma14113073 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3073

Author(s):

Abbas Mukhtar Adnan ◽

Chaofeng Lü ◽

Xue Luo ◽

Jinchang Wang

Keyword(s):

Graphene Oxide ◽

Fatigue Life ◽

Low Temperature ◽

Shear Viscosity ◽

Storage Stability ◽

Asphalt Binder ◽

Asphalt Binders ◽

Test Results ◽

Zero Shear Viscosity ◽

Modified Asphalt

This study has investigated the impact of graphene oxide (GO) in enhancing the performance properties of an asphalt binder. The control asphalt binder (60/70 PEN) was blended with GO in contents of 0%, 0.5%, 1%, 1.5%, 2%, and 2.5%. The permanent deformation behavior of the modified asphalt binders was evaluated based on the zero shear viscosity (ZSV) parameter through a steady shear test approach. Superpave fatigue test and the linear amplitude sweep (LAS) method were used to evaluate the fatigue behavior of the binders. A bending beam rheometer (BBR) test was conducted to evaluate the low-temperature cracking behavior. Furthermore, the storage stability of the binders was investigated using a separation test. The results of the ZSV test showed that GO considerably enhanced the steady shear viscosity and ZSV value, showing a significant contribution of the GO to the deformation resistance; moreover, GO modification changed the asphalt binder’s behavior from Newtonian to shear-thinning flow. A notable improvement in fatigue life was observed with the addition of GO to the binder based on the LAS test results and Superpave fatigue parameter. The BBR test results revealed that compared to the control asphalt, the GO-modified binders showed lower creep stiffness (S) and higher creep rate (m-value), indicating increased cracking resistance at low temperatures. Finally, the GO-modified asphalt binders exhibited good storage stability under high temperatures.

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Effects of Nano-CaCO3 on the Compressive Strength and Microstructure of High Strength Concrete in Different Curing Temperature

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.121-126.126 ◽

2011 ◽

Vol 121-126 ◽

pp. 126-131 ◽

Cited By ~ 3

Author(s):

Qing Lei Xu ◽

Tao Meng ◽

Miao Zhou Huang

Keyword(s):

Compressive Strength ◽

Low Temperature ◽

High Strength Concrete ◽

High Strength ◽

Curing Temperature ◽

Test Results ◽

Strength Concrete ◽

Calcium Nitrite ◽

Orientation Index ◽

Early Strength

In this paper, effects of nano-CaCO3 on compressive strength and Microstructure of high strength concrete in standard curing temperature(21±1°C) and low curing temperature(6.5±1°C) was studied. In order to improve the early strength of the concrete in low temperature, the early strength agent calcium nitrite was added into. Test results indicated that 0.5% dosage of nano-CaCO3 could inhibit the effect of calcium nitrite as early strength agent, but 1% and 2% dosage of nano-CaCO3 could improve the strength of the concrete by 13% and 18% in standard curing temperature and by 17% and 14% in low curing temperature at the age of 3days. According to the XRD spectrum, with the dosage up to 1% to 2%, nano-CaCO3 can change the orientation index significantly, leading to the improvement of strength of concrete both in standard curing temperature and low curing temperature.

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