Temperature measurements in the cutting zone, mass, chip fragmentation and analysis of chip metallography images during AZ31 and AZ91HP magnesium alloy milling

2018 ◽  
Vol 90 (3) ◽  
pp. 496-505 ◽  
Author(s):  
Ireneusz Zagórski ◽  
Jozef Kuczmaszewski
Keyword(s):  
Chip Morphology ◽  
Practical Aspect ◽  
Mg Alloys ◽  
Unit Weight ◽  
Metallographic Analysis ◽  
Dry Milling ◽  
Technological Parameters ◽  
Content Type ◽  
Chip Temperature ◽  
Cutting Zone

Purpose This paper presents the results of mean unit weight of chips and their time to ignition measured on a test stand specially designed for this purpose. In addition, the temperature of chips in the cutting area and the morphology of chips produced in HSM milling (as a temperature indicator in the cutting area) are investigated. Also, different fractions of chips produced in the dry milling of Mg alloys AZ31 and AZ91HP by a PCD end mill are examined. Finally, the paper presents conclusions and recommendations with regard to safety and efficiency of dry milling processes for the aforementioned magnesium alloys. Design/methodology/approach Milling can be used as a finishing operation, particularly when using PCD end mills. The application of this mill type isparticularly important when producing different machine and device components, especially in the aircraft industry. What can occur in dry machining operations is self-ignition. It is therefore justified to investigate chip temperature in the cutting zone, to classify produced chip fractions and to determine their mass. Safe ranges of technological parameters can be additionally determined based on metallographic analysis of chip edge partial-melting. Findings The experimental results helped determine the effect of technological parameters of milling on chip temperature in the cutting zone, chip mass and fragmentation and chip morphology images. Practical implications The results reported in this work are innovative in both cognitive and practical aspect. The authors are convinced that this work can contribute to overcoming the mistrust of industrial practitioners toward dry milling of Mg alloys, and also with respect to the application of relatively higher cutting speeds in dry milling of these alloys than it is common practice in industry today. The study investigates the problem of safety in dry milling of Mg alloys. The study was motivated by the milling process itself and the formation of broken chip, which causes a significant change in the character of heat transfer. Originality/value The paper presents a method for multi-criteria safety assessment in dry milling operations. Safe and effective parameter ranges are defined with respect to chip temperature in the cutting zone, fraction number and chip mass.

scholarly journals Thermographic Study of Chip Temperature in High-Speed Dry Milling Magnesium Alloys

2016 ◽  
Vol 7 (2) ◽  
pp. 86-92 ◽  
Author(s):  
Józef Kuczmaszewski ◽  
Ireneusz Zagórski ◽  
Piotr Zgórniak
Keyword(s):  
Temperature Measurement ◽  
Magnesium Alloys ◽  
High Speed ◽  
Machining Process ◽  
Dry Milling ◽  
Technological Parameters ◽  
Chip Temperature ◽  
Thermographic Study ◽  
On Chip ◽  
The Impact

Abstract This paper presents an overview of the state of knowledge on temperature measurement in the cutting area during magnesium alloy milling. Additionally, results of own research on chip temperature measurement during dry milling of magnesium alloys are included. Tested magnesium alloys are frequently used for manufacturing elements applied in the aerospace industry. The impact of technological parameters on the maximum chip temperature during milling is also analysed. This study is relevant due to the risk of chip ignition during the machining process.

Reliability analysis of static liquefaction of loose sand using the random finite element method

2015 ◽  
Vol 32 (7) ◽  
pp. 2100-2119 ◽  
Author(s):  
Ali Johari ◽  
Jaber Rezvani Pour ◽  
Akbar Javadi
Keyword(s):  
Finite Element ◽  
Pressure Ratio ◽  
Monotonic Loading ◽  
Unit Weight ◽  
Soil Parameters ◽  
Loose Sand ◽  
Element Analysis ◽  
Content Type ◽  
Static Liquefaction ◽  
Random Finite Element

Purpose – Liquefaction of soils is defined as significant reduction in shear strength and stiffness due to increase in pore water pressure. This phenomenon can occur in static (monotonic) or dynamic loading patterns. However, in each pattern, the inherent variability of the soil parameters indicates that this problem is of a probabilistic nature rather than being deterministic. The purpose of this paper is to present a method, based on random finite element method, for reliability assessment of static liquefaction of saturated loose sand under monotonic loading. Design/methodology/approach – The random finite element analysis is used for reliability assessment of static liquefaction of saturated loose sand under monotonic loading. The soil behavior is modeled by an elasto-plastic effective stress constitutive model. Independent soil parameters including saturated unit weight, peak friction angle and initial plastic shear modulus are selected as stochastic parameters which are modeled using a truncated normal probability density function (pdf). Findings – The probability of liquefaction is assessed by pdf of modified pore pressure ratio at each depth. For this purpose pore pressure ratio is modified for monotonic loading of soil. It is shown that the saturated unit weight is the most effective parameter, within the selected stochastic parameters, influencing the static soil liquefaction. Originality/value – This research focuses on the reliability analysis of static liquefaction potential of sandy soils. Three independent soil parameters including saturated unit weight, peak friction angle and initial plastic shear modulus are considered as stochastic input parameters. A computer model, coded in MATLAB, is developed for the random finite element analysis. For modeling of the soil behavior, a specific elasto-plastic effective stress constitutive model (UBCSAND) was used.

Experimental study on the accuracy and surface quality of printed versus machined holes in PEI Ultem 9085 FDM specimens

2021 ◽  
Vol 27 (11) ◽  
pp. 1-12
Author(s):  
Giovanni Gómez-Gras ◽  
Marco A. Pérez ◽  
Jorge Fábregas-Moreno ◽  
Guillermo Reyes-Pozo
Keyword(s):  
Surface Quality ◽  
Fused Deposition Modeling ◽  
Three Dimensional ◽  
Dimensional Accuracy ◽  
Technological Parameters ◽  
Content Type ◽  
Fused Deposition ◽  
Comparison Of The Results ◽  
Through Hole

Purpose This paper aims to investigate the quality of printed surfaces and manufacturing tolerances by comparing the cylindrical cavities machined in parts obtained by fused deposition modeling (FDM) with the holes manufactured during the printing process itself. The comparison focuses on the results of roughness and tolerances, intending to obtain practical references when making assemblies. Design/methodology/approach The experimental approach focuses on the comparison of the results of roughness and tolerances of two manufacturing strategies: geometric volumes with a through-hole and the through-hole machined in volumes that were initially printed without the hole. Throughout the study, both alternates are explained to make appropriate recommendations. Findings The study shows the best combinations of technological parameters, both machining and three-dimensional printing, which have been decisive for obtaining successful results. These conclusive results allow enunciating recommendations for use in the industrial environment. Originality/value This paper fulfills an identified need to study the dimensional accuracy of the geometries obtained by additive manufacturing, as no experimental evidence has been found of studies that directly address the problem of the FDM-printed part with geometric and dimensional tolerances and desirable surface quality for assembly.

Research on microstructure and mechanical behaviour of smaller microbumps for high density solder interconnects

2017 ◽  
Vol 29 (3) ◽  
pp. 156-163
Author(s):  
Man He ◽  
Bo Wang ◽  
Weisheng Xia ◽  
Shijie Chen ◽  
Jinzhuan Zhu
Keyword(s):  
Mechanical Behaviour ◽  
Bulk Solder ◽  
High Density ◽  
The Body ◽  
Nanoindentation Test ◽  
Metallographic Analysis ◽  
Content Type ◽  
Solder Interconnects ◽  
Free Replacement ◽  
The One

Purpose The purpose of this paper is to study the microstructure and mechanical behaviour of smaller microbumps for high density solder interconnects. Design/methodology/approach The microstructure was analyzed by scanning electron microscopy and electron backscatter diffraction tests to determine the Sn grain number of the resultant microbumps. The nanomechanical properties of Sn microbumps were investigated by the nanoindentation and shearing tests to understand the failure mechanism and assess the reliability of ultra-high density solder interconnects with numbered grains. Findings Only one Sn grain is observed in the interconnect matrix when the microbumps are miniaturized to 40 μm or less. Because of the body-centred tetragonal lattice of ß-Sn unit cell, the mechanical properties of the one-grain Sn microbumps are remarkably anisotropic, which are proved by the difference of the elastic modulus and the stiffness in the different orientations. The shearing tests show that the one-grain Sn microbump has a typical brittle sliding fracture of monocrystal at different shearing speeds. Practical implications The paper provides a comparable study for the performance of the bigger solder joints and also makes preliminary research on the microstructure and mechanical behaviour of Sn microbumps with the diameter of 40 μm. Originality/value The findings in this paper provide methods of microstructure study by combination of EBSD test and metallographic analysis, mechanical study by combination of nanoindentation test and shearing test, which can provide good guidelines for other smaller microbumps. The strain rate sensitivity exponent of the one-grain Sn microbumps is consistent with the Pb-free bulk solder. This implies that the one-grain Sn microbump has a comparable flow stress to Sn37Pb solder, which is beneficial for Pb-free replacement in higher density microelectronic packaging.

Solder joint quality evaluation based on heating factor

Circuit World ◽  
2018 ◽  
Vol 44 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Petr Veselý ◽  
Eva Horynová ◽  
Jiří Starý ◽  
David Bušek ◽  
Karel Dušek ◽  
...  
Keyword(s):  
Shear Strength ◽  
Solder Alloy ◽  
Isothermal Aging ◽  
Solder Joints ◽  
Strength Increase ◽  
Technological Parameters ◽  
Content Type ◽  
Soldering Process ◽  
Before And After ◽  
Joint Quality

Purpose The purpose of this paper is to increase the reliability of manufactured electronics and to reveal reliability significant factors. The experiments were focused especially on the influence of the reflow oven parameters presented by a heating factor. Design/methodology/approach The shear strength of the surface mount device (SMD) resistors and their joint resistance were analyzed. The resistors were assembled with two Sn/Ag/Cu-based and one Bi-based solder pastes, and the analysis was done for several values of the heating factor and before and after isothermal aging. The measurement of thickness of intermetallic compounds was conducted on the micro-sections of the solder joints. Findings The shear strength of solder joints based on the Sn/Ag/Cu-based solder alloy started to decline after the heating factor reached the value of 500 s · K, whereas the shear strength of the solder alloy based on the Bi alloy (in the measured range) always increased with an increase in the heating factor. Also, the Bi-based solder joints showed shear strength increase after isothermal aging in contrast to Sn/Ag/Cu-based solder joints, which showed shear strength decrease. Originality/value The interpretation of the results of such a comprehensive measurement leads to a better understanding of the mutual relation between reliability and other technological parameters such as solder alloy type, surface finish and parameters of the soldering process.

Dynamic drape behaviours of wool woven suiting fabrics considering real-time use

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Gonca Balci Kilic ◽  
Murat Demir ◽  
Musa Kilic
Keyword(s):  
Real Time ◽  
Time Use ◽  
Design Methodology ◽  
Rotation Speed ◽  
Woven Fabrics ◽  
Unit Weight ◽  
Bending Rigidity ◽  
Content Type ◽  
Deformation Properties ◽  
Time Usage

PurposeThe purpose of this paper is to analyse dynamic drape behaviours of 100% wool woven suiting fabrics considering real-time usage.Design/methodology/approachDynamic drape coefficients of 100% wool woven fabrics were measured at different rotation speeds (25, 75, 125 and 175 rpm) with a commercially used fabric drape tester which works on image processing principle. Average daily walking speed of male and female volunteers was determined and the closest rotation speed was selected to calculate dynamic drape coefficient at walking (DDCw). Besides, bending rigidity and shear deformation properties, which are known to be related to the static drape behaviours of the fabrics, were also measured and the relationships between these parameters and DDCw were examined.FindingsAs a result of the experimental study, it was found that dynamic drape coefficients become greater, which means the fabrics take flatter position, with the increase of the rotation speed. In addition, it was also seen that parameters known to be related to static drape behaviours such as unit weight and bending stiffness have less effect on the dynamic drapes of fabrics. For the estimation of dynamic drape behaviour of fabrics, parameters such as static perimeter, dynamic perimeter, etc. are found more significant.Originality/valueTo date, although studies about dynamic drape behaviours of the fabrics claimed that dynamic drape gives more realistic results for in wearer experience, few of them focused on the rotation speed of dynamic drape tester for real-time usage. As dynamic drape behaviours of fabrics may differ for different rotation speed, determining appropriate speed in accordance with real-time usage gives more realistic results.

Impact of training design on trainees' motivation: an empirical study

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yasmin Yaqub ◽  
Arun Kumar Singh
Keyword(s):  
Human Resource Development ◽  
Online Survey ◽  
Critical Role ◽  
Skills Training ◽  
Practical Aspect ◽  
Self Report ◽  
Training Design ◽  
Identical Element ◽  
Content Type ◽  
The Impact

Purpose This study aims to advance understanding of the critical role of training variables (trainer performance, transfer design and an identical element) and motivation to improve work through learning (MTIWL) the least researched construct of motivation in human resource development (HRD). Design/methodology/approach A self-report online survey was conducted to collect responses from 280 managers working in different industries. Participants attended open skills training program organized by an in-house training institute in India. Findings The trainer performance and transfer design had a positive and significant impact on MTIWL. However, an identical element found no significant direct impact on MTIWL. Practical implications The trainer performance positively cultivates trainees’ MTIWL and training approaches according to trainees’ preferences improve MTIWL. The training content is needed to resemble with work assignment for enhancement of trainees MTIWL. Originality/value This study improved understanding of the impact of training variables on a comprehensive and practical aspect of trainees' motivation in HRD, MTIWL.

Machinability of the EBM Ti6Al4V in Cryogenic Turning

2015 ◽  
Vol 651-653 ◽  
pp. 1183-1188 ◽  
Author(s):  
Stefano Sartori ◽  
Alberto Bordin ◽  
Stefania Bruschi ◽  
Andrea Ghiotti
Keyword(s):  
Tool Wear ◽  
Liquid Nitrogen ◽  
Surface Integrity ◽  
Cutting Temperature ◽  
Chip Morphology ◽  
Cutting Fluid ◽  
Cobalt Chromium ◽  
Machined Surface ◽  
Surgical Implants ◽  
Cutting Zone

In machining operations, the adoption of a cutting fluid is necessary to mitigate the effects of the high temperatures generated on the cutting zone, and, therefore, to avoid severe detrimental effects on the tool wear and surface integrity. In the biomedical field, the traditional processes to manufacture surgical implants made of Titanium and Cobalt Chromium Molybdenum alloys involve turning and milling operations. To cool the cutting tool with standard oil emulsions leaves contaminants on the machined surfaces, which require further cleaning steps that are expensive in terms of time and costs. Currently, this limitation is marginally overcome by machining without the coolant; however, as a consequence, severe tool wear and poor surface integrity take place. In the last years, many studies have been conducted on the application of Liquid Nitrogen as a coolant in machining difficult-to-cut materials such as Ti6Al4V. Thanks to its properties to evaporate immediately when getting in contact with the cutting zone, thus living the workpiece and chips dry and clean other than its ability to lower the cutting temperature. The adoption of Liquid Nitrogen as a cooling mean in machining surgical implants may represent an optimum solution enhancing the benefits of dry machining. This work is aimed at evaluating the performances of the Liquid Nitrogen as a coolant in semi-finishing turning of Ti6Al4V produced by Electron Beam Melting, a comparison with dry turning is presented. The alloy machinability in such conditions is evaluated in terms of tool wear, machined surface integrity and chip morphology.

scholarly journals Comparing the web and mobile platforms of a social Q&A service from the user’s perspective

2018 ◽  
Vol 70 (2) ◽  
pp. 176-191 ◽  
Author(s):  
Xiaoyu Chen ◽  
Alton Y.K. Chua ◽  
Shengli Deng
Keyword(s):  
Information Seeking ◽  
Service Providers ◽  
Information Service ◽  
Theoretical Aspect ◽  
Practical Aspect ◽  
Three Dimensions ◽  
Mobile Users ◽  
Mobile Platforms ◽  
Content Type ◽  
The Web

Purpose As an increasing number of users have acquired information across the web and mobile platforms for social question and answering (Q&A), it is of interest to explore whether there are differences in social Q&A usages between the two platforms. The purpose of this paper is to compare web and mobile platforms of a social Q&A service from the user’s perspective in terms of three dimensions, namely, demographics, individual-based constructs, and information-based constructs. Design/methodology/approach Because Zhihu.com is one of the most popular social Q&A sites in China, the authors used online questionnaires to investigate its users’ perceptions of these three dimensions. From January to March 2016, the authors obtained 278 valid responses in total through snowball and convenient sampling. Collected data are analyzed through descriptive statistics and inferential statistics. Findings The results indicate that there exist significant differences between web users and mobile users on Zhihu.com in terms of gender, affinity, and information seeking. More specifically, compared to the male users, more female users rely on the mobile platform to access the information service; mobile users perceive higher affinity with Zhihu.com than web users; and mobile users perceive higher information-seeking intention than web users do. Originality/value Regarding the theoretical aspect, this study proposes a conceptual framework for comparison between the web and mobile platforms of social Q&A from the user’s perspective. Regarding the practical aspect, the comparative results of this study could give social Q&A service providers useful information about users’ differences between web and mobile platforms of social Q&A services.

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