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This paper aims to discuss the combination of electrospinning and melt blowing in theory, which may be a good way to produce nanofibers.
Abstract
Purpose
This paper aims to discuss the combination of electrospinning and melt blowing in theory, which may be a good way to produce nanofibers.
Design/methodology/approach
In this paper, the electrostatic field and the air flow field were numerical simulated and analyzed, the compound field of which was also discussed.
Findings
It is pointed out that the air flow angle will be a key factor to produce nanofibers in the compound process of electrospinning and melt blowing.
Originality/value
The combination of electrostatic force and air drawing force may be a good way to produce nanofibers when the material is high viscosity melt. Air jets with high temperature and high velocity will provide favorable conditions for attenuating the polymer jet. The flow angle of the air jets effect the whole attenuation force exerted to the polymer jet and should be selected properly.
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Khaldoun K. Tahboub and Ibrahim A. Rawabdeh
This paper presents a study on implementing design of experiments for optimizing the extrusion blow molding process. The effect of screw speed, melting temperature, cooling time…
Abstract
This paper presents a study on implementing design of experiments for optimizing the extrusion blow molding process. The effect of screw speed, melting temperature, cooling time, pressure, mold temperature, and ambient temperatures on the outcome of the process is investigated. The significant factors affecting the volume and mass of the blow molded bottles are identified. The results show that melting temperature, pressure, and ambient temperature have a significant impact on the variation of produced bottle quality. An optimization technique is implemented to identify the best operating conditions to meet the required product output.
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– The purpose of this paper is to attempt to predict the fiber diameter of melt blowing nonwovens by means of physics model.
Abstract
Purpose
The purpose of this paper is to attempt to predict the fiber diameter of melt blowing nonwovens by means of physics model.
Design/methodology/approach
The effects of the processing parameters on the fiber diameter is studied using the established physics model.
Findings
The results show that the predicted and experimental values agree well, the physics model produces more accurate and stable predictions, which also indicates that the physics model is really an effective and available modeling method for predictors.
Originality/value
The results show the great potential of this research for computer assisted design of the melt blowing technology.
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Neeraj Ahuja, Uma Batra and Kamal Kumar
Magnesium alloys are becoming prominent as an alternative to the permanent biomedical implants. In present work, electric discharge drilling (EDD) process has been investigated…
Abstract
Purpose
Magnesium alloys are becoming prominent as an alternative to the permanent biomedical implants. In present work, electric discharge drilling (EDD) process has been investigated and optimized for ZM21 Mg alloy that can be used for producing perforated bone implants having geometrically precise micro holes.
Design/methodology/approach
Planning of experiments has been carried out in accordance to the Taguchi mixed L18 orthogonal array (OA). The hole overcut (HO), circularity at entrance (Cent) and circularity at exit (Cext) of drilled micro holes were measured as response characteristics during experimentation corresponding to different settings of EDD input parameters. For optimizing multiresponse characteristics, the hybrid approach of grey relational analysis, regression analysis and particle swarm optimization has been implemented.
Findings
It is found from hybrid approach that brass electrode along with Ip; 3 Amp, Ton; 50 µs and Toff; 52 µs outperformed over all other parametric settings against the collective result of response characteristics. The experimental values of response characteristics at suggested optimized setting are HO: 93.48 µm; Cent: 0.988 and Cext: 0.992, respectively.
Originality/value
The optimization of EDD process for developing perforated Mg alloy bone implants, using hybrid approach is still missing.
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Yalcin Yesil and Gajanan S. Bhat
Recently, the usage of melt blown products in many areas has increased. In melt blown process, generally polymers have been used. There are a variety of polymers. Characteristics…
Abstract
Purpose
Recently, the usage of melt blown products in many areas has increased. In melt blown process, generally polymers have been used. There are a variety of polymers. Characteristics of melt blown nonwovens have changed significantly depending on the polymer type. Also, there are several parameters such as die temperature, die-to-collector distance (DCD), air pressure, etc. that modify the nonwovens in melt blown process. The purpose of this paper is to investigate the effect of these parameters on the characteristics of nonwovens made up of polyethylene (PE).
Design/methodology/approach
In the melt blown process, two die temperatures, three different die air pressures and three different DCDs were used. In total, 18 samples were produced. On produced samples, thickness, tear and tensile strengths, fiber diameter, basis weight tests were done. Also SEM observations were obtained.
Findings
It was observed that parameters studied have a significant effect on characteristics of the produced nonwoven. Fiber diameter, basis weight and strength decrease by depending on factors. Also, it was observed that temperature has an effect, but slight. This work shows that higher temperatures should be studied. Finer and uniform fiber diameter is obtained with an increase in air pressure.
Research limitations/implications
PE is becoming increasingly important in nonwovens due to its lower melting point for processing and softer feel in nonwoven products.
Practical implications
Although the use of PE in polymer-laid nonwovens, especially as bicomponent fibers, has been growing in recent years, there are limited data on their processability and performance. In this context, with the availability of relatively higher melt flow rate PE, understanding the processability and structure and properties of the melt blown PE is very helpful in designing and developing the right products. This research was conducted to evaluate the processability of the PE resin using a typical PP melt blowing pilot line and to determine the structure and properties of the formed webs.
Originality/value
PE has superior properties such as excellent chemical resistance, good fatigue, wear resistance and higher impact strength. Also, PE provides good resistance to organic solvents, degreasing agents and electrolytic attack. PE has lower working temperatures than polypropylene, is light in weight, resistant to staining and has low moisture absorption rates. Thus, this study provides important contributions to the area since there are no data reported about the effect of various processing parameters on the structure and properties of PE melt blown nonwovens.
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The purpose of this paper is to varify, the air drawing model and the air jet flow field model of dual slot shape die for a polymer in a melt blowing process were established, by…
Abstract
Purpose
The purpose of this paper is to varify, the air drawing model and the air jet flow field model of dual slot shape die for a polymer in a melt blowing process were established, by the experimental results obtained with experimental equipment.
Design/methodology/approach
The air jet flow field model is solved by introducing the finite difference method. The air drawing model of polymers in the melt blowing process was studied with the help of the simulation results of the air jet flow field.
Findings
The higher air initial velocity and air initial temperature can all yield finer fibers and causes the fibers to be attenuated to a greater extent.
Originality/value
The predicted fiber diameter agrees well with the experimental result, which verifies the reliability of these models. At the same time, the results also reveal the great potential of this research for the computer-assisted design of melt blowing technology.
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The polymer air-drawing model of spunbonding nonwovens has been established. The influence of the density and the specific heat capacity of polymer melt at constant pressure…
Abstract
Purpose
The polymer air-drawing model of spunbonding nonwovens has been established. The influence of the density and the specific heat capacity of polymer melt at constant pressure changing with polymer temperature on the fiber diameter have also been studied. The paper aims to discuss these issues.
Design/methodology/approach
TDMA method is used to solve the difference equations.
Findings
It can be concluded that a lower polymer throughput rate, a higher polymer melt initial temperature, a higher air initial temperature, and a higher air initial velocity can all produce finer fibers.
Originality/value
The results also reveal the great potential for this research in the computer-assisted design of spunbonding technology.
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C. Lea, F.H. Howie and M.P. Seah
The amount of gas blowing into the molten solder in plated‐through‐holes during wave soldering is dependent upon the moisture content of the board and the strength of the copper…
Abstract
The amount of gas blowing into the molten solder in plated‐through‐holes during wave soldering is dependent upon the moisture content of the board and the strength of the copper barrels to withstand the pressure of gas. This strength is dependent, in turn, upon both the thickness of the copper electroplate and the quality of the original electroless copper deposit. The problem of blowholing may be overcome by improving the copper quality and/or by baking the PCB prior to soldering. This paper gives a scientific framework linking the important parameters involved in the control of blowholing. Full data are given to enable the allowable moisture content of a PCB to be calculated in respect of the pressure generated during soldering and of the strength of the copper barrels. If baking is required to attain the required low moisture levels, then certain data are required to quantify the effects of the storage times and the environment conditions between that bake and the subsequent soldering. These data are given.
R. Elshereef, J. Vlachopoulos and A. Elkamel
The main purpose of this paper is to present and compare two different models for bubble growth and foam formation and to conduct a thorough assessment in terms of their numerical…
Abstract
Purpose
The main purpose of this paper is to present and compare two different models for bubble growth and foam formation and to conduct a thorough assessment in terms of their numerical implementation and prediction accuracy.
Design/methodology/approach
The two models are assessed and validated against experimental measurements. The first model is known as a single bubble growth model and treats the foaming process as a single bubble growing in a large pool with enough gas available for growth, while the second model (cell model) takes into account the finiteness of gas supply availability as well as the effects of surrounding bubbles. The models are based on the application of the conservation of continuity and momentum principles and on constitutive equations to represent the viscosity of the melt. The models are numerically implemented using a finite difference scheme and their predictions are compared against experimental measurements.
Findings
The results demonstrate that the single bubble model predicts an infinite bubble growth with time due to the assumption of unlimited supply of the blowing agent. Meanwhile the cell model gives an equilibrium bubble size because it accounts for gas depletion. From this work, it was concluded that the cell model is the best model that adequately describes experimental data.
Practical implications
The problem of bubble growth and foam formation is of great importance in the process industry as it plays a key role in diverse technological fields such as the production of foamed plastics.
Originality/value
The findings here are important for the appropriate modeling of bubble growth and foam formation and for scheduling and optimizing the process. A simple model will suffice for the early stage of the process while a cell model is more appropriate for the entire duration of the process.
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Michele Chiumenti, Xin Lin, Miguel Cervera, Wei Lei, Yuxiang Zheng and Weidong Huang
This paper aims to address the numerical simulation of additive manufacturing (AM) processes. The numerical results are compared with the experimental campaign carried out at…
Abstract
Purpose
This paper aims to address the numerical simulation of additive manufacturing (AM) processes. The numerical results are compared with the experimental campaign carried out at State Key Laboratory of Solidification Processing laboratories, where a laser solid forming machine, also referred to as laser engineered net shaping, is used to fabricate metal parts directly from computer-aided design models. Ti-6Al-4V metal powder is injected into the molten pool created by a focused, high-energy laser beam and a layer of added material is sinterized according to the laser scanning pattern specified by the user.
Design/methodology/approach
The numerical model adopts an apropos finite element (FE) activation technology, which reproduces the same scanning pattern set for the numerical control system of the AM machine. This consists of a complex sequence of polylines, used to define the contour of the component, and hatches patterns to fill the inner section. The full sequence is given through the common layer interface format, a standard format for different manufacturing processes such as rapid prototyping, shape metal deposition or machining processes, among others. The result is a layer-by-layer metal deposition which can be used to build-up complex structures for components such as turbine blades, aircraft stiffeners, cooling systems or medical implants, among others.
Findings
Ad hoc FE framework for the numerical simulation of the AM process by metal deposition is introduced. Description of the calibration procedure adopted is presented.
Originality/value
The objectives of this paper are twofold: firstly, this work is intended to calibrate the software for the numerical simulation of the AM process, to achieve high accuracy. Secondly, the sensitivity of the numerical model to the process parameters and modeling data is analyzed.
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