Skip Nav Destination
Close Modal
Update search
Filter
- Title
- Author
- Author Affiliations
- Full Text
- Abstract
- Keyword
- DOI
- ISBN
- ISBN-10
- ISSN
- EISSN
- Issue
- Volume
- References
- Conference Volume
- Paper No
Filter
- Title
- Author
- Author Affiliations
- Full Text
- Abstract
- Keyword
- DOI
- ISBN
- ISBN-10
- ISSN
- EISSN
- Issue
- Volume
- References
- Conference Volume
- Paper No
Filter
- Title
- Author
- Author Affiliations
- Full Text
- Abstract
- Keyword
- DOI
- ISBN
- ISBN-10
- ISSN
- EISSN
- Issue
- Volume
- References
- Conference Volume
- Paper No
Filter
- Title
- Author
- Author Affiliations
- Full Text
- Abstract
- Keyword
- DOI
- ISBN
- ISBN-10
- ISSN
- EISSN
- Issue
- Volume
- References
- Conference Volume
- Paper No
Filter
- Title
- Author
- Author Affiliations
- Full Text
- Abstract
- Keyword
- DOI
- ISBN
- ISBN-10
- ISSN
- EISSN
- Issue
- Volume
- References
- Conference Volume
- Paper No
Filter
- Title
- Author
- Author Affiliations
- Full Text
- Abstract
- Keyword
- DOI
- ISBN
- ISBN-10
- ISSN
- EISSN
- Issue
- Volume
- References
- Conference Volume
- Paper No
NARROW
Format
Journal
Article Type
Conference Series
Subject Area
Topics
Date
Availability
1-17 of 17
John E. Wentz
Close
Follow your search
Access your saved searches in your account
Would you like to receive an alert when new items match your search?
Sort by
Proceedings Papers
Proc. ASME. IMECE2015, Volume 2A: Advanced Manufacturing, V02AT02A010, November 13–19, 2015
Paper No: IMECE2015-52261
Abstract
Fused deposition modelling (FDM) creates three-dimensional parts by feeding a rigid thermoplastic filament through a heated barrel to achieve a semi-fluid state and then extruding it layer-by-layer to create a part geometry. The melt flow behavior within FDM must be analyzed in order to correctly understand the temperature gradients within the system to promote part quality, process control, and efficiency. The presented research consists of analyzing the melt flow behavior of polymer poly(lactic) acid (PLA) within FDM. This includes an experimental analysis of the power output of the resistive heat source, a theoretical analysis of external coefficients of heat-transfer, and an experimental validation of liquefier temperatures. A three-dimensional fluid-flow model is created using the accurate geometry of the extruder assembly, calculated conditions from initial experimental results, and referenced material properties. Results of this research include a significant temperature difference between the areas of the liquefier assembly close in proximity to the power source to those further away such as the inlet and outlet, suggesting that external heat transfer mechanisms play a significant role in liquefier dynamics, contrary to the more common assumption of constant wall temperature or constant heat flux used in modeling. The research presented provides new information regarding the melt flow of PLA, a method of modeling external heat transfer, and a way of understanding power consumption that can lead to liquefier design improvements. The process itself will also aid in identifying modeling considerations for further investigations of melt flow involving various extruder designs and material options. Specifically, the use of this type of comprehensive model is of interest to the additive manufacturing community with respect to thermally sensitive component specification and heating and cooling needs within process based on changing system parameters such as extrusion temperature and mass flow rates (i.e. material feed rate and/or change in extrusion diameter).
Journal Articles
Article Type: Research-Article
J. Manuf. Sci. Eng. March 2016, 138(3): 031002.
Paper No: MANU-14-1393
Published Online: October 1, 2015
Abstract
The depletion of native oil components from semisynthetic metalworking fluids (MWFs) during microfiltration is caused in part by the deposition of the MWF components on the pore walls, a mechanism that also results in the decline of the filtration rate of MWF over time. Simulated experiments with a fluid dynamic model that considers interparticle and particle–wall interactions show that membrane pore walls' surface charge density can be tailored to reduce system flux decline. However, results of the model show that the tailored membrane pore design may still see depletion of the oil components from the filtered MWF due to oil components being trapped in a suspended position above the pore mouth.
Journal Articles
Article Type: Technical Briefs
J. Micro Nano-Manuf. June 2015, 3(2): 024501.
Paper No: JMNM-14-1031
Published Online: June 1, 2015
Abstract
Atomization-based cutting fluid systems (ACFs) are increasingly being used in micromachining applications to provide cooling and lubrication to the tool–chip interface. In this research, a shielding nozzle design is presented. A computational fluid dynamic model is developed to perform parameter analysis of the design. The numerical simulations were accomplished using the Eulerian approach to the continuous phase and a Lagrangian approach for droplet tracking. Based on the results of the simulations it is determined that the shielding nozzle is effective at providing droplets to the cutting surface at an appropriate speed and size to create a lubricating microfilm.
Journal Articles
Article Type: Research-Article
J. Manuf. Sci. Eng. February 2015, 137(1): 011001.
Paper No: MANU-13-1167
Published Online: February 1, 2015
Abstract
Recent studies show that interparticle interaction can affect particle trajectories and particle deposition causing fouling in the microfilters used for metal working fluids (MWFs). Interparticle interaction depends on various factors: particle geometry and surface properties, membrane pore geometry and surface properties, MWF's properties and system operating conditions, etc. A mathematical model with a Langevin equation for particle trajectory and a hard-sphere model for particle deposition has been used to study the effect of particle's size, particle's surface zeta potential, interparticle distance, and shape of membrane pore wall surface on particle trajectory and its deposition on membrane pore wall. The study reveals the microlevel force phenomena behind bigger particles having a lesser tendency to be deposited on membrane pore walls than smaller particles. Deposition of particles on pore walls with asperities such as previously deposited particles is also examined and it is found that such cases can reduce repulsive electrostatic forces and lead to a higher probability of particle capture.
Topics:
Particulate matter
Journal Articles
Article Type: Research-Article
J. Micro Nano-Manuf. June 2014, 2(2): 021003.
Paper No: JMNM-13-1032
Published Online: April 8, 2014
Abstract
A recent development in cooling and lubrication technology for micromachining processes is the use of atomized spray cooling systems. These systems have been shown to be more effective than traditional methods of cooling and lubrication for extending tool life in micromachining. Typical nozzle systems for atomization spray cooling incorporate the mixing of high-speed gas and an atomized fluid carried by a gas stream. In a two-phase atomization spray cooling system, the atomized fluid can easily access the tool–workpiece interface, removing heat through evaporation and lubricating the region by the spreading of oil micro-droplets. The success of the system is determined in a large part by the nozzle design, which determines the atomized droplet's behavior at the cutting zone. In this study, computational fluid dynamics are used to investigate the effect of nozzle design on droplet delivery to the tool. An eccentric-angle nozzle design is evaluated through droplet flow modeling. A design of simulations methodology is used to study the design parameters of initial droplet velocity, high-speed gas velocity, and the angle change between the two inlets. The system is modeled as a steady-state multiphase system without phase change, and droplet interaction with the continuous phase is dictated in the model by drag forces and fluid surface tension. The Lagrangian method, with a one-way coupling approach, is used to analyze droplet delivery at the cutting zone. Following a factorial experimental design, deionized water droplets and a semisynthetic cutting fluid are evaluated through model simulations. Statistical analysis of responses (droplet velocity at tool, spray thickness, and droplet density at tool) show that droplet velocity is crucial for the nozzle design and that modifying the studied parameters does not change droplet density in the cutting zone.
Proceedings Papers
Proc. ASME. IMECE2013, Volume 2A: Advanced Manufacturing, V02AT02A093, November 15–21, 2013
Paper No: IMECE2013-63982
Abstract
A recent development of cooling and lubrication technology for micromachining processes is the use of spray cooling. Atomization spray cooling systems have been shown to be more effective than traditional methods of cooling and lubrication for micromachining. Typical nozzle systems for atomization spray cooling incorporate the mixing of high speed air and atomized fluid. In a two-phase atomization spray cooling system, the atomized fluid can easily access the tool-workpiece interface, removing heat by water evaporation and lubricating the region by oil droplet spreading. The success of the system is determined in a large part by the nozzle design, which determines the droplet behavior at the cutting zone. In this study, computational fluid dynamics are used to investigate nozzle design and droplet delivery to the tool. An eccentric-angle nozzle design is evaluated through droplet flow modeling. This study focuses on the design parameters of initial droplet velocity, high speed air velocity, and the angle change between the two inlets. The system is modeled as a steady-state multiphase system without phase change. Droplet interaction with the continuous phase is dictated in the model by drag forces and fluid surface tension. The Lagragian method with a one-way coupling approach is used to analyze droplet delivery at the cutting zone. Following a factorial experimental design, deionized water droplets and a semi-synthetic cutting fluid are evaluated through model simulations. Statistical analysis of responses (droplet velocity at tool, tool positioning, and droplet density at tool) show that droplet velocity is crucial for the nozzle design and that modifying the parameters does not change droplet density in the cutting zone. Based on results, suggestions for future nozzle design are presented.
Journal Articles
Article Type: Research-Article
J. Manuf. Sci. Eng. June 2014, 136(3): 031001.
Paper No: MANU-11-1257
Published Online: March 26, 2014
Abstract
This paper presents a fluid dynamic-based approach to the prediction of the flux decline due to partial and complete pore blocking in the microfiltration process. The electrostatic force model includes both particle–particle (PP) and particle–membrane (PM) electrostatic forces. The addition of such forces was shown to affect particle trajectories in a tortuous three-dimensional microfilter membrane geometry. The model was validated by comparing experimental flux decline data with simulation flux decline data. A design of experiments was conducted to investigate the effects of transmembrane pressure, PM- and PP-zeta potential on flux decline. The simulation experiments revealed that low flux decline was associated with relatively low transmembrane pressures and near-zero values of PP- and PM-zeta potential; and relatively high transmembrane pressures and more-negative values of PP- and PM-zeta potential. The amount of flux decline was shown to be correlated to the specific nature of partial and complete pore blocking in the pore structure.
Proceedings Papers
Proc. ASME. MSEC2013, Volume 2: Systems; Micro and Nano Technologies; Sustainable Manufacturing, V002T04A014, June 10–14, 2013
Paper No: MSEC2013-1211
Abstract
Recent studies show that inter-particle interaction can affect particle trajectories and particle deposition causing fouling in the microfilters used for metal working fluids (MWFs). Inter-particle interaction depends on various factors: particle geometry and surface properties, membrane pore geometry and surface properties, MWF’s properties and system operating conditions, etc. A mathematical model with a Langevin equation for particle trajectory and a hard sphere model for particle deposition has been used to study the effect of particle’s size, particle’s surface zeta potential, inter-particle distance, and shape of membrane pore wall surface on particle trajectory and its deposition on membrane pore wall. The study reveals that bigger particles have a lesser tendency to be deposited on membrane pore walls than smaller particles. The shape of the membrane pore wall surface can also affect the particle deposition behavior.
Proceedings Papers
Proc. ASME. IMECE2012, Volume 7: Fluids and Heat Transfer, Parts A, B, C, and D, 3075-3082, November 9–15, 2012
Paper No: IMECE2012-88154
Abstract
Metalworking fluids are a vital part of modern machining processes but have significant negative economic, health, and environmental impacts. In-process purification of these fluids by microfiltration has been shown to reduce these impacts. This research uses a two-stage computational modeling methodology to investigate how particles within the membrane are transported from the turbulent flow within the center of the tubular membrane to the laminar sub-layer near the membrane wall and finally into the membrane pores. A macro-model of the complete flow within the tubular membrane is used to determine the steady-state flow profile within 25 microns of the membrane surface. This flow profile is then used to develop a micro-model of the flow at the membrane wall using a flat-plate assumption. The micro-model includes individual pores randomly located and sized based on statistical analysis of alumina membrane surfaces. A 2 3 full factorial design of experiments was used with variables of cross-flow velocity, transmembrane pressure, and membrane resistance. The responses of effective filtration region and total mass flowing through the pores were analyzed. Based on the simulation results, recommendations are made for future membrane design to provide the most efficient transport of particles from the bulk into the pores.
Proceedings Papers
Proc. ASME. IMECE2012, Volume 3: Design, Materials and Manufacturing, Parts A, B, and C, 1979-1986, November 9–15, 2012
Paper No: IMECE2012-87825
Abstract
Accelerated tool wear and tool breakage are significant problems in micro-machining processes such as micro-milling. Traditional flood cooling processes are unsuitable for micro-milling due to the excessive collision force between the fluid stream and the tool being large enough to affect the accuracy of the cutting process. In this research an atomization-based cooling and lubrication system is presented that delivers atomized cutting fluids to a micro-milling tool through the use of an original nozzle design based on two orthogonally-directed streams. The system and nozzle is used to investigate the relative importance of cooling and lubrication on micro-milling of 6061 T6 cold-rolled aluminum with a 0.508 mm diameter two-fluted end mill. Six cutting conditions are experimentally evaluated based on cutting forces and tool life. Lubrication is investigated through two concentrations (10% and 25%) of a semi-synthetic cutting fluid. Cooling is investigated through the use of atomized deionized water as well as dry cutting with cooling provided by a Ranque-Hilsch vortex tube. Dry cutting was used as a control. Statistical testing revealed the importance of lubrication relative to cooling when machining on the micro-scale as deionized water performed the worst of all tests conducted. Based on the experimental results, recommendations are made for the design of future micro-machining cooling and lubrication systems.
Proceedings Papers
Proc. ASME. ISFA2012, ASME/ISCIE 2012 International Symposium on Flexible Automation, 637-643, June 18–20, 2012
Paper No: ISFA2012-7222
Abstract
The micro-factory concept has gained wide support and acceptance based on the ability of small machine tools to accomplish the same tasks as traditionally sized machine tools while using a fraction of the space. Although it is frequently mentioned that a micro-factory is an energy saving endeavor, there is a dearth of hard data on how much energy is actually saved. The intent of this report is to quantify the difference in energy consumed in a micro-factory and a macro-factory though experimentation with a micro- and a macro-mill. This quantification allows for the potential of unit life cycle analyses to be performed in the future. A fluidic channel was machined in workpieces of aluminum and steel by both micro- and macro-mills under a variety of machining conditions and the recorded data has been analyzed to this end. The variables investigated were the spindle speed, the mill type, and the material the cutting process was performed on. The conclusions reached through experimentation were that the micro-mill used between 13.5% and 21.7% of the energy used for the macro-mill. Additionally the energy differences in climate control were investigated for comparable macro- and micro-factories. The mock macro-factory used for this analysis was three times the size of the micro-factory. Due to the larger size of the macro-building, the climate control energy usages were also about three times as high as in the micro-building.
Proceedings Papers
Proc. ASME. IMECE2011, Volume 3: Design and Manufacturing, 873-880, November 11–17, 2011
Paper No: IMECE2011-65437
Abstract
Wind turbines have seen increasing use over the past decades as an alternative mode of energy production. One specific use of vertical axis wind turbines is for the powering of rural telecommunication towers. In this research a cradle-to-gate life cycle analysis is used to compare three different designs for a stackable, capped, Savonius-style vertical axis wind turbine blade capable of producing from one to three kilowatts. The analysis compares the energy consumed and carbon dioxide emissions from material production and manufacturing of two different aluminum blade designs and a polypropylene design each having the same energy generation capacity. Primary and secondary aluminum materials were included in the analysis. Life cycle inventories from two software programs were used and compared with values gleaned from published literature. The results of the analysis revealed that the least energy and carbon dioxide impact came from using a recycled aluminum design while the most was from manufacturing using primary aluminum.
Proceedings Papers
Proc. ASME. IMECE2011, Volume 3: Design and Manufacturing, 667-676, November 11–17, 2011
Paper No: IMECE2011-65302
Abstract
Traditional flood cooling processes can cause problems in micromachining due to the collision force between the fluid stream and the tool being greater in magnitude than the cutting forces. The traditional processes produce insufficient cooling rates and are unable to effectively evacuate chips from the cutting zone. Atomization-based cooling addresses these issues through high evaporative cooling rates, low impact forces, and the use of a high velocity air stream to clear the cutting zone of chips. This paper presents a probabilistic model to determine the thickness of a microfilm forming on a rotating cylindrical surface, such as a microturning workpiece or a microendmill, and the relative importance of system parameters on film formation. The rate of microfilm formation is dependent upon droplet losses in the tube, at the nozzle, and the scatter of the atomized spray. Droplet diameters and Weber numbers in the tube and at the cylinder were experimentally determined and modeled as lognormally distributed. Parameters investigated in this model are fluid and mist properties (surface tension and droplet size) and system parameters (delivery tube air velocity, spray air velocity, spray geometry, cylinder diameter, and cylinder rotational velocity). A maximum film thickness effect was found for the variables of delivery tube velocity, droplet diameter, and surface tension with a value for each variable that provided a thickest film. As the variables increased or decreased from that value the film thickness decreased.
Journal Articles
Article Type: Research Papers
J. Manuf. Sci. Eng. August 2011, 133(4): 041001.
Published Online: July 20, 2011
Abstract
A three-dimensional fluid dynamic model is developed to predict flux decline due to membrane fouling during the microfiltration of semisynthetic metalworking fluids. The model includes surface forces as well as hydrodynamic effects. Two pore model geometries are developed based on sintered aluminum oxide membranes. Simulations conducted using a single-pathway pore geometry illustrate the ability of the three-dimensional model to represent how flow continues through a partially blocked pore and how partial blocking reduces effective cross-sectional area. A four-disk pore geometry is used to compare flux decline behavior for different pore size distributions representing a new membrane and a membrane that had become partially blocked. Flux decline results are found to be consistent with published experimental results for similar membranes. An example shows how the three-dimensional fluid dynamic model may be used to determine the best membrane pore size distribution for a given situation and therefore demonstrates its overall utility as a design tool.
Proceedings Papers
Proc. ASME. MSEC2009, ASME 2009 International Manufacturing Science and Engineering Conference, Volume 1, 57-66, October 4–7, 2009
Paper No: MSEC2009-84107
Abstract
Microfiltration is an in-process recycling method that shows great potential to extend fluid life and reduce bacterial concentrations in synthetic and semi-synthetic metalworking fluids (MWFs). The primary problem facing this use of microfiltration is membrane fouling, which is the blocking of membrane pores causing reduced flux. In this paper a fluid dynamic model of partial and complete blocking in sintered alumina membranes is developed that includes hydrodynamic, electrostatic, and Brownian forces. Model simulations are employed to study the impact of electrostatic and Brownian motion forces on the progression of partial blocking. The simulations also examine the effects of fluid velocity, particle size, and particle surface potential. The inclusion of electrostatic and Brownian forces is shown to significantly impact the progression of the partial blocking mechanism. The addition of a strong inter-particle electrostatic force is shown to eliminate the partial blocking build-up of small particles due to the presence of the repulsive forces between the particles. As a result, the time to complete blocking of the test pore was lengthened, suggesting that flux decline is reduced in the presence of electrostatic forces. Brownian motion is shown to have a large impact at low fluid velocities. The most effective parameter set is a low fluid velocity, small particle sizes, high microemulsion surface potential, and high membrane surface potential.
Journal Articles
Article Type: Research Papers
J. Manuf. Sci. Eng. December 2008, 130(6): 061015.
Published Online: November 19, 2008
Abstract
The recycling of semisynthetic metalworking fluids (MWFs) using alumina membranes is significantly impacted by aggregated MWF microemulsions that cause partial and complete blocking of membrane pores. In this paper, computational fluid dynamic methods are employed to model both a portion of a sintered alumina membrane with tortuous pores and the microemulsions passing through it. Several particle size distributions, measured experimentally at various times through the membrane service life and under two different cross-flow velocities, were used to determine the particle sizes simulated in the flow. Simulated MWF particles smaller than the largest pore diameter were found to completely block the pore through the build-up of a network of particles that blocked smaller diameter inlets and outlets. The results demonstrate as well that significant membrane flux reduction can occur by partial blocking of pore inlets and outlets even in the absence of complete blocking.
Journal Articles
Article Type: Research Papers
J. Manuf. Sci. Eng. August 2008, 130(4): 041014.
Published Online: July 17, 2008
Abstract
In this paper, the fouling of sintered α -alumina membranes by an uncontaminated semisynthetic metalworking fluid (MWF) is addressed. Experimental evidence of the form of flux reduction curves, scanning electron microscope images of the membranes, and MWF particle size measurements is used to identify two fouling mechanisms, pore blocking and partial pore blocking, as the major contributors to flux decline. A probability-based mechanistic model is developed based on the time-dependent particle size distribution and membrane pore sizes. The model is fitted to experimental data from two commonly used membrane pore sizes with good agreement. Partial blocking is shown to be a predominant first step in the pore blocking mechanism in microfiltration of semisynthetic MWFs due to the tortuous nature of the pores present in sintered ceramic membranes.