Microfiltration of Synthetic Metalworking Fluids Using Aluminum Oxide Membranes

Metalworking fluids (MWFs) are used in manufacturing as coolants, lubricants,mand corrosion inhibitors. Growing MWF acquisition and disposal costs, together with concerns about microbiological health hazards and environmental impact have led to increased interest in MWF recycling, contaminant control, and alternative application strategies. Membrane filtration can remove microbes, particulate, and tramp oils that contaminate metalworking fluids and has the potential to reduce health risks and extend MWF life in the machine tool industry. However, poorly understood relationships between the compatibility of metalworking fluid ingredients, contaminants, membrane materials, and membrane pore-size distributions have precluded the widespread industrial application of the technology. This research assesses the mechanisms of productivity decline during the microfiltration of an uncontaminated synthetic MWF using aluminum oxide membranes. It is revealed that while the majority of synthetic MWF ingredients have a negligible impact on microfiltration productivity, specialty additives such as lubricants, defoamers, and biocides can significantly reduce productivity. This is due to adsorption of these ingredients to the membrane surface that serves to increase resistance to MWF flow through the membrane pores. MWF ingredient characteristics such as hydrophilic/hydrophobic content and electrostatic charge can influence adsorption and productivity-loss during microfiltration. These findings demonstrate that the chemistry and concentration of specialty additives are important to account for during the design of membrane filtration systems for MWF recycling.RRT-027unpublishednot peer reviewe

On the Existence of Bertrand-Nash Equilibrium Prices Under Logit Demand

This article presents a proof of the existence of Bertrand-Nash equilibrium prices with multi-product firms and under the Logit model of demand that does not rely on restrictive assumptions on product characteristics, firm homogeneity or symmetry, product costs, or linearity of the utility function. The proof is based on conditions for the indirect utility function, fixed-point equations derived from the first-order conditions, and a direct analysis of the second-order conditions resulting in the uniqueness of profit-maximizing prices. Several subsequent results also demonstrate that price equilibrium under the Logit model of demand cannot adequately describe multi-product pricing.Comment: 39 Page

Supercritical Carbon Dioxide in Microelectronics Manufacturing: Marginal Cradle-to-grave Emissions

AbstractThis paper presents and discusses the marginal cradle-to-grave environmental impacts of using VLSI grade supercritical carbon dioxide (scCO2) as a rinsing agent in place of ultrapure water (UPW) in semiconductor fabrication. Impacts are estimated using a consequential life cycle assessment framework for recovered CO2. Upon factoring the cumulative yields of the CO2 recovery and purification processes, compressor energy use (566kJ/kg CO2 output) together with refrigeration (540kJ/kg CO2 output) accounts for about 90% of total on-site electricity use. Upstream emissions from production of propylene carbonate co-solvent contribute to more than 50% of the life cycle impacts of scCO2-based wafer cleaning. Overall impacts of scCO2-wafer cleaning, particularly water and energy use, are found to be significantly lower than UPW

Fixed-Point Approaches to Computing Bertrand-Nash Equilibrium Prices Under Mixed Logit Demand: A Technical Framework for Analysis and Efficient Computational Methods

This article presents a detailed technical framework for modeling with Bertrand-Nash equilibrium prices under Mixed Logit demand. Two coercive fixed-point equations provide more stable computational methods than those obtained from the literal first-order conditions. Assumptions to justify derivation and use of these equations are provided. A brief discussion of a GMRES-Newton method with hookstep globalization strategy originally due to Viswanath is also given. This article can be considered a supplement to an article by the authors forthcoming in the journal {\em Operations Research}.Comment: 57 page

Comparing energy and water use of aqueous and gas‐based metalworking fluids

Gas‐based metalworking fluids (MWFs) have been proposed as alternative coolants and lubricants in machining operations to mitigate concerns surrounding water use and pollution, industrial hygiene, occupational health, and performance limitations associated with water‐based (aqueous) MWFs that are ubiquitously used in the metals manufacturing industry. This study compares the primary energy and water use associated with the consumptive use, delivery, and disposal of aqueous MWFs with three gas‐based MWFs in the literature—minimum quantity lubricant‐in‐compressed air (MQL), liquid/gaseous N2, and liquid/supercritical CO2. The comparison accounts for reported differences in machining performance in peer‐reviewed experimental studies across several machining processes and materials. The analysis shows that despite the reported improvement in tool life with N2 and CO2‐based MWFs, the electricity‐ and water‐intensive separation and purification processes for N2 and CO2 lead to their higher primary energy and water use per volume of material machined relative to water‐based MWFs. Although MQL is found to have lower primary energy use, significant consumptive water use associated with the vegetable oil commonly used with this MWF leads to higher overall water use than aqueous MWF, which is operated in a recirculative system. Gas‐based MWFs thus shift the water use upstream of the manufacturing plant. Primary energy and water use of gas‐based MWFs could be reduced by focusing on achieving higher material removal rates and throughput compared to aqueous MWF instead of solely targeting improvements in tool life. Additionally, the consumptive use of CO2 and N2 MWFs could be minimized by optimizing their flow rates and delivery to precisely meet the cooling and lubrication needs of specific machining processes instead of flooding the tool and workpiece with these gases. This article met the requirements for a gold–gold JIE data openness badge described at http://jie.click/badges.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163496/3/jiec12992.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163496/2/jiec12992-sup-0001-SuppMat.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163496/1/jiec12992_am.pd

Design of Heat-Activated Reversible Integral Attachments for Product-Embedded Disassembly

Disassembly is a fundamental process needed for component reuse and material recycling in all assembled products. Integral attachments, also known as snap" fits, are favored fastening means in design for assembly (DFA) methodologies, but are not necessarily a favored choice for design for disassembly. Several prototype designs of a new class of integral attachments are presented, where the snapped joints can be disengaged by the application of localized heat sources. The design problem of reversible integral attachments is posed as the optimization of compliant mechanisms actuated with localized thermal expansion of materials. The Homogenization Design Method is utilized to obtain an optimal structural topology that realizes a desired deformation of snapped features for joint release. The obtained optimal topologies are simplified to enhance the manufacturability for the conventional injection molding technologies. Results of the example designs are verified by finite element analysesPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87259/4/Saitou101.pd

Feasibility of Metalworking Fluids Delivered in Supercritical Carbon Dioxide (TECHNICAL NOTE SUBMITTED TO JOURNAL OF MANUFACTURING PROCESSES)

Abstract This paper presents a new method to lubricate, cool, and evacuate chips in metalworking operations using supercritical carbon dioxide (scCO

Membrane biofilm development improves COD removal in anaerobic membrane bioreactor wastewater treatment

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113134/1/mbt212311.pd

Membrane biofilm development improves COD

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113134/1/mbt212311.pd