The Material Removal Mechanism in Magnetic Fluid Grinding of Ceramic Ball Bearings

1994 ◽  
Vol 208 (1) ◽  
pp. 47-59 ◽  
Author(s):  
T H C Childs ◽  
S Mahmood ◽  
H J Yoon
Keyword(s):  
Magnetic Fluid ◽  
Material Removal ◽  
Permanent Magnets ◽  
Experimental Studies ◽  
Wear Coefficient ◽  
Rotating Shaft ◽  
Removal Rates ◽  
Kinematic Theory ◽  
New Process ◽  
A Cell

Recently a new process known as magnetic fluid grinding has been developed in Japan which can remove material in the finishing of ceramic balls some fifty times more rapidly than can the lapping processes that are conventionally used. Balls are driven round a cell by a rotating shaft in an arrangement similar to a thrust race but submerged in a magnetic fluid placed above permanent magnets. The magnets and fluid create buoyancy forces that levitate grinding grits in the fluid and also provide the loads for the process, but it is not clear why the process is more effective than lapping. This paper reports on experimental studies of the grinding rates of silicon nitride balls in magnetic fluids loaded with diamond grits and of the motion of the balls through the fluids. The high removal rates occur when skidding occurs between the balls and drive shaft. A kinematic theory is developed to calculate sliding speeds and is used to deduce an abrasive wear coefficient for the process of 0.07 ± 0.02, indicative of two-body abrasion. The high removal rates are a consequence of the large sliding speeds that can be developed, of several metres per second.

PENGGUNAAN AIR SUPER KRITIS PADA DEPOLIMERISASI NYLON-12 (BATCH PROCESS)

2018 ◽  
Vol 5 (3) ◽  
Author(s):  
Mohamad Yusman
Keyword(s):  
Supercritical Water ◽  
Scale Up ◽  
Experimental Studies ◽  
Reaction System ◽  
Batch Process ◽  
Chemical Recycling ◽  
Water Decomposition ◽  
Product Distributions ◽  
New Process ◽  
Nylon 12

Water at the supercritical state is a new process for the chemical recycling. At this thermodynamic state i.e. Pc = 218 atmospheres and Tc = 374oC , water behaves very differently from its everyday temperament and it is a very good solvent for organic components. Experimental studies show that supercritical water can decompose hydrocarbons/polymers and produce useful products like 2-Azacyclotridecanone /lactam-1 from Nylon-12 (batch process). The decomposition process itself was carried out in batch reaction system in order to get more information about product distributions, time dependence, and scale-up possibilities.Keywords: supercritical water, decomposition, batch, polymer, hydrocarbon

scholarly journals Experimental study of the stratification of polydisperse emulsions in a cell with heated walls

2021 ◽  
Vol 2057 (1) ◽  
pp. 012041
Author(s):  
V I Valiullina ◽  
A I Mullayanov ◽  
A A Musin ◽  
L A Kovaleva
Keyword(s):  
Experimental Study ◽  
Deposition Rate ◽  
Thermal Convection ◽  
Dispersion Medium ◽  
Experimental Studies ◽  
Oil Emulsion ◽  
Convective Flows ◽  
A Cell ◽  
Increasing Temperature ◽  
Water In Oil Emulsion

Abstract Experimental studies of the gravitational deposition of a polydisperse water-in-oil emulsion under heat influence are carried out. When the rate of thermal convection exceeds the rate of precipitation, partial delamination of the emulsion is found to occur. The viscosity of the dispersion medium decreases with increasing temperature, which contributes to an increase in the deposition rate of water droplets in the emulsion. In the presence of a temperature difference, convective flows occur in the liquid, while the drops of the emulsion coagulate and form larger agglomerates that settle faster to the bottom of the cell.

scholarly journals Human Periapical Cyst-Derived Stem Cells Can Be A Smart “Lab-on-A-Cell” to Investigate Neurodegenerative Diseases and the Related Alteration of the Exosomes’ Content

2019 ◽  
Vol 9 (12) ◽  
pp. 358 ◽  
Author(s):  
Tatullo ◽  
Codispoti ◽  
Spagnuolo ◽  
Zavan
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Circadian Rhythm ◽  
Neurodegenerative Diseases ◽  
Clock Genes ◽  
Experimental Studies ◽  
Cell Aging ◽  
A Cell ◽  
Periapical Cyst

Promising researches have demonstrated that the alteration of biological rhythms may be consistently linked to neurodegenerative pathologies. Parkinson’s disease (PD) has a multifactorial pathogenesis, involving both genetic and environmental and/or molecular co-factors. Generally, heterogeneous alterations in circadian rhythm (CR) are a typical finding in degenerative processes, such as cell aging and death. Although numerous genetic phenotypes have been discovered in the most common forms of PD, it seems that severe deficiencies in synaptic transmission and high vesicular recycling are frequently found in PD patients. Neuron-to-neuron interactions are often ensured by exosomes, a specific type of extracellular vesicle (EV). Neuron-derived exosomes may carry several active compounds, including miRNAs: Several studies have found that circulating miRNAs are closely associated with an atypical oscillation of circadian rhythm genes, and they are also involved in the regulation of clock genes, in animal models. In this context, a careful analysis of neural-differentiated Mesenchymal Stem Cells (MSCs) and the molecular and genetic characterization of their exosome content, both in healthy cells and in PD-induced cells, could be a strategic field of investigation for early diagnosis and better treatment of PD and similar neurodegenerative pathologies. A novel MSC population, called human periapical cyst–mesenchymal stem cells (hPCy–MSCs), has demonstrated that it naively expresswa the main neuronal markers, and may differentiate towards functional neurons. Therefore, hPCy–MSCs can be considered of particular interest for testing of in vitro strategies to treat neurological diseases. On the other hand, the limitations of using stem cells is an issue that leads researchers to perform experimental studies on the exosomes released by MCSs. Human periapical cyst-derived mesenkymal stem cells can be a smart “lab-on-a-cell” to investigate neurodegenerative diseases and the related exosomes’ content alteration.

Feasibility Study on Grinding of Titanium Alloys with Electroplated CBN Wheels

2013 ◽  
Vol 797 ◽  
pp. 73-78 ◽  
Author(s):  
Zhong De Shi ◽  
Helmi Attia
Keyword(s):  
Titanium Alloy ◽  
Titanium Alloys ◽  
Material Removal ◽  
High Pressures ◽  
Surface Cleaning ◽  
Depth Of Cut ◽  
Wheel Surface ◽  
Removal Rates ◽  
Grinding Fluid ◽  
Creep Feed

An experimental investigation is reported on the grinding of a titanium alloy using electroplated CBN wheels with water-based grinding fluid and wheel surface cleaning fluid applied at high pressures. This work was motivated by applying grinding fluid and wheel surface cleaning fluid both at high pressures for avoiding wheel loading, which is commonly seen in titanium alloy grinding. The objective is to explore the feasibility to grind titanium alloys with electroplated CBN wheels and high pressure wheel surface cleaning fluid for enhancing material removal rates. Straight surface grinding experiments were conducted on titanium alloy blocks in both shallow depth of cut and creep-feed modes. Grinding power, forces, and surface roughness were measured. Specific material removal rates of 8 mm2/s in shallow cut mode and 3 mm2/s at a depth of cut as high as 3 mm in creep-feed mode were achieved without burning and smearing of ground surfaces. It was showed that it is feasible to grind titanium alloys with electroplated CBN wheels at enhanced removal rates by applying grinding and wheel cleaning fluid at high pressures.

Pitch polishing of silica: correlation between material removal rates and surface finishes

2007 ◽  
Author(s):  
I. Roberts ◽  
P. Murray ◽  
W. Williams ◽  
A. Landis ◽  
B. Mullany
Keyword(s):  
Material Removal ◽  
Removal Rates ◽  
Surface Finishes

The Experimental Study on Mechanical Polishing on Materials with Hydrolysis Reaction

2017 ◽  
Vol 739 ◽  
pp. 182-186
Author(s):  
Hung Jung Tsai ◽  
Pay Yau Huang ◽  
Chung Ming Tan ◽  
Tang Feng Chang
Keyword(s):  
Experimental Study ◽  
Material Removal Rate ◽  
Material Removal ◽  
Removal Rate ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Hydrolysis Reaction ◽  
Polishing Process ◽  
Surface Polishing ◽  
Material Removal Rate Model

The hydrolytic properties of LiAlO2 (LAO) are important factors for its applications on LED fabrication. During soft pad polishing process, the H2O in the slurry is deleterious for LAO surface polishing results. The current study develops a material removal rate model for materials with hydrolysis reaction to predict the result of polishing process.The current research conducts the experimental studies to investigate the material removal rate and its mechanism during the soft pad polishing process. In the experimental study, the hydrolytic properties of LAO have been tested to understand the hydrolysis speed with different operation parameters to assist the development of the theoretical model. Also the material removal rates of LAO with hydrolytic property have been measured under different soft pad polishing operating conditions. The experimental results provide the hydrolytic properties of LiAlO2 to understanding of the mechanism on polishing process.

Mathematical Model for Chip Serration Frequency in Turning of Stainless Steel with Magnetic Damping from Bottom of Tool Shank

2013 ◽  
Vol 393 ◽  
pp. 108-114
Author(s):  
A.K.M. Nurul Amin ◽  
Fawaz Mohsen Abdullah ◽  
Muammer Din Arif ◽  
Israd H. Jaafar
Keyword(s):  
Mathematical Model ◽  
Stainless Steel ◽  
Material Removal ◽  
Control Method ◽  
Research Work ◽  
Chip Morphology ◽  
Work Piece ◽  
Removal Rates ◽  
Serrated Chip ◽  
Tool Shank

Chatter, a violent and often unpredictable relative oscillatory motion between the tool and work-piece, is a serious concern in turning operations. Its occurrence is usually associated with a loud monotonous sound and usually results in increased surface roughness, reduced material removal rates, shortened tool life, and damaged machine-tool bearings. The established theories for chatter are very limited in scope and are often contradicted by empirical evidences. Therefore, chatter avoidance in the past has relied on inefficient techniques like limiting material removal rates or expensive setups such as actuators and ultrasonic vibration damping systems. However, a deeper investigation into chatter formation reveals that chip morphology and segmentation play a significant role during the incidence of chatter. The novel Resonance theory of chatter combines the concept of mode coupling of the machining setup and serrated chip formation, to explain and predict chatter. To validate the postulates of this theory, models for chip serration frequency are essential. At the same time, a reliable and economical chatter control method is required. With this goal, the current research work has developed an empirical mathematical model of chip serration frequency in turning of stainless steel AISI 304 using Response Surface Methodology (RSM). Also, it investigated the influence of damping provided by magnetic field from a permanent ferrite magnet placed beneath the tool shank. The developed chip serration model is in good accord with the experimental data, demonstrating that the empirical model could be used for further chip morphology and chatter analyses.

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