• Journal of the Korean Society for Precision Engineering
• /
• v.29 no.3
• /
• pp.266-272
• /
• 2012

This paper has aims to share fundamental knowledge for magnetic abrasive polishing and to mainly introduce recent research results. In order to enhance a magnetic flux density for nonferrous materials, advanced magnetic abrasive polishing system which is called 2nd generation system was established by electro-magnet array table, and the effectiveness of the electromagnet array table was evaluated in real polishing experiments. To increase adhesiveness of the abrasives in high speed polishing, a silicone gel agent was proposed and carbon nanotube particles as new magnetic abrasives were applied in the magnetic abrasive polishing. In addition, a strategy for optimal step-over determination by heuristic algorithm was introduced for applying large size workpiece. Curved surfaces having a uniform radius were simulated and tested with installed electro-magnet array table.

• Journal of the Korean Society for Heat Treatment
• /
• v.20 no.2
• /
• pp.72-77
• /
• 2007

Abrasive wear between piston ring face and cylinder liner is an extremely unpredictable and hard-to-reproduce phenomenon that significantly decreases engine performance. Wear by abrasion are forms of wear caused by contact between a particle and solid material. Abrasive wear is the loss of material by the passage of hard particles over a surface. From the pin-on-disk test, particle dent test and scuffing test, abrasive wear characteristics of diesel engine cylinder liner-piston ring have been investigated. Pin-on-disk test results indicate that abrasive wear resistance is not simply related to the hardness of materials, but is influenced also by the microstructure, temperature, lubricity and micro- fracture properties. In particle dent test, dent resistance stress decreases with increasing temperature. From the scuffing test by using pin-on-disk tester, scuffing mechanisms for the soft coating and hard coating were proposed and experimentally confirmed.

• Journal of the Korean Society for Precision Engineering
• /
• v.30 no.12
• /
• pp.1253-1258
• /
• 2013

Ceramic particles as polishing abrasives are often used in a magnetic abrasive polishing process because they have strong wear resistance. Non-ferromagnetic ceramic abrasives should be mixed with ferromagnetic iron particles for controlling the mixture within a magnetic brush during the polishing process. This study describes the application of the ceramic particles for the magnetic abrasive polishing. The distribution of the magnetic abrasives attached on a tool varies with magnetic flux density and tool rotational speed. From the correlation between abrasive adhesion ratio in the tool and surface roughness produced on a workpiece, practical polishing conditions can be determined. A step-over for polishing a large sized workpiece is able to be selected by a S curve, and an ultrasonic vibration assisted MAP produces a better surface roughness and increases a polishing efficiency.

• Asian-Australasian Journal of Animal Sciences
• /
• v.17 no.10
• /
• pp.1465-1471
• /
• 2004

A trial was conducted to determine the effect of abrasive strips and abrasive paint in layer cages on claw length and claw sharpness, foot condition, feather cover and mortality of hens. During the preparation of the cages for the experiment it was simpler and took less time to apply the pre-prepared paint with a spatula to the egg guard compared to sticking the abrasive strips onto the egg guard. Fitting the strips took longer because it had to be cut from a 25 mm roll, cut into the appropriate lengths, the tape backing removed and then stuck onto the egg guard section. Abrasive paint was more effective as a claw shortener than abrasive strips. The birds using the abrasive paint had the shortest (p<0.05) claw length and lowest (p<0.05) claw sharpness. One of the original reasons for reducing claw length with claw shorteners was to reduce mortality by minimising skin skin abrasions caused by the claws. Surprisingly hen mortality from prolapse and cannibalism was higher (p<0.05) in cages fitted with abrasives. There are no other reports in the literature showing an increase in prolapse and cannibalism from hens using abrasives.

• Journal of the Korean Society for Precision Engineering
• /
• v.18 no.12
• /
• pp.192-199
• /
• 2001

Chemical mechanical planarization (CMP) has emerged as the planarization technique of choice in both front-end and back-end integrated circuit manufacturing. Conventional CMP process utilize a polyurethane polishing pad and liquid chemical slurry containing abrasive particles. There hale been serious problems in CMP in terms of repeatability and deflects in patterned wafers. Especial1y, dishing and erosion defects increase the resistance because they decrease the interconnection section area, and ultimately reduce the lifetime of the semiconductor. Methods to reduce dishing & erosion have recently been interface hardness of the pad, optimization of the pattern structure as dummy patterns. Dishing & erosion are initially generated an uneven pressure distribution in the materials. These defects are accelerated by free abrasives and chemical etching. Therefore, it is known that dishing & erosion can be reduced by minimizing the abrasive concentration. Minimizing the abrasive concentration by using CeO$_2$is the best solution for reducing dishing & erosion and for removal rate. This paper introduce dishing & erosion generating mechanism and a method fur developing a semi-rigid abrasive pad to minimize dishing & erosion during CMP.

• Tribology and Lubricants
• /
• v.26 no.4
• /
• pp.219-223
• /
• 2010

Despite the increasing need of nanometer-scale accuracy in abrasive machining using ultrasmall particles such as abrasive jet and chemical mechanical polishing(CMP), the process mechanism is still unknown. Based on the background, research on the effects of various process parameters on the machined surface at abrasive machining was motivated and performed by using finite element analysis where the effect of slurry fluid flow involved. The effect of particle shape on the machined surface during particle-surface collision was discussed in this paper. The results from FEA simulation revealed that any damage or defect generation on machined surface by the impact may occur only if the particle has enough impact energy. Therefore, it could be concluded that generation of the defects and damage on the wafer surface after CMP process was mainly due to direct contact of the 3 bodies, i.e., pad-particle-wafer.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.1296-1301
• /
• 2003

The chemical mechanical polishing(CMP) is necessarily applied to manufacturing the dielectric layer and metal line in the semiconductor device. The conditioning of polishing pad in CMP process additionally operates for maintaining the removal rate, within wafer non-uniformity, and wafer to wafer non-uniformity. But the fixed abrasive pad(FAP) using the hydrophilic polymer with abrasive that has the swelling characteristic by water owns the self-conditioning advantage as compared with the general CMP. FAP also takes advantage of planarity, resulting from decreasing pattern selectivity and defects such as dishing due to the reduction of abrasive concentration. This paper introduces the manufacturing technique of FAP. And the tungsten CMP using FAP achieved the good conclusion in point of the removal rate, non-uniformity, surface roughness, material selectivity, micro-scratch free contemporary with the pad life-time.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.8 no.6
• /
• pp.16-25
• /
• 1999

In recent years, grinding techniques for precision machining of brittle materials used in die, model and optical parts have been improved by using superfine abrasive wheel and precision grinding machine. The completion of optimum dressing of superfine abrasive wheel makes possible the effective precision grinding of die steel(STD-11). In this study, a new system and the grinding mechanism of optimum in-process electrolytic dressing were proposed. This method can carry out optimum in-process electrolytic dressing of superfine abrasive wheel. Therefore, the optimum in-process electrolytic dressing is a good method to obtain the efficiency and mirror-like grinding of STD-11.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.16 no.12S
• /
• pp.1157-1164
• /
• 2003

This paper shows the results of atomistic modeling for the interaction between spherical nano abrasive and substrate in chemical mechanical polishing processes. Atomistic modeling was achieved from 2-dimensional molecular dynamics simulations using the Lennard-Jones 12-6 potentials. The abrasive dynamics was modeled by three cases, such as slipping, rolling, and rotating. Simulation results showed that the different dynamics of the abrasive results the different features of surfaces. This model can be extended to investigate the 3-dimensional chemical mechanical polishing processes.

• Journal of Powder Materials
• /
• v.15 no.6
• /
• pp.509-513
• /
• 2008

High-pressure abrasive entrained jet have rapidly become important machining technology over the last two decades. However, suspension jet by high-pressure has been recently developed for packaging sawing. Ideally, diamond materials should be used for components in abrasive water-jet systems that are subject to high erosive conditions. Using the diamond orifices improve maintenance and extend wear part life. This paper gives insights to using an abrasive suspension jet with diamond orifice. The influences of orifice material and orifice design are evaluated.