• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.3
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• pp.8-13
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• 2020

Carbon fiber-reinforced plastics (CFRPs) are extremely strong and light fiber-reinforced plastics containing carbon fibers. CFRPs can be expensive to produce, but are commonly used wherever high strength-to-weight ratio and rigidity are required, such as in the aerospace, automotive, and ship superstructure industries. In CFRP drilling, the tool performance greatly varies depending on the tool shapes, cutting conditions, and diamond coating. This study developed a new type of tungsten carbide drill with multi-blade edges to evaluate the surface quality of CFRP materials according to the coating thickness of diamond-coated drills. Experiments on tool wear, surface roughness, and burr formation were conducted. The bore exit quality of a 12 mμ -coated drill was better than that of a 6 mμ -coated drill. The superior effects of the 12 mμ -coated drill and the good surface quality of CFRP were also demonstrated.

• Resources Recycling
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• v.21 no.1
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• pp.82-92
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• 2012

There are several kinds of tungsten carbide(WC) such as light bulbs, metal cutting tools, drill bits, mining tools, military ordinance, high speed tool steels, chemicals/catalysts, wear resistance parts, jet engine turbine blades, etc.. These days it has been widely studied for the recycling technologies of the used tungsten carbide(WC) from view points of economy and efficiency. In this paper, open/registered patents of US, JP, EP, and KR and SCI Journal related to recycling technologies of the used Tungsten Carbide(WC) between 1969-2011 were reviewed. Patents and papers were collected using key-words searching and filtered by filtering criteria. The trends of the patents and papers was analyzed by the years, countries, companies, and technologies.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.403-404
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• 2008

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.4 no.3
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• pp.32-38
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• 2005

Electrical discharge machining is the method of using thermal energy by electrical discharge. Generally, if the material of workpiece has conductivity even though very hard materials and complicated shape which are difficult to cut such as quenching steel, cemented carbide, diamond and conductive ceramics, the EDM process is favorable one of possible machining processes. But, the process is necessarily required of finish cut and heat treatment because of slow cutting speed, no mirror surface, brittleness and crack due to the residual stress for manufactured goods. In this experimental thesis, the super EDM drilling was developed for high precision semiconductor die steel and for minimization of leadframe width. It was possible to development of EDM drilling machine for high precision semiconductor die with the electrode guide and its modelling and stress analysis. The development of electrode with the copper pipe type was conducted to drill the hole from the diameter of 0.1mm to 3.0mm with the error of from 0.02mm to 0.12mm. From the SEM and EDX analysis, the entrance of the EDM drill was found the resolidification of not only the component of tungsten but also the component of copper.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.435-440
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• 2000

In this study, we aims to develop the machining technology for the ultra precision surface and profile accuracy. For this purpose, we construct the electrolytic in process grinding system (ELID grinding) and apply to the cylindrical and internal grinding. Through the various machining experiments such as SCM steel., ceramics, tungsten carbide etc., we have obtained nanometer surface roughness. And we have applied this mirror grinding technique to hydraulic manual valve and mold core of mini disk optical pick-up base. For the development of fine mechanical part machining technology, e have made multi fiber optical connector using fine grinding technology. And constructed micro drilling system with process monitoring system which is possible to drill 50${\mu}{\textrm}{m}$ diameter hole.

• Resources Recycling
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• v.26 no.6
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• pp.65-72
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• 2017

APT (Ammonium paratungstate) is widely used in various industries such as metal cutting tools, drill bits, mining tools, and military inorganic materials. In order to produce high purity APT(S), an impurity purification step in an aqueous $Na_2WO_4$ convert $H_2WO_4$ solution is required. It is difficult to remove impurity Na of 200 ppm or less when $H_2WO_4(S)$ is prepared by adding HCl(Aq) to an aqueous solution of $Na_2WO_4$, which is a well-known conventional wet method. However, in this study, a more economical and efficient method of removing Na through electrodialysis using a cationic membrane was studied. A large amount of Na in aqueous solution of $H_2WO_4$ due to $Na_2CO_3(S)$ which was added to dissolve waste tungsten carbide drill and scrap was removed to 20ppm or less through electrodialysis process, and it was confirmed that the effect of Na removal was great when using electrodialysis.