1997 Fiscal Year Final Research Report Summary
SIMPLIFICATION IN POLISHING METAL MOLD OF CEMENTED CARBIDE MACHINED BY EDM USING OXIDATION
| Project/Area Number |
08650838
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Material processing/treatments
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| Research Institution | NIIGATA UNIVERSITY |
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Principal Investigator |
TAMURA Takeo NIIGATA UNIVERSITY,ENGINEERING,ASSOCIATE PROFESSOR, 工学部, 助教授 (90115048)
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| Project Period (FY) |
1996 – 1997
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| Keywords | ELECTRICAL DISCHARGE MACHINING / CEMENTED CARBIDE / HIGH-TEMPERATURE OXIDATION / SURFACE MODIFICATION / HEAT-AFFECTED ZONES / INDUCTION HEATING / METAL MOLD |
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| Research Abstract |
Recently, the use of cemented carbides has become widespread for various kinds of meal molds because of their superior wear and heat resistance. However, the heat-affected zones (HAZ), in which ihere are many cracks and microcraters, are generated by electrical discharge machining (EDM) of cemented carbides during the metal mold manufacturing process.
Under the present situation, HAZ are removed by polishing, which is dependent on hand finishing. However, this process extends the machining time and increases the cost of production of metal molds.
Therefore, a surface modification method using oxidation is proposed as a new surface modification method instead of the mechanical removal one. The proposed method uses a high-temperature oxidation of the surface of cemented carbides, softening the layrs with many pores so that they can be easily removed by rubbing with a wire brush.
The following results were obtained :
(1) The heat-affected zones generated by EDM of cemented carbides could be completely removed by this oxidizing treatment. The oxidzed surface is comprised of cobalt and tungsten oxides.
(2) The crystal structures remaining after oxide removal are transformed into the hexagonal lattice of tungsten carbide, WC,in a stable structure. Consequently, the surface modification method is expected to greatly facilitate polishing during the metal mold manufacturing process.
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