Research on electrical discharge machining of polycrystalline diamond
The non-contact process of Electrical Discharge Machining (EDM) eliminates cutting forces, and is regarded as the most effective process to machine polycrystalline diamond (PCD). However, the EDM plasma temperature of up to 12000K in the EDM process will cause damage to the machined surface. With em...
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| Format: | Thesis |
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2015
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| Online Access: | http://eprints.uthm.edu.my/7780/ http://eprints.uthm.edu.my/7780/1/Mohammad_Zulafif_Rahim.pdf |
| Summary: | The non-contact process of Electrical Discharge Machining (EDM) eliminates cutting forces, and is regarded as the most effective process to machine polycrystalline diamond (PCD). However, the EDM plasma temperature of up to 12000K in the EDM process will cause damage to the machined surface. With emphasis on the cutting tool product, this study focuses on the analysis of the PCD surface damage caused by the Electrical Discharge Grinding (EDG) process and its optimization strategies. In addition to the graphitization and residual stress, several issues that assumed to be thermal damage indications caused by the process are highlighted. These include the formation of porous surfaces, cutting edge undercuts and some cosmetic aspects at the WC-PCD interface. It was found that the high temperature generated during erosion resulted in the partial conversion of diamond to graphite phase under the surface. Higher finishing in-feed proved to produce better surface quality by means of lower surface graphitization and lower tensile residual stress. The comprehensive discussion undertaken includes the theoretical modelling of the process, together with the validated results. The structural difference and residual stress between PCD manufactured with EDG and conventional grinding have been compared. Performance tests have also been conducted at the end of the methodology to evaluate and validate the models. |
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