The influence of migrated materials on Tool wear ratio

• Type: Thesis
• Date: 2002

Authors

José Duarte Ribeiro Marafona (Author) FEUP; Sem Nome (Technical adviser) FEUP; Catherine Wykes (Technical adviser) Other

Scientific classification

FOS: Engineering and technology > Mechanical engineering

CORDIS: Technological sciences > Engineering > Mechanical engineering

Associated Institutions

UNOTT - University of Nottingham

Other information

Resumo (PT): The Electrical Discharge Machining (EDM) process was developed to produce cavities in hard metals which were impossible to be manufactured. One of the main limitations with the EDM process is the control of the process in order to achieve better performance. To-date the control of the process has been done using techniques that relate EDM settings such as current intensity, pulse duration and others. Research has shown however, that these techniques must be study directed towards the effect caused by those on the EDM phenomenon. The object of this research is to assess a main cause of the EDM process control related with the use of EDM settings control and demonstrate developing techniques that can be used during the manufacture process to reduce the number of tools need to produce the cavity. To do this a comparison of the two stages of an optimisation process was undertaken to identify the attributes causing effects on Tool Wear Ratio (TWR). From these attributes it was discovered the effect of black layer on tool surface composed by migrated materials from workpiece and dielectric. The black layer was characterised and a number of empirical models were developed relating the migrated materials and TWR.

Abstract (EN): The Electrical Discharge Machining (EDM) process was developed to produce cavities in hard metals which were impossible to be manufactured. One of the main limitations with the EDM process is the control of the process in order to achieve better performance. To-date the control of the process has been done using techniques that relate EDM settings such as current intensity, pulse duration and others. Research has shown however, that these techniques must be study directed towards the effect caused by those on the EDM phenomenon. The object of this research is to assess a main cause of the EDM process control related with the use of EDM settings control and demonstrate developing techniques that can be used during the manufacture process to reduce the number of tools need to produce the cavity. To do this a comparison of the two stages of an optimisation process was undertaken to identify the attributes causing effects on Tool Wear Ratio (TWR). From these attributes it was discovered the effect of black layer on tool surface composed by migrated materials from workpiece and dielectric. The black layer was characterised and a number of empirical models were developed relating the migrated materials and TWR. These models show that carbon is the most important migrated material to reduce the TWR. It was identified the stage of the EDM process where carbon is more important to reduce the TWR. Identified the carbon effect on TWR were identified the EDM settings that more contribute for the variation of the amount of carbon. To demonstrate the improvement of the TWR aused by the carbon influence it was used a new technique. This technique uses the black layer as coating of the tool surface. In the technique was possible due to the use of EDM settings that maximise the amount of carbon during the beginning of the experiment. A better understanding of the EDM process control has now been achieved and a new EDM two-stage process has been developed.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 135