Study on the machining performance of Ti6Al4V titanium alloy by negative polarity Near-dry electrical discharge milling

• This paper focuses on the experimental study of negative polarity processing of titanium alloys. Affected by the bombardment of different particles in the interpolar channel, compared with positive polarity processing, the material removal rate (MRR) of negative polarity processing is reduced by 80%, the electrode wear ratio is increased, and the surface roughness (Ra) value is reduced by 50%, showing better surface quality. • Based on orthogonal experimental data, the correlation between different parameter combinations and process indicators was analyzed to explore and study the process characteristics of negative polarity machining. • The gray correlation analysis (GRA) method was used to analyze and obtain the multi-objective optimal processing parameter combination that comprehensively considers multiple optimization indicators. That is, the combination of current of 2A, duty cycle of 40%, air pressure of 0.4 MPa, and atomization volume of 10ml/min can effectively improve processing efficiency and surface quality. Near-dry electrical discharge milling (EDM) technology is a green machining technology variant of electrical discharge machining, and there is also a phenomenon of processing polarity effects where positive and negative polarity machining produce different results. This paper focuses on the experimental study of negative polarity processing of titanium alloys. Affected by the bombardment of different particles in the interpolar channel, compared with positive polarity processing, the material removal rate (MRR) of negative polarity processing is reduced by 80%, the electrode wear ratio is increased, and the surface roughness (Ra) value is reduced by 50%, showing better surface quality. The One-factor-at-a-time (OFAT) method was used to explore and study the influence of milling thickness on various process indicators. Based on orthogonal experimental data, the correlation between different parameter combinations and process indicators was analyzed to explore and study the process characteristics of negative polarity machining. The gray correlation analysis (GRA) method was used to analyze and obtain the multi-objective optimal processing parameter combination that comprehensively considers multiple optimization indicators. That is, the combination of current of 2A, duty cycle of 40%, air pressure of 0.4 MPa, and atomization volume of 10ml/min can effectively improve processing efficiency and surface quality.