Research on precision pulse power technology of WEDM

High speed wire electrical discharge machining (WEDM-HS) has been an extremely important and irreplaceable means of processing precision parts in aerospace, mold and other fields owing to its unique advantages. The pulse power is the key component of the WEDM, which directly restricts the improvement of WEDM overall performance. At present, the pulse power used in commercial WEDM-HS equipment, whose processing surface roughness and machining accuracy are low, is generally applied to rough machining. This paper develops a multi-mode precision pulse power based on micro controller unit (MCU) and double complex programmable logic devices (CPLD), of which electric parameters can be widely adjusted. Effects of capacitance on achievable processing thickness and surface roughness are analyzed under controllable resistance and capacitance precision pulse power mode. By properly selecting capacitance to make triple of charging time equal to pulse duration, the best surface roughness and minimum single pulse energy are obtained when pulse duration, pulse interval and current-limiting resistance remain constant. The paper also analyzes and optimizes the parameters affecting surface roughness and processing speed through orthogonal experiment. Then five-cutting experiments are conducted using the optimized machining parameters, obtaining that the best surface roughness reaches 0.96μm when workpiece thickness is 40mm.