In order to fabricate the micro mould cavities with complex structures on 304 stainless steel, laser-assisted electrochemical micromachining (EMM) based on surface modification by fiber laser masking was studied,and a new device of laser-assisted EMM was developed. Laser marking on the surface of 304 stainless steel can first be realized by fiber laser heating scanning. Through analysis of X ray diffraction analysis (XRD), metal oxide layer with predefined pattern can be formed by laser marking, and phase transformation can also occur on the 304 stainless steel surface, which produce the laser masking layer with corrosion resistance. The stainless steel surface with laser masking layer is subsequently etched by EMM, the laser masking layer severs as the temporary protective layer without relying on lithography mask, the fabrication of formed electrodes is also avoided, so micro pattern cavities can fast be fabricated. The impacts on machining accuracy during EMM with laser masking were discussed to optimize machining parameters, such as machining voltage, electrolyte concentration, duty cycle of pulse power supply and electrode gap size, the typical mould cavities 23μm deep were fabricated under the optimized parameters.
This paper describes a new method of die surface modification by ordinary Electrical Discharge Machining (EDM) tool.
First, the principle of this method is studied. Secondly, the reason for appearance of cracks on the surface of coating
layer in the electrical discharge coating with conventional pulse power supply are analyzed. At last, the new type special
pulse power supply with additional pulse current is designed. Scenix single-chip is selected as pulse generator, which
runs the fastest among all single-chips. The corresponding program can make the pulse power supply produce the
additional pulse current. At the same time, the special pulse power supply can communicate different machining
parameters with industrial personal computer by serial port of PIC single-chip according to the coating requires, and then
PIC single-chip convey machining parameters to Scenix single-chip by the communication interface. Through process
experiment, the special pulse power supply for electrical discharge coating behaves well, and the compacted coating
layer without cracks deposited on the surface of die by EDM can be obtained, which can prolong the life of die.