Experimental Investigation On Laser-Low Pressure Medium Jet Compound Machining

The water jet machining and laser etching have been developing with a high speed over the past30-40years, they are the quite ripe industries now. Due to its good processing superiority, they are widely used in microelectronic device fabrication and precision machining industry. Laser-low pressure medium jet etching processing bases on the water jet machining and laser etching technology, it combines laser etching, jet-assisted erosion and chemical corrosion; The processing principle of the technology is studied, laser processing is the primary means of processing, the jet machining and the chemical corrosion are used to removal the slag and debris as two auxiliary methods in the laser processing, it can eliminate micro-crack of brittle material surface due to laser thermal stress, and improve the quality of the machined surface.We have invented the following method about Laser-low pressure medium jet etching processing:a corrosive medium solution is changed into a low pressure jet through high-pressure pump plunger, it can machine simultaneously on the sample such as silicon, fine ceramics, quartz and high-alloy hard material with the laser beam. In order to achieve the fast processing of difficult materials, the technology takes full advantage of the high-density laser energy ablation and a certain pressure of corrosive media solution. The solution of a certain pressure scour the surface slag, and reduce the machined surface roughness. The liquid medium has a cooling effect during processing, and it can reduce the temperature gradient of the machined surface, avoid micro-cracks due to thermal stress in the machined surface of brittle materials.To achieve the above purpose, we carried out the following tasks:(1) A test system is self-developed, the device includes laser processing section and jet machining part. It can ensure that the jet pressure immediately is adjusted, jet media can recycling and the jet beam and the laser beam are well focused on one point, the processing ensures that jet and laser beam can basically reach the machined region and achieve the synchronization processing.(2) Experiments on Laser-low pressure jet composite processing of Al2O3ceramic material in different media (H2O and KOH solution) have been studied. We have a research about compound machining on ceramic etching amount and etching quality through the different process parameters (laser energy, laser pulse width, laser repetition rate, media concentration, jet pressure).The results showed that:compared with laser ablation, water-jet and KOH solution-jet have a marked increase on etching amount and the surface slag is significantly reduced and the etching quality has greatly improved. KOH solution-jet compound etching has a certain degree of improvement in the etching and etching qulity than water-jet compound etching.(3) By the experimental study of laser-low pressure water and HCl solution jet composite processing of W18Cr4V stainless steel material. We can know about that: with the laser energy and pulse width are gradually increased, the combined etching capacity is greater than before and the surface has the trend of gradual improvement; The etching capacity has increased firstly and then decreased with the repetition rate increasing, the quality of machined surface is better than before; The higher the concentration of the liquid and the greater the pressure of the jet beam, the combined etching capacity is greater increased,and the quality of the machined surface is best.This experiment provide a method to achieve millimeter cutting, drilling and slotting processing of difficult materials, and it can eliminate the processing of surface microcracks, the heat-affected zone and slag,it is a clean and efficient processing, the method also provides a dedicated processing device.