ULTRASONICALLY AIDED LASER DRILLING OF PARTICLE-REINFORCED ALUMINUM-BASED COMPOSITES

An ultrasonically aided laser drilling technique has been developed to raise the performance of traditional laser drilling on metal matrix c omposite materials. In the process, the workpiece is rigidly attached on top of a transducer which vibrates at a frequency of 20 kHz. Ultras onic vibration has significantly increased liquid expulsion in laser d rilling. For blind hole drilling of an aluminium alloy 2124/SiC compos ite, the thickness of the recast layer was reduced greatly by about 30 -80% at different segments of the hole. In the recast layer the size a nd the amount of carbides were reduced when vibration was employed. Mo reover, the depth of drill can be increased by as much as 20% when vib ration was used. In through hole drilling of some 0.6-1.2 mm thick mat erials the recast layer was virtually removed and a reduced heat affec ted zone was obtained with no apparent deposition found at either end of the hole. Also the diameter of the through hole became more uniform . MST/4022.