Investigation of abrasive water jet cutting parameters influence on 6082 aluminium alloy surface roughness

The paper provides the analysis of surface roughness of the workpiece cut using abrasive water jet. The main cutting process parameters are presented: the type of abrasive material, water feed pressure, the diameter of the used nozzle and the course of the cutting head. The abrasive cutting using water jet has two typical cases of the cut surface are: smooth and coarse. In the case of finished cutting the surface of the necessary roughness forms below the critical depth - in so called cutting zone. The coarse surface forms under the critical depth - in so called deformation zone. The performed tests of cutting the Al-6068 alloy workpiece with different cutting head traverse speeds revealed that due to the higher traverse speeds the cutting trace forms on the surface which are noticed in the deeper deformation layer of the workpiece cut. According to the provided results the selected of the 37.8 mm/min cutting head traverse speed achieves the roughness of the surface of R-a makes 3.9 mu m in a whole workpiece thickness of 30 mm. When the head moves by 48.9 mm/min and 68.1 mm/min speeds the resulted roughness was R-a = 4.2 mu m, but the cutting zone makes 26 mm and 22 mm respectively of the whole thickness of the workpiece.When cutting the workpiece the greater speeds such as 97.2 mm/min and 163.5 mm/min the resulted roughness makes R-a = 4.8 mu m, but the cutting depth does not exceed 16-20 mm of the whole thickness of the workpiece. The results of this study will be used for the forecast of possible surface roughness when cutting various workpieces made of aluminium.