In order to improve the utilization of jet energy,an experiment was conducted with a kind of polymer(PAM) added into the injection abrasive water jet for cutting.The roughness of machined surface was measured by mitutoyo surftest to evaluate the influence of PAM concentration on the surface quality.The results showed that the roughness of machined surface shaped by abrasive water jet with PAM slightly decreased at first and then remarkably increased with the increase of cutting depth.Meanwhile,the roughness formed by abrasive water jet without PAM had a similar tendency.Furthermore,it was worth noting that the roughness was significantly reduced when the PAM concentration arrived at 400 mg/kg,where the drag reduction effect was remarkable.When the PAM concentration came up to 600 mg/kg,the optimal surface quality was obtained because of the occurrence of the maximum drag reduction effect.At that point,the viscoelastic stress of polymer showed good match with the energy level of most small vortexes.In addition,the effect of PAM concentration on the roughness became more and more remarkable with the increase of standoff distance or feed rate,such behavior was of great importance in optimizing the operating parameters of water cutter so as to improve its efficiency.Also,the kerf width of workpiece along cutting depth gave a minimum change at the PAM concentration of 600 mg/kg.It was concluded that the appropriate PAM concentration increased the energy of the jets,and greatly improved the cutting ability.
