ALTERNATIVE METHOD FOR THE EVALUATION OF THE ABRASIVE WATER-JET CUTTING OF GREY CAST-IRON

A method has been developed and used for estimating the erosion debris size, D, and the contact number, C-N, for material erosion by abrasiv e water jets with velocities of up to 370 m/s. Based on abrasive water -jet cutting tests on grey cast iron samples, and on measurements of t he particle sizes of the removed material debris, the contact number i s calculated as the ratio of the number of removed material particles to the number of impacting abrasive particles, the contact numbers ran ging between C-N=3 and C-N=11. It is found that the contact number inc reases linearly with the abrasive particle velocity in the medium velo city range, but for very low and very high abrasive velocities the con tact number is less influenced by the abrasive velocity. A model is de veloped for approximating the contact numbers for various cutting cond itions. Estimated high contact numbers suggest that a complex impact e rosion process may occur which is associated with the formation of a m icrocrack network by solid particle impact and the widening of the cra cks by a high-speed water flow entering the crack. (C) 1997 Elsevier S cience S.A.