Study on kerf characteristics and surface integrity based on physical energy model during abrasive waterjet cutting of thick CFRP laminates

Abrasive waterjet machining was an effective method for cutting CFRP materials in various industries, while machining defects are inevitably observed especially for thick CFRP laminates due to the inherent characteristics of waterjet. In this work, a full factorial experimental array was employed totally involving 18 trials when using abrasive waterjet to cut CFRP laminate up to 10.0 mm thick. The influence of process parameters including hydraulic pressure, traverse speed, and stand-off distance on jet energy was deeply analyzed and the power-to-speed ratio ((E)over dot/u) parameter was obtained, which was combined with the physical energy model of abrasive waterjet based on the energy method. The influence of process parameters on kerf characteristics/surface integrity and the mechanism of defects were further analyzed. Various surface defects along thickness direction were observed and corresponding mechanisms were investigated. Results showed that higher hydraulic pressure, lower traverse speed, and stand-off distance within in the selected range were preferred to obtain better surface quality. From the perspective of power-to-speed ratio ((E)over dot/u), the surface roughness decreased rapidly up to similar to 68% with (E)over dot/u increased from 20,000 to 40,000 J/m. When it exceeded 40,000 J/m, the downward trend gradually reduced and even became stable in the case of high stand-off distance. The level of kerf width generally increased with the increase of (E)over dot/u irrespective of stand-off distance.

Automated summary

Abrasive waterjet machining is an effective method for cutting CFRP materials, but machining defects are often observed, especially for thick CFRP laminates. This study utilized a full factorial experimental design to analyze the influence of process parameters on jet energy and the mechanism of surface defects. Results showed that higher hydraulic pressure, lower traverse speed, and stand-off distance within the selected range were preferred for better surface quality. Moreover, the power-to-speed ratio had a significant impact on surface roughness and kerf width.