Maintaining a close distance between the nozzle and the work piece, between 0.040" and 0.060" (1.0 - 1.5 mm), is critical for producing accurate parts while also getting the maximum efficiency from the waterjet. Cutting closer to the material limits the amount of atmosphere that the jet has to travel through before reaching the work piece. This limits the expansion of the waterjet stream, since as the jet expands, the effective power of the jet is reduced. Cutting speeds will need to be reduced to compensate. If the distance between the nozzle and the work piece is increased by ¼", cutting speeds must be reduced by approximately 20% to achieve similar results with respect to tolerance and edge quality. Cutting under water with CNC height control will allow for ultimate control of the waterjet stream.

See effect of nozzle height below for more information.