Speed and Quality

Below is a guide to the influence of pressure, abrasive quantity and cutting speed on the quality of cut.

As you can see the characteristic of the surface cut by a water jet is that the cutting stream at the bottom lags behind the point of entry to the material at the top, causing the characteristic curve. This effect worsens with an increase in speed and improves with an increase in pressure or abrasive flow, up to an optimum setting. Taper of the cut is also a problem which gets worse with speed and can be virtually parallel at the optimum feed rate.

See illustration below :-

The cut edge quality and parallelism, at a fixed pressure and abrasive flow rate for a particular material, are dependent on the cutting speed. It is not always necessary to produce a very high quality cut, so there are generally three types of cut that are commonly used - the separation cut in which the parameters are selected to provide the fastest possible cut, the quality cut in which the parameters are selected to give good edge and corner quality and reasonable parallelism and the high quality or precision cut in which the parameters are optimized to give a very smooth, square cut with perfect corner definition.

Speed and quality continued. Materials and cutting speeds.