Waterjet cut quality and the role of the cutting head explained
As is true with plasma, when cutting with a waterjet system, there are several things that combine to impact your cut quality. You need to have a well designed system with a solid table, an advanced CNC and torch height control, software, and a pump.
The cutting head is also an important component. Here we look at five things that impact cut quality.
1) Length of the abrasive mixing tube: Generally, longer is better with an optimum length of between 3 and 4 inches.
2) Component alignment: It's important that your orifice, mixing chamber, and nozzle be precisely machined and carefully assembled as poorly aligned parts will give you problems.
3) Orifice shape: We talk a lot about the importance of precision manufacturing with it comes to our plasma and laser consumables. The same is true with waterjet. If your orifice isn't perfectly round, the stream of water shooting out of it, will not be round either.
4) Orifice size / stream diameter: Smaller orifices produce smaller diameter streams and the best cut quality. Keep in mind though that smaller orifices also translate to slower cut speeds. The trick is finding the right balance.
5) Stand-off distance: Again like plasma, you want your cutting head to be close, but not too close, to the workpiece. The sweet spot is between 0.040 and 0.060 of an inch (1 mm to 1.5 mm).