A reader asked about Slurryjet, and why there are no ultrahigh-pressure units out there in the world today cutting in production.

First of all, let’s make sure everyone who has not studied the subject understands what we’re talking about here.  Abrasive waterjets today are created by pressurizing water, forcing it through a small jewel orifice where the pressure is converted to velocity, and then the abrasive particles are metered into a mixing chamber and accelerated like a bullet out of a rifle down the mixing tube.  Abrasive slurry jet is where a water/abrasive slurry is pressurized and pushed through an orifice.  It is inherently more efficient because the water and abrasive are going the same speed, and no momentum transfer from the water to the abrasive is taking place.