In Waterjet, Fast Cutting Found at Lower Pressure

In abrasive waterjet machining, does higher pump pressure translate to faster cutting?
Power is proportional to flow times pressure, he notes. As a result, “for a given electrical input power, any increase in pressure must be matched by a decrease in volume flow rate. This means that a higher-pressure pump must use a nozzle with a smaller orifice.” Thus, the 50-hp pump that would use a 0.014-inch nozzle orifice at 60,000 psi is constrained to a 0.010-inch orifice at 90,000 psi,

Water jet cutting machine

In waterjet applications in soft materials where the water alone does the cutting, a smaller-diameter jet stream might be more effective. But in abrasive waterjet applications, it’s the abrasive doing the cutting rather than the water. The water’s role is to accelerate the abrasive particles. A smaller-diameter stream “actually carries less momentum for entraining and accelerating abrasive particles than a lower pressure jet of the same horsepower

Water cutting products

Efficiency might be the better indicator of cutting performance. That is, how well motor power is converted into power at the nozzle. A direct-drive pump delivering 60,000 psi features lower efficiency losses than pumps designed to achieve higher pressure, Dr. Olsen says. This means less of the power of the motor is wasted as heat. He says a 50-hp direct-drive pump can deliver about 45 hp to the nozzle. Higher-pressure pumps potentially impose greater power losses than this. They also impose costs related to the added strain of the higher pressure on the machine’s valves, tubes and fittings. Because of all of these costs, he argues that there is significant value in discovering just how much cutting performance a 60,000-psi waterjet machine can deliver