November 2019 – Manufacturers evaluating intensifier and direct-drive high-pressure pumps should also consider the benefits of electro-servo.
Any manufacturer seeking a new waterjet cutting machine faces a critical choice early in the research process: whether to invest in a direct-drive or intensifier pump. Techni Waterjet offers a third option that combines the advantages of both.
The two traditional types of waterjet pumps draw, pressurize and eject water by moving a piston-plunger assembly back and forth within a sealed chamber. The difference lies in the mechanism used to drive the plunger. Direct-drive models use three cylinders driven directly by the crankshaft of an electric motor, whereas intensifiers use the electric motor to generate hydraulic oil pressure, converting it to water pressure through a reciprocating motion between two opposing cylinders.
Intensifier pumps can deliver higher operating pressures, can support multiple nozzles and can be “dead-headed” by holding pressure without any water being displaced. Dead-heading pauses the cutting operation. However, it can result in pressure spikes of up to 10 percent, which may harm components and cause failure in high-pressure piping and fittings. Intensifier pumps are typically not as efficient and are larger and noisier than the smaller direct-drive crankshaft pumps.
Although they are more efficient than intensifier pumps, direct-drive crankshaft pumps cannot dead-head and must displace water whenever the motor is on by dumping it over a relief valve to drain. They are not practical for multiple heads or varying orifices, not suitable for running varying pressures, and less reliable due to their high plunger piston speeds.
Techni Waterjet, in business for 30 years, developed its own pump.
“We knew we weren’t going to make another intensifier pump. That technology has been around since 1975 and hasn’t really changed,”
Techni Waterjet Managing Director Darren Reukers says.
“During the design stage, I came up with the idea to get rid of the hydraulic cylinder used in traditional intensifier pumps and replace it with a servo motor. We had experience building our own servo motors … in house.”
Replacing hydraulics with servo motors is not a new concept. The direct servo technology was first applied by NASA for the space shuttle program by replacing hydraulic cylinders with highly compact, efficient, reliable and infinitely controllable servo linear actuators.
“The biggest advantage for most customers is probably the considerable noise reduction compared to traditional systems,” Reukers explains. “But [Techni’s] Quantum ESP is also the only waterjet pump that uses only the power required for any given pressure and flow rate.”
The pump is about 90 percent efficient because it is only working when producing water that is expelled from the head. So, on an average machine, “you are talking about a 60 to 70 percent improvement in energy efficiency over an intensifier pump.”
Other advantages over traditional waterjet pumps include up to 75 percent less cooling water requirement, as well as long-lasting fittings and tubing, due to the elimination of dead-head pressure spikes; easy maintenance; and a 50 percent footprint reduction.
The ESP actuator is widely controllable and was designed to easily adapt to other pumping applications. Quantum NXT, at its fourth generation of development, has been applied successfully in other industries, like robotics for vehicle manufacturing.
Aztech Cutting Solutions was accustomed to operating a standard hydraulic intensifier on its first waterjet machine, but when the company swapped that out with the Quantum NXT (ESP), its savings increased. Coupled with energy savings Aztech realizes by using solar power, the Quantum NXT (ESP) helps the shop save between $12,000 and $16,000 each year on electricity, says Aaron Chambers, co-owner.
The company cuts multiple materials, from 50-mm-thick Bisalloy steel on one waterjet to 2-mm-thick aluminum on the second waterjet, to 20-mm-thick marble on its third twin-head waterjet. Aztech has added a PAC 60 five-axis cutting head to one waterjet for bevel cutting and taper compensation. In total, Aztech operates four waterjets and seven cutting heads.
The Quantum NXT servo pump can be retrofit to any brand of waterjet machine. So all waterjet operators can benefit from the efficiency and ease of maintenance engineered into this pump technology.
Jim Fields is U.S. national sales manager for Techni Waterjet. He has more than 25 years of relevant experience, including working three years with Dr. Mohamed Hashish in the R&D Centre for Advanced Waterjet Technology at Quest Integrated Inc. He has helped many companies advance their understanding of ultrahigh-pressure waterjet cutting.