Flow's preventive maintenance service includes an exchange program for high pressure pump components, a consumables package and maintenance inspections.Click image to enlargeby Noelle Stapinsky

Advancements in waterjet pump technologies are improving pressure delivery 

 

Waterjet cutting systems have become a tried and true technology over the years, but advancements in pump technology have evolved these robust cutting solutions, ridding them of their generic application reputation. And while many will argue direct drive versus intensifier pump technology, most agree that both have a rightful place in the market. Choosing the right pump technology boils down to the application and what the user is trying to achieve. And today, suppliers are offering a wide range of waterjet cutting systems designed for a variety of applications. 

“Some customers shop for pumps and systems online and feel they know exactly what they need, but we will always ask customers what they want to achieve as they may not be looking at the best machine for their particular application,” says Sean Schramm, Shape Technologies’ director of product management. “We want to know what their plans are with the waterjet today and where they see themselves in five years. We will align the customer with a pump or system that has a matching upgrade path, allowing the equipment to grow with their business. There are a lot of solutions available.”

Hypertherm's HyPrecision Predictive waterjet pump line incorporates the company's Seal Maintenance Technology. Click image to enlargeShape Technologies represents several waterjet manufacturers, such as Flow, KMT and H2O Jet. Using Flow as an example Schramm explains that these cutting systems come in a wide range—from small entry-level to large systems for more advanced markets. “These systems range in horsepower, from 30 up to 200 horsepower, and have pressure ranges of 40,000 psi up to 94,000 psi,” he says. “We don’t try to shoehorn a customer into a particular product. We have pump systems to meet every need.”

Strategic Service
As with any machine, maintenance and service are essential. But according to John Caron, Hypertherm’s waterjet marketing manager, it’s always been difficult to predict when waterjet pumps require service. There is a certain amount of weepage through the seals that is normal and the operator can continue cutting, but if it becomes too great, production can come to a grinding halt and the shop is faced with unplanned downtime while it services the system. Another costly issue that occurs frequently is when operators preemptively change the seals.

“That’s kind of like leaving money on the table,” says Caron. “There are two ends of the spectrum here. You’re either changing seals too soon and you’re throwing away seal life, or you’re waiting too long and interrupting your operation.” 

OMAX's variable frequency drives (VFD) for its waterjet pumps rememdies pressure control.Click image to enlarge Last Fall, Hypertherm unveiled its HyPrecision Predictive waterjet pump line, a new system that incorporates its Seal Maintenance Technology. “All waterjet pumps leak some water and oil due to the very high pressures that are involved. That is very typical. But what we’ve done with the new line is put a catching mechanism under the intensifier to capture all of that fluid to monitor the leakage,” says Caron. “There’s a green standing light on the waterjet, and when the rate of leakage increases beyond a certain threshold, the light turns yellow and blinks. This is an early warning that maintenance needs to be scheduled sometime in the next few days.”

Caron adds, “it doesn’t increase the seal life, but it does improve seal utilization from 10 to 40 per cent.”

Two years ago, Flow launched its FlowCare Complete, a preventive maintenance program that includes an exchange program for high pressure pump components, a consumable package and maintenance inspections. “Instead of having major components rebuilt in the field, we pull the entire piece and have it professionally rebuilt by Flow technicians,” says Schramm. “Many customers want to know how much it’s going to cost to operate their waterjet. That can depend on a lot of things. But with any of these aftermarket service packages, which we tailor to the customer’s needs, it’s a fixed cost for the year. We are trying to change the market because it has been trained to be self-sufficient. We do not expect our customers to be experts. My goal is to allow the customer to focus on growing their business, and we will focus on optimizing their waterjet. We will do the maintenance and the performance optimization.” 

Part of the process
Waterjet intensifier pump manufacturers have also made huge advancements in reengineering components and parts to make them easier to service. 

To further reduce the operating cost of its intensifier pumps, Hypertherm has been focused on redesigning component parts. “We’ve taken about 10 per cent of the parts out of our new line,” says Caron. “We look at every critical component and see if it could be consolidated.”

A couple of years ago Hypertherm was looking at what they could do to increase production time. Seal life was a main focus as it’s the number one maintenance item with waterjet systems. “But once we looked beyond that, we focused on reducing the number of parts, which resulted in an increase in the overall reliability,” says Caron.

Of course, waterjet pressure control is also top of mind for manufacturers and operators alike. Cut consistency is paramount, especially when it comes to abrasive waterjet cutting processes. 

OMAX's variable frequency drives (VFD) for its waterjet pumps rememdies pressure control.Click image to enlargeSchramm says even though abrasives appear relatively inexpensive when you look at the cost per pound, many people don’t consider the entire process. “Abrasive has to be loaded into the system, the spent abrasive has to be captured in a catcher tank, the captured abrasive has to be removed, and finally it is disposed of. All of these steps consume time and money. We decrease the total abrasive used, and cost, by increasing the cutting pressure. By doing so, we actually decrease the size of the waterjet stream itself, focusing the cutting energy into a smaller area, which requires less abrasive and cuts faster. Increasing pressure has opened up applications that were traditionally abrasive waterjet applications. By increasing the pressure to 90,000 psi or higher, we can get away from abrasives altogether and just use water for certain materials.” 

For OMAX, which provides a full line of direct drive waterjet pumps, understanding high psi issues at the pump and waterjet nozzle has allowed it to address overall efficiency in the cutting process—a concern for most operators. To remedy pressure control, OMAX has added variable frequency drives (VFD) to its line of waterjet pumps. 

“VFD technology has been around for years, but it’s an important advancement in pump efficiency,” says Raga Raghaven, high pressure pump supervisor for OMAX. “The VFD allows for a smoother operation of abrasive waterjet cutting and adjusts its rpm to compensate for variations in seal and check-valve wear over the life of these parts and keeps the pressure constant. Without this technology, direct drives would have to run at a high speed all of the time, and dump water in order to ensure constant operating pressure. Thus, the VFD helps reduce overall energy costs.”

To further improve cutting consistency, Hypertherm has also incorporated a closed loop proportional pressure control system as a standard technology in its new HyPrecision line. It works similar to an automotive cruise control. “We have sensors that continuously monitor the pressure developed by the pump. Without a feedback loop to facilitate adjustments, a drop in pressure would decrease your cutting speed and quality of cut, while cutting at too high of a pressure can reduce your components’ life. The proportional pressure control system monitors pressure and makes the necessary adjustments to ensure you’re cutting at the pressure you deemed appropriate during your initial setup.”

As more manufacturers continue to dial in on pressure delivery and cutting efficiencies, as well as making the unpredictable predictable with preventive maintenance monitoring systems, waterjet technology is seemingly experiencing resurgence as a flexible, cost effective cutting solution on the shop floor. SMT

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