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3-D waterjet software ingredients are the right mix for easy operation

Figure 1
A 3-D soccer ball part was created using two separate domes that were pathed and cut separately using OMAX software and welded together. Photo courtesy of OMAX.

Companies with the staff, time, and budget have been programming articulating 5-axis waterjet heads for 2-D and 3-D tables for decades. When these heads were first introduced, knowledge of multiple software packages was required to complete the electronic communications flow, and complex computations were needed to position the nozzle to accomplish accurate angles while eliminating the natural taper of the cut.

Each additional axis added variables to the process. Material thickness changed as the cutting angle changed. The material thickness shift affected the cut speed and edge quality. Experience, knowledge, and patience were needed to build a program to produce 3-D shapes. The capability was there, but executing the process was a chore.

As technology progressed, the 5-axis revolution was ushered in. Waterjet bevel cutting became common, and smaller shops with limited staff, time, and budget began cutting bevels and simple contours.

Just a Few Clicks

Recent software advances continue the progression. Technology tables to bridge software communications gaps and complete complex computations have been developed to simplify both the programming and operation of 3-D cutting (see Figure 1). The process has moved from being a time-consuming chore to a couple of clicks, and from requiring extensive process and software knowledge to being operator-friendly.

Overall time to produce a 3-D part has been dramatically reduced because the software does the heavy lifting. 3-D features have morphed from a fairly straightforward weld surface to complex components like blades that have multiple thicknesses and angles on a single length. And accuracy has improved.

Jerry Thomas, software supervisor for OMAX Corp., Kent, Wash., said, “The mechanics of water and abrasive cutting haven’t changed much in the last few years. What has changed is the computational accuracy and the complexity of the parts that can be produced.”
A major software change is the ability to work with nearly any CAD/CAM file. Three or four mouse clicks will open virtually any file format, rotate it in full 3-D rendering, and export the selected section of the drawing for cutting.

“A couple of years ago we would go in and manually program the system to change the Z height or the angle for a complicated part, but it was tedious,” Thomas added. “Our most recent software, Intelli-CAM®, has all the tilts and bevels done automatically. It takes in the major 3-D CAD formats and translates the files.”

Brian Kent, global product manager at Flow International Corp., Kent, Wash., said, “in the past you had to bring in either a 2-D DXF or DWG file and then assign an angle to the part. We just launched our FlowXpert™ integrated 3-D CAD/CAM system that allows us to go beyond bevel cutting to full 3-D programming and work directly off the original solid model. It eliminates the need for a secondary program to create the 3-D model or to create the path.

“The potential for error is reduced because you are not taking a model from a customer, making a 2-D representation, and then trying to do a 3-D part. You don’t have the risk of losing data during translation.”

Selecting the correct nozzle angle for a 45-degree edge for a weld surface or a complex cut that flows from a positive to a negative angle has also been reduced to a couple of mouse clicks. Choose the material, the degree, and the type of angle and the software does the work. Nozzle position is determined, and the optimum cutting speed is recommended (see Figure 2). Change the speed and the nozzle angle will be adjusted for the taper differential.

Figure 2
Advanced 3-D software adjusts the nozzle angle and speed to compensate for material thickness changes due to cut angle. Integrated software like Flow-Xpert eliminates the need for secondary programs to create 3-D models or secondary programs to create cut paths. Photos courtesy of Flow International.

The automatically programmed nozzle movements have the tilts that will provide a beveled edge without taper and compensate for a draft angle that can occur when the cutting speed is turned up (see Figure 3). The nozzle angle to produce a 45-degree bevel may be positioned at 45 degrees plus, depending on variables.

Scott Wirtanen, northeastern regional manager at Jet Edge, St. Michael, Minn., said, “Instead of going through a lengthy process of producing a part program, you simply click and choose a particular geometry. You are detail-enabled with the capability of assigning different bevels and angles with our EDGE X-5™. You can put a positive and negative bevel all on one side of a cut as well as the contour bevel.”

Stress Relievers

Standoff between the nozzle and the material gains importance when cutting 3-D configurations. Laser premapping of the material surface, built into many newer software packages, automatically adjusts the Z axis to compensate for material height fluctuations. Mechanical standoff guides such as a terrain follower will compensate for material changes resulting from stress relief during a cut.

“If you are cutting a straight 0-degree angle and the distance from the tip of the nozzle to the material is off a little, it doesn’t make much of a difference, but as you tilt the nozzle, that changes the focal point of the stream. You have to be very precise in measuring the standoff,” said Thomas. “Either the X- and Y-axis position or the Z-axis height must be changed to keep the focal point in the correct position. Tell the software the correct information and it calculates everything.”

Wirtanen said, “When you are putting a bevel on an edge during 3-D cutting, the position of the cut will change with the material thickness and affect the geometry of the cut much more than in 2-D cutting when the nozzle is straight up and down. When you process a 10-foot-long plate, bowing or stress relieving can change the plate height dramatically. When you look at a nozzle that is angled at the proper height, the overall geometry of the part will be accurate. But if it is off by 1⁄4 inch, the actual entry point of the waterjet stream is completely different and dramatically affects accuracy.”

Added Protection

A 45-degree jet stream also requires an element of equipment protection that is not inherent in 2-D cutting. The angled stream needs to be kept at a safe distance from the walls of the tank. These computations are also handled in the background of 5-axis programs.

“If you angle too close to the catch tank, you can cut through the material, the catch tank water, and the walls of the tank,” said Wirtanen. “We have a protection zone built into our controller software so that when a programmer or operator produces a large part that is close to the edge of the tank, it provides a virtual protection zone to protect the walls and the operator. Our 5-axis machines also have catch tanks that are about 2 ft. larger in X and Y to allow full travel.”

A safety zone for the jet stream requires about 32 in. of water from the plate to the bottom of the tank to dissipate the energy of the stream in 2-D cutting, according to Wirtanen. When the stream is angled and close to the catch tank, that distance is reduced.

On the process side, the pressure keeps going up, said Kent, and that increases cut speed. “As the water pressure goes up, we can use less garnet per inch of cut, and recent advancements in high-pressure technology continue to increase component life. Seal and component life at lower pressure also continue to rise. That technology has created a kind of 3-D technology waterfall in smaller shops.”

Software advances for 3-D waterjet cutting have expanded the types and complexities of parts that can be efficiently produced in one operation (see Figure 4). But a degree of operator creativity and experience is still needed to determine if waterjet is the most efficient process and when adjustments to standard programming can be beneficial.

Figure 3
The software handles computations to position the nozzle to cut angles without taper for chamfers, weld bevels, and sophisticated parts. Photo courtesy of Jet Edge Inc.

“There are some things that job shops learn with experience, such as when to use a low-pressure pierce. Carbon fiber, for example, cuts beautifully with a waterjet when you use a pierce that might be 10,000 PSI rather than 50,000 PSI. By using the gentler start, the material is less likely to delaminate as the jet comes out the back side of the material,” said Thomas.

He added, “There are still some limitations to abrasive waterjet cutting, but it’s still one of the most versatile technologies available.”

Figure 4
Blisk parts and complex bevels and chamfers can be programmed and cut using advanced software such as Jet Edge’s EDGE-5. Photos courtesy of Jet Edge Inc.