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2-D + 3-D = 5-axis waterjet cutting The cutting technology is a gateway to Figure 1 One of the things for which articulated cutting heads can be used is to new fabricating opportunities compensate for the natural taper that occurs with a waterjet stream. By Dr. John Olsen, Contributing Writer Some articulating cutting heads were initial- ly developed for making beveled (see Figure hile five-axis operations such as 2) and angled cuts. With the advancements in bevel cutting and other weld prep machine control software, articulating heads Woperations have been possible on now can perform taper compensation to fur- abrasive waterjet machines for some time, ther improve cutting accuracy. the capability to process 3-D parts such as Some articulating heads work within the tubes and pipes on the same waterjet is rela- safety limitations of abrasive waterjet cutting tively new. This is opening up new possibili- (see Within the Limitations of Safety sidebar). ties for metal fabricators. While there are five axes of motion, the range of Shops that once focused primarily on flat the two tilt axes is controlled to a specific limit- 2-D work now have the opportunity to take ed distance so that the abrasive waterjet stream Figure 2 on 3-D work with one five-axis abrasive wa- is always shooting in a generally downward di- Most of the time bevel cuts are for weld prep. terjet machine. And those shops specializing rection toward the machine’s water tank. However, when a very deep bevel is needed for in tube and pipe fabrication can now process a large part, a five-axis abrasive waterjet can their 3-D cylindrical parts on the same type Cylinder Cutting on the Waterjet handle that job as well. of machine. Additionally, that same five-axis Currently the most common use of 2-D ma- abrasivejet machine allows fabricators to pro- chines with added articulating cutting heads cess flat 2-D parts, such as gussets and sup- is for bevels associated with weld prep and ports, that may have been previously farmed miter cuts for parts that intersect at an angle. out to other shops. They also are used to cut countersinks on Because abrasive waterjet machines cut large holes. practically any material, fabricating shops with When a bolt-on rotary axis unit is paired five-axis machine capability can broaden their with an articulating head (see Figure 3), the markets in terms of the materials they are able combination gives fabricating shops the ability to process. Shops can waterjet-cut glass and to perform five-axis operations on tubes, pipes, help customers avoid the headaches associated and other cylindrical parts. Such operations in- Figure 3 with machining these types of brittle materials. clude cutting fish-mouth shapes and other end The combination of an articulated cutting The waterjet, without the use of abrasive, can shapes necessary to join tubes or pipes to one head and a rotary chuck allows fabricators to be used to cut rubber gaskets and forms much another (see Figure 4). use a waterjet for intricate tube cutting. more quickly and cleanly than conventional cut- ting equipment. The waterjet, using low-pres- Software Makes Five-axis Cutting To make these waterjet cutting machines sure piercing, also can cut stone for architectural Work even more user-friendly, advanced control or decorative purposes. Articulating heads and rotary units provided the software has a multitude of tube- and pipe- In some instances, shops can easily and machine motion needed for five-axis waterjet cut subroutines embedded in the machine cost-effectively upgrade their existing bridge- cutting, but improvements in machine program- control. How easy is it to use? If an operator type 2-D abrasive waterjet machines by adding ming really advanced the cutting capability (see wants to program the machine to cut a cyl- software, articulating heads, and rotary units Figure 5). Early on parts could be programmed inder, he calls up the control’s subprogram to obtain full 3-D cutting capabilities. manually, but the task was very involved and ex- screen. The operator then enters the two di- tremely time-consuming. Today, however, devel- ameters of the cylinders being joined, as well Exploring the Articulating Head opers have created software specifically to sup- as the desired angle of intersection. From Articulating heads (see Figure 1) are the key port multiple-axis, coordinated machine motion there the software automatically performs all to five-axis waterjet cutting. In addition to a and 3-D part processing. With this software, the necessary calculations. machine’s X, Y, and Z axes, articulating heads shops can quickly and easily program and cut Leading programming software for these provide two tilt angles—one perpendicular 3-D patterns for several applications, from the types of five-axis machines often can link to to the X axis and the other perpendicular to peripheries of tubes and pipes, to fitting opera- other common CAD/CAM systems. This al- the Y axis. tions, to prep cuts and bevels. lows shops to program machines in software Within the Limitations of Safety A true five-axis machining system is one that moves and cuts in any direction. But in the case of abrasive waterjet cutting, do- ing so raises an important safety issue. Abrasive waterjet streams pack a lot of Figure 5 power, even after cutting through a part Several years ago, programming a waterjet to surface or periphery. So where the stream cut a complex part with multiple sharp angles is pointed and where it goes next must be and bevels could have taken a long time. Today carefully considered. Plain waterjet streams advanced machine control software makes the break down quickly in the air, but the abra- job easier by simply taking the CAD file and cre- ating the cutting path in seconds. sives in an abrasive waterjet stream do not Figure 4 dissolve and will continue moving at a high The cut may not look exotic, but the ability of jet cutting is inside diameter (ID) size. The small- rate of speed. This fact is why abrasive wa- a five-axis abrasive waterjet to deliver precise er the ID of a tube or pipe, the greater the risk is terjet machine OEMs are required to work of the abrasive waterjet stream cutting into an end cuts on a tube or pipe is very important within safety limitations and restrict the opposite part side wall while processing an end in some industries where first-time fit-up could movement of articulating heads for five- be the difference between a profitable and un- or side. To prevent such an occurrence, pieces axis machining. profitable job. of ceramic can be inserted into the tube or pipe that deflect the waterjet stream and prevent it While true five-axis abrasive waterjet packages that they are already comfortable with from cutting the opposite part surface. The use cutting systems have been around for some and using. The CAD files are then transferred to of a deflector applies only if the part ID is big time, they have been housed in special the machine control software and directions are enough. A 0.062-in. part ID, for instance, would containment rooms or enclosures lined produced for proper machine movement. not provide enough room for a deflector. with either concrete or steel to prevent Today fabricating shops typically consider the abrasive waterjet from wearing out the What Parts Make the Most Sense? five-axis abrasive waterjet cutting for process- walls. Within these systems, a stand-alone While technology advancements have simpli- ing mostly short lengths of tubes and pipes robot hanging from the ceiling points the fied five-axis cutting, certain factors must be with diameters of 1.5 in. and larger. The bulk of abrasive waterjet in any desired direction. considered before moving a part over to the these types of parts are used for interconnect- abrasive waterjet table. ing spaceframe structures. Because of safety concerns, machinists are Workpiece shapes, for example, can limit However, introductions of larger abrasive not able to be in the contained area while the use of five-axis cutting. Shops must be waterjet table sizes are enabling shops to pro- the system runs. cognizant of exactly where an abrasive water- cess longer tubes and pipes. Because minimal As opposed to a dangerous, true five- jet stream will be pointing, especially when force/torque is involved in the rotation of axis abrasive waterjet, modern articulating cutting angled features such as countersinks parts, the fabricator really only has to be con- head movement is limited to any angle on holes. If the angle of the countersink is too cerned with providing a steady rest for sup- within specific safety parameters. These small or the corresponding hole diameter is porting the long part. machines still provide five-axis movement, not big enough, the waterjet will cut into the but the abrasive waterjet stream cannot opposite side wall of the hole. Visualize coun- Fabricating for the Future be programmed to move into a position tersinking a 0.5-in.-diameter hole in a 3-in.- As more fabricating shops adopt five-axis abra- other than generally downward toward thick part as compared with countersinking a sive waterjet cutting in an attempt to diversify 3-in.-diameter hole in a 0.5-in.-thick part. their businesses, many industry experts foresee the machine’s water tank. Most fabricating shops work with part mate- the technology being used to cut new kinds of rial thicknesses of 2 in. or less. In most instances, materials—not just metals. Such a capability will shops wanting to remain relevant in the next five-axis waterjet cutting is used to create bev- prove extremely beneficial as more component 20 years will be those that continue to adapt els and angles that are 0.25 in., 0.375 in., or 0.5 in.

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