In the world of abrasive waterjet cutting, the nozzle is where all the proverbial magic happens. It’s here that the high-pressure water makes its way to a jewel orifice that focuses the water into a thin beam. The water beam then enters the mixing tube where the cutting abrasive is introduced to the stream. The water and abrasive then exit the nozzle, ready to cut.
Historically, most abrasive waterjet nozzle assemblies used a removable orifice with a ruby, sapphire or diamond focusing jewel. The orifice in these non-integrated nozzles is taken out and replaced as part of routine maintenance, or if the jewel is damaged or broken.
The three different orifice jewels, ruby, sapphire, and diamond, wear out at different rates due to the difference in material hardness. While both ruby and sapphire are hard relative to other materials, rating 9 out of 10 on the Mohs scale, they are both softer than diamond, which ranks a perfect 10. When taking into account the absolute hardness of the materials, diamond is actually four times harder than ruby and sapphire. Ruby and sapphire, also known as corundum, don’t last nearly as long as diamond when exposed to the harsh conditions of abrasive waterjet cutting. These corundum orifice jewels are very susceptible to cracking and wear from foreign particles, limiting their lifespan to about 40-60 operating hours before needing replacement.
Conversely, diamond is a much harder, more reliable orifice jewel, able to withstand more of these particles lasting for approximately 1000 hours of use. The diamond’s hardness allows the orifice to retain its shape many times longer than ruby or sapphire, resulting in a more cohesive abrasive water stream, which better collimates (makes parallel) the abrasive particles. The collimation reduces the amount of stray abrasive particles breaking out of the stream and impacting the mixing tube. OMAX MAXJET5i and other integrated nozzles use diamond orifices exclusively because of their proven reliability and cost-effectiveness. The diamond orifice’s reliability and long operational life make it possible to achieve longer cuts, even some which span multiple days, without the need to change out the orifice. With a corundum orifice jewel, the orifice may need to be replaced midway through the cut, potentially resulting in a scrapped or damaged project.
Although a non-integrated nozzle gives the machine operator the ability to use different sizes and types of orifice jewels in the same nozzle, in most cases, the benefits of using an integrated nozzle vastly outweigh this flexibility. For example, during the manufacture of the MAXJET5i integrated nozzle, OMAX technicians fix the diamond orifice to the inside of the nozzle using precision alignment tools so the jet stream is centered exactly in the mixing tube. The abrasive water stream makes only minimal contact with the mixing tube. The mixing tube typically lasts for 60-100 hours of operation in an integrated nozzle. With non-integrated nozzles, there is a good chance the orifice will be positioned slightly out of alignment during maintenance or replacement, leading to dramatically faster wear and a considerably shorter lifespan of the mixing tube. The precision alignment in the integrated nozzle also allows the beam to maintain its shape, producing a much cleaner, more accurate cut. An incorrectly aligned orifice will cause the jet stream to warp and produce less accurate cuts.
Non-integrated nozzles require rebuilds when the orifice needs to be swapped out or re-aligned. With a ruby or sapphire jewel, the orifice may need to be replaced once every three weeks. The nozzle rebuild can be a lengthy process and may mean down time for the waterjet if there’s no spare nozzle. Plus, as with any small removable part, there’s a chance the orifice could be lost or even dropped in the catcher tank. All this is eliminated with an integrated orifice since there’s no rebuild required. The harder diamond orifice will last much longer than the weaker jewels, and at the end of the orifice life, users can simply replace the full nozzle assembly. Down time is minimal and you can keep your machine productive. Some may be hesitant about the idea of replacing an entire assembly when only a single part has been worn, but this limits several issues that arise when constantly taking the nozzle off to replace the orifice. Any time the nozzle is removed there is a chance for garnet or other unwanted particles to break loose and enter the assembly. These particles could damage the orifice, causing it to crack or wear, distorting the jet stream and ruining the cut. Also, by only replacing the orifice in the nozzle assembly, the assembly itself will start to wear. Wearing of the assembly can cause distortion of the orifice housing which will adversely affect the cutting accuracy. With an integrated nozzle, once it’s attached it doesn’t need to be removed except when switching to a different nozzle or replacing it with a new one.
Diamond integrated nozzles are improving the abrasive waterjet industry by making it more accurate and improving cost effectiveness. The benefits of an aligned integrated nozzle allow the user to perform more precise cuts while reducing maintenance and possible damage. Utilizing the reliability of the diamond orifice with the potential to reach 1000 operational hours leads to opportunities for cuts spanning days using a single orifice. For those that have been hesitant to upgrade, OMAX has a 500 hour warranty on the integrated nozzles to help make the switch even easier.