Waterjet Cutting: Diamond vs. Ruby Orifices
When should you use a ruby orifice or diamond orifice with your waterjet? Though either can be used, the answer depends upon the environment the machine is working in, along with a number of other considerations.
Should you use ruby or diamond orifices with a waterjet? That answer depends on the environment the machine will be working in and a number of other issues.
Cost is a major factor in deciding between the two. A ruby (or sapphire) orifice costs in the $15–20 range. These orifices can last anywhere from zero to 40 hours. If proper break-in procedures are not used, a ruby orifice could fail the first time you turn high pressure water on. Following a recommended break-in procedure can help you to avoid orifice failure. Unfortunately, even with proper break-in, the life of a ruby orifice is highly variable.
Currently, diamonds cost around $425. With proper water quality and a thimble filter installed at the cutting head, diamonds are guaranteed to last for at least 600 hours. The thimble filter is a very small, very fine filter that is located above the orifice to trap any debris before it gets to the diamond orifice.
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Here are some reasons to choose a diamond orifice:
- Because of their long life, diamonds offer a major benefit when cutting long-running jobs, especially those out of very expensive materials. For instance, a 6 in thick Inconel part that takes 20 hours to cut would probably be a poor candidate for a ruby orifice that could potentially fail before the cutting program is complete.
- When cutting with multiple cutting heads, diamonds are a benefit because you can plan to change them all out at one time, once or twice a year (depending upon usage). Just imagine trying to cut with four cutting heads equipped with ruby orifices: the ruby in head one lasts 19 hours, the ruby in head two lasts for 24.7 hours, the ruby in head three lasts 12.5 hours and the ruby in head four lasts 43 hours. You can either change all four out when the first one fails or you will end up changing an orifice every couple of hours.
- Stream quality with a diamond is better than ruby or sapphires, and as a result, cut quality is smoother.
There are also reasons to choose a ruby orifice. If none of the benefits of diamonds listed above applies to you or if you are frequently changing nozzle/orifice combinations, you may find it better to stick with rubies.
In a job shop or short-run environment, rubies may be a better choice because every time you take the cutting head off the machine to change the orifice/nozzle combination, you increase the risk of debris getting to the orifice that could cause damage.
Also, every time the operator changes the orifice, there is a chance that it may accidentally drop in the waterjet tank. (Note: Always change the orifice and nozzle away from the machine to avoid this.) Dropping a $20 ruby orifice in the tank, while unfortunate, is not heart breaking. Conversely, dropping a $425 diamond orifice in the tank would drastically impact your potential profits on a job.