Ultra High Pressure Waterjet Cutting is a term that has been used for many years but the definition changes periodically. Back years ago I used to struggle with how to help make people understand the concept of how much pressure a waterjet operates under and came up with an idea. In rough terms if you were to take a small square wooden block that we played with as children (which is roughly 1.5″ cubed), and then if you were to take a fully loaded semi truck (the 18-wheeler variety) which in most states the weight limit is about 40 tons or 80,000 pounds and parked it on top of the wooden block, the pressure the block would put on whatever it sat on would be somewhere near the 40,000 PSI of pressure of the early waterjet cutting machines. So, now if you were to park 2 fully loaded 18 wheelers and then 1 empty 18 wheeler (just the truck and trailers without any cargo) and add an F350 4X4 Diesel Pickup on top of that the pressure under that same block would be somewhere around the pressure of the cutting stream of exiting the nozzle of a 90,000 PSI waterjet cutting machine
40 KPSI Machines
When I first started out in this business 19 years ago, most machines built before that time actually operated in the range of about 40,000 PSI (40 KPSI) of water pressure.
55 KPSI Machines
About the time that I was introduced into the waterjet cutting industry most of the new machines that were being built were 55 KPSI at that was touted as the latest technology. We used to cut up to 12″ thick Titanium with that pressure but it was a pretty slow process and tolerances were not as good as we are capable of holding now.
60 KPSI Machines
Then along about 2 years later the industry started producing 60 KPSI machines. I am not sure exactly why the jump of only 5 KPSI but that was when I first started to hearing the term of Ultra High Pressure Waterjet Cutting being used. It was the latest thing and about all waterjet cutting machines were build to either the 55 or 60 KPSI standard for the next several years.
87 KPSI Machines
Then in about 2007 the 87 KPSI machines arrived on the market. I was very hesitant about owning one of these machines as I had already been in the industry for 10 years and had a lot of first hand information as to the extremely high maintenance costs due to the very high failure rate of the high pressure components. Common sense told me that if the manufacturers were only able to make seals that would hold up for 300 – 500 hours at 60 KPSI then they would be lucky to hold up for 200 hours at 87 KPSI. From the conversations I had with operators in those early days that was about the normal lifespan of components. Then there was the fact that because they were supposedly able to stand up to the higher pressure they cost considerably more. So, due to the combination of these two factors the operating cost of the Ultra High Pressure Waterjet Cutting systems are considerably higher per hour.
90 KPSI Machines
In about 2009 another manufacturer came on the scene with a 90 KPSI machine. Once the second generation of this machine came out I started to get a little bit more comfortable with the idea of owning one and finally in 2014 we ended up getting one in our shop. It has turned out to be a mixed blessing some days and overall it definitely has its strong points as well as its weak ones. It does have a somewhat higher operating cost not as much because of the higher failure rate but because of the higher cost of the components. It obviously takes more electrical power to generate 90 KPSI than it does to generate 60 KPSI.
So while different waterjet cutting service companies use different machines and different pressure most do not have Ultra High Pressure Waterjet Cutting Machines and there is definitely a place where they have a distinct advantage. Click here to read more about the differences and or advantages of HP & UHP Waterjet Cutting.
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I love your analogy about the semi trucks when trying to explain ultra high pressure water jet cutting. When you put it in those terms, it is mind goggling how much pressure is generated by these tools! Are there projects were having a 90 KPSI machine is necessary as opposed to a lower powered machine (say 60 KPSI)? Thanks for sharing!
Actually, you can do almost any job with a 60KPSI machine that you can do with a 90KPSI machine, it will just take longer on the lower pressure machine and require more abrasive to do it. The cutting stream will also normally be larger removing more material on the lower pressure machine so that you can not nest parts quite as tight and the stream will likely not stay as tight during cuttting. So you end up with a part that will not be as tight of tolerance, taking longer to cut, thus likely costing more. All of these issues are much more pronounced in thicker material and the thicker you are cutting the more it matters. At 1/4″ thick it won’t make much difference but at 12″ thick it makes a major difference. Thanks for your comments.