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Waterjet Group -> General Chat & Discussion -> Waterjet cutting in New Zealand
Post Info TOPIC: Waterjet cutting in New Zealand
rd400f


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Waterjet cutting in New Zealand
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Hi
We have a Kinetic Water-jet that runs two KMT AUTOLINE II cutting heads.
Being new to water cutting and not having many people to bounce ideas off here in New Zealand. I want to ask if anyone has ever had a problem like the one we ran into this week.
Basically we were cutting 25mm mild steel using a 0.025mm Diamond and a 0.762mm focusing tube. Garnet is 80 grit.
This setup was cutting fine for about 6.5 hrs and then for no obvious reason the jet stopped cutting through.
In fact it was so bad that ,using the 25mm mild steel settings ,we could not even cut 12mm nylon sheet.
After swapping different parts from both cutting heads and trying everything we could think of we final found that if we put a worn out focusing tube in the head we could cut fine.

So same settings...new focus tube means barely piercing through and not cutting a straight line.

Same settings plus old focus tube means it pierces and cuts just fine.

At this stage we cannot tell you what the water line pressure is as there is no pressure gauge fitted but it cuts as per normal with the old focus tube fitted.

So anyone have any idea what is going on here ?
Thanks
Richard 

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rd400f


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Hi
Ok so no one is even going to have a stab at what the problem might have been ???disbelief

So let me tell you what we have found.
The Focusing tube was a Roctec 100 that had about 12hrs work on it. Using the same setting this focusing tube wouldn't cut anything. When we put brand new Roctec 100 focusing tube in and everything cut just fine...no settings were changed just the focusing tube.

The bad focusing tube was not blocked or worn but it just wouldn't let the stream cut.
Maybe the stream was losing power some how whilst moving through the bad focusing tube .
We couldn't hear or see any great difference in the stream being produced. But something must have been going wrong.Unfortunately I dropped the bad focusing tube and it shattered so we couldn't do any more testing.

So thats how we solved our problem...changing the focusing tube. Still would love the know if anyone else has a focusing tube go bad like this ?
Thanks
Richard 

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TFabian


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I am not very familiar with this cutting head, but if it has a mixing chamber, that may contribute greatly to this issue and how long the mixing tube is lasting. A new mixing tube will often cover up and issue like this or a blown orifice. The symptoms usually are that it will cut fine for a couple hours and then the mixing tube fails early. I have also seen garnet with a lot of dust in it cake up a bit and cause issues with the abrasive entraining properly into the mixing tube. If the top of the mixing tube and area below the orifice is clean when you disassemble, this is not the likely cause.

If there is no mixing chamber in the nozzle body, check to see if the nozzle body itself has wear. This is usually seen on the ID, opposite side of where the abrasive feed enters and is seen as divit created by the garnet coming in and causing wear. Good luck.

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rd400f


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Hi
Thanks for the reply.
Yes the KMT heads have replaceable mixing chamber.
But as we have two cutting heads we have been able to swap the bad nozzle between them thus eliminating all the other parts in the head.
It was all down to something about that particular nozzle. The bad nozzle showed no signs of wear that we could see.
But as I said I dropped the bloody thing on the ground and it shattered so we couldn't even send it back for the manufacture to check.
Guess we might never know why.
Thanks
Richard

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TFabian


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Another unsolved waterjet mystery!

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splashandburn


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I would suggest it could be mis alignnment of the tube.

This will normally stop cutting before the damage is visible at the bottom or top. I might check that you had not got carbide chip in the tube. that will cause just the problem you descibe as will the odd grain of oversize abrasive. Also as the guy on top said check you jewel it could have been a small chip off the stone.

a cheap usb microscpoe will be useful along with an ultrasonic cleaner, in fact these should be compusary items for all awj owners they will save you a small fortune on jewewls and keep your parts properly clean. Clean parts live longer on waterjets.

Regards,

Ian

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Just because it cuts
rd400f


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Hi

We have a Jewelers Lope and an Ultrasonic cleaner but to be honest I have not been able to say yes I can see some damage or buildup on the diamond.

Never having seen a bad diamond all we can compare our to are brand new ones and as I said I cant say I have ever seen a great difference between a diamond that has done say 400 hrs and a new one.

We have had other people say that we have most likely got some misalignment and that caused the focus tube to go bad.But the way I see it is that by the time you have added the garnet, just before the water stream enters the focus tube, the water stream has spread out wider than the ID of the focus tube.

Then the focus tube does its job and focuses the stream back down to the required stream width.

So how can a misaligned water stream "bounce" down the inside of the focus tube and lose some of its power because this is what some suppliers are telling us might be the problem.

Thanks

Richard 



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blucepeak


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Te probem is the ruby, or Concentricity is not good(Ruby and nozzle. Try to reinstall ruby and nozzle,make sure they are at the same concentricity.



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Roger xi

Teenking Waterjet
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