Flow waterjet blowing out mixing tube

[MarineMachinist]

I cannot figure out why my machine keeps blowing out mixing tubes... Replaced 3 yesterday before I gave up in the interest of NOT wasting another $100! Please tell me why. . .

I am running a .030 tube with a .010 orifice, 80 HPA at 50K PSI.

Thanks for any input.

Brad

[JakeM]

I would check the abrasive mixing chamber and the inside of the cutting head for wear. I know when the mixing chamber on our omax heads is worn it chews through mixing tubes quite quickly. I would also make sure the orifice is lined up good with the mixing tube, if it miss aligned that could also cause your mixing tube wear.

[MarineMachinist]

Thanks Jake, I will check all that you suggested.

[OmaxTech]

It sounds like one of the following in likely order.

1 poor quality abrasive causing plugs in the mixing tube

2 leaking on off valve causing blockages in the mixing tube

3 faulty abrasive metering disc again causing tube blockage.

4 Try adjusting abrasive delay in the software to allow more time to clear abrasive and ensure all parts are clean and free of debris prior to inserting new nozzle.

4 Could also be carbide chips from the mating face on the nozzle body

[MarineMachinist]

It sounds like one of the following in likely order.

1 poor quality abrasive causing plugs in the mixing tube

2 leaking on off valve causing blockages in the mixing tube

3 faulty abrasive metering disc again causing tube blockage.

4 Try adjusting abrasive delay in the software to allow more time to clear abrasive and ensure all parts are clean and free of debris prior to inserting new nozzle.

4 Could also be carbide chips from the mating face on the nozzle body

It has been a while since we have changed a metering disc so I will check that. The garnett we are using is 80 HPA from Barton... Seems pretty good to me. I will run through the rest of your suggestions as well. We replaced the Mixing tube, orifice and cleaned the mixing body and have been good to go for the past couple of days. Fingers crossed that we fixed the problem. Thanks for your assistance.

[OmaxTech]

You can rule out the abrasive being the problem.

Barton is without doubt the best alluvial abrasive on the market. also the crushed rock HPX is the rolls royce of abrasives. It may be worth asking for a sample of Barton 85 for slightly smaller grain size.

It could still be leaking on off valve or metering disc.

I would still look at the abrasive delay timings too.

[amishmafia00]

i'm sure you figured this out by now but my guess would be a bad orifice.

[Signmaker]

What brand mixing nozzles are you using?

We had similar excessive wear problems, not with the nozzle itself but with the ruby just above it. We finally worked out that an entire batch of jewels were some el cheapo generic brand rather than the Swiss made ones we normally have.

With a Swiss ruby we can leave it in the chamber for weeks... with the el cheapo ones we were blowing through 3 per sheet cut.

[Waterjet user]

Does anyone have a process or solution to minimize rusting of mild steel while sheet is on water jet table during cutting and what to do with parts after you remove them to stop rusting.

[heavycnc]

This is a question for you guys with a waterjet. How deep is your tank and what pressure do you run it at? Is there a risk of you cutting the bottom of your tank?