Sciencemadness Discussion Board

High pressure micro cutter.

dann2 - 17-10-2008 at 16:13

Hello,

Reading up on high pressure diesel injections systems I began to wonder could the system be used as a small cutter.
The pressure in some 'common rail' systems runs at 1600 bar (about 25000 psi). They have a diesel pump that pumps continously going to injectors that are opened by piezo actuators. I dont know the flow rate.
If you were to get a pump + injector as a cutting lance you should be able to cut some pretty hard materials in all sorts of ways. The cutting fluid would have to be diesel (messy).
It would be an extremly dangerous device and a mistake would have you needing some of your bits lopped off. (not a pleasent thought :o) Protection would be essential. The diesel would penetrate deep into flesh ,and bone too!
Pumps can be had in scrap yards or ebay for not too much.

What hardness of material could one tackle with this device.



Dann2

[Edited on 18-10-2008 by dann2]

12AX7 - 17-10-2008 at 18:23

I'm familiar with fuel systems up in the 1-2ksi range, but 25? Surely you misread PSI for bar?

Waterjets run around 10k's of PSI, and abrasive waterjets will just pretty well anything, including their nozzles, which are made from sapphire with good reason.

Tim

Xenoid - 17-10-2008 at 18:45

A quick "google" indicates engine manufacturers are now looking at pressures of;

2000 bar = 200MPa = 29000 psi :o

watson.fawkes - 18-10-2008 at 08:57

Quote:
Originally posted by dann2
Reading up on high pressure diesel injections systems I began to wonder could the system be used as a small cutter.
The pressure in some 'common rail' systems runs at 1600 bar (about 25000 psi). They have a diesel pump that pumps continously going to injectors that are opened by piezo actuators. I dont know the flow rate.
You're certainly going to be flow rate limited. You can estimate the flow rate by taking a presumed gas mileage at a particular speed. This is going to be in the 10-20 l/hr range. The limitation is going to be the length of an uninterrupted cut. You could get a longer cut with a larger pressure reservoir, at the cost of a longer start-up and recovery time.

dann2 - 22-12-2009 at 14:19

Some impressive stuff on water jet cutting at link:

http://www.waterjets.org/

Dann2

ChrisWhewell - 22-12-2009 at 14:24

Quote: Originally posted by 12AX7  
I'm familiar with fuel systems up in the 1-2ksi range, but 25? Surely you misread PSI for bar?

Waterjets run around 10k's of PSI, and abrasive waterjets will just pretty well anything, including their nozzles, which are made from sapphire with good reason.

Tim


Yep, would need to treat the surfaces at the injector nozzle somehow. I like firing things in a furnace. maybe a detatchable tip that is specially treated would be a good idea, plus using the right contours taking into account fluid dynamics and resonances. Could try various calculations to get close, and then tweak it from there. Lost wax casting might be a way to get prototypes.