Waterjet End of Cut

[hutchndi]

Hi, newbie waterjet operator, also pretty new with g code.

I work running a pair of waterjet tables cutting some pretty thick stuff, and it goes pretty slow. The parts are either preprogrammed or I edit a standard shape from a library, and edit code if needed. The programs are on file and can be copied between folders for plasma and laser machines also, so things like speeds (F-codes?) and other application specific perameters are not in the files. These are loaded as seperate "SDP" files.

As these waterjets are running, I tend to have to do other duties around the shop and cant sit and wait until each part nears its end, at which point most of the operators slow things way down manually, so the drag at the bottom catchs up, fully cutting the peice before moving to the next. This requires full operator attention. Just slowing it down an inch or so before the end to be safe while your not available doesnt really work, because this lengthens the time lingering at the end of cut, and you are still shooting garnet into the stop point of the peice longer than you would at normal speed. After the peice is completely cut free from the plate, it can drop or move slightly and this method always leaves a scar. So you have to slow it way down, watch for the peice to cut free, then imediately stop the garnet flow manually.

Would it be possible to add an F code (again I am not sure that is correct) to slow down the at last 3/4 inch of cut, then again speed up again at the last 1/16 inch? I guess that would mean splitting the last motion block into three sections, but compared to the present method, no big deal. Or maybe use a G04 (delay timer?) code somehow for this?

If this helps, I run ESAB machines.

Thanks, Russ

[Switcher]

From what I read in your post, all your doing is manually turning the feed down by hand (correct)?

If that's the case, all your doing is changing the percentage, of the programmed feedrate.

You could (should) change the feedrate a few lines before the program ends (M17,M30). I'ts hard for anyone here to say just where to change the feed, without seeing the g-code your working with.

This is how I tweak my new programs (feed) at work.

1) Run the program & program the feed to what I think is appropriate (sounds like that has been done for you already)

2) Use the dial on the control panel to turn the percentage of the feed down, when needed (sounds like that's what your doing at the end of your program).

3) Make a note of what percentage I had to turn the dial on the control panel to, to get the desired feedrate.

4) Go to the g-code change my feedrate on the appropriate line.

5) Run the program again (new feedrate).


note

Example:

Feedrate programed at 100.0 , lets say I had to turn down the feedrate on the control panel to 30.0 to get what feedrate I wanted.

100%
-70%
_____
= 30%

So the new feedrate is "F30"

The important thing is to make a note of what you have to keep manually setting the feedrate percent to.



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[Switcher]

Make sure you watch the new code run, so you can stop the machine If needed.


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[hutchndi]

Thanks Switcher. The Sdp files are adjustable in feedrate percentage, but the manual states that an F code will over-ride the SDP file . So this would work, but I would not want to slow down the feed for the entire last leg of a part, it could be 100 inches. So the only option is to break it up right?

(LAST LEG OF 10" X 10" SQUARE, broken up so seperate feed rates could apply) full speed for 9", 30% speed for 7/8", full speed again till stop. The full speed at the end is needed to speed up the ending of the cutting cycle. I believe we use EIA.)

G01 X1.000 Y1.000
G01 X1.000 Y10.000
F30
G01 X1.000 Y10.875
F100
G01 X1.000 Y11.000
M71

Russ

[Switcher]

Your g-code sounds correct from what I've read, remember the feedrates I posted are only examples (100% & 30%).

Was the last feedrate active (before your new g-code) set at F100?

F100 is = to 100 inch per minute (it's not a percentage).

Double check and see what the last programmed feedrate was (before your new g-code).



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[hutchndi]

Well, I tried this, and the f codes were ignored. Reading the programming manual, I came across this (most examples given for plasma, but same programs are used on waterjet):

"F FEED RATE
Programmed Feedrate provides feedrate changes
during automatic program execution. "F" followed
by the feedrate in inches per minute will cause a
feedrate change upon execution of this block.
Operator override of feedrate is still functional.
EIA FORMAT: Fnnn
ESSI FORMAT: 39+nnn
The following program cuts a 10 x 10 inch square
with a 4 inch hole in the center. The hole is cut at
75 inches per minute, the square is cut at 100
inches per minute.
EXAMPLE
G91 Incremental Mode
G00 X5.0 Y-6.5 Rapid move to 1st pierce point
F75 Set Feed rate at 75 IPM
M65 Plasma On
G03 J-.25 Lead In
G03 J2.0 Cut Circle
G03 J.25 Lead Out
M66 Plasma Off
G00 X-5.5 Y6.5 Rapid move to 2nd pierce point
F100 Set Feed rate at 100 IPM
M65 Plasma On
G01 X10.5 Cut Square
Y-10.0 .
X-10.0 .
Y10.5 .
M66 Plasma Off

So maybe the f code has to be inserted when the machine is "down"? and cannot work to change speeds of a cut in progress?

[Switcher]

Most controls don't allow you to change the Feed value, while the machine is running, only the feed overide (percentage) on the control panel.

The way I make edits to g-code is, make my edit to the g-code (program not running).

Re-Save the program (after edits).

Re-Load the program so that the edits take, in the control.

Run the program.

---------------------------------------------------------------------

NOTE:
Most controls look way ahead of the actual line of code it is running.



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[hutchndi]

I believe I failed in trying to convey what I was attempting to do here Switcher. Yes, that is exactly how I save and use g-code too, I dont try to edit it as the program is running. My reference to "down time" was aimed at non-motion blocks in the program. The example given from the manual in my previous reply shows f-codes inserted in these areas, following a rapid move and before starting the initial or next cutting sequence.

So what I am really trying to figure out is if that is how the f-code must to be used, as in before starting a new cut. I see it utilized in this way, either before as in the code we use, or following the x,y coordinates of an initial motion block.

So in the simple rectangle I am trying to program with three speeds in the last leg, what I am seeing is that I would have to stop the cut at each point, add my f-code, restart the process, and then continue (G01) to my next point. (I of course am refering to writing and saving the program, not editing the code during process as I accidentily led you to believe earlier).

Russ

[Switcher]

The "F" (feedrate) on the control that I use (840D) can be programmed 2 ways.

1)

F100 G01 X1.000 Y1.000 G01 X1.000 Y10.000 F30 G01 X1.000 Y10.875 F100 G01 X1.000 Y11.000 M71

2)

N01 G01 X1.000 Y1.000 F100 N02 G01 X1.000 Y10.000 N03 G01 X1.000 Y10.875 F30 N04 G01 X1.000 Y11.000 F100 N05 M71

Both of the above examples will do the exact same thing when you run the program.

You should, (& I say should because all controls are not equal) be able to run both code examples.

You'll notice I didn't put an "F" on line N02 thats ok because it is picking up the last feedrate from the previous line "N01" so the feedrate for line N02 = "F100".

You could have a feedrate "F" on every line If you wanted.

Hope I'm helping.




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[hutchndi]

Thanks, thats what I needed to know. I was looking into the system constants, and there are a couple that may be set to ignore speeds in programs, while using speeds in the "cutting package". I will check with higher ups about this. It also appears that our machines are set to read F codes as IPM instead of percentage (F100 =100 inches per minute) according to the programming manual.

Russ

[Switcher]

The way most Controls work, when you program a Feedrate "F" is:


1) inch per minute

or

2) millimeter per minute

Sounds like your Control is setup for "inch per minute" (IPM), I work in metric because thats what my Control is setup to run (German Machine).

Thanks, thats what I needed to know. I was looking into the system constants, and there are a couple that may be set to ignore speeds in programs, while using speeds in the "cutting package". I will check with higher ups about this. It also appears that our machines are set to read F codes as IPM instead of percentage (F100 =100 inches per minute) according to the programming manual. Russ

When I referred to percentage, I was talking about the Feed overide dial on your control panel.

So, say you have a program that is running, & the Feedrate (F) is programmed at "F100" in the G-Code.

If you turn the Feed overide dial on your control panel, down to 70%, that would be the equivalent of programming the G-Code to "F70"

Hope I don't make things confusing



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