[gtdinc]

When milling a 3-D part, I set a feed rate in my programming software (say F10). When the program runs in the Seiki mill, Fanuc 11 controller, it changes the feed rate all over the place, sometimes slowing down to F2.0. Does anyone know why this happens? Is there someway to turn this off? Do I need to change some parameter settings somewhere? Very frustrating1 Thanks for the hlep.

[FuddMcDee]

On the program check screen, does it show you a programmed vs. actual feedrate? If it is changing the actual and the programmed rate remains the same, I'd take a look at the feedrate override switch and related circuitry, maybe something is at fault there?
Also, try to program it into MDI mode, a simple X move at F10., see if it holds speed in MDI?

[txcncman]

Some machines also have a feed rate compensation feature for milling around radii and corners. Might check your machine manual for that and see if it can be turned on and off with a G-code or M-code.

[TheManWGTD]

When milling a 3-D part, I set a feed rate in my programming software (say F10). When the program runs in the Seiki mill, Fanuc 11 controller, it changes the feed rate all over the place, sometimes slowing down to F2.0. Does anyone know why this happens? Is there someway to turn this off? Do I need to change some parameter settings somewhere? Very frustrating1 Thanks for the hlep.

The problem is the bubble memory, it can't get the data out fast enough for your 3d profile. Try upgrading to a Semiconductor memory board, PM me if you need a source.

[mariojl]

it changes the feed rate all over the place, sometimes slowing down to F2.0..

So you're milling a 3D part, which it means that your program has a lot of very small moves in G01, some as little as 0.003”. The problem probably is that the control lacks of a “Look Ahead” function. So reading one block, execute it, then go to read the next block makes the machine to slow down that much. (I used to own a VMC with a Fanuc control). You may run a little test; reprogram the part changing the parameter that checks the tolerance of the surface, so it makes the moves to be much longer (10X), (makes the part look very faceted) and run this program. If your machine now runs faster than before, it proves my point. Sorry, there is no way to modify this action.
Kind regards
Mario

[FuddMcDee]

I've got a 3 block look ahead on both of the 11M's i run regularly, not saying it isnt a possibility though.

[mariojl]

The 3 block look ahead may be good for 2D contour or pocketing purposes where it have longer moves; but not enough for 3D, where typical moves are way too short. Gtdinc is complaining for slowing down the programmed F10 feed; I used to have several VMC Haas which has 200 blocks of look ahead, and while cutting aluminum blow mold 3D cavities, I ran them at F100 without noticing any slowing down. Set the screen to show the current block, you must see the blocks flying by. Really don’t know where the threshold for 3D is. Let me tell you my story, trying to improve, I replaced a Haas VF3 for a Okuma MC 4020 (great production machine) but on the same mould it took twice as much time as the Haas did; so in less than 6 months I switched again but to a HaasVM3 ( for me, the best moldmaker machine). Hope didn’t bored out you with all the talk.
Kind regards, Mario