Re: Absolute vs Incremental 3D programming

Black Dragon wrote:
Seeing how we're not far from taking delivery of a machine with a
Fanuc 18i control for which we do not have a post processor which
means I'm in the process of tweaking a stock generic Fanuc post, I'm
wondering if there is speed advantage or otherwise using incremental
positioning vs absolute for 3D mold/die type work? I've never posted
3D tool paths in anything but absolute, but have done manual
programming in incremental.

If it's a wash, I'll be giving incremental a try anyway. In that case,
is there anything that might bite me in the ass that I should be
looking for while debugging a post?

1) As a MC user you'll want to set the NCI output to at least 7 decimal
places, 9 is better but not much.
2) Set the control to accept 5 decimal place input. Some of the newer
hardware will take up to 7 and if yours will, use it, and program in metric
units.
3) No arcs. Do everything point to point.
4) Turn on AI if you have it and HPCC off if you have that. I don't think
HPCC is avaliable on an 18i.
5) Don't mix modes but do add an absolute positioning sequence periodically.
IOW, add a G90 ind lift the tool once in a while. The A5 probably doesn't
need this if you bought the Nano option.
6) Don't use work coordinate offsets or tool length compensation in the
control. You can but it will defeat your purpose.
7) Don't leave your balls at home. You'll need them.

Mitsubishi used to have what was known as HS Mode III and if you have the
stones for it it was worth the effort.
The MPFR was 29 M/min - accurately, and many Japanese mold shops won't
program cavity work other than in incrimental.
See if your FANUC/FADAL has something similar.

Good luck.

--
John R. Carroll
Machining Solution Software, Inc.
Los Angeles San Francisco
www.machiningsolution.com


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