25% is slower than sh* I only use that when I am scared / un-vetted part or probing routine
50% is what I always use. and I have older DC motor and inch pitch ballscrew machines so its 400 ipm stated rapid max rate.
100% sometimes I feel that I should run 100% rapids. Especially when I am making a lot of the same part (i.e. greater than 10 of them?) I get thinking to myself as I'm standing there watching like the 3rd or so part get made, and I wonder if 100% rapids would help to make it faster. It almost always takes off a pretty useless reduction in cycle time.
here's whats wrong with 100% rapids. I usually save about 30 seconds on a program and I supose most of my programs have about 6 tool changes on average, maybe up to 10. it seems that no matter what program I'm running, I save 30 seconds off the cycle time for running 100% rapids. so basically on a 5 minute program it is 10% off the cycle time. does that matter at all? maybe it does if you're running so many parts that its a whole 10 hour day of running the same thing over and over.
For me I spend more time setting up and programming than making parts on most jobs. typical qty is 20 to 30 pieces per order including all line items so it may be 3 part types on that order. that accounts for about
0.5 of my orders... another
0.4 are qty 30 ea per part type (these are my fav orders), and
0.05 big orders like 500 pieces for very little money per piece, and
0.05 1 or 2 off crazy parts that cost like $2k ea. or even more
so maybe on the big volumes it matters? usually on those i run a whole bunch of mitee bites and the machine just doesnt rapid around much anyhow - actually even less because there are very few tool changes per part on a pallet of mitee bites and no reason to rapid around because the arrays are dense.
Why I see no point in running 100% rapids on my old fadal at 400 ipm:
(newer ones with even better rapids would be even more pointless I think)
1.) 30 seconds saved for running 100% vs. 50% per part on a 5 to 10 minute part with 5 or so tool changes.
2.) the spindle takes a long time to start and stop. when on 100% rapids a lot of the time my spindle isn't up to speed before it enters the cut, and for sure it is never off and stopped by the time the z axis is back to the tool changer for a tool change, so you end up just waiting anyhow on both ends as I have the setp wait for spindle speed parameter set on.
3.) the coolant is never on fast enough - due to this problem I program a 3400 millisecond which is like G4 P3400 or something like that after every tool change to allow time for the flood coolant to be flowing. therefore on 100% rapids i get to the part, then wait a long time.
4.) it only serves to heat up your machine's ways and make parts drift around tolerance wise
5.) it only adds wear and tare to the machine
there's just no point at all because everything else is slower than the rapids. not to mention that the tool changer is glacial.
i guess the point of all this *****ing is that 100% rapids never help, and i feel like it just takes life off of my machines. it pisses me right off that the machine cannot cycle faster - there should be ways to help move faster. any suggestions?
some things I have thought of so far:
- make the tool changer motor faster (i dont have servo turret or side mount)
- get the air to discharge faster into the slide on the tool change and put some buffer springs or something at each end so it will move faster in and out
- mess with the spindle drive's acceleration parameters - you see modern machines reverse in like 10 miliseconds its crazy fast. my fadals get to 5000 rpm in like 3 to 4 seconds on to steady speed, or steady speed to off.
- put a check valve on the coolant line so it cannot drain back to the sump when pump is off
- put a faster pump on the coolant line
also, i dont need a lesson in effecient programming, no g-code tricks or order of operations will speed up the processes I'm talking about above, unless its some kind of crazy servo gain g-code and i already have those written into my post