NZ2000 multi turret thermal growth

[aaron p]

Ok guys, I have been givin the privelege to run a 1 year old NZ2000 dual spindle/turrett mill/turn center. Its a 8 axis basicly with complete live tooling and a 4' bar feeder from LNS. We run very very tight tollerance parts (+/-.0005 and tighter on bores) and locations. Parts are small and we drill some very tiny holes .01" and smaller on some parts. The problem we are having is that when I fire it up in the morning, I have to offset all of my turning tools approx .002" on tool wear. After about 3 hours of solid running, the machine finally settles and holds tollerances for the rest of the day. This is mostly on aluminum parts that were are having the issue with. Machine a lot of 2011 bar. Is this common or is it something due to coolant temp or is the base of the machine just growing from heat? The shop is climate controled and very very clean. Some of our orders are 1,000-4,000 parts at a time of the same item. Very nice machine other than that issue. Any ideas would be good. We have looked into a chiller system as well, just waiting on a quote.

[CNCRim]

.002-.003 is common, All machine have some kind of thermal difference when hot and cold. I used to work for a company, they bough all their machine in brand new and they doing the same thing. What we did was write a small warn up program for it and every morning we run it for about 15-25 mins depend on the weather, and it work out pretty good... we don't need to offset at all for a part that have +-.0015 sometime tigher.

[aaron p]

These grow for about 2 hours. I make gauge every part and have to keep on it. We start work at 7am, and by the time 10am or so comes around, I feel the machine has finally stabalized. I would think a $500K machine would be a little more solid.

[CNCRim]

Originally Posted by aaron p . I would think a $500K machine would be a little more solid.

From many years setup and operate machine I don't think expensive machine meaning small things can take out of the equation. $ only pay for the brand name, options, rigidity, power, quality and size, but mother nature can still has her role we can try control it but can't eliminate it.

[aaron p]

The other thing is that its only X axis dimensions that change. Diameters only.

[underthetire]

Well, It very well could be coolant heating up, Mori recommends a coolant chiller for tight work. Both turrets or just one? Might have lost some ballscrew stretch, Mori preloads screws for thermal change, but I wouldn't think it would be both X axis if that was the case. X axis always shows growth first because of the 2 to one ratio on that axis.

[aaron p]

both turrets. sub and main. they are looking into a chiller unit I think. We have high pressure coolant system on it now.

[underthetire]

Well, high pressure coolant will make things hotter for sure. Call all world machinery parts, they have chillers. Probably a lot cheaper, but it may be a more DIY solution for plumbing and electrical.

[hacdlux]

the simplest solution for long run parts with tight tolerances, dont stop!

we ran our nl 24/7 from june to september last year only shutting down for maintainence (500,1000 hours) never changed a tool or an offset.

aluminum is excelent once you get the chip control down. we see a small shift between morning and after noon with temperature change but tool wear is non existant.

16 hours a day unattended will make any boss happy

[aaron p]

The Mori reps came down, and they also ran thermal tests on the machine for 2-1/2 days. I think a chiller is in our near future. I have found that 2011-T3 is a little easier than 6061-T6 when it comes to long runs.

[hacdlux]

is your shop climate controlled 40 degree temperature swings can factor in to your thermal growth,

2000 series aluminum is nice its not as gummy as 6061, my biggest challenge is keeping stringer from wrapping up in the parts catcher and alarming out

[aaron p]

Well, the building does have A/C and heat, but the sorry ass's barely turn it on. I walked into a 60* room today. Multi-million dollar company, and they cant even turn on the damn heat. Cant pay me worth a **** either. There completely against using the CAPPS or MAPPS systems either, they want us to raw code all the parts. Must still be stuck in the 80s!

We had a problem with the last part we ran (6061) with stringers on the boring bars. The parts and I/Ds are fairly small, and my lead-man was saying the cycle time was too long, so he ramped it all up and broke the boring bar(smart guy). So we re-programed it with some dwells and lighter cuts and turned on the high pressure to blast the stringers off. Biggest problem I see on the sub side is when the turrett index's, its picking up stringers off the way covers and getting wrapped up in our roughing drill. The machine IMO needs much more space inside for chip evacuation. Mori must not hav realized that a high production machine is gonna produce ALOT of swarf and chips/stringers. We are using solid carbide in-house made boring bars that dont have a chip-breaker. 1/8"-3/8" I.C.