Need Help!- Chatter getting out of control.

[patdawg114]

I am working nights and just recently was promoted to lead man. I have never been stuck with this before. We cut the first 9 or 10 parts with no problem. We're going back 10 1/4". It was turning 400 surface footage with a feedrate of .005. Boring out with a 2" devibe bar VNMG 432. Average of 5.1" diameter. Wall thickness averaging 1" thick. When i came to work this after noon the guys had trouble. The first part they cut came out right but after that it all went down hill. We tried to speed it up slow it down speed up the feed as muchas we could to achieve a 63 finish, but it seems like no matter what we do, it still chatters. We changed bars put a 2 1/2" devibe with a DNMG 431 and spun it as low as 200 surface footage and as much as 800 surface footage. I put 2 mighty magnets and an indicator magnet on the bar and wrapped it with rubber anti chatter strap. I mean i literally tried everything i could dream up. Any help would be appreciated.



Patrick Arnaud

[neilw20]

Gives us a picture of article in the machine please.
Material?

[Red Frog]

If it is'nt producing good parts tear it down and start all over. I would have to say your boring bar is off center or the spindle bearings are going. You may even try running an indicator down the length of the bar to make sure an idiot didn't crash it and cover it up. Did you have enough room for the boring bar at the end of the cut? Is there something external on the turret touching another component of the machine? Chip buildup? Do your jaws show wear? Try one solution at a time. If you try more than one remedy at a time, you will never know which remedy cured it.

[patdawg114]

thanks for the help but we think we know the problem. A while back they had a lot of trouble with chatter on the machine and they couldnt fix it no matter what they did. The haas place came and said that the wrong truck was on the machine. Well aparently the replacement they put is going bad already. Thanks for the help though.