[robmx57]

Hello all,
We are machining a very large cast iron timing cover, 175lbs. The material is grey iron and is around .350" thick in most places. We have tried cutting the part with a 5" 45 deg mitsubishi facemill which worked but would start chattering again after two pcs. We have tried a 5" 20 deg ingersol "Deca" face mill which would work sometimes and not others. We have tried a 6" 90 deg SP3 CBN facemill wich worked for a while but is now chattering again. I beleive there is a difference in hardness of the casting lots. I know we have tried almost all combonations of feeds and speeds for each tool as well. My question is: has anyone else had similar issues before? and if so, what did you do to remedy it? I have a hard time beleiving that no one makes a cutter out there that will be reliable enough not to chatter. We have been battling this issue for some time now and it is starting to get very discouraging. Any help or advice on this topic would be greatly appriciated!!!

Thanks,
Rob

[underthetire]

We have had good luck with the Sandvik facemill with adjustable pocket, but its $$$$.

[victorofga]

while I worked in machineshop, some larger cast iron we had to slow down the rpm and raise the feed..

sometime helped
it is acting like a ""bell""

you might also try to squeeze under some insulation foam and that might dampen the resonance..

but all my suggestion is indeed for geometry..

if casting removed too early from the mold , then it can hardening up just as much to makes a very hard time to mill...